diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,46 @@
 
 ## [Unreleased]
 
+## [0.5.0.0] - 2026-10-02
+
+### Added
+
+- Log test suite commands.
+- `session.build`, `session.test`, and `session.eval` config sections, each
+  independently configuring the command used to build the project, run test
+  suites, and evaluate eval comments. See
+  [Configuring Tricorder] for a complete,
+  up-to-date description of these options.
+- `tricorder daemon info` subcommand showing daemon info. This information was
+  moved from `tricorder ui`.
+- Tricorder now supports running tests with regular `cabal test` or
+  `stack test`. Tricorder will automatically detect whether the tests are ran
+  in GHCi or through a regular `cabal/stack test` by inspecting the configured
+  `session.test.command_template`. You can force the output mode to use by
+  setting `session.test.output_mode`. See [Configuring Tricorder] for more
+  information.
+
+### Changed
+
+- Deprecate configuration options `session.command`, `session.targets` and
+  `session.test_targets` in favor of `session.build.command_template`,
+  `session.build.targets` and `session.test.targets`, respectively.
+- Tricorder now uses `brick` `3.0` for its TUI.
+
+### Fixed
+
+- Multi-package Stack projects were being resolved as single-package Stack
+  projects. (Thanks @marcosh!)
+- When Tricorder detects that the project is a Stack project, it now correctly
+  inspects `stack.yaml` for packages instead of assuming packages are listed in
+  `cabal.project`.
+
+### Removed
+
+- `tricorder ui` no longer has the "Daemon info" tab. This tab contains
+  information that is rarely necessary to have as accessible as in the TUI, so it
+  has been moved to a separate `tricorder daemon info` subcommand.
+
 ## [0.4.1.1] - 2026-09-21
 
 ### Fixed
@@ -226,3 +266,4 @@
   (fixes ghcid's crash-on-file-removal bug).
 
 [Features of Tricorder - Eval Comments]: ../docs/features-of-tricorder.md#eval-comments
+[Configuring Tricorder]: /docs/configuring-tricorder.md
diff --git a/src/Tricorder/Build.hs b/src/Tricorder/Build.hs
--- a/src/Tricorder/Build.hs
+++ b/src/Tricorder/Build.hs
@@ -15,7 +15,6 @@
 import GHC.Generics (Generically (..))
 
 import Tricorder.Build.Duration (Duration)
-import Tricorder.Daemon.DaemonInfo (DaemonInfo)
 import Tricorder.Session.TestTarget (TestTarget)
 
 import Tricorder.Build.EvalComment qualified as Eval
@@ -23,8 +22,7 @@
 
 
 data BuildState = BuildState
-    { daemonInfo :: DaemonInfo
-    , phase :: BuildPhase
+    { phase :: BuildPhase
     , buildId :: BuildId
     }
     deriving stock (Eq, Generic, Show)
diff --git a/src/Tricorder/CLI/App.hs b/src/Tricorder/CLI/App.hs
--- a/src/Tricorder/CLI/App.hs
+++ b/src/Tricorder/CLI/App.hs
@@ -8,7 +8,7 @@
 import Atelier.Effects.Exit (Exit)
 import Atelier.Effects.File (File)
 import Atelier.Effects.FileSystem (FileSystem)
-import Atelier.Effects.Input (Input)
+import Atelier.Effects.Input (Input, input)
 import Atelier.Effects.Log (Log)
 import Atelier.Effects.Posix.Daemons (Daemons)
 import Atelier.Effects.Process (Process)
@@ -21,8 +21,8 @@
 
 import Atelier.Effects.Console qualified as Console
 import Data.Text qualified as T
+import Tricorder.CLI.Command.Daemon qualified as DaemonCommand
 
-import Tricorder.Build (BuildState (..))
 import Tricorder.CLI.Arguments (Command (..), LogMode (..))
 import Tricorder.CLI.Daemon
     ( restartDaemon
@@ -31,7 +31,8 @@
     , waitForDaemon
     )
 import Tricorder.CLI.Operations
-    ( showEvalComments
+    ( showDaemonInfo
+    , showEvalComments
     , showLog
     , showSource
     , showStatus
@@ -40,10 +41,10 @@
 import Tricorder.CLI.UI (viewUi)
 import Tricorder.CLI.UI.Brick (Brick)
 import Tricorder.CLI.UI.BrickChan (BrickChan)
-import Tricorder.Daemon.DaemonInfo (DaemonInfo (..))
+import Tricorder.Daemon.DaemonInfo (DaemonInfo)
 import Tricorder.Runtime (LogPath (..), PidFile (..), SocketPath (..))
-import Tricorder.Session.Command (Repl)
-import Tricorder.Socket.Client (isDaemonRunning, queryStatus)
+import Tricorder.Session.Repl (Repl)
+import Tricorder.Socket.Client (isDaemonRunning)
 import Tricorder.Socket.UnixSocket (UnixSocket)
 import Tricorder.SourceLookup (ModuleSourceResult)
 import Tricorder.SourceLookup.GhcPkg (GhcPkg)
@@ -71,6 +72,7 @@
        , GhcPkg :> es
        , Hackage :> es
        , IOE :> es
+       , Input DaemonInfo :> es
        , Input Repl :> es
        , Log :> es
        , PackageStore :> es
@@ -124,18 +126,7 @@
                 else
                     showTests opts
         Log logMode -> do
-            running <- isDaemonRunning
-            logFile <-
-                if running
-                    then do
-                        SocketPath sp <- ask
-                        result <- queryStatus sp
-                        LogPath fallback <- ask
-                        pure $ case result of
-                            Right state -> state.daemonInfo.logFile
-                            Left _ -> fallback
-                    else
-                        asks @LogPath (.getLogPath)
+            logFile <- asks @LogPath (.getLogPath)
             case logMode of
                 ShowLog -> showLog logFile
                 ShowLogPath -> Console.putTextLn (toText logFile)
@@ -157,3 +148,6 @@
                 startDaemon
                 void waitForDaemon
             showEvalComments opts
+        Daemon (DaemonCommand.Info format) -> do
+            daemonInfo <- input
+            showDaemonInfo format daemonInfo
diff --git a/src/Tricorder/CLI/Arguments.hs b/src/Tricorder/CLI/Arguments.hs
--- a/src/Tricorder/CLI/Arguments.hs
+++ b/src/Tricorder/CLI/Arguments.hs
@@ -1,7 +1,6 @@
 module Tricorder.CLI.Arguments
     ( Command (..)
     , LogMode (..)
-    , OutputFormat (..)
     , StatusOptions (..)
     , TestOptions (..)
     , EvalCommentsOptions (..)
@@ -41,7 +40,6 @@
     , EvalCommentsOptions (..)
     , Force (..)
     , LogMode (..)
-    , OutputFormat (..)
     , StatusOptions (..)
     , TestOptions (..)
     , Verbosity (..)
@@ -49,6 +47,8 @@
     )
 import Tricorder.SourceLookup.SourceQuery (SourceQuery, parseSourceQuery)
 
+import Tricorder.CLI.Arguments.Daemon qualified as Daemon
+import Tricorder.CLI.Arguments.OutputFormat qualified as OutputFormat
 import Tricorder.Version qualified as Version
 
 
@@ -92,6 +92,7 @@
             <> command
                 "eval-comments"
                 (info evalCommentsParser (progDesc "Show eval comments from the latest build"))
+            <> command "daemon" (info (Daemon <$> Daemon.parser) (progDesc "Daemon sub-commands"))
         )
 
 
@@ -113,7 +114,7 @@
     Status
         <$> ( StatusOptions
                 <$> waitParser
-                <*> jsonFormatToggleParser
+                <*> OutputFormat.parser
                 <*> flag
                     Concise
                     Verbose
@@ -171,7 +172,7 @@
     EvalComments
         <$> ( EvalCommentsOptions
                 <$> waitParser
-                <*> jsonFormatToggleParser
+                <*> OutputFormat.parser
             )
 
 
@@ -182,16 +183,6 @@
         WaitForBuild
         ( long "wait"
             <> help "Block until the current build cycle completes"
-        )
-
-
-jsonFormatToggleParser :: Parser OutputFormat
-jsonFormatToggleParser =
-    flag
-        TextOutput
-        JsonOutput
-        ( long "json"
-            <> help "Output full build state as JSON"
         )
 
 
diff --git a/src/Tricorder/CLI/Arguments/Daemon.hs b/src/Tricorder/CLI/Arguments/Daemon.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/CLI/Arguments/Daemon.hs
@@ -0,0 +1,14 @@
+module Tricorder.CLI.Arguments.Daemon (parser) where
+
+import Options.Applicative (Parser, command, hsubparser, info, progDesc)
+import Tricorder.CLI.Command.Daemon (DaemonCommand (..))
+
+import Tricorder.CLI.Arguments.OutputFormat qualified as OutputFormat
+
+
+parser :: Parser DaemonCommand
+parser = hsubparser (command "info" (info infoParser (progDesc "Information about the daemon")))
+
+
+infoParser :: Parser DaemonCommand
+infoParser = Info <$> OutputFormat.parser
diff --git a/src/Tricorder/CLI/Arguments/OutputFormat.hs b/src/Tricorder/CLI/Arguments/OutputFormat.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/CLI/Arguments/OutputFormat.hs
@@ -0,0 +1,12 @@
+module Tricorder.CLI.Arguments.OutputFormat (parser) where
+
+import Options.Applicative (Parser, flag, help, long)
+import Tricorder.CLI.Command.OutputFormat (OutputFormat (..))
+
+
+parser :: Parser OutputFormat
+parser =
+    flag
+        TextOutput
+        JsonOutput
+        $ long "json" <> help "Output full build state as JSON"
diff --git a/src/Tricorder/CLI/Main.hs b/src/Tricorder/CLI/Main.hs
--- a/src/Tricorder/CLI/Main.hs
+++ b/src/Tricorder/CLI/Main.hs
@@ -33,12 +33,15 @@
 import Tricorder.Runtime (runLogPath, runPidFile, runProjectRoot, runRuntimeDir, runSocketPath)
 import Tricorder.Session (Session (..), loadSession)
 import Tricorder.Session.CabalFile (inputCabalFiles)
-import Tricorder.Session.Command (Command (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..))
+import Tricorder.Session.Stage.Build.Session (BuildSession (..))
 import Tricorder.Socket.UnixSocket (runUnixSocketIO)
 import Tricorder.SourceLookup.PackageId (PackageId)
 
 import Tricorder.CLI.App qualified as App
 import Tricorder.CLI.UI.Keys qualified as Keys
+import Tricorder.Daemon.DaemonInfo qualified as DaemonInfo
+import Tricorder.Session.StackProject qualified as StackProject
 import Tricorder.SourceLookup qualified as SourceLookup
 import Tricorder.SourceLookup.GhcPkg qualified as GhcPkg
 import Tricorder.SourceLookup.Hackage qualified as Hackage
@@ -75,15 +78,17 @@
         . runEnv
         . inputLoadedConfig
         . runLogNoOp
+        . StackProject.inputWithCache
         . inputCabalFiles
         . runInputEff loadSession
-        . runInputEff ((.command.repl) <$> input)
+        . runInputEff ((.buildSession.commandTemplate.repl) <$> input)
         . runReader @CacheConfig.Config def
         . Cache.runCacheTtl @ModuleName @PackageId
         . Cache.runCacheTtl @(PackageId, SourceQuery) @SourceLookup.ModuleSourceResult
         . GhcPkg.runGhcPkgIO
         . PackageStore.run
         . Hackage.run
+        . DaemonInfo.runInput
         $ do
             installTerminationHandler
             App.run
diff --git a/src/Tricorder/CLI/Operations.hs b/src/Tricorder/CLI/Operations.hs
--- a/src/Tricorder/CLI/Operations.hs
+++ b/src/Tricorder/CLI/Operations.hs
@@ -4,6 +4,7 @@
     , showStatus
     , showTests
     , showEvalComments
+    , showDaemonInfo
     )
 where
 
@@ -15,10 +16,11 @@
 import Atelier.Effects.FileSystem (FileSystem, doesFileExist, readFileLbs)
 import Atelier.Effects.Input (Input)
 import Atelier.Effects.Log (Log)
-import Data.Aeson (encode)
+import Data.Aeson (ToJSON, encode)
 import Data.Time.Format (defaultTimeLocale, formatTime)
 import Data.Time.LocalTime (utcToLocalTime)
 import Effectful.Reader.Static (Reader, ask)
+import Tricorder.CLI.Command.OutputFormat (OutputFormat (..))
 import Tricorder.SourceLookup.SourceQuery (ModuleName, SourceQuery)
 
 import Atelier.Effects.Console qualified as Console
@@ -31,7 +33,6 @@
 import Tricorder.Build.Test (Suites (..))
 import Tricorder.CLI.Arguments
     ( EvalCommentsOptions (..)
-    , OutputFormat (..)
     , StatusOptions (..)
     , TestOptions (..)
     , Verbosity (..)
@@ -42,9 +43,9 @@
     , formatDuration
     , renderSourceResults
     )
+import Tricorder.Daemon.DaemonInfo (DaemonInfo (..))
 import Tricorder.Runtime (SocketPath (..))
-import Tricorder.Session.Command (Repl)
-import Tricorder.Session.TestTarget (renderTestTarget)
+import Tricorder.Session.Repl (Repl)
 import Tricorder.Socket.Client (queryStatus, queryStatusWait)
 import Tricorder.Socket.UnixSocket (UnixSocket)
 import Tricorder.SourceLookup (ModuleSourceResult, lookupModuleSource)
@@ -58,6 +59,8 @@
 import Tricorder.Build.EvalComment qualified as Eval
 import Tricorder.Build.Test qualified as Test
 import Tricorder.Build.Test qualified as Tests
+import Tricorder.Session.Target qualified as Target
+import Tricorder.Session.TestTarget qualified as TestTarget
 
 
 -- | Print a build-command failure message and exit non-zero.
@@ -147,7 +150,7 @@
                 mapM_ (Console.putTextLn . ("  " <>)) (stripGhciNoise (T.lines c.output))
             _ -> pure ()
       where
-        t = renderTestTarget tgt
+        t = TestTarget.render tgt
 
     buildHasErrors r = any ((== SError) . (.severity)) r.diagnostics
     buildSummary tz r =
@@ -216,7 +219,7 @@
         | Map.null suites = Console.putStrLn "No test results."
         | Map.null filteredSuites = do
             Console.putStrLn "All passed."
-            mapM_ (Console.putTextLn . ("  " <>) . renderTestTarget) $ Map.keys suites
+            mapM_ (Console.putTextLn . ("  " <>) . TestTarget.render) $ Map.keys suites
         | otherwise = do
             mapM_ (uncurry printTestOutput) $ Map.toList filteredSuites
             when (any Test.isFailedRun filteredSuites) exitFailure
@@ -248,7 +251,7 @@
                 else
                     mapM_ (Console.putTextLn . ("  " <>)) (stripGhciNoise (lines c.output))
       where
-        t = renderTestTarget tgt <> "  "
+        t = TestTarget.render tgt <> "  "
 
     printFailedCase tc = do
         Console.putTextLn $ "  " <> tc.description
@@ -293,6 +296,23 @@
         JsonOutput -> displayJsonOutput result
 
 
+showDaemonInfo :: (Console :> es) => OutputFormat -> DaemonInfo -> Eff es ()
+showDaemonInfo format daemonInfo = case format of
+    TextOutput -> text
+    JsonOutput -> json
+  where
+    text = do
+        Console.putTextLn "Targets:"
+        for_ daemonInfo.targets \target ->
+            Console.putTextLn $ "- " <> Target.render target
+        Console.putTextLn "Watch directories:"
+        for_ daemonInfo.watchDirs \dir ->
+            Console.putTextLn $ "- " <> toText dir
+        Console.putTextLn $ "Socket file path: " <> toText daemonInfo.sockPath
+        Console.putTextLn $ "Log file path: " <> toText daemonInfo.logFile
+    json = putJson daemonInfo
+
+
 displayTextOutput
     :: ( Console :> es
        , Exit :> es
@@ -302,7 +322,7 @@
     Left err -> do
         Console.putTextLn $ "Error: " <> err
         exitFailure
-    Right (BuildState _ phase _) -> case phase of
+    Right (BuildState phase _) -> case phase of
         Build.Starting -> Console.putStrLn "Starting..."
         Build.Building _ _ -> Console.putStrLn "Building..."
         Build.PostBuilding _ postBuild -> txtEvalComments postBuild
@@ -357,7 +377,7 @@
     Left err -> do
         putJson $ Eval.Failed err
         exitFailure
-    Right (BuildState _ phase _) -> case phase of
+    Right (BuildState phase _) -> case phase of
         Build.Starting -> putJson Eval.Starting
         Build.Building _ _ -> putJson Eval.Building
         Build.Failed msg -> do
@@ -372,7 +392,10 @@
         Eval.Found comments
             | Eval.anyRunningComments comments -> putJson Eval.Evaluating
             | otherwise -> putJson $ Eval.Done comments
-    putJson = Console.putStrLn . toStrict . encode
+
+
+putJson :: (Console :> es, ToJSON a) => a -> Eff es ()
+putJson = Console.putStrLn . toStrict . encode
 
 
 displayPendingBuildStatus
diff --git a/src/Tricorder/CLI/UI/Keys.hs b/src/Tricorder/CLI/UI/Keys.hs
--- a/src/Tricorder/CLI/UI/Keys.hs
+++ b/src/Tricorder/CLI/UI/Keys.hs
@@ -77,8 +77,7 @@
 -- 'KeyEvent', update that list to match — @tagref check@ flags the dangling
 -- reference if this tag is renamed or dropped without touching the docs.
 data KeyEvent
-    = ToggleDaemonInfoView
-    | ToggleHelp
+    = ToggleHelp
     | CycleTestView
     | ToggleEvalComments
     | RestartDaemon
@@ -104,8 +103,7 @@
 keys :: KeyEvents KeyEvent
 keys =
     keyEvents
-        [ ("toggle daemon info", ToggleDaemonInfoView)
-        , ("toggle help", ToggleHelp)
+        [ ("toggle help", ToggleHelp)
         , ("cycle test view", CycleTestView)
         , ("toggle eval comments", ToggleEvalComments)
         , ("restart daemon", RestartDaemon)
@@ -118,8 +116,7 @@
 
 bindings :: [(KeyEvent, [Binding])]
 bindings =
-    [ (ToggleDaemonInfoView, [bind 'g'])
-    , (ToggleHelp, [bind 'h'])
+    [ (ToggleHelp, [bind 'h'])
     , (CycleTestView, [bind 't'])
     , (ToggleEvalComments, [bind 'e'])
     , (RestartDaemon, [bind 'R'])
@@ -181,14 +178,7 @@
     either (error . ("Invalid key dispatcher config: " <>) . stringify) id
         $ keyDispatcher
             cfg
-            [ onEvent ToggleDaemonInfoView "Toggle daemon info view" do
-                modify \s ->
-                    if currentRoute s == Route.DaemonInfo
-                        then
-                            navigate Route.Main s
-                        else
-                            navigate Route.DaemonInfo s
-            , onEvent ToggleHelp "Toggle help" do
+            [ onEvent ToggleHelp "Toggle help" do
                 modify \s ->
                     if currentRoute s == Route.Help
                         then
@@ -263,7 +253,6 @@
 keybindForRoute :: KeyConfig KeyEvent -> Route -> Maybe Binding
 keybindForRoute kc = \case
     Route.Main -> Nothing
-    Route.DaemonInfo -> firstActiveBinding kc ToggleDaemonInfoView
     Route.Help -> firstActiveBinding kc ToggleHelp
     Route.Tests -> firstActiveBinding kc CycleTestView
     Route.Evals -> firstActiveBinding kc ToggleEvalComments
diff --git a/src/Tricorder/CLI/UI/Route.hs b/src/Tricorder/CLI/UI/Route.hs
--- a/src/Tricorder/CLI/UI/Route.hs
+++ b/src/Tricorder/CLI/UI/Route.hs
@@ -8,7 +8,6 @@
 data Route
     = Main
     | Help
-    | DaemonInfo
     | Tests
     | Evals
     deriving stock (Bounded, Enum, Eq)
@@ -18,6 +17,5 @@
 name = \case
     Main -> "Dashboard"
     Help -> "Help"
-    DaemonInfo -> "Daemon info"
     Tests -> "Tests"
     Evals -> "Eval comments"
diff --git a/src/Tricorder/CLI/UI/View.hs b/src/Tricorder/CLI/UI/View.hs
--- a/src/Tricorder/CLI/UI/View.hs
+++ b/src/Tricorder/CLI/UI/View.hs
@@ -26,7 +26,6 @@
     , withVScrollBars
     )
 import Data.Time (UTCTime, defaultTimeLocale, formatTime, utcToLocalTime)
-import System.FilePath (isAbsolute)
 
 import Data.Map.Strict qualified as Map
 import Data.Text qualified as T
@@ -45,9 +44,7 @@
     , Viewports (..)
     , currentRoute
     )
-import Tricorder.Daemon.DaemonInfo (DaemonInfo (..))
-import Tricorder.Session.Target (Target, renderTarget)
-import Tricorder.Session.TestTarget (TestTarget, renderTestTarget)
+import Tricorder.Session.TestTarget (TestTarget)
 import Tricorder.TestOutput (stripGhciNoise)
 
 import Tricorder.Build qualified as Build
@@ -55,7 +52,7 @@
 import Tricorder.Build.Test qualified as Test
 import Tricorder.CLI.UI.Keys qualified as Keys
 import Tricorder.CLI.UI.Route qualified as Route
-import Tricorder.Version qualified as Version
+import Tricorder.Session.TestTarget qualified as TestTarget
 
 
 mkAttrMap :: State -> AttrMap
@@ -83,8 +80,6 @@
         , case currentRoute ws of
             Route.Help ->
                 viewHelp kc
-            Route.DaemonInfo ->
-                viewDaemonInfo ws
             Route.Tests ->
                 viewTests ws
             Route.Main ->
@@ -111,19 +106,12 @@
     keyBind = maybe "" showBinding $ keybindForRoute kc route
 
 
-viewDaemonInfo :: State -> Widget Viewports
-viewDaemonInfo ws =
-    withBuildState ws (viewExpandedDaemonInfo . (.daemonInfo))
-
-
 viewTests :: State -> Widget Viewports
-viewTests ws =
-    withBuildState ws (viewTestResultsPanel ws)
+viewTests ws = withBuildState ws (viewTestResultsPanel ws)
 
 
 viewEvals :: State -> Widget Viewports
-viewEvals ws =
-    withBuildState ws $ viewEvalCommentsPanel ws
+viewEvals ws = withBuildState ws $ viewEvalCommentsPanel ws
 
 
 viewMain :: State -> Widget Viewports
@@ -167,7 +155,6 @@
         TestFilterAll -> Just "Tests"
         TestFilterFailedOnly -> Just "Tests - Failed only"
     Route.Help -> Just "Help"
-    Route.DaemonInfo -> Just "Daemon info"
     Route.Main -> Nothing
     Route.Evals -> Just "Eval comments"
 
@@ -228,67 +215,6 @@
                     ]
 
 
-viewExpandedDaemonInfo :: DaemonInfo -> Widget n
-viewExpandedDaemonInfo di =
-    vBox
-        [ viewVersion
-        , viewTargets di.targets
-        , viewWatchDirs di.watchDirs
-        , viewSockPath di.sockPath
-        , viewLogFile di.logFile
-        ]
-
-
-viewVersion :: Widget n
-viewVersion =
-    hBoxSpaced
-        1
-        [ emphasis $ txt "Client version:"
-        , txt Version.gitHash
-        ]
-
-
-viewTargets :: [Target] -> Widget n
-viewTargets targets =
-    hBoxSpaced
-        1
-        [ emphasis $ txt "Targets:"
-        , if null targets
-            then
-                txt "(all)"
-            else
-                vBox $ (map (txt . renderTarget) targets)
-        ]
-
-
-viewLogFile :: FilePath -> Widget n
-viewLogFile p = hBoxSpaced 1 [emphasis $ txt "Log:", txt $ toText p]
-
-
-viewSockPath :: FilePath -> Widget n
-viewSockPath sockPath =
-    hBoxSpaced 1 [emphasis $ txt "Socket:", txt $ toText sockPath]
-
-
-viewWatchDirs :: [FilePath] -> Widget n
-viewWatchDirs watchDirs =
-    vBox
-        [ emphasis $ txt "Watching:"
-        , padLeft (Pad 2)
-            $ vBox
-            $ viewWatchDir <$> watchDirs
-        ]
-
-
-viewWatchDir :: FilePath -> Widget n
-viewWatchDir dir = hBox [txt "- ", txt $ toText displayDir]
-  where
-    displayDir
-        | isAbsolute dir = dir
-        | dir == "." = "./"
-        | otherwise = "./" <> dir
-
-
 viewBuildPhase :: TimeZone -> BuildPhase -> Widget Viewports
 viewBuildPhase tz = \case
     Build.Starting ->
@@ -320,7 +246,7 @@
 viewPendingTestTargets tgts =
     vBox
         . ([txt "Pending test suites:"] <>)
-        . fmap (subtle . txt . renderTestTarget)
+        . fmap (subtle . txt . TestTarget.render)
         $ tgts
 
 
@@ -404,7 +330,7 @@
 
 viewTestRun :: TestTarget -> Test.Suite -> Widget n
 viewTestRun tgt run =
-    hBox $ [txt $ renderTestTarget tgt, txt "  "] <> status
+    hBox $ [txt $ TestTarget.render tgt, txt "  "] <> status
   where
     status = case run of
         Test.SuiteRunning Nothing ->
@@ -459,7 +385,7 @@
 
 
 -- | Single-line build status with no scrollable diagnostics list, used as a
--- compact header when a secondary panel (test results, daemon info) is open.
+-- compact header when a secondary panel (test results) is open.
 viewBuildPhaseLine :: TimeZone -> BuildPhase -> Widget n
 viewBuildPhaseLine tz = \case
     Build.Starting ->
@@ -541,7 +467,7 @@
             , viewTestOutput tvf c
             ]
   where
-    t = renderTestTarget tgt
+    t = TestTarget.render tgt
 
 
 viewTestOutput :: TestFilter -> Test.SuiteCompletion -> Widget n
diff --git a/src/Tricorder/Daemon/Builder.hs b/src/Tricorder/Daemon/Builder.hs
--- a/src/Tricorder/Daemon/Builder.hs
+++ b/src/Tricorder/Daemon/Builder.hs
@@ -47,10 +47,11 @@
 import Tricorder.Daemon.GhciSession (GhciSession, LoadResult (..))
 import Tricorder.Daemon.GhciSession.GhciParser (resolveKnownTargets)
 import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.Command (Command)
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand)
 import Tricorder.Session.WatchDirs (WatchDirs)
 
 import Tricorder.Daemon.GhciSession qualified as GhciSession
+import Tricorder.Session.Stage qualified as Stage
 
 
 data Builder :: Effect where
@@ -87,7 +88,7 @@
        , Reader ProjectRoot :> es
        )
     => BuildId
-    -> Command
+    -> RenderedCommand 'Stage.Build
     -> WatchDirs
     -> (BuilderState -> NewLoadResult -> Eff (Builder : es) a)
     -> Eff es (Either SomeException a)
diff --git a/src/Tricorder/Daemon/Core.hs b/src/Tricorder/Daemon/Core.hs
--- a/src/Tricorder/Daemon/Core.hs
+++ b/src/Tricorder/Daemon/Core.hs
@@ -19,7 +19,6 @@
 import Effectful.State.Static.Shared (State)
 import Relude.Extra.Tuple (dup)
 import System.FilePath ((</>))
-import Text.Regex.TDFA.Pattern (showPattern)
 
 import Atelier.Effects.Conc qualified as Conc
 import Atelier.Effects.FileSystem qualified as FileSystem
@@ -28,7 +27,6 @@
 import Atelier.Effects.Publishing.Pub qualified as Pub
 import Atelier.Effects.Publishing.Sub qualified as Sub
 import Data.Map.Strict qualified as Map
-import Data.Text qualified as T
 import Effectful.Reader.Static qualified as Reader
 import Effectful.State.Static.Shared qualified as State
 
@@ -42,15 +40,8 @@
     , NewLoadResult
     , compileBuildResults
     )
-import Tricorder.Daemon.Dispatch
-    ( BuilderState (..)
-    , DispatchAction
-    , emptyBuilderState
-    )
-import Tricorder.Daemon.EvalCommentRunner
-    ( EvalCommentRunner
-    , findEvalCommentsInModules
-    )
+import Tricorder.Daemon.Dispatch (BuilderState (..), DispatchAction, emptyBuilderState)
+import Tricorder.Daemon.EvalCommentRunner (EvalCommentRunner, findEvalCommentsInModules)
 import Tricorder.Daemon.GhciSession (GhciSession)
 import Tricorder.Daemon.GhciSession.GhciParser
     ( LoadResult
@@ -62,14 +53,13 @@
 import Tricorder.Daemon.Watch (WatchedFile)
 import Tricorder.Runtime (ProjectRoot (..))
 import Tricorder.Session (Session (..))
-import Tricorder.Session.Command (Command (..), Repl)
 import Tricorder.Session.GenerateWithHpack (GenerateWithHpack (..))
 import Tricorder.Session.IdleTimeout (IdleTimeout)
-import Tricorder.Session.ReplBuildDir (ReplBuildDir (..))
-import Tricorder.Session.TestTarget (TestTarget, renderTestTarget)
+import Tricorder.Session.Repl (Repl)
+import Tricorder.Session.Stage.Build.Session (BuildSession (..))
+import Tricorder.Session.Stage.Test.Command (RenderedTestCommand (..))
+import Tricorder.Session.Stage.Test.Session (TestSession (..))
 import Tricorder.Session.TestTimeout (TestTimeout (..))
-import Tricorder.Session.WatchDirs (WatchDirs (..))
-import Tricorder.Session.WatchExclusionPatterns (WatchExclusionPatterns (..))
 import Tricorder.Waiters (Waiters)
 
 import Tricorder.Build qualified as Build
@@ -81,9 +71,11 @@
 import Tricorder.Daemon.Hpack qualified as Hpack
 import Tricorder.Daemon.TestRunner qualified as TestRunner
 import Tricorder.Daemon.Watch qualified as Watch
-import Tricorder.Session.Command qualified as Command
+import Tricorder.Session qualified as Session
+import Tricorder.Session.CommandTemplate qualified as Command
 import Tricorder.Session.Hooks qualified as Hooks
-import Tricorder.Session.Target qualified as Target
+import Tricorder.Session.Stage.Build.Command qualified as BuildCommand
+import Tricorder.Session.Stage.Test.Command qualified as TestCommand
 import Tricorder.Session.TestTarget qualified as TestTarget
 import Tricorder.Waiters qualified as Waiters
 
@@ -122,44 +114,88 @@
        , Waiters :> es
        )
     => Eff es Void
-main = runPubSub @ReloadSession
-    . runPubSub @WatchedFile
-    . runPubSub @CabalChangeDetected
-    . runPubSub @SourceChangeDetected
-    . runPubSub @RestartBuilder
-    . runPubSub @ReloadBuilder
-    $ Conc.restartableFork waitForReloadSession do
-        root <- Reader.ask
-        session <- input
-        logSession session
+main =
+    runPubSub @ReloadSession
+        . runPubSub @WatchedFile
+        . runPubSub @CabalChangeDetected
+        . runPubSub @SourceChangeDetected
+        . runPubSub @RestartBuilder
+        . runPubSub @ReloadBuilder
+        . Conc.restartableFork waitForReloadSession
+        $ do
+            Log.debug "Before session"
+            session <- input
+            Log.debug "After session"
+            withSession session
+  where
+    waitForReloadSession = Waiters.wait $ Sub.listenOnce_ @ReloadSession
 
-        State.put session.command.repl
-        State.put session.idleTimeout
-        Conc.fork_ $ watchConfigFile root
-        conditionallyWatchStackYaml root
 
-        Conc.fork_ $ Watch.files root session
-        Conc.fork_ $ Sub.listen_ Watch.publishChange
+withSession
+    :: ( Chan :> es
+       , Clock :> es
+       , Conc :> es
+       , Concurrent :> es
+       , Debounce FilePath :> es
+       , EvalCommentRunner :> es
+       , FileSystem :> es
+       , FileWatcher :> es
+       , GhciSession :> es
+       , Hpack :> es
+       , Input Session :> es
+       , Log :> es
+       , Process :> es
+       , Pub BuildPhase :> es
+       , Pub CabalChangeDetected :> es
+       , Pub ReloadBuilder :> es
+       , Pub ReloadSession :> es
+       , Pub RestartBuilder :> es
+       , Pub SourceChangeDetected :> es
+       , Pub WatchedFile :> es
+       , Reader ProjectRoot :> es
+       , State BuildId :> es
+       , State IdleTimeout :> es
+       , State Repl :> es
+       , Sub CabalChangeDetected :> es
+       , Sub ReloadBuilder :> es
+       , Sub RestartBuilder :> es
+       , Sub SourceChangeDetected :> es
+       , Sub WatchedFile :> es
+       , TestRunner :> es
+       , Waiters :> es
+       )
+    => Session -> Eff es Void
+withSession session = do
+    root <- Reader.ask
+    logSession session
 
-        Conc.fork_ $ Sub.listen_ \(CabalChangeDetected _ _) -> do
-            needsSessionReload <- shouldReloadSession session
-            if needsSessionReload
-                then
-                    Pub.publish ReloadSession
-                else
-                    Pub.publish RestartBuilder
+    State.put session.buildSession.commandTemplate.repl
+    State.put session.idleTimeout
+    Conc.fork_ $ watchConfigFile root
+    conditionallyWatchStackYaml root
 
-        Conc.fork_ $ Sub.listen_ \(SourceChangeDetected fp event) ->
-            Pub.publish $ ReloadBuilder fp event
+    Conc.fork_ $ Watch.files root session
+    Conc.fork_ $ Sub.listen_ Watch.publishChange
 
-        when session.generateWithHpack.getGenerateWithHpack do
-            void $ Conc.fork Hpack.main
+    Conc.fork_ $ Sub.listen_ \(CabalChangeDetected _ _) ->
+        ifM
+            (shouldReloadSession session)
+            (Pub.publish ReloadSession)
+            (Pub.publish RestartBuilder)
 
-        State.evalState emptyBuilderState $ withSession session
-  where
-    waitForReloadSession = Waiters.wait $ Sub.listenOnce_ @ReloadSession
+    Conc.fork_ $ Sub.listen_ \(SourceChangeDetected fp event) ->
+        Pub.publish $ ReloadBuilder fp event
 
+    when (coerce session.generateWithHpack)
+        $ void
+        $ Conc.fork Hpack.main
 
+    State.evalState emptyBuilderState do
+        Conc.restartableFork (Waiters.wait $ Sub.listenOnce_ @RestartBuilder) do
+            buildId <- State.state (\s -> (s, s + 1))
+            runBuilder buildId session
+
+
 shouldReloadSession :: (Input Session :> es) => Session -> Eff es Bool
 shouldReloadSession oldSession = do
     newSession <- input
@@ -194,34 +230,8 @@
             \_ _ -> Pub.publish RestartBuilder
 
 
--- | For a given session, handles controlling the build process itself,
--- restarting it as necessary.
-withSession
-    :: ( Clock :> es
-       , Conc :> es
-       , Concurrent :> es
-       , EvalCommentRunner :> es
-       , GhciSession :> es
-       , Log :> es
-       , Process :> es
-       , Pub BuildPhase :> es
-       , Reader ProjectRoot :> es
-       , State BuildId :> es
-       , State BuilderState :> es
-       , Sub ReloadBuilder :> es
-       , Sub RestartBuilder :> es
-       , TestRunner :> es
-       , Waiters :> es
-       )
-    => Session -> Eff es Void
-withSession session = do
-    Conc.restartableFork (Waiters.wait $ Sub.listenOnce_ @RestartBuilder) do
-        buildId <- State.state (\s -> (s, s + 1))
-        runSession buildId session
-
-
 -- | Starts the initial build with GHCi, and waits for source changes.
-runSession
+runBuilder
     :: ( Clock :> es
        , Conc :> es
        , Concurrent :> es
@@ -237,13 +247,13 @@
        , Waiters :> es
        )
     => BuildId -> Session -> Eff es ()
-runSession buildId session = do
+runBuilder buildId session = do
     Log.info $ "Starting session " <> show buildId.getBuildId
     Pub.publish Build.Starting
     whenJust (session.hooks.start >>= (.before)) Hooks.runHook
     startupError <- fmap (either id absurd)
-        $ Pub.map (Build.Building session.testTargets)
-        $ Builder.with buildId session.command session.watchDirs \_ initialLoad -> do
+        $ Pub.map (Build.Building session.testSession.targets)
+        $ Builder.with buildId buildCommand session.watchDirs \_ initialLoad -> do
             whenJust (session.hooks.start >>= (.after)) Hooks.runHook
             processPostBuild session $ Right initialLoad
             Log.debug "Waiting for reload"
@@ -263,6 +273,8 @@
                     $ waitForReload session event
 
     Pub.publish $ Build.Failed $ show startupError
+  where
+    buildCommand = BuildCommand.render session.buildSession.commandTemplate session.buildSession.targets
 
 
 -- | Handles source changes as they come, determining whether the source change
@@ -374,7 +386,7 @@
             let pendingComments =
                     sconcat $ (\(lm, ecs) -> toPending lm.relPath <$> ecs) <$> nonEmptyComments
             Pub.publish $ Eval.Found $ Eval.Comments pendingComments
-            evaluatedComments <- EvalCommentRunner.evaluateComments session.command.repl nonEmptyComments
+            evaluatedComments <- EvalCommentRunner.evaluateComments session.evalSession nonEmptyComments
             pure $ Eval.Found $ Eval.Comments evaluatedComments
   where
     toPending file comment =
@@ -392,12 +404,11 @@
        )
     => Session -> BuildResult -> Eff es Test.Suites
 runTests session buildResult
-    | hasTargets session.testTargets && noErrors buildResult.diagnostics =
+    | hasTargets session.testSession.targets && noErrors buildResult.diagnostics =
         runTestsForTargets
-            session.command
+            session.testSession
             session.testMemoryLimit
             session.testTimeout
-            session.testTargets
     | otherwise = pure mempty
   where
     hasTargets = not . null
@@ -409,31 +420,37 @@
        , Pub Test.Suites :> es
        , TestRunner :> es
        )
-    => Command
+    => TestSession
     -> Maybe ByteSize
     -> TestTimeout
-    -> [TestTarget]
     -> Eff es Test.Suites
-runTestsForTargets command memoryLimit testTimeout testTargets = do
+runTestsForTargets testSession memoryLimit testTimeout = do
     Pub.publish $ Test.Suites initial
-    Log.info $ "Running " <> show (length testTargets) <> " test suite(s)"
-    fmap Test.Suites . State.execState initial $ traverse_ go testTargets
+    Log.info $ "Running " <> show (length testSession.targets) <> " test suite(s)"
+    fmap Test.Suites . State.execState initial $ traverse_ go testSession.targets
   where
-    initial = Map.fromList $ (,Test.SuiteRunning Nothing) <$> testTargets
+    initial = Map.fromList $ (,Test.SuiteRunning Nothing) <$> testSession.targets
     go target = do
-        Log.info $ "Running tests: " <> renderTestTarget target
-        finishedSuite <-
-            TestRunner.runTestSuite
-                ( \suite -> do
-                    updated <- State.state $ dup . Map.insert target suite
-                    Pub.publish $ Test.Suites updated
-                )
-                memoryLimit
-                command.repl
-                testTimeout
-                target
+        Log.info $ "Running tests: " <> renderedTarget
+        let testCommand = TestCommand.render testSession memoryLimit target
+            publishProgress suite = do
+                updated <- State.state $ dup . Map.insert target suite
+                Pub.publish $ Test.Suites updated
+        Log.info
+            $ "Test suite "
+                <> renderedTarget
+                <> " command:\n"
+                <> show testCommand.command
+        finishedSuite <- TestRunner.runTestSuite publishProgress testTimeout testCommand
+        case finishedSuite of
+            Test.SuiteErrored (Test.SuiteError message) ->
+                Log.warn $ "Test suite " <> renderedTarget <> "failed: " <> message
+            _ ->
+                pure ()
         updated <- State.state $ dup . Map.insert target finishedSuite
         Pub.publish $ Test.Suites updated
+      where
+        renderedTarget = TestTarget.render target
 
 
 newLoadResultToBuildResult
@@ -452,25 +469,4 @@
 
 
 logSession :: (Log :> es) => Session -> Eff es ()
-logSession session =
-    Log.info
-        $ T.intercalate
-            "\n"
-            [ "Loaded session"
-            , "Command: " <> Command.render session.command
-            , "Targets:"
-            , showList Target.renderTarget session.targets
-            , "Test targets:"
-            , showList TestTarget.renderTestTarget session.testTargets
-            , "Watch dirs:"
-            , showList toText session.watchDirs.getWatchDirs
-            , "Watch exclusion patterns:"
-            , showList (toText . showPattern . fst) session.watchExclusionPatterns.getWatchExclusionPatterns
-            , "Repl build dir: " <> toText session.replBuildDir.getReplBuildDir
-            , -- TODO: Remove " seconds" when TestTimeout is converted to a proper time unit.
-              "Test timeout: " <> show session.testTimeout.getTestTimeout <> " seconds"
-            , "Test memory limit: " <> show session.testMemoryLimit
-            , "Generate with hpack: " <> show session.generateWithHpack.getGenerateWithHpack
-            ]
-  where
-    showList f = T.intercalate "\n" . fmap (("- " <>) . f)
+logSession = Log.info . (<> "\n") . Session.show
diff --git a/src/Tricorder/Daemon/DaemonInfo.hs b/src/Tricorder/Daemon/DaemonInfo.hs
--- a/src/Tricorder/Daemon/DaemonInfo.hs
+++ b/src/Tricorder/Daemon/DaemonInfo.hs
@@ -13,6 +13,7 @@
 
 import Tricorder.Runtime (LogPath (..), ProjectRoot (..), SocketPath (..))
 import Tricorder.Session (Session (..))
+import Tricorder.Session.Stage.Build.Session (BuildSession (..))
 import Tricorder.Session.Target (Target)
 import Tricorder.Session.WatchDirs (WatchDirs (..))
 
@@ -41,7 +42,7 @@
     LogPath logFile <- ask
     pure
         $ DaemonInfo
-            { targets = session.targets
+            { targets = session.buildSession.targets
             , watchDirs = map (makeRelative projectRoot) session.watchDirs.getWatchDirs
             , sockPath
             , logFile
diff --git a/src/Tricorder/Daemon/EvalCommentRunner.hs b/src/Tricorder/Daemon/EvalCommentRunner.hs
--- a/src/Tricorder/Daemon/EvalCommentRunner.hs
+++ b/src/Tricorder/Daemon/EvalCommentRunner.hs
@@ -32,9 +32,11 @@
 import Tricorder.Daemon.GhciSession.GhciParser (LoadedModule (..))
 import Tricorder.Daemon.GhciSession.GhciProcess (execGhci, withGhciProcess)
 import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.Command (Command (..), Repl)
+import Tricorder.Session.CommandTemplate (CommandTemplate)
 
 import Tricorder.Build.EvalComment qualified as Eval
+import Tricorder.Session.Stage qualified as Stage
+import Tricorder.Session.Stage.Eval.Command qualified as EvalCommand
 import Tricorder.Session.Target qualified as Target
 
 
@@ -42,7 +44,7 @@
     -- | Scan all loaded source files for eval comments and evaluate them, each
     -- in a fresh GHCi session started in that file's module context.
     EvaluateComments
-        :: Repl
+        :: CommandTemplate 'Stage.Eval
         -> NonEmpty (LoadedModule, NonEmpty Eval.Comment)
         -> EvalCommentRunner m (NonEmpty Eval.Evaluation)
     -- | Extract eval comments from provided source files. Returns a map of all
@@ -80,13 +82,9 @@
                         case Eval.findComments $ decodeUtf8Lenient bs of
                             [] -> []
                             x : xs -> [(lm, x :| xs)]
-        EvaluateComments repl moduleComments -> do
-            fmap sconcat $ for moduleComments \(lm, comments) -> do
-                runFileEvals
-                    repl
-                    lm.relPath
-                    lm.moduleName
-                    comments
+        EvaluateComments template moduleComments -> do
+            fmap sconcat $ for moduleComments \(lm, comments) ->
+                runFileEvals template lm.relPath lm.moduleName comments
 
 
 -- ---------------------------------------------------------------------------
@@ -108,23 +106,22 @@
        , Reader ProjectRoot :> es
        , Timeout :> es
        )
-    => Repl
+    => CommandTemplate 'Stage.Eval
     -> FilePath
     -- ^ Relative path to the source file (stored in results).
     -> Text
-    -- ^ Module name (e.g. @"Tricorder.Builder"@), used to load the module
-    -- in interpreted mode so that its full local scope is available.
     -> NonEmpty Eval.Comment
     -> Eff es (NonEmpty Eval.Evaluation)
-runFileEvals repl relPath moduleName comments = do
+runFileEvals template relPath moduleName comments = do
     ProjectRoot projectRoot <- ask
     let noProgress = \_ -> pure ()
         noSetup = \_ -> pure ()
         wrapForGhci expr
             | T.elem '\n' expr = ":{" <> "\n" <> expr <> "\n" <> ":}"
             | otherwise = expr
+        command = EvalCommand.render template [Target.Bare moduleName]
     sessionResult <- trySync
-        $ withGhciProcess def (Command repl [] [Target.Bare moduleName]) projectRoot noProgress noSetup \ghci _ -> do
+        $ withGhciProcess def command projectRoot noProgress noSetup \ghci _ -> do
             _ <- execGhci ghci (":m *" <> moduleName) noProgress
             for comments \comment -> do
                 outputResult <- trySync $ execGhci ghci (wrapForGhci comment.expression) noProgress
diff --git a/src/Tricorder/Daemon/GhciSession.hs b/src/Tricorder/Daemon/GhciSession.hs
--- a/src/Tricorder/Daemon/GhciSession.hs
+++ b/src/Tricorder/Daemon/GhciSession.hs
@@ -59,7 +59,8 @@
     , withGhciProcess
     )
 import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.Command (Command)
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand)
+import Tricorder.Session.Stage (Stage (..))
 
 
 data GhciSession :: Effect where
@@ -70,7 +71,7 @@
     WithGhciWith
         :: (BuildProgress -> m ())
         -- ^ Action to run when reporting progress
-        -> Command
+        -> RenderedCommand 'Build
         -> ProjectRoot
         -> (LoadResult -> Controls m -> m a)
         -> GhciSession m a
@@ -99,7 +100,7 @@
 
 withGhci
     :: (GhciSession :> es, Pub BuildProgress :> es)
-    => Command
+    => RenderedCommand 'Build
     -> ProjectRoot
     -> (LoadResult -> Controls (Eff es) -> Eff es a)
     -> Eff es a
diff --git a/src/Tricorder/Daemon/GhciSession/GhciProcess.hs b/src/Tricorder/Daemon/GhciSession/GhciProcess.hs
--- a/src/Tricorder/Daemon/GhciSession/GhciProcess.hs
+++ b/src/Tricorder/Daemon/GhciSession/GhciProcess.hs
@@ -2,6 +2,7 @@
     ( Config (..)
     , GhciProcess (..)
     , GhciProcessError (..)
+    , UnexpectedExit (..)
     , SessionState (..)
     , InterruptDecision (..)
     , decideInterrupt
@@ -59,9 +60,7 @@
     , stripAnsi
     , unattributedFailure
     )
-import Tricorder.Session.Command (Command (..))
-
-import Tricorder.Session.Command qualified as Command
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
 
 
 -- | Configuration for GHCi process management.
@@ -122,7 +121,7 @@
 -- | Errors that can occur during GHCi process management.
 data GhciProcessError
     = StartupTimeout
-    | UnexpectedExit Text (Maybe Text)
+    | UnexpectedExit UnexpectedExit
     | -- | The build command exited (or printed nothing parseable) before GHCi
       -- produced its version banner. The 'Text' is the captured stderr+stdout
       -- output so callers can surface a useful error (e.g. cabal's dependency
@@ -131,6 +130,13 @@
     deriving stock (Eq, Show)
 
 
+data UnexpectedExit = MkUnexpectedExit
+    { marker :: Text
+    , errorMessage :: Text
+    }
+    deriving stock (Eq, Show)
+
+
 instance Exception GhciProcessError
 
 
@@ -223,7 +229,7 @@
 withGhciProcess
     :: (Conc :> es, Concurrent :> es, File :> es, Log :> es, Process :> es, Timeout :> es)
     => Config
-    -> Command
+    -> RenderedCommand stage
     -> FilePath
     -> (GhciLoading -> Eff es ())
     -> (GhciProcess -> Eff es ())
@@ -240,8 +246,7 @@
             $ setStderr createPipe
             $ setWorkingDir dir
             $ shell
-            $ toString
-            $ Command.render cmd
+            $ toString cmd.getRenderedCommand
 
 
 -- | Execute a command in GHCi and return the combined stdout+stderr output
@@ -384,32 +389,31 @@
         case result of
             Left ex -> do
                 let accumulatedLines = T.intercalate "\n" $ toList acc
-                Log.err
-                    $ T.intercalate
-                        "\n"
-                        [ "Reached EOF before reading marker from GHCi."
-                        , "Was looking for marker '" <> marker <> "', but no such marker was found."
-                        , ""
-                        ]
-                        <> if T.null accumulatedLines
-                            then
-                                T.intercalate
-                                    "\n"
-                                    [ "GHCi returned no output before we reached what we believe is EOF."
-                                    , "Got the following exception when attempting to read from GHCi:"
-                                    , toText $ displayException ex
-                                    ]
-                            else
-                                T.intercalate
-                                    "\n"
-                                    [ "Accumulated output from GHCi so far:"
-                                    , accumulatedLines
-                                    ]
+                    errorMessage =
+                        T.intercalate
+                            "\n"
+                            [ "Reached EOF before reading marker from GHCi."
+                            , "Was looking for marker '" <> marker <> "', but no such marker was found."
+                            , ""
+                            ]
+                            <> if T.null accumulatedLines
+                                then
+                                    T.intercalate
+                                        "\n"
+                                        [ "GHCi returned no output before we reached what we believe is EOF."
+                                        , "Got the following exception when attempting to read from GHCi:"
+                                        , toText $ displayException ex
+                                        ]
+                                else
+                                    T.intercalate
+                                        "\n"
+                                        [ "Accumulated output from GHCi so far:"
+                                        , accumulatedLines
+                                        ]
+                Log.err errorMessage
                 throwIO
-                    $ UnexpectedExit marker
-                    $ if T.null accumulatedLines
-                        then Nothing
-                        else Just accumulatedLines
+                    $ UnexpectedExit
+                    $ MkUnexpectedExit {marker, errorMessage}
             Right line
                 | marker `T.isInfixOf` line -> pure $ toList acc
                 -- A stale marker from an interrupted command: drop it, keep going.
diff --git a/src/Tricorder/Daemon/Main.hs b/src/Tricorder/Daemon/Main.hs
--- a/src/Tricorder/Daemon/Main.hs
+++ b/src/Tricorder/Daemon/Main.hs
@@ -36,17 +36,18 @@
 import Tricorder.Session (inputSession)
 import Tricorder.Session.CabalFile (inputCabalFiles)
 import Tricorder.Session.IdleTimeout (IdleTimeout)
+import Tricorder.Session.Repl (Repl)
 import Tricorder.Socket.UnixSocket (runUnixSocketIO)
 import Tricorder.SourceLookup.GhcPkg (runGhcPkgIO)
 import Tricorder.SourceLookup.PackageId (PackageId)
 
 import Tricorder.Daemon.Core qualified as Core
-import Tricorder.Daemon.DaemonInfo qualified as DaemonInfo
 import Tricorder.Daemon.EvalCommentRunner qualified as EvalCommentRunner
 import Tricorder.Daemon.Hpack.Effect qualified as Hpack
 import Tricorder.Daemon.IdleTimer qualified as IdleTimer
 import Tricorder.Daemon.TestRunner qualified as TestRunner
-import Tricorder.Session.Command qualified as Repl
+import Tricorder.Session.Repl qualified as Repl
+import Tricorder.Session.StackProject qualified as StackProject
 import Tricorder.Socket.Server qualified as Server
 import Tricorder.SourceLookup qualified as SourceLookup
 import Tricorder.SourceLookup.Hackage qualified as Hackage
@@ -79,10 +80,10 @@
         . inputLoadedConfig
         . runLogging
         . runChan
+        . StackProject.inputWithCache
         . inputCabalFiles
         . inputSession
         . runReader @CacheConfig.Config def
-        . DaemonInfo.runInput
         . runCacheTtl @ModuleName @PackageId
         . runCacheTtl @(PackageId, SourceQuery) @SourceLookup.ModuleSourceResult
         . runProcessIO
@@ -92,7 +93,7 @@
         . evalState (BuildId 1)
         . Input.fromState @BuildId
         . evalState Repl.Unknown
-        . Input.fromState @Repl.Repl
+        . Input.fromState @Repl
         . evalState @IdleTimeout def
         . Input.fromState @IdleTimeout
         . IdleTimer.quitOnTimeout
diff --git a/src/Tricorder/Daemon/TestRunner.hs b/src/Tricorder/Daemon/TestRunner.hs
--- a/src/Tricorder/Daemon/TestRunner.hs
+++ b/src/Tricorder/Daemon/TestRunner.hs
@@ -19,36 +19,56 @@
 import Atelier.Effects.Conc (Conc)
 import Atelier.Effects.File (File)
 import Atelier.Effects.Log (Log)
-import Atelier.Effects.Process (Process)
+import Atelier.Effects.Process
+    ( Process
+    , createPipe
+    , getStderr
+    , getStdin
+    , getStdout
+    , setStderr
+    , setStdin
+    , setStdout
+    , setWorkingDir
+    , shell
+    )
 import Atelier.Effects.Timeout (Timeout, timeout)
+import Control.Concurrent.STM (modifyTVar')
 import Control.Exception (throwIO)
 import Data.Default (def)
+import Data.Sequence ((|>))
 import Data.Time.Units (Second)
 import Effectful (Effect, IOE, Limit (..), Persistence (..), UnliftStrategy (ConcUnlift))
 import Effectful.Concurrent (Concurrent)
+import Effectful.Concurrent.STM (atomically, newTVarIO, readTVarIO)
 import Effectful.Dispatch.Dynamic (interpretWith, localUnlift, reinterpret_)
 import Effectful.Exception (trySync)
 import Effectful.Reader.Static (Reader, ask)
 import Effectful.State.Static.Shared (State, evalState, get, put)
 import Effectful.TH (makeEffect)
+import System.Exit (ExitCode (..))
 
-import Atelier.Effects.Log qualified as Log
+import Atelier.Effects.Conc qualified as Conc
+import Atelier.Effects.File qualified as File
+import Atelier.Effects.Process qualified as Process
 import Data.List qualified as List
 import Data.Text qualified as T
 
-import Tricorder.Build.ByteSize (ByteSize)
-import Tricorder.Daemon.GhciSession.GhciParser (GhciLoading (..))
+import Tricorder.Daemon.GhciSession.GhciParser (GhciLoading (..), parseProgressLine)
 import Tricorder.Daemon.GhciSession.GhciProcess
-    ( execGhci
+    ( GhciProcessError (..)
+    , UnexpectedExit (..)
+    , execGhci
     , withGhciProcess
     )
 import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.Command (Command (..), Repl (..))
-import Tricorder.Session.TestTarget (TestTarget, getTestTarget, renderTestTarget)
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.Stage (Stage (..))
+import Tricorder.Session.Stage.Test.Command (RenderedTestCommand (..))
+import Tricorder.Session.Stage.Test.Config (OutputMode (..))
+import Tricorder.Session.Stage.Test.Session (ResolvedTestOptions (..))
 import Tricorder.Session.TestTimeout (TestTimeout (..))
 import Tricorder.TestOutput (parseHspecDuration, parseHspecOutput)
 
-import Tricorder.Build.ByteSize qualified as ByteSize
 import Tricorder.Build.Test qualified as Test
 
 
@@ -58,11 +78,8 @@
     RunTestSuite
         :: (Test.Suite -> m ())
         -- ^ Handler for test run progress
-        -> Maybe ByteSize
-        -- ^ Memory limit for test suite
-        -> Repl
         -> TestTimeout
-        -> TestTarget
+        -> RenderedTestCommand
         -> TestRunner m Test.Suite
 
 
@@ -84,86 +101,161 @@
     => Eff (TestRunner : es) a -> Eff es a
 run act = do
     interpretWith act \env -> \case
-        RunTestSuite progressHandler mMemoryLimit repl testTimeout target ->
+        RunTestSuite progressHandler testTimeout cmd ->
             localUnlift env (ConcUnlift Persistent Unlimited) \unlift -> do
                 let onProgress = unlift . progressHandler . loadingToProgress
-                    noProgress _ = pure ()
-                    noReady _ = pure ()
-                    memoryLimitArg =
-                        maybe
-                            []
-                            ( \limit ->
-                                let
-                                    stack =
-                                        [ "--ghc-options"
-                                        , "+RTS -M"
-                                            <> ByteSize.toRTSSize limit
-                                            <> " -RTS"
-                                        ]
-                                    cabal =
-                                        [ "--repl-options"
-                                        , "+RTS -M"
-                                            <> ByteSize.toRTSSize limit
-                                            <> " -RTS"
-                                        ]
-                                in
-                                    case repl of
-                                        Stack -> stack
-                                        StackMulti -> stack
-                                        Cabal -> cabal
-                                        Unknown -> cabal
-                            )
-                            mMemoryLimit
-                ProjectRoot projectRoot <- ask
-                result <- trySync
-                    $ withGhciProcess
-                        def
-                        (Command repl memoryLimitArg [getTestTarget target])
-                        projectRoot
-                        onProgress
-                        noReady
-                        \ghci _ ->
-                            case testTimeout of
-                                TestTimeout secs | secs <= 0 -> Right <$> execGhci ghci ":main" noProgress
-                                TestTimeout secs ->
-                                    let duration = fromIntegral secs :: Second
-                                    in  maybeToRight secs
-                                            <$> timeout duration (execGhci ghci ":main" noProgress)
-                case result of
-                    Left ex ->
-                        pure
-                            $ Test.SuiteErrored
-                            $ Test.SuiteError {message = show ex}
-                    Right (Left secs) -> do
-                        Log.warn
-                            $ mconcat
-                                [ "Test suite "
-                                , renderTestTarget target
-                                , " timed out after "
-                                , show secs
-                                , "s"
-                                ]
-                        pure
-                            $ Test.SuiteErrored
-                            $ Test.SuiteError
-                                { message = "Test suite timed out after " <> show secs <> "s"
-                                }
-                    Right (Right mainLines) ->
-                        pure
-                            $ let output = T.unlines mainLines
-                              in  case detectOutcome output of
-                                    GhciCrashed msg ->
-                                        Test.SuiteErrored $ Test.SuiteError {message = msg}
-                                    outcome ->
-                                        Test.SuiteCompleted
-                                            $ Test.SuiteCompletion
-                                                { passed = outcome == GhciPassed
-                                                , output
-                                                , testCases = parseHspecOutput output
-                                                , duration = parseHspecDuration output
-                                                }
+                case cmd.options.outputMode of
+                    ReplOutput -> runTestSuiteWithGHCi onProgress testTimeout cmd.command
+                    StdoutOutput -> runTestSuiteWithStdout onProgress testTimeout cmd.command
 
 
+runTestSuiteWithStdout
+    :: ( Conc :> es
+       , Concurrent :> es
+       , File :> es
+       , Process :> es
+       , Reader ProjectRoot :> es
+       , Timeout :> es
+       )
+    => (GhciLoading -> Eff es ())
+    -> TestTimeout
+    -> RenderedCommand 'Test
+    -> Eff es Test.Suite
+runTestSuiteWithStdout onProgress testTimeout cmd = do
+    ProjectRoot projectRoot <- ask
+    -- Lines from both streams, in the order they arrived.
+    outputVar <- newTVarIO (mempty :: Seq Text)
+    let processConfig =
+            setStdin createPipe
+                $ setStdout createPipe
+                $ setStderr createPipe
+                $ setWorkingDir projectRoot
+                $ shell
+                $ toString cmd.getRenderedCommand
+
+        drain h =
+            unlessM (File.hIsEOF h) do
+                line <- File.hGetLine h
+                atomically $ modifyTVar' outputVar (|> line)
+                traverse_ onProgress (parseProgressLine line)
+                drain h
+
+        runToCompletion p = do
+            -- The suite gets no input; close stdin so it sees EOF if it reads.
+            File.hClose (getStdin p)
+            Conc.scoped do
+                stdoutThread <- Conc.fork $ drain (getStdout p)
+                stderrThread <- Conc.fork $ drain (getStderr p)
+                Conc.await stdoutThread
+                Conc.await stderrThread
+            Process.waitExitCode p
+
+    result <- trySync
+        $ Process.withProcessGroup processConfig \p ->
+            case testTimeout of
+                TestTimeout secs | secs <= 0 -> Right <$> runToCompletion p
+                TestTimeout secs ->
+                    let duration = fromIntegral secs :: Second
+                    in  maybeToRight secs <$> timeout duration (runToCompletion p)
+    output <- T.unlines . toList <$> readTVarIO outputVar
+    let completed passed =
+            Test.SuiteCompleted
+                $ Test.SuiteCompletion
+                    { passed
+                    , output
+                    , testCases = parseHspecOutput output
+                    , duration = parseHspecDuration output
+                    }
+    pure $ case result of
+        Left ex ->
+            Test.SuiteErrored
+                $ Test.SuiteError
+                    { message = "Test suite failed to run:\n" <> show ex
+                    }
+        Right (Left secs) ->
+            Test.SuiteErrored
+                $ Test.SuiteError
+                    { message = "Test suite timed out after " <> show secs <> "s"
+                    }
+        Right (Right ExitSuccess) -> completed True
+        Right (Right (ExitFailure _)) -> case detectOutcome output of
+            GhciCrashed msg -> Test.SuiteErrored $ Test.SuiteError {message = msg}
+            _ -> completed False
+
+
+runTestSuiteWithGHCi
+    :: ( Conc :> es
+       , Concurrent :> es
+       , File :> es
+       , Log :> es
+       , Process :> es
+       , Reader ProjectRoot :> es
+       , Timeout :> es
+       )
+    => (GhciLoading -> Eff es ())
+    -> TestTimeout
+    -> RenderedCommand 'Test
+    -> Eff es Test.Suite
+runTestSuiteWithGHCi onProgress testTimeout cmd = do
+    ProjectRoot projectRoot <- ask
+    result <- trySync
+        $ withGhciProcess
+            def
+            cmd
+            projectRoot
+            onProgress
+            noReady
+            \ghci _ ->
+                case testTimeout of
+                    TestTimeout secs | secs <= 0 -> Right <$> execGhci ghci ":main" noProgress
+                    TestTimeout secs ->
+                        let duration = fromIntegral secs :: Second
+                        in  maybeToRight secs
+                                <$> timeout duration (execGhci ghci ":main" noProgress)
+    case result of
+        Left ex -> case fromException ex of
+            Just (e :: GhciProcessError) -> case e of
+                UnexpectedExit (MkUnexpectedExit marker msg) ->
+                    pure
+                        $ Test.SuiteErrored
+                        $ Test.SuiteError
+                            { message = "Test suite failed while waiting for marker (" <> marker <> "):\n" <> msg
+                            }
+                StartupTimeout -> pure $ Test.SuiteErrored $ Test.SuiteError "Test suite timed out before it could finish"
+                StartupFailed msg ->
+                    pure
+                        $ Test.SuiteErrored
+                        $ Test.SuiteError
+                        $ "Test suite failed on startup, before Tricorder could start running the test suite itself:\n" <> msg
+            Nothing ->
+                pure
+                    $ Test.SuiteErrored
+                    $ Test.SuiteError {message = show ex}
+        Right (Left secs) -> do
+            pure
+                $ Test.SuiteErrored
+                $ Test.SuiteError
+                    { message = "Test suite timed out after " <> show secs <> "s"
+                    }
+        Right (Right mainLines) ->
+            pure
+                $ let output = T.unlines mainLines
+                  in  case detectOutcome output of
+                        GhciCrashed msg ->
+                            Test.SuiteErrored $ Test.SuiteError {message = msg}
+                        outcome ->
+                            Test.SuiteCompleted
+                                $ Test.SuiteCompletion
+                                    { passed = outcome == GhciPassed
+                                    , output
+                                    , testCases = parseHspecOutput output
+                                    , duration = parseHspecDuration output
+                                    }
+  where
+    noReady _ = pure ()
+    noProgress _ = pure ()
+
+
 -- | Scripted interpreter for testing.
 --
 -- Each call to 'runTestSuite' pops the next result from the pre-loaded list.
@@ -177,7 +269,7 @@
 runScripted results =
     reinterpret_
         (evalState results)
-        (\(RunTestSuite _ _ _ _ _) -> popResult)
+        (\(RunTestSuite _ _ _) -> popResult)
   where
     popResult :: Eff (State [Either SomeException Test.Suite] : es) Test.Suite
     popResult =
diff --git a/src/Tricorder/Session.hs b/src/Tricorder/Session.hs
--- a/src/Tricorder/Session.hs
+++ b/src/Tricorder/Session.hs
@@ -2,6 +2,7 @@
     ( Session (..)
     , loadSession
     , inputSession
+    , show
     )
 where
 
@@ -11,35 +12,54 @@
 import Atelier.Effects.Log (Log)
 import Data.Default (Default (..))
 import Effectful.Reader.Static (Reader, ask)
+import Text.Regex.TDFA.Pattern (showPattern)
+import Prelude hiding (show)
 
 import Atelier.Effects.Log qualified as Log
 import Data.Text qualified as T
+import Prelude qualified as P
 
 import Tricorder.Build.ByteSize (ByteSize)
 import Tricorder.Runtime (ProjectRoot (..))
 import Tricorder.Session.CabalFile (CabalFile)
-import Tricorder.Session.Command (Command (..), resolveCommand)
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate
+    ( CommandTemplate (..)
+    , hasPlaceholder
+    , targetPlaceholder
+    )
 import Tricorder.Session.Config (Config (..))
 import Tricorder.Session.GenerateWithHpack (GenerateWithHpack (..))
 import Tricorder.Session.Hooks (Hooks)
 import Tricorder.Session.IdleTimeout (IdleTimeout (..))
+import Tricorder.Session.Repl (resolveRepl)
 import Tricorder.Session.ReplBuildDir (ReplBuildDir (..))
-import Tricorder.Session.Target (Target, definesCustomPrelude, resolveTargets)
-import Tricorder.Session.TestTarget (TestTarget, resolveTestTargets)
+import Tricorder.Session.Stage.Build.Session (BuildSession (..))
+import Tricorder.Session.Stage.Test.Config (TestConfig (..))
+import Tricorder.Session.Stage.Test.Session (TestSession (..))
+import Tricorder.Session.Target (definesCustomPrelude)
+import Tricorder.Session.TestTarget (getTestTarget)
 import Tricorder.Session.TestTimeout (TestTimeout (..))
-import Tricorder.Session.WatchDirs (WatchDirs (..), resolveWatchDirs)
+import Tricorder.Session.Util (indent, showList)
+import Tricorder.Session.WatchDirs (WatchDirs (..))
 import Tricorder.Session.WatchExclusionPatterns
     ( WatchExclusionPatterns (..)
     , resolveWatchExclusionPatterns
     )
 
 import Tricorder.Build.ByteSize qualified as ByteSize
+import Tricorder.Session.Stage qualified as Stage
+import Tricorder.Session.Stage.Build.Session qualified as BuildSession
+import Tricorder.Session.Stage.Eval.Command qualified as EvalCommand
+import Tricorder.Session.Stage.Eval.Session qualified as EvalSession
+import Tricorder.Session.Stage.Test.Session qualified as TestSession
+import Tricorder.Session.WatchDirs qualified as WatchDirs
 
 
 data Session = Session
-    { command :: Command
-    , targets :: [Target]
-    , testTargets :: [TestTarget]
+    { buildSession :: BuildSession
+    , testSession :: TestSession
+    , evalSession :: CommandTemplate 'Stage.Eval
     , testMemoryLimit :: Maybe ByteSize
     , watchDirs :: WatchDirs
     , watchExclusionPatterns :: WatchExclusionPatterns
@@ -55,9 +75,9 @@
 instance Default Session where
     def =
         Session
-            { command = def
-            , targets = []
-            , testTargets = []
+            { buildSession = def
+            , testSession = def
+            , evalSession = def
             , testMemoryLimit = Nothing
             , watchDirs = def
             , watchExclusionPatterns = def
@@ -80,14 +100,16 @@
 loadSession = do
     projectRoot <- ask @ProjectRoot
     loadedCfg <- input
+    Log.debug "Got config file"
     projectFiles <- input
+    Log.debug "Got project files"
 
     let cfgFile = extractConfig @"session" @Config loadedCfg
-        effectiveTargets = resolveTargets projectFiles cfgFile.targets
-        testTargets = resolveTestTargets cfgFile effectiveTargets
-        watchDirs = resolveWatchDirs projectRoot projectFiles cfgFile effectiveTargets
         hooks = fromMaybe def cfgFile.hooks
 
+    warnDeprecatedConfig cfgFile
+    Log.debug "Warned about deprecated config stuff"
+
     testMemoryLimit <- case cfgFile.testMemoryLimit of
         Nothing -> pure Nothing
         Just limit -> case ByteSize.fromText limit of
@@ -110,6 +132,13 @@
                 pure $ WatchExclusionPatterns []
             Right pts -> pure pts
 
+    repl <- resolveRepl projectRoot
+    buildSession <- BuildSession.resolve cfgFile repl projectFiles
+    let testSession = TestSession.resolve repl buildSession.targets cfgFile
+        evalSession = EvalCommand.resolve repl cfgFile
+        effectiveTargets = buildSession.targets <> (getTestTarget <$> testSession.targets)
+        watchDirs = WatchDirs.resolve projectRoot projectFiles cfgFile effectiveTargets
+
     when (not (null effectiveTargets) && all (definesCustomPrelude projectFiles) effectiveTargets)
         $ Log.warn
             "Every resolved target exposes a custom Prelude module. GHCi may \
@@ -118,16 +147,27 @@
             \not define its own Prelude, or set an explicit command in your \
             \tricorder configuration."
 
-    command <- resolveCommand projectRoot cfgFile effectiveTargets testTargets
+    warnMissingTargetPlaceholder "test" cfgFile.test.commandConfig.commandTemplate
+    warnMissingTargetPlaceholder "eval" cfgFile.eval.commandTemplate
 
+    warnIgnoredextraAutoArguments
+        "build"
+        (cfgFile.build.commandTemplate <|> cfgFile.command)
+        cfgFile.build.extraAutoArguments
+    warnIgnoredextraAutoArguments
+        "test"
+        cfgFile.test.commandConfig.commandTemplate
+        cfgFile.test.commandConfig.extraAutoArguments
+    warnIgnoredextraAutoArguments "eval" cfgFile.eval.commandTemplate cfgFile.eval.extraAutoArguments
+
     pure
         $ Session
-            { targets = effectiveTargets
-            , command
+            { buildSession
+            , testSession
+            , evalSession
             , watchDirs
             , watchExclusionPatterns
             , testMemoryLimit
-            , testTargets
             , replBuildDir = ReplBuildDir cfgFile.replBuildDir
             , testTimeout = TestTimeout cfgFile.testTimeout
             , generateWithHpack = GenerateWithHpack cfgFile.generateWithHpack
@@ -145,3 +185,78 @@
        )
     => Eff (Input Session : es) a -> Eff es a
 inputSession = runInputEff loadSession
+
+
+-- | Warn once per session load for each deprecated top-level config key
+-- still in use, regardless of whether its replacement also takes
+-- precedence.
+warnDeprecatedConfig :: (Log :> es) => Config -> Eff es ()
+warnDeprecatedConfig cfgFile = do
+    whenJust cfgFile.command
+        $ const
+        $ Log.warn "session.command is deprecated; use session.build.command_template instead."
+    unless (null cfgFile.targets)
+        $ Log.warn "session.targets is deprecated; use session.build.targets instead."
+    whenJust cfgFile.testTargets
+        $ const
+        $ Log.warn "session.test_targets is deprecated; use session.test.targets instead."
+
+
+-- | Warn when a section's @extra_auto_arguments@ is set alongside a custom
+-- @command_template@, since 'Tricorder.Session.Config.extraAutoArguments'
+-- would otherwise be silently ignored.
+warnIgnoredextraAutoArguments :: (Log :> es) => Text -> Maybe Text -> [Text] -> Eff es ()
+warnIgnoredextraAutoArguments section customTemplate extraAutoArguments =
+    when (isJust customTemplate && not (null extraAutoArguments))
+        $ Log.warn
+        $ "session."
+            <> section
+            <> ".command_template is set; session."
+            <> section
+            <> ".extra_auto_arguments is ignored (it only applies to Tricorder's \
+               \automatically resolved command)."
+
+
+-- | Warn when a custom @test@\/@eval@ @command_template@ has no @{target}@
+-- placeholder — without it, every invocation (one per test target or
+-- module) silently runs the exact same command. @build@ isn't checked this
+-- way: a missing @{targets}@ there mirrors past custom-@command@ behavior,
+-- more likely deliberate than an oversight.
+warnMissingTargetPlaceholder :: (Log :> es) => Text -> Maybe Text -> Eff es ()
+warnMissingTargetPlaceholder section customTemplate =
+    case customTemplate of
+        Just tpl
+            | not (hasPlaceholder targetPlaceholder tpl) ->
+                Log.warn
+                    $ "session."
+                        <> section
+                        <> ".command_template has no {target} placeholder — every "
+                        <> section
+                        <> " invocation will run the same command."
+        _ -> pure ()
+
+
+show :: Session -> Text
+show session =
+    T.intercalate
+        "\n"
+        [ "Loaded session"
+        , "Build configuration:"
+        , indent $ BuildSession.show session.buildSession
+        , "Test configuration:"
+        , indent $ TestSession.show session.testSession
+        , "Eval comments configuration:"
+        , indent $ EvalSession.show session.evalSession
+        , "Watch dirs:"
+        , indent $ showList toText session.watchDirs.getWatchDirs
+        , "Watch exclusion patterns:"
+        , indent
+            $ showList
+                (toText . showPattern . fst)
+                session.watchExclusionPatterns.getWatchExclusionPatterns
+        , "Repl build dir: " <> toText session.replBuildDir.getReplBuildDir
+        , -- TODO: Remove " seconds" when TestTimeout is converted to a proper time unit.
+          "Test timeout: " <> P.show session.testTimeout.getTestTimeout <> " seconds"
+        , "Test memory limit: " <> P.show session.testMemoryLimit
+        , "Generate with hpack: " <> P.show session.generateWithHpack.getGenerateWithHpack
+        ]
diff --git a/src/Tricorder/Session/CabalFile.hs b/src/Tricorder/Session/CabalFile.hs
--- a/src/Tricorder/Session/CabalFile.hs
+++ b/src/Tricorder/Session/CabalFile.hs
@@ -1,29 +1,37 @@
 module Tricorder.Session.CabalFile
     ( CabalFile (..)
     , inputCabalFiles
-    , discoverCabalFiles
+    , discoverPackages
+    , discoverCabalPackages
+    , discoverStackPackages
+    , readProjectFile
     )
 where
 
 import Atelier.Effects.Env (Env)
 import Atelier.Effects.FileSystem (FileSystem, doesFileExist, listDirectory, readFileBs)
 import Atelier.Effects.FileSystem.Glob (Glob, globDir1)
-import Atelier.Effects.Input (Input, runInputEff)
+import Atelier.Effects.Input (Input, input, runInputEff)
 import Atelier.Effects.Log (Log)
 import Data.Traversable (for)
 import Distribution.Fields (Field (..), FieldLine (..), Name (..), readFields)
 import Distribution.PackageDescription.Parsec (parseGenericPackageDescriptionMaybe)
 import Distribution.Types.GenericPackageDescription (GenericPackageDescription)
+import Effectful.Exception (catch, throwIO)
 import Effectful.Reader.Static (Reader, ask)
 import System.FilePath (normalise, takeExtension, (</>))
 import System.FilePath.Glob (compile)
+import System.IO.Error (userError)
 
 import Atelier.Effects.Env qualified as Env
+import Atelier.Effects.FileSystem qualified as FileSystem
 import Atelier.Effects.Log qualified as Log
 import Data.ByteString.Char8 qualified as BC
+import Data.List qualified as List
 import Data.Text qualified as T
 
 import Tricorder.Runtime (ProjectRoot (..))
+import Tricorder.Session.StackProject (StackProject (..))
 
 
 data CabalFile = CabalFile
@@ -37,42 +45,93 @@
     :: ( Env :> es
        , FileSystem :> es
        , Glob :> es
+       , Input StackProject :> es
        , Log :> es
        , Reader ProjectRoot :> es
        )
     => Eff (Input [CabalFile] : es) a -> Eff es a
-inputCabalFiles = runInputEff do
-    projectFilePaths <- discoverCabalFiles
-    (faileds, packageDescriptions) <-
-        partitionEithers <$> for projectFilePaths \p -> do
-            contents <- readFileBs p
-            case parseGenericPackageDescriptionMaybe contents of
-                Nothing -> pure $ Left p
-                Just gpd -> pure $ Right $ CabalFile p gpd
-    unless (null faileds) do
-        Log.warn
-            $ "Failed to parse .cabal files for the following packages: "
-                <> T.intercalate ", " (toText <$> faileds)
-    pure $ packageDescriptions
+inputCabalFiles = runInputEff $ Log.withNamespace "CabalFile" do
+    packageRes <- discoverPackages
+    case packageRes of
+        Left err -> throwIO $ userError $ toString err
+        Right projectFilePaths -> do
+            (faileds, packageDescriptions) <-
+                logFailure
+                    $ partitionEithers <$> for projectFilePaths readProjectFile
+            unless (null faileds) do
+                Log.warn
+                    $ "Failed to parse .cabal files for the following packages: "
+                        <> T.intercalate ", " (toText <$> faileds)
+            pure $ packageDescriptions
+  where
+    logFailure =
+        ( `catch`
+            \(e :: SomeException) -> do
+                Log.err $ "Failed to read package descriptions"
+                Log.err $ show e
+                throwIO e
+        )
 
 
+readProjectFile
+    :: (FileSystem :> es)
+    => FilePath -> Eff es (Either FilePath CabalFile)
+readProjectFile projectFilePath = do
+    fileExists <- FileSystem.doesFileExist projectFilePath
+    if fileExists
+        then readFile projectFilePath
+        else do
+            dirExists <- FileSystem.doesDirectoryExist projectFilePath
+            if dirExists
+                then do
+                    files <- FileSystem.listDirectory projectFilePath
+                    let mCabalFile = find (".cabal" `List.isSuffixOf`) files
+                    case mCabalFile of
+                        Nothing -> pure $ Left projectFilePath
+                        Just cabalFile -> readFile $ projectFilePath </> cabalFile
+                else
+                    pure $ Left projectFilePath
+  where
+    readFile path = do
+        contents <- readFileBs path
+        case parseGenericPackageDescriptionMaybe contents of
+            Nothing -> pure $ Left path
+            Just gpd -> pure $ Right $ CabalFile path gpd
+
+
+discoverPackages
+    :: ( Env :> es
+       , FileSystem :> es
+       , Glob :> es
+       , Input StackProject :> es
+       , Reader ProjectRoot :> es
+       )
+    => Eff es (Either Text [FilePath])
+discoverPackages = do
+    ProjectRoot projectRoot <- ask
+    hasStackYaml <- FileSystem.doesFileExist $ projectRoot </> "stack.yaml"
+    if hasStackYaml
+        then discoverStackPackages
+        else discoverCabalPackages
+
+
 -- | Discovers `.cabal` files in all locations and formats Cabal itself
 -- supports.
-discoverCabalFiles
+discoverCabalPackages
     :: ( Env :> es
        , FileSystem :> es
        , Glob :> es
        , Reader ProjectRoot :> es
        )
-    => Eff es [FilePath]
-discoverCabalFiles = do
+    => Eff es (Either Text [FilePath])
+discoverCabalPackages = do
     ProjectRoot projectRoot <- ask
     homeCabalFiles <- maybe [] (one . (</> ".cabal/config")) <$> Env.lookupEnv "HOME"
     let projectFilePaths = projectCabalFiles projectRoot <> homeCabalFiles
     projectFiles <- filterM doesFileExist projectFilePaths
     if null projectFiles
         then
-            cabalFilesIn projectRoot
+            Right <$> cabalFilesIn projectRoot
         else do
             packages <- fmap (find (not . null))
                 $ for projectFiles \projectFile -> do
@@ -82,8 +141,8 @@
                             (cabalFilesForEntry projectRoot)
                             (projectPackageEntries contents)
             case packages of
-                Nothing -> cabalFilesIn projectRoot
-                Just pkgs -> pure pkgs
+                Nothing -> Right <$> cabalFilesIn projectRoot
+                Just pkgs -> pure $ Right pkgs
   where
     projectCabalFiles projectRoot =
         (projectRoot </>) <$> ["cabal.project.local", "cabal.project.freeze", "cabal.project"]
@@ -98,6 +157,15 @@
         resolveMatch path
             | isCabalFile path = pure [path]
             | otherwise = cabalFilesIn path
+
+
+discoverStackPackages
+    :: (Input StackProject :> es, Reader ProjectRoot :> es)
+    => Eff es (Either Text [FilePath])
+discoverStackPackages = do
+    ProjectRoot projectRoot <- ask
+    project <- input
+    pure $ Right $ normalise . (projectRoot </>) <$> project.packages
 
 
 -- | List the @.cabal@ files directly inside a directory.
diff --git a/src/Tricorder/Session/Command.hs b/src/Tricorder/Session/Command.hs
deleted file mode 100644
--- a/src/Tricorder/Session/Command.hs
+++ /dev/null
@@ -1,141 +0,0 @@
-module Tricorder.Session.Command
-    ( Command (..)
-    , Repl (..)
-    , render
-    , resolveCommand
-    )
-where
-
-import Atelier.Effects.FileSystem (FileSystem)
-import Data.Default (Default (..))
-import Effectful.NonDet (NonDet, OnEmptyPolicy (..), emptyEff, plusEff, runNonDet)
-import System.FilePath ((</>))
-
-import Atelier.Effects.FileSystem qualified as FileSystem
-import Data.List qualified as List
-
-import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.Config (Config, command, replBuildDir)
-import Tricorder.Session.Target (Target (..))
-import Tricorder.Session.TestTarget (TestTarget, getTestTarget)
-
-import Tricorder.Session.Target qualified as Target
-
-
-data Command = Command
-    { repl :: Repl
-    , arguments :: [Text]
-    , targets :: [Target]
-    }
-    deriving stock (Eq, Generic, Show)
-
-
-data Repl = StackMulti | Stack | Cabal | Unknown
-    deriving stock (Eq, Generic, Show)
-
-
-render :: Command -> Text
-render command = unwords $ renderRepl command.repl <> command.arguments <> tgts
-  where
-    tgts = case command.repl of
-        Stack -> List.nub $ Target.componentName <$> command.targets
-        StackMulti -> List.nub $ Target.renderTarget <$> command.targets
-        Cabal -> Target.renderTarget <$> command.targets
-        Unknown -> Target.renderTarget <$> command.targets
-
-
-renderRepl :: Repl -> [Text]
-renderRepl StackMulti = ["stack", "ghci"]
-renderRepl Stack = ["stack", "ghci"]
-renderRepl Cabal = ["cabal", "repl"]
-renderRepl Unknown = []
-
-
-instance Default Command where
-    def = Command Unknown [] []
-
-
--- | Resolve the GHCi command, using config if set or autodetecting otherwise.
---
--- The @testTargets@ are the discovered @test:@ components; they are appended to
--- the auto-detected @all@ target (see 'detectCommand'). They are ignored when
--- the user has pinned an explicit @command@ or explicit @targets@ in config.
-resolveCommand
-    :: (FileSystem :> es) => ProjectRoot -> Config -> [Target] -> [TestTarget] -> Eff es Command
-resolveCommand projectRoot@(ProjectRoot root) cfg targets testTargets =
-    case cfg.command of
-        Just cmd -> case words cmd of
-            "stack" : "repl" : args -> detectStackKind args
-            "stack" : "ghci" : args -> detectStackKind args
-            "cabal" : "repl" : args -> pure $ Command Cabal args []
-            args -> pure $ Command Unknown args []
-        Nothing ->
-            detectCommand targets testTargets cfg.replBuildDir projectRoot
-  where
-    detectStackKind args = do
-        hasCabalFileInRoot <- any (".cabal" `List.isSuffixOf`) <$> FileSystem.listDirectory root
-        let repl =
-                if hasCabalFileInRoot
-                    then
-                        Stack
-                    else
-                        StackMulti
-        pure $ Command repl args []
-
-
-detectCommand
-    :: (FileSystem :> es) => [Target] -> [TestTarget] -> FilePath -> ProjectRoot -> Eff es Command
-detectCommand targets testTargets replBuildDir projectRoot = do
-    cmd <-
-        fmap (fromMaybe (fallback replBuildDir) . rightToMaybe)
-            $ runNonDet OnEmptyKeep
-            $ useStack projectRoot
-                `plusEff` useMultiCabal projectRoot replBuildDir
-    pure
-        $ cmd
-            { targets =
-                if not (null targets)
-                    then
-                        targets
-                    else
-                        Bare "all" : (getTestTarget <$> testTargets)
-            }
-
-
-useStack :: (FileSystem :> es, NonDet :> es) => ProjectRoot -> Eff es Command
-useStack (ProjectRoot projectRoot) = do
-    hasStack <- FileSystem.doesFileExist $ projectRoot </> "stack.yaml"
-    if hasStack
-        then
-            pure $ Command Stack [] []
-        else
-            emptyEff
-
-
-useMultiCabal :: (FileSystem :> es, NonDet :> es) => ProjectRoot -> FilePath -> Eff es Command
-useMultiCabal (ProjectRoot projectRoot) replBuildDir = do
-    hasCabalProject <- FileSystem.doesFileExist $ projectRoot </> "cabal.project"
-    hasCabalFiles <- any (".cabal" `List.isSuffixOf`) <$> FileSystem.listDirectory projectRoot
-    if hasCabalFiles || hasCabalProject
-        then
-            pure
-                $ Command
-                    { repl = Cabal
-                    , arguments = ["--enable-multi-repl"] <> buildDirFlag replBuildDir
-                    , targets = []
-                    }
-        else
-            emptyEff
-
-
-fallback :: FilePath -> Command
-fallback replBuildDir =
-    Command
-        { repl = Cabal
-        , arguments = buildDirFlag replBuildDir
-        , targets = [Bare "all"]
-        }
-
-
-buildDirFlag :: FilePath -> [Text]
-buildDirFlag replBuildDir = ["--builddir", toText replBuildDir]
diff --git a/src/Tricorder/Session/Command/RenderedCommand.hs b/src/Tricorder/Session/Command/RenderedCommand.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Command/RenderedCommand.hs
@@ -0,0 +1,9 @@
+module Tricorder.Session.Command.RenderedCommand (RenderedCommand (..)) where
+
+import Tricorder.Session.Stage (Stage (..))
+
+
+-- | A fully rendered, ready-to-spawn shell command, tagged with the 'Stage'
+-- it was rendered for.
+newtype RenderedCommand (stage :: Stage) = RenderedCommand {getRenderedCommand :: Text}
+    deriving (Eq, Show) via Text
diff --git a/src/Tricorder/Session/CommandConfig.hs b/src/Tricorder/Session/CommandConfig.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/CommandConfig.hs
@@ -0,0 +1,37 @@
+module Tricorder.Session.CommandConfig (CommandConfig (..)) where
+
+import Atelier.Types.QuietSnake (QuietSnake (..))
+import Data.Aeson (FromJSON, ToJSON)
+import Data.Default (Default (..))
+
+import Tricorder.Session.Stage (Stage)
+
+
+-- | Configuration shared by the @build@, @test@, and @eval@ sections: an
+-- optional command template (falls back to Tricorder's automatically
+-- resolved command per detected REPL kind when unset), an optional explicit
+-- target list, and extra CLI arguments appended to that automatically
+-- resolved command.
+data CommandConfig (stage :: Stage) = CommandConfig
+    { commandTemplate :: Maybe Text
+    -- ^ User-provided template string to use for the shell command for the
+    -- given stage. Takes priority over 'extraAutoArguments'. The exact
+    -- template variable name depends on the stage the 'CommandConfig' is for.
+    , targets :: Maybe [Text]
+    -- ^ List of targets to run the stage against.
+    , extraAutoArguments :: [Text]
+    -- ^ Arguments to pass to the Tricorder-detected command for the given
+    -- stage. Mutually exclusive with 'commandTemplate'. If both
+    -- 'commandTemplate' and 'extraAutoArguments' are set, a warning is logged.
+    }
+    deriving stock (Eq, Generic, Show)
+    deriving (FromJSON, ToJSON) via QuietSnake (CommandConfig stage)
+
+
+instance Default (CommandConfig stage) where
+    def =
+        CommandConfig
+            { commandTemplate = Nothing
+            , targets = Nothing
+            , extraAutoArguments = []
+            }
diff --git a/src/Tricorder/Session/CommandTemplate.hs b/src/Tricorder/Session/CommandTemplate.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/CommandTemplate.hs
@@ -0,0 +1,123 @@
+module Tricorder.Session.CommandTemplate
+    ( CommandTemplate (..)
+    , renderText
+    , renderTargetsFor
+    , hasPlaceholder
+    , targetsPlaceholder
+    , targetPlaceholder
+    , show
+    )
+where
+
+import Data.Default (Default (..))
+import Prelude hiding (show)
+
+import Data.List qualified as List
+import Data.Text qualified as T
+import Prelude qualified as P
+
+import Tricorder.Session.Repl (Repl (..))
+import Tricorder.Session.Stage (Stage (..))
+import Tricorder.Session.Target (Target (..))
+import Tricorder.Session.Util (indent, showList)
+
+import Tricorder.Session.Target qualified as Target
+
+
+-- | A command string to be rendered with a provided list of targets.
+data CommandTemplate (stage :: Stage) = CommandTemplate
+    { repl :: Repl
+    , template :: Text
+    , arguments :: [Text]
+    , placeholder :: Text
+    -- ^ The bare placeholder name (without braces) 'template' may contain —
+    -- see 'targetsPlaceholder' and 'targetPlaceholder'.
+    }
+    deriving stock (Eq, Generic, Show)
+
+
+-- | The @{targets}@ placeholder, used by @build@: one invocation covers
+-- every target.
+targetsPlaceholder :: Text
+targetsPlaceholder = "targets"
+
+
+-- | The @{target}@ placeholder, used by @test@ and @eval@: one invocation
+-- per target.
+targetPlaceholder :: Text
+targetPlaceholder = "target"
+
+
+instance Default (CommandTemplate 'Build) where
+    def = CommandTemplate Unknown ("cabal repl {" <> targetsPlaceholder <> "}") [] targetsPlaceholder
+
+
+instance Default (CommandTemplate 'Test) where
+    def = CommandTemplate Unknown ("cabal repl {" <> targetPlaceholder <> "}") [] targetPlaceholder
+
+
+instance Default (CommandTemplate 'Eval) where
+    def = CommandTemplate Unknown ("cabal repl {" <> targetPlaceholder <> "}") [] targetPlaceholder
+
+
+-- | Substitute 'placeholder' in 'template' with the REPL-rendered target(s),
+-- then append 'arguments'. Not exported — each phase renders differently (a
+-- memory-limit flag for test), so use 'renderBuild'\/'renderTest'\/'renderEval'
+-- instead, which return the phase-tagged
+-- 'Tricorder.Session.Command.RenderedCommand.RenderedCommand'.
+renderText :: CommandTemplate stage -> [Target] -> Text
+renderText commandTemplate targets =
+    T.unwords $ substituted <> commandTemplate.arguments
+  where
+    substituted =
+        T.words
+            $ substitutePlaceholder
+                commandTemplate.placeholder
+                (renderTargetsFor commandTemplate.repl targets)
+                commandTemplate.template
+
+
+-- | Render targets the way each REPL kind expects on the command line.
+-- Plain (single-package) @stack ghci@ only understands bare component
+-- names, and needs deduplication since multiple targets can share one;
+-- every other kind takes the fully qualified @[package:]kind:name@ form.
+renderTargetsFor :: Repl -> [Target] -> [Text]
+renderTargetsFor = \case
+    Stack -> List.nub . fmap Target.componentName
+    StackMulti -> List.nub . fmap Target.render
+    Cabal -> fmap Target.render
+    Unknown -> fmap Target.render
+
+
+-- | Substitute every unescaped @{<placeholderName>}@ in a template with the
+-- (already REPL-rendered) target list, space-joined. @\\{<placeholderName>}@
+-- escapes to a literal @{<placeholderName>}@, with no substitution.
+substitutePlaceholder :: Text -> [Text] -> Text -> Text
+substitutePlaceholder placeholderName renderedTargets =
+    T.replace escapeSentinel bareholder
+        . T.replace bareholder (T.unwords renderedTargets)
+        . T.replace ("\\" <> bareholder) escapeSentinel
+  where
+    bareholder = "{" <> placeholderName <> "}"
+    -- Must not itself contain the literal substring "{<placeholderName>}" —
+    -- the unescaped-placeholder pass above would otherwise match inside it.
+    escapeSentinel = "\NUL__escaped_" <> placeholderName <> "_placeholder__\NUL"
+
+
+-- | Whether a template contains @{<placeholderName>}@, escaped or not. Used
+-- to warn when a @test@\/@eval@ @command_template@ omits it (see
+-- 'Tricorder.Session.loadSession').
+hasPlaceholder :: Text -> Text -> Bool
+hasPlaceholder placeholderName template = ("{" <> placeholderName <> "}") `T.isInfixOf` template
+
+
+show :: CommandTemplate stage -> Text
+show tmpl =
+    T.intercalate
+        "\n"
+        [ "Template: " <> tmpl.template
+        , "Repl: " <> P.show tmpl.repl
+        , "Template placeholder: " <> P.show tmpl.placeholder
+        , "Arguments:"
+        , indent $ showList id tmpl.arguments
+        ]
diff --git a/src/Tricorder/Session/Config.hs b/src/Tricorder/Session/Config.hs
--- a/src/Tricorder/Session/Config.hs
+++ b/src/Tricorder/Session/Config.hs
@@ -5,21 +5,34 @@
 import Data.Aeson (FromJSON (..))
 import Data.Default (Default (..))
 
+import Tricorder.Session.CommandConfig (CommandConfig)
 import Tricorder.Session.Hooks (Hooks)
+import Tricorder.Session.Stage.Test.Config (TestConfig)
 
+import Tricorder.Session.Stage qualified as Stage
 
+
 data Config = Config
-    { command :: Maybe Text
-    , targets :: [Text]
+    { build :: CommandConfig 'Stage.Build
+    , test :: TestConfig
+    , eval :: CommandConfig 'Stage.Eval
     , watchDirs :: [FilePath]
     , watchExclusionPatterns :: [Text]
-    , testTargets :: Maybe [Text]
     , replBuildDir :: FilePath
     , testTimeout :: Int
     , generateWithHpack :: Bool
     , testMemoryLimit :: Maybe Text
     , hooks :: Maybe Hooks
     , idleTimeoutSeconds :: Int
+    , command :: Maybe Text
+    -- ^ DEPRECATED: use 'build'.'commandTemplate' instead.
+    -- TODO: Remove at or after version 0.8.0.0.
+    , targets :: [Text]
+    -- ^ DEPRECATED: use 'build'.'targets' instead.
+    -- TODO: Remove at or after version 0.8.0.0.
+    , testTargets :: Maybe [Text]
+    -- ^ DEPRECATED: use 'test'.'targets' instead.
+    -- TODO: Remove at or after version 0.8.0.0.
     }
     deriving stock (Eq, Generic, Show)
     deriving (FromJSON) via WithDefaults (QuietSnake Config)
@@ -28,15 +41,18 @@
 instance Default Config where
     def =
         Config
-            { command = Nothing
-            , targets = []
+            { build = def
+            , test = def
+            , eval = def
             , watchDirs = []
             , watchExclusionPatterns = []
-            , testTargets = Nothing
             , replBuildDir = "dist-newstyle/tricorder"
             , testTimeout = 10
             , generateWithHpack = True
             , testMemoryLimit = Nothing
             , hooks = Nothing
             , idleTimeoutSeconds = 300
+            , command = Nothing
+            , targets = []
+            , testTargets = Nothing
             }
diff --git a/src/Tricorder/Session/Repl.hs b/src/Tricorder/Session/Repl.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Repl.hs
@@ -0,0 +1,45 @@
+module Tricorder.Session.Repl
+    ( Repl (..)
+    , resolveRepl
+    )
+where
+
+import Atelier.Effects.FileSystem (FileSystem)
+import Data.Yaml (decodeEither')
+import Effectful.Exception (throwIO)
+import System.FilePath ((</>))
+import System.IO.Error (userError)
+
+import Atelier.Effects.FileSystem qualified as FileSystem
+import Data.Aeson qualified as Aeson
+import Data.Aeson.KeyMap qualified as KM
+
+import Tricorder.Runtime (ProjectRoot (..))
+
+
+data Repl = StackMulti | Stack | Cabal | Unknown
+    deriving stock (Eq, Generic, Show)
+
+
+-- | Resolve the project's REPL kind from the filesystem, independent of any
+-- @build@\/@test@\/@eval@ command template — this decides both the
+-- automatically resolved templates and how targets are rendered for all
+-- three phases.
+resolveRepl :: (FileSystem :> es) => ProjectRoot -> Eff es Repl
+resolveRepl pr@(ProjectRoot projectRoot) = do
+    hasStack <- FileSystem.doesFileExist $ projectRoot </> "stack.yaml"
+    if hasStack
+        then stackReplKind pr
+        else pure Cabal
+
+
+stackReplKind :: (FileSystem :> es) => ProjectRoot -> Eff es Repl
+stackReplKind (ProjectRoot projectRoot) = do
+    stackYaml <- FileSystem.readFileBs $ projectRoot </> "stack.yaml"
+    case decodeEither' stackYaml of
+        Left err -> throwIO $ userError $ "Could not read and decode stack.yaml: " <> show err
+        Right value -> pure $ case value of
+            Aeson.Object km -> case KM.lookup "packages" km of
+                Just (Aeson.Array arr) | length arr > 1 -> StackMulti
+                _ -> Stack
+            _ -> Stack
diff --git a/src/Tricorder/Session/StackProject.hs b/src/Tricorder/Session/StackProject.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/StackProject.hs
@@ -0,0 +1,70 @@
+module Tricorder.Session.StackProject
+    ( StackProject (..)
+    , inputWithCache
+    )
+where
+
+import Atelier.Effects.FileSystem (FileSystem)
+import Atelier.Effects.Input (Input, runInputEff)
+import Data.Aeson (FromJSON, ToJSON)
+import Data.Time (UTCTime)
+import Data.Time.Clock.POSIX (posixSecondsToUTCTime)
+import Effectful.Concurrent.MVar.Strict (Concurrent)
+import Effectful.Concurrent.STM
+    ( TVar
+    , atomically
+    , newTVarIO
+    , readTVar
+    , writeTVar
+    )
+import Effectful.Exception (throwIO)
+import Effectful.Reader.Static (Reader, ask)
+import GHC.Generics (Generically (..))
+import System.FilePath ((</>))
+import System.IO.Error (userError)
+
+import Atelier.Effects.FileSystem qualified as FileSystem
+import Data.Yaml qualified as Yaml
+
+import Tricorder.Runtime (ProjectRoot (..))
+
+
+newtype StackProject = StackProject
+    { packages :: [FilePath]
+    }
+    deriving stock (Eq, Generic, Show)
+    deriving (FromJSON, ToJSON) via Generically StackProject
+
+
+inputWithCache
+    :: ( Concurrent :> es
+       , FileSystem :> es
+       , Reader ProjectRoot :> es
+       )
+    => Eff (Input StackProject : es) a -> Eff es a
+inputWithCache act = do
+    cache :: TVar StackProject <- newTVarIO $ StackProject []
+    lastModified :: TVar UTCTime <- newTVarIO $ posixSecondsToUTCTime 0
+    flip runInputEff act do
+        ProjectRoot projectRoot <- ask
+        let stackYamlPath = projectRoot </> "stack.yaml"
+        exists <- FileSystem.doesFileExist stackYamlPath
+        if not exists
+            then throwIO $ userError "stack.yaml does not exist"
+            else do
+                newLastMod <- FileSystem.getModificationTime stackYamlPath
+                oldLastMod <- atomically $ readTVar lastModified
+                if oldLastMod /= newLastMod
+                    then do
+                        contents <- FileSystem.readFileBs stackYamlPath
+                        let result = Yaml.decodeEither' contents
+                        case result of
+                            Right x -> do
+                                atomically do
+                                    writeTVar cache x
+                                    writeTVar lastModified newLastMod
+                                pure x
+                            Left err ->
+                                throwIO $ userError $ "Could not parse stack.yaml: " <> show err
+                    else
+                        atomically $ readTVar cache
diff --git a/src/Tricorder/Session/Stage.hs b/src/Tricorder/Session/Stage.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage.hs
@@ -0,0 +1,4 @@
+module Tricorder.Session.Stage (Stage (..)) where
+
+
+data Stage = Build | Test | Eval
diff --git a/src/Tricorder/Session/Stage/Build/Command.hs b/src/Tricorder/Session/Stage/Build/Command.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage/Build/Command.hs
@@ -0,0 +1,78 @@
+module Tricorder.Session.Stage.Build.Command
+    ( render
+    , resolve
+    )
+where
+
+import Atelier.Effects.FileSystem (FileSystem)
+import System.FilePath ((</>))
+
+import Atelier.Effects.FileSystem qualified as FileSystem
+import Data.List qualified as List
+
+import Tricorder.Runtime (ProjectRoot (..))
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..), renderText, targetsPlaceholder)
+import Tricorder.Session.Config (Config (..))
+import Tricorder.Session.Repl (Repl (..))
+import Tricorder.Session.Stage (Stage (..))
+import Tricorder.Session.Target (Target (..))
+
+
+-- | Render the @build@ command: every target goes into the one invocation
+-- that covers all of them.
+render :: CommandTemplate 'Build -> [Target] -> RenderedCommand 'Build
+render commandTemplate targets = RenderedCommand $ renderText commandTemplate targets
+
+
+resolve
+    :: (FileSystem :> es)
+    => ProjectRoot
+    -> Config
+    -> Repl
+    -> [Target]
+    -> Eff es (CommandTemplate 'Build, [Target])
+resolve projectRoot cfg repl effectiveTargets = do
+    template <- case customTemplate of
+        Just tpl -> pure tpl
+        Nothing -> defaultBuildTemplate projectRoot repl cfg.replBuildDir
+    pure
+        ( CommandTemplate
+            { repl
+            , template
+            , arguments = maybe cfg.build.extraAutoArguments (const []) customTemplate
+            , placeholder = targetsPlaceholder
+            }
+        , if not (null effectiveTargets)
+            then effectiveTargets
+            else [Bare "all"]
+        )
+  where
+    customTemplate = cfg.build.commandTemplate <|> cfg.command
+
+
+-- | Whether the project has a @cabal.project@ or any @*.cabal@ file. Used
+-- only to pick the automatically resolved template's flags — it has no
+-- bearing on 'Repl', which is 'Cabal' either way.
+isCabalProject :: (FileSystem :> es) => ProjectRoot -> Eff es Bool
+isCabalProject (ProjectRoot projectRoot) = do
+    hasCabalProject <- FileSystem.doesFileExist $ projectRoot </> "cabal.project"
+    hasCabalFiles <- any (".cabal" `List.isSuffixOf`) <$> FileSystem.listDirectory projectRoot
+    pure $ hasCabalProject || hasCabalFiles
+
+
+-- | Tricorder's automatically resolved @build@ template for a resolved
+-- 'Repl'. Cabal projects additionally probe the filesystem to decide whether
+-- @--enable-multi-repl@ applies.
+defaultBuildTemplate :: (FileSystem :> es) => ProjectRoot -> Repl -> FilePath -> Eff es Text
+defaultBuildTemplate projectRoot repl replBuildDir = case repl of
+    Stack -> pure "stack ghci {targets}"
+    StackMulti -> pure "stack ghci {targets}"
+    Unknown -> pure "cabal repl {targets}"
+    Cabal -> do
+        isProject <- isCabalProject projectRoot
+        pure
+            $ if isProject
+                then "cabal repl --enable-multi-repl --builddir " <> toText replBuildDir <> " {targets}"
+                else "cabal repl --builddir " <> toText replBuildDir <> " {targets}"
diff --git a/src/Tricorder/Session/Stage/Build/Session.hs b/src/Tricorder/Session/Stage/Build/Session.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage/Build/Session.hs
@@ -0,0 +1,66 @@
+module Tricorder.Session.Stage.Build.Session
+    ( BuildSession (..)
+    , resolve
+    , show
+    )
+where
+
+import Atelier.Effects.FileSystem (FileSystem)
+import Data.Default (Default (..))
+import Effectful.Reader.Static (Reader)
+import Prelude hiding (show)
+
+import Data.Text qualified as T
+import Effectful.Reader.Static qualified as Reader
+
+import Tricorder.Runtime (ProjectRoot (..))
+import Tricorder.Session.CabalFile (CabalFile)
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate)
+import Tricorder.Session.Config (Config (..))
+import Tricorder.Session.Repl (Repl)
+import Tricorder.Session.Target (Target)
+import Tricorder.Session.Util (indent, showList)
+
+import Tricorder.Session.CommandTemplate qualified as CommandTemplate
+import Tricorder.Session.Stage qualified as Stage
+import Tricorder.Session.Stage.Build.Command qualified as BuildCommand
+import Tricorder.Session.Target qualified as Target
+
+
+data BuildSession = BuildSession
+    { commandTemplate :: CommandTemplate 'Stage.Build
+    , targets :: [Target]
+    }
+    deriving stock (Eq)
+
+
+instance Default BuildSession where
+    def = BuildSession def []
+
+
+resolve
+    :: (FileSystem :> es, Reader ProjectRoot :> es)
+    => Config -> Repl -> [CabalFile] -> Eff es BuildSession
+resolve config repl projectFiles = do
+    projectRoot <- Reader.ask
+    (commandTemplate, targets) <- BuildCommand.resolve projectRoot config repl effectiveTargets
+    pure
+        $ BuildSession
+            { commandTemplate
+            , targets
+            }
+  where
+    rawBuildTargets = fromMaybe config.targets config.build.targets
+    effectiveTargets = Target.resolve projectFiles rawBuildTargets
+
+
+show :: BuildSession -> Text
+show cfg =
+    T.intercalate
+        "\n"
+        [ "Command template:"
+        , indent $ CommandTemplate.show cfg.commandTemplate
+        , "Targets:"
+        , indent $ showList Target.render cfg.targets
+        ]
diff --git a/src/Tricorder/Session/Stage/Eval/Command.hs b/src/Tricorder/Session/Stage/Eval/Command.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage/Eval/Command.hs
@@ -0,0 +1,34 @@
+module Tricorder.Session.Stage.Eval.Command
+    ( render
+    , resolve
+    )
+where
+
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..), renderText, targetPlaceholder)
+import Tricorder.Session.Config (Config (..))
+import Tricorder.Session.Repl (Repl)
+import Tricorder.Session.Stage (Stage (..))
+import Tricorder.Session.Stage.Test.Session (defaultTestTemplate)
+import Tricorder.Session.Target (Target)
+
+
+-- | Render the @eval@ command for a single source file's short-lived
+-- session: the module being evaluated is substituted as the one target.
+render :: CommandTemplate 'Eval -> [Target] -> RenderedCommand 'Eval
+render commandTemplate targets = RenderedCommand $ renderText commandTemplate targets
+
+
+resolve :: Repl -> Config -> CommandTemplate 'Eval
+resolve repl cfg =
+    CommandTemplate
+        { repl
+        , template = fromMaybe (defaultEvalTemplate repl) cfg.eval.commandTemplate
+        , arguments = maybe cfg.eval.extraAutoArguments (const []) cfg.eval.commandTemplate
+        , placeholder = targetPlaceholder
+        }
+
+
+defaultEvalTemplate :: Repl -> Text
+defaultEvalTemplate = defaultTestTemplate
diff --git a/src/Tricorder/Session/Stage/Eval/Session.hs b/src/Tricorder/Session/Stage/Eval/Session.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage/Eval/Session.hs
@@ -0,0 +1,27 @@
+module Tricorder.Session.Stage.Eval.Session
+    ( EvalSession
+    , show
+    )
+where
+
+import Prelude hiding (show)
+
+import Data.Text qualified as T
+
+import Tricorder.Session.CommandTemplate (CommandTemplate)
+import Tricorder.Session.Util (indent)
+
+import Tricorder.Session.CommandTemplate qualified as CommandTemplate
+import Tricorder.Session.Stage qualified as Stage
+
+
+type EvalSession = CommandTemplate 'Stage.Eval
+
+
+show :: EvalSession -> Text
+show cfg =
+    T.intercalate
+        "\n"
+        [ "Command template:"
+        , indent $ CommandTemplate.show cfg
+        ]
diff --git a/src/Tricorder/Session/Stage/Test/Command.hs b/src/Tricorder/Session/Stage/Test/Command.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage/Test/Command.hs
@@ -0,0 +1,60 @@
+module Tricorder.Session.Stage.Test.Command
+    ( RenderedTestCommand (..)
+    , render
+    )
+where
+
+import Tricorder.Build.ByteSize (ByteSize)
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..))
+import Tricorder.Session.Repl (Repl (..))
+import Tricorder.Session.Stage (Stage (..))
+import Tricorder.Session.Stage.Test.Session (ResolvedTestOptions (..), TestSession (..))
+import Tricorder.Session.TestTarget (TestTarget (..))
+
+import Tricorder.Build.ByteSize qualified as ByteSize
+import Tricorder.Session.CommandTemplate qualified as CommandTemplate
+
+
+data RenderedTestCommand = RenderedTestCommand
+    { command :: RenderedCommand 'Test
+    , options :: ResolvedTestOptions
+    }
+
+
+render :: TestSession -> Maybe ByteSize -> TestTarget -> RenderedTestCommand
+render testSession mMemoryLimit target =
+    RenderedTestCommand
+        { command =
+            RenderedCommand
+                $ CommandTemplate.renderText
+                    testSession.commandTemplate {arguments = testSession.commandTemplate.arguments <> memoryLimitArg}
+                    [getTestTarget target]
+        , options = testSession.options
+        }
+  where
+    memoryLimitArg =
+        maybe
+            []
+            ( \limit ->
+                let
+                    stack =
+                        [ "--ghc-options"
+                        , "+RTS -M"
+                            <> ByteSize.toRTSSize limit
+                            <> " -RTS"
+                        ]
+                    cabal =
+                        [ "--repl-options"
+                        , "+RTS -M"
+                            <> ByteSize.toRTSSize limit
+                            <> " -RTS"
+                        ]
+                in
+                    case testSession.commandTemplate.repl of
+                        Stack -> stack
+                        StackMulti -> stack
+                        Cabal -> cabal
+                        Unknown -> cabal
+            )
+            mMemoryLimit
diff --git a/src/Tricorder/Session/Stage/Test/Config.hs b/src/Tricorder/Session/Stage/Test/Config.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage/Test/Config.hs
@@ -0,0 +1,60 @@
+module Tricorder.Session.Stage.Test.Config
+    ( TestConfig (..)
+    , Options (..)
+    , OutputMode (..)
+    )
+where
+
+import Atelier.Types.QuietSnake (QuietSnake (..))
+import Data.Aeson (FromJSON (..), ToJSON, Value (..))
+import Data.Aeson.Types (ToJSON (..))
+import Data.Default (Default (..))
+import GHC.Generics (Generically (..))
+
+import Tricorder.Session.CommandConfig (CommandConfig)
+
+import Tricorder.Session.Stage qualified as Stage
+
+
+data TestConfig = TestConfig
+    { commandConfig :: CommandConfig 'Stage.Test
+    , options :: Options
+    }
+    deriving stock (Eq, Generic, Show)
+
+
+instance Default TestConfig where
+    def =
+        TestConfig
+            { commandConfig = def
+            , options = def
+            }
+
+
+instance ToJSON TestConfig where
+    toJSON cfg = case (toJSON cfg.commandConfig, toJSON cfg.options) of
+        (Object a, Object b) -> Object (a <> b)
+        (a, _) -> a
+
+
+instance FromJSON TestConfig where
+    parseJSON v = TestConfig <$> parseJSON v <*> parseJSON v
+
+
+newtype Options = Options
+    { outputMode :: Maybe OutputMode
+    }
+    deriving stock (Eq, Generic, Show)
+    deriving (FromJSON, ToJSON) via QuietSnake Options
+
+
+instance Default Options where
+    def =
+        Options
+            { outputMode = Nothing
+            }
+
+
+data OutputMode = ReplOutput | StdoutOutput
+    deriving stock (Eq, Generic, Show)
+    deriving (FromJSON, ToJSON) via Generically OutputMode
diff --git a/src/Tricorder/Session/Stage/Test/Session.hs b/src/Tricorder/Session/Stage/Test/Session.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Stage/Test/Session.hs
@@ -0,0 +1,111 @@
+module Tricorder.Session.Stage.Test.Session
+    ( TestSession (..)
+    , ResolvedTestOptions (..)
+    , resolve
+    , defaultTestTemplate
+    , show
+    )
+where
+
+import Data.Default (Default (..))
+import Prelude hiding (show)
+
+import Data.Text qualified as T
+import Prelude qualified as P
+
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..), targetPlaceholder)
+import Tricorder.Session.Config (Config (..))
+import Tricorder.Session.Repl (Repl (..))
+import Tricorder.Session.Stage.Test.Config (Options (..), OutputMode (..), TestConfig (..))
+import Tricorder.Session.Target (Target)
+import Tricorder.Session.TestTarget (TestTarget (..))
+import Tricorder.Session.Util (indent, showList)
+
+import Tricorder.Session.CommandTemplate qualified as CommandTemplate
+import Tricorder.Session.Stage qualified as Stage
+import Tricorder.Session.TestTarget qualified as TestTarget
+
+
+data TestSession = TestSession
+    { commandTemplate :: CommandTemplate 'Stage.Test
+    , targets :: [TestTarget]
+    , options :: ResolvedTestOptions
+    }
+    deriving stock (Eq)
+
+
+instance Default TestSession where
+    def =
+        TestSession
+            { commandTemplate = def
+            , targets = []
+            , options = def
+            }
+
+
+data ResolvedTestOptions = ResolvedTestOptions
+    { outputMode :: OutputMode
+    }
+    deriving stock (Eq)
+
+
+instance Default ResolvedTestOptions where
+    def = ResolvedTestOptions ReplOutput
+
+
+resolve :: Repl -> [Target] -> Config -> TestSession
+resolve repl buildTargets cfg =
+    TestSession
+        { commandTemplate =
+            CommandTemplate
+                { repl
+                , template
+                , arguments =
+                    maybe
+                        cfg.test.commandConfig.extraAutoArguments
+                        (const [])
+                        cfg.test.commandConfig.commandTemplate
+                , placeholder = targetPlaceholder
+                }
+        , targets = TestTarget.resolve cfg buildTargets
+        , options =
+            ResolvedTestOptions
+                { outputMode = fromMaybe detectedOutputMode cfg.test.options.outputMode
+                }
+        }
+  where
+    template = fromMaybe (defaultTestTemplate repl) cfg.test.commandConfig.commandTemplate
+    detectedOutputMode
+        | "stack repl" `T.isPrefixOf` template
+            || "stack ghci" `T.isPrefixOf` template
+            || "cabal repl" `T.isPrefixOf` template =
+            ReplOutput
+        | otherwise = StdoutOutput
+
+
+defaultTestTemplate :: Repl -> Text
+defaultTestTemplate = \case
+    Stack -> "stack ghci {target}"
+    StackMulti -> "stack ghci {target}"
+    Cabal -> "cabal repl {target}"
+    Unknown -> "cabal repl {target}"
+
+
+show :: TestSession -> Text
+show cfg =
+    T.intercalate
+        "\n"
+        [ "Command template:"
+        , indent $ CommandTemplate.show cfg.commandTemplate
+        , "Test targets:"
+        , indent $ showList TestTarget.render cfg.targets
+        , "Options:"
+        , indent $ showTestOptions cfg.options
+        ]
+  where
+    showTestOptions opts =
+        T.intercalate
+            "\n"
+            [ "Output mode: " <> P.show opts.outputMode
+            ]
diff --git a/src/Tricorder/Session/Target.hs b/src/Tricorder/Session/Target.hs
--- a/src/Tricorder/Session/Target.hs
+++ b/src/Tricorder/Session/Target.hs
@@ -1,12 +1,12 @@
 module Tricorder.Session.Target
     ( Target (..)
     , ComponentKind (..)
-    , parseTarget
-    , renderTarget
+    , parse
+    , render
+    , resolve
+    , compare
     , componentName
-    , resolveTargets
     , definesCustomPrelude
-    , compareTargets
     , allComponentTargets
     )
 where
@@ -29,9 +29,11 @@
 import Distribution.Types.PackageId (pkgName)
 import Distribution.Types.PackageName (unPackageName)
 import Distribution.Types.UnqualComponentName (mkUnqualComponentName, unUnqualComponentName)
+import Prelude hiding (compare)
 
 import Data.Text qualified as T
 import Distribution.Types.BuildInfo.Lens qualified as Lens
+import Prelude qualified as P
 
 import Tricorder.Session.CabalFile (CabalFile (..))
 
@@ -55,11 +57,11 @@
 
 
 instance ToJSON Target where
-    toJSON = toJSON . renderTarget
+    toJSON = toJSON . render
 
 
 instance FromJSON Target where
-    parseJSON = fmap parseTarget . parseJSON
+    parseJSON = fmap parse . parseJSON
 
 
 instance ToJSONKey Target
@@ -93,29 +95,29 @@
     Bench -> "bench"
 
 
--- | Parse a kind prefix, derived as the inverse of 'kindPrefix' so the two
--- never drift apart [ref:kind_prefix_sole_source].
-parseKind :: Text -> Maybe ComponentKind
-parseKind = inverseMap kindPrefix
-
-
 -- | Classify a target's textual form. The grammar is @[kind:]name@ where
 -- @kind@ is one of @lib@, @flib@, @exe@, @test@, or @bench@; anything else (an
 -- unknown kind, a cabal alias such as @executable@, or extra colons) is
 -- 'Unrecognized'.
-parseTarget :: Text -> Target
-parseTarget target = case T.splitOn ":" target of
+parse :: Text -> Target
+parse target = case T.splitOn ":" target of
     [packageName, prefix, name] | Just kind <- parseKind prefix -> PackageQualified packageName kind name
     [prefix, name] | Just kind <- parseKind prefix -> Qualified kind name
     [name] -> Bare name
     _ -> Unrecognized target
 
 
+-- | Parse a kind prefix, derived as the inverse of 'kindPrefix' so the two
+-- never drift apart [ref:kind_prefix_sole_source].
+parseKind :: Text -> Maybe ComponentKind
+parseKind = inverseMap kindPrefix
+
+
 -- | Render a 'Target' back to the textual form cabal understands. Inverse of
 -- 'parseTarget' (lossless: @parseTarget . renderTarget == id@). Builds prefixes
 -- via 'kindPrefix' rather than hardcoding them [ref:kind_prefix_sole_source].
-renderTarget :: Target -> Text
-renderTarget = \case
+render :: Target -> Text
+render = \case
     Qualified kind name -> kindPrefix kind <> ":" <> name
     PackageQualified packageName kind name -> packageName <> ":" <> kindPrefix kind <> ":" <> name
     Bare name -> name
@@ -134,14 +136,14 @@
 -- raw target strings (from config) are parsed into structured 'Target's: the
 -- configured targets are parsed as-is, or all components across every
 -- discovered package are auto-detected when no targets are configured. Either
--- way the result is sorted with 'compareTargets' so libraries exposing a custom
+-- way the result is sorted with 'compare' so libraries exposing a custom
 -- @Prelude@ come last [ref:lib_sort_order].
-resolveTargets :: [CabalFile] -> [Text] -> [Target]
-resolveTargets cabalFiles = \case
-    targets@(_ : _) -> sortTargets $ parseTarget <$> targets
+resolve :: [CabalFile] -> [Text] -> [Target]
+resolve cabalFiles = \case
+    targets@(_ : _) -> sortTargets $ parse <$> targets
     [] -> sortTargets $ foldMap (allComponentTargets . (.projectPackageDescription)) cabalFiles
   where
-    sortTargets = sortBy (compareTargets (definesCustomPrelude cabalFiles))
+    sortTargets = sortBy (compare (definesCustomPrelude cabalFiles))
 
 
 -- | [tag:lib_sort_order] When running @cabal repl <package defining custom
@@ -154,16 +156,16 @@
 -- 'definesCustomPrelude': only those that expose a @Prelude@ module are sorted
 -- last. This is more precise than sorting every @lib:@ target last — only the
 -- libraries that actually cause the failure are reordered.
-compareTargets :: (Target -> Bool) -> Target -> Target -> Ordering
-compareTargets definesPrelude a b
+compare :: (Target -> Bool) -> Target -> Target -> Ordering
+compare definesPrelude a b
     | definesPrelude a && not (definesPrelude b) = GT
     | not (definesPrelude a) && definesPrelude b = LT
-    | otherwise = compare (renderTarget a) (renderTarget b)
+    | otherwise = P.compare (render a) (render b)
 
 
 -- | Check whether any of the discovered packages' libraries expose a @Prelude@
 -- module for the given target. Used to build the predicate passed to
--- 'compareTargets' so that only the libraries that actually cause the GHCi
+-- 'compare' so that only the libraries that actually cause the GHCi
 -- startup failure are sorted last [ref:lib_sort_order].
 definesCustomPrelude :: [CabalFile] -> Target -> Bool
 definesCustomPrelude cabalFiles target = any check cabalFiles
diff --git a/src/Tricorder/Session/TestTarget.hs b/src/Tricorder/Session/TestTarget.hs
--- a/src/Tricorder/Session/TestTarget.hs
+++ b/src/Tricorder/Session/TestTarget.hs
@@ -1,50 +1,56 @@
 module Tricorder.Session.TestTarget
     ( TestTarget (..)
-    , renderTestTarget
-    , parseTestTargets
-    , resolveTestTargets
-    , projectTestTargets
+    , render
+    , parse
+    , resolve
+    , project
     )
 where
 
 import Data.Aeson (FromJSON (..), FromJSONKey, ToJSON (..), ToJSONKey)
 
+import Tricorder.Session.CommandConfig (CommandConfig (..))
 import Tricorder.Session.Config (Config (..))
-import Tricorder.Session.Target (ComponentKind (..), Target (..), parseTarget, renderTarget)
+import Tricorder.Session.Stage.Test.Config (TestConfig (..))
+import Tricorder.Session.Target (ComponentKind (..), Target (..))
 
+import Tricorder.Session.Target qualified as Target
 
+
 newtype TestTarget = TestTarget {getTestTarget :: Target}
     deriving stock (Eq, Generic, Ord, Show)
     deriving (FromJSON, ToJSON) via Target
     deriving (FromJSONKey, ToJSONKey) via Target
 
 
-renderTestTarget :: TestTarget -> Text
-renderTestTarget = renderTarget . getTestTarget
+render :: TestTarget -> Text
+render = Target.render . getTestTarget
 
 
 -- | Parse raw target strings (e.g. the @test_targets@ config) and project them
 -- onto their test suites — non-test entries are dropped.
-parseTestTargets :: [Text] -> [TestTarget]
-parseTestTargets = projectTestTargets . map parseTarget
+parse :: [Text] -> [TestTarget]
+parse = project . map Target.parse
 
 
 -- | [tag:test_targets_invariant] Project a target list onto its test suites —
 -- the only way to build a 'TestTargets', so the @test:@-only invariant holds by
 -- construction.
-projectTestTargets :: [Target] -> [TestTarget]
-projectTestTargets = mapMaybe mkTestTarget
+project :: [Target] -> [TestTarget]
+project = mapMaybe mk
   where
-    mkTestTarget tgt@(Qualified Test _) = Just $ TestTarget tgt
-    mkTestTarget tgt@(PackageQualified _ Test _) = Just $ TestTarget tgt
-    mkTestTarget _ = Nothing
+    mk tgt@(Qualified Test _) = Just $ TestTarget tgt
+    mk tgt@(PackageQualified _ Test _) = Just $ TestTarget tgt
+    mk _ = Nothing
 
 
--- | Resolve which test suites to run after a clean build. Either source — the
--- explicit @test_targets@ config or the build 'targets' — is projected onto its
--- @test:@ components (see 'projectTestTargets'), so non-test entries are
--- dropped and the result only ever names test suites [ref:test_targets_invariant].
-resolveTestTargets :: Config -> [Target] -> [TestTarget]
-resolveTestTargets cfg targets = case cfg.testTargets of
-    Just explicit -> parseTestTargets explicit
-    Nothing -> projectTestTargets targets
+-- | Resolve which test suites to run after a clean build. The explicit
+-- source — @test.targets@, falling back to the deprecated top-level
+-- @test_targets@ — is projected onto its @test:@ components (see
+-- 'projectTestTargets'), so non-test entries are dropped and the result only
+-- ever names test suites [ref:test_targets_invariant]. With neither source
+-- set, falls back to deriving test targets from the build 'targets'.
+resolve :: Config -> [Target] -> [TestTarget]
+resolve cfg targets = case cfg.test.commandConfig.targets <|> cfg.testTargets of
+    Just explicit -> parse explicit
+    Nothing -> project targets
diff --git a/src/Tricorder/Session/Util.hs b/src/Tricorder/Session/Util.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/Session/Util.hs
@@ -0,0 +1,17 @@
+module Tricorder.Session.Util
+    ( showList
+    , indent
+    )
+where
+
+import Data.Text qualified as T
+
+
+showList :: (a -> Text) -> [a] -> Text
+showList f xs
+    | null xs = "<empty list>"
+    | otherwise = T.intercalate "\n" $ (("- " <>) . f) <$> xs
+
+
+indent :: Text -> Text
+indent = T.unlines . fmap ("  " <>) . T.lines
diff --git a/src/Tricorder/Session/WatchDirs.hs b/src/Tricorder/Session/WatchDirs.hs
--- a/src/Tricorder/Session/WatchDirs.hs
+++ b/src/Tricorder/Session/WatchDirs.hs
@@ -1,6 +1,6 @@
 module Tricorder.Session.WatchDirs
     ( WatchDirs (..)
-    , resolveWatchDirs
+    , resolve
     , sourceDirsForTarget
     )
 where
@@ -51,8 +51,8 @@
 -- 1. @watch_dirs@ from config, if non-empty (used as-is relative to project root)
 -- 2. @hs-source-dirs@ inferred from cabal targets, if targets are set
 -- 3. Falls back to @["."]@ (project root) if neither is available
-resolveWatchDirs :: ProjectRoot -> [CabalFile] -> Config -> [Target] -> WatchDirs
-resolveWatchDirs projectRoot projectFiles cfg targets =
+resolve :: ProjectRoot -> [CabalFile] -> Config -> [Target] -> WatchDirs
+resolve projectRoot projectFiles cfg targets =
     case cfg.watchDirs of
         dirs@(_ : _) -> WatchDirs $ map (coerce projectRoot </>) dirs
         [] -> resolveWatchDirsFromTargets projectFiles targets
diff --git a/src/Tricorder/Socket/Server.hs b/src/Tricorder/Socket/Server.hs
--- a/src/Tricorder/Socket/Server.hs
+++ b/src/Tricorder/Socket/Server.hs
@@ -18,7 +18,6 @@
 import Effectful.State.Static.Shared qualified as State
 
 import Tricorder.Build (BuildId, BuildPhase, BuildState (..), Diagnostic)
-import Tricorder.Daemon.DaemonInfo (DaemonInfo)
 import Tricorder.Daemon.IdleTimer (IdleTimer)
 import Tricorder.Runtime (SocketPath (..))
 import Tricorder.Socket.Protocol
@@ -57,7 +56,6 @@
        , Exit :> es
        , IdleTimer :> es
        , Input BuildId :> es
-       , Input DaemonInfo :> es
        , Log :> es
        , Reader SocketPath :> es
        , Sub BuildPhase :> es
@@ -78,7 +76,6 @@
        , Exit :> es
        , IdleTimer :> es
        , Input BuildId :> es
-       , Input DaemonInfo :> es
        , Log :> es
        , Reader SocketPath :> es
        , State BuildPhase :> es
@@ -101,7 +98,6 @@
        , Exit :> es
        , IdleTimer :> es
        , Input BuildId :> es
-       , Input DaemonInfo :> es
        , Log :> es
        , State BuildPhase :> es
        , Sub BuildPhase :> es
@@ -127,7 +123,6 @@
     :: ( Conc :> es
        , Exit :> es
        , Input BuildId :> es
-       , Input DaemonInfo :> es
        , Log :> es
        , State BuildPhase :> es
        , Sub BuildPhase :> es
@@ -164,7 +159,6 @@
 
 respondOnce
     :: ( Input BuildId :> es
-       , Input DaemonInfo :> es
        , State BuildPhase :> es
        , UnixSocket :> es
        )
@@ -177,7 +171,6 @@
 respondWhenDone
     :: ( Conc :> es
        , Input BuildId :> es
-       , Input DaemonInfo :> es
        , State BuildPhase :> es
        , Sub BuildPhase :> es
        , UnixSocket :> es
@@ -202,7 +195,6 @@
 -- | Stream a JSON object after each state change event.
 watchStream
     :: ( Input BuildId :> es
-       , Input DaemonInfo :> es
        , State BuildPhase :> es
        , Sub BuildPhase :> es
        , UnixSocket :> es
@@ -240,8 +232,7 @@
 sendJson h val = sendLine h (decodeUtf8 (BSL.toStrict (encode val)))
 
 
-mkBuildState :: (Input BuildId :> es, Input DaemonInfo :> es) => BuildPhase -> Eff es BuildState
+mkBuildState :: (Input BuildId :> es) => BuildPhase -> Eff es BuildState
 mkBuildState phase = do
-    daemonInfo <- input
     buildId <- input
-    pure $ BuildState {daemonInfo, buildId, phase}
+    pure $ BuildState {buildId, phase}
diff --git a/src/Tricorder/SourceLookup.hs b/src/Tricorder/SourceLookup.hs
--- a/src/Tricorder/SourceLookup.hs
+++ b/src/Tricorder/SourceLookup.hs
@@ -14,7 +14,7 @@
 
 import Atelier.Effects.Log qualified as Log
 
-import Tricorder.Session.Command (Repl)
+import Tricorder.Session.Repl (Repl)
 import Tricorder.SourceLookup.GhcPkg (GhcPkg)
 import Tricorder.SourceLookup.Hackage (Hackage)
 import Tricorder.SourceLookup.PackageId (PackageId (..))
diff --git a/src/Tricorder/SourceLookup/GhcPkg.hs b/src/Tricorder/SourceLookup/GhcPkg.hs
--- a/src/Tricorder/SourceLookup/GhcPkg.hs
+++ b/src/Tricorder/SourceLookup/GhcPkg.hs
@@ -16,7 +16,7 @@
 
 import Data.Text qualified as T
 
-import Tricorder.Session.Command (Repl (..))
+import Tricorder.Session.Repl (Repl (..))
 import Tricorder.SourceLookup.PackageId (PackageId (..))
 
 
diff --git a/test/Driver.hs b/test/Driver.hs
--- a/test/Driver.hs
+++ b/test/Driver.hs
@@ -1,2 +1,2 @@
-{-# OPTIONS_GHC -F -pgmF tasty-discover #-}
+{-# OPTIONS_GHC -F -pgmF tasty-discover -optF --tree-display #-}
 
diff --git a/test/Unit/Tricorder/Build/ByteSizeSpec.hs b/test/Unit/Tricorder/Build/ByteSizeSpec.hs
--- a/test/Unit/Tricorder/Build/ByteSizeSpec.hs
+++ b/test/Unit/Tricorder/Build/ByteSizeSpec.hs
@@ -1,73 +1,61 @@
-module Unit.Tricorder.Build.ByteSizeSpec (spec_ByteSize) where
+module Unit.Tricorder.Build.ByteSizeSpec (test_ByteSize) where
 
-import Test.Hspec (Spec, describe, it, shouldBe)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Tricorder.Build.ByteSize (ByteSize (..), Unit (..))
 
 import Tricorder.Build.ByteSize qualified as ByteSize
 
 
-spec_ByteSize :: Spec
-spec_ByteSize = describe "fromText" testFromText
+test_ByteSize :: TestTree
+test_ByteSize =
+    testGroup
+        "ByteSize"
+        [ testGroup "fromText" testFromText
+        ]
 
 
-testFromText :: Spec
-testFromText = do
-    it "parses no unit as bytes" do
-        ByteSize.fromText "1000" `shouldBe` Just (ByteSize 1000 B)
-
-    it "parses bytes with unit" do
-        ByteSize.fromText "1000B" `shouldBe` Just (ByteSize 1000 B)
-
-    it "parses decimal kilobytes" do
-        ByteSize.fromText "10kb" `shouldBe` Just (ByteSize 10 KB)
-
-    it "parses binary kibibytes" do
-        ByteSize.fromText "10kib" `shouldBe` Just (ByteSize 10 KiB)
-
-    it "parses decimal megabytes" do
-        ByteSize.fromText "1mb" `shouldBe` Just (ByteSize 1 MB)
-
-    it "parses binary mebibytes" do
-        ByteSize.fromText "1mib" `shouldBe` Just (ByteSize 1 MiB)
-
-    it "parses decimal gigabytes" do
-        ByteSize.fromText "1gb" `shouldBe` Just (ByteSize 1 GB)
-
-    it "parses binary gibibytes" do
-        ByteSize.fromText "1gib" `shouldBe` Just (ByteSize 1 GiB)
-
-    it "parses decimal terabytes" do
-        ByteSize.fromText "1tb" `shouldBe` Just (ByteSize 1 TB)
-
-    it "parses binary tebibytes" do
-        ByteSize.fromText "1tib" `shouldBe` Just (ByteSize 1 TiB)
-
-    it "parses decimal petabytes" do
-        ByteSize.fromText "1pb" `shouldBe` Just (ByteSize 1 PB)
-
-    it "parses binary pebibytes" do
-        ByteSize.fromText "1pib" `shouldBe` Just (ByteSize 1 PiB)
-
-    it "allows a space between the number and the unit" do
-        ByteSize.fromText "10 kb" `shouldBe` Just (ByteSize 10 KB)
-
-    it "allows multiple spaces between the number and the unit" do
-        ByteSize.fromText "10   kb" `shouldBe` Just (ByteSize 10 KB)
-
-    it "is case-insensitive on the unit" do
-        ByteSize.fromText "10KB" `shouldBe` Just (ByteSize 10 KB)
-        ByteSize.fromText "10Kb" `shouldBe` Just (ByteSize 10 KB)
-        ByteSize.fromText "10KiB" `shouldBe` Just (ByteSize 10 KiB)
-
-    it "fails when there is no number" do
-        ByteSize.fromText "kb" `shouldBe` Nothing
-
-    it "fails on an unrecognized unit" do
-        ByteSize.fromText "10xb" `shouldBe` Nothing
-
-    it "fails on empty text" do
-        ByteSize.fromText "" `shouldBe` Nothing
-
-    it "fails on unrelated text" do
-        ByteSize.fromText "hello world" `shouldBe` Nothing
+testFromText :: [TestTree]
+testFromText =
+    [ testCase "parses no unit as bytes" do
+        ByteSize.fromText "1000" @?= Just (ByteSize 1000 B)
+    , testCase "parses bytes with unit" do
+        ByteSize.fromText "1000B" @?= Just (ByteSize 1000 B)
+    , testCase "parses decimal kilobytes" do
+        ByteSize.fromText "10kb" @?= Just (ByteSize 10 KB)
+    , testCase "parses binary kibibytes" do
+        ByteSize.fromText "10kib" @?= Just (ByteSize 10 KiB)
+    , testCase "parses decimal megabytes" do
+        ByteSize.fromText "1mb" @?= Just (ByteSize 1 MB)
+    , testCase "parses binary mebibytes" do
+        ByteSize.fromText "1mib" @?= Just (ByteSize 1 MiB)
+    , testCase "parses decimal gigabytes" do
+        ByteSize.fromText "1gb" @?= Just (ByteSize 1 GB)
+    , testCase "parses binary gibibytes" do
+        ByteSize.fromText "1gib" @?= Just (ByteSize 1 GiB)
+    , testCase "parses decimal terabytes" do
+        ByteSize.fromText "1tb" @?= Just (ByteSize 1 TB)
+    , testCase "parses binary tebibytes" do
+        ByteSize.fromText "1tib" @?= Just (ByteSize 1 TiB)
+    , testCase "parses decimal petabytes" do
+        ByteSize.fromText "1pb" @?= Just (ByteSize 1 PB)
+    , testCase "parses binary pebibytes" do
+        ByteSize.fromText "1pib" @?= Just (ByteSize 1 PiB)
+    , testCase "allows a space between the number and the unit" do
+        ByteSize.fromText "10 kb" @?= Just (ByteSize 10 KB)
+    , testCase "allows multiple spaces between the number and the unit" do
+        ByteSize.fromText "10   kb" @?= Just (ByteSize 10 KB)
+    , testCase "is case-insensitive on the unit" do
+        ByteSize.fromText "10KB" @?= Just (ByteSize 10 KB)
+        ByteSize.fromText "10Kb" @?= Just (ByteSize 10 KB)
+        ByteSize.fromText "10KiB" @?= Just (ByteSize 10 KiB)
+    , testCase "fails when there is no number" do
+        ByteSize.fromText "kb" @?= Nothing
+    , testCase "fails on an unrecognized unit" do
+        ByteSize.fromText "10xb" @?= Nothing
+    , testCase "fails on empty text" do
+        ByteSize.fromText "" @?= Nothing
+    , testCase "fails on unrelated text" do
+        ByteSize.fromText "hello world" @?= Nothing
+    ]
diff --git a/test/Unit/Tricorder/Build/EvalCommentSpec.hs b/test/Unit/Tricorder/Build/EvalCommentSpec.hs
--- a/test/Unit/Tricorder/Build/EvalCommentSpec.hs
+++ b/test/Unit/Tricorder/Build/EvalCommentSpec.hs
@@ -1,177 +1,153 @@
-module Unit.Tricorder.Build.EvalCommentSpec (spec_EvalComment) where
+module Unit.Tricorder.Build.EvalCommentSpec (test_EvalComment) where
 
-import Test.Hspec (Spec, describe, it, shouldBe, shouldMatchList, shouldSatisfy)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertBool, testCase, (@?=))
 import Text.Megaparsec (parse)
 
 import Tricorder.Build.EvalComment qualified as Eval
 
 
-spec_EvalComment :: Spec
-spec_EvalComment = do
-    describe "singleLineEvalCommentP" testSingleLine
-    describe "multiLineEvalCommentP" testMultiLine
-    describe "blockCommentEvalP" testBlockComment
-    describe "findComments" testFindComments
+test_EvalComment :: TestTree
+test_EvalComment =
+    testGroup
+        "EvalComment"
+        [ testGroup "singleLineEvalCommentP" testSingleLine
+        , testGroup "multiLineEvalCommentP" testMultiLine
+        , testGroup "blockCommentEvalP" testBlockComment
+        , testGroup "findComments" testFindComments
+        ]
 
 
 --------------------------------------------------------------------------------
 -- singleLineEvalCommentP
 --------------------------------------------------------------------------------
 
-testSingleLine :: Spec
-testSingleLine = do
-    it "parses a basic expression" do
+testSingleLine :: [TestTree]
+testSingleLine =
+    [ testCase "parses a basic expression" do
         parse Eval.singleLineEvalCommentP "" "-- $> 1 + 2"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "1 + 2"}
-
-    it "handles no space between marker and expression" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "1 + 2"}
+    , testCase "handles no space between marker and expression" do
         parse Eval.singleLineEvalCommentP "" "-- $>expr"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "expr"}
-
-    it "strips leading whitespace from the expression" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "expr"}
+    , testCase "strips leading whitespace from the expression" do
         parse Eval.singleLineEvalCommentP "" "-- $>   expr"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "expr"}
-
-    it "captures the full expression including inner spaces" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "expr"}
+    , testCase "captures the full expression including inner spaces" do
         parse Eval.singleLineEvalCommentP "" "-- $> foo bar baz"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "foo bar baz"}
-
-    it "stops at a newline, not consuming it" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "foo bar baz"}
+    , testCase "stops at a newline, not consuming it" do
         parse Eval.singleLineEvalCommentP "" "-- $> expr\nnext line"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "expr"}
-
-    it "fails when there is no expression after the marker" do
-        parse Eval.singleLineEvalCommentP "" "-- $>" `shouldSatisfy` isLeft
-
-    it "fails on the multi-line opening marker" do
-        parse Eval.singleLineEvalCommentP "" "-- $$> expr -- <$$" `shouldSatisfy` isLeft
-
-    it "fails on other text between comment start and eval marker" do
-        parse Eval.singleLineEvalCommentP "" "-- foo $> 1 + 2" `shouldSatisfy` isLeft
-
-    it "fails on unrelated text" do
-        parse Eval.singleLineEvalCommentP "" "hello world" `shouldSatisfy` isLeft
+            @?= Right Eval.Comment {lineNumber = 1, expression = "expr"}
+    , testCase "fails when there is no expression after the marker" do
+        assertBool "expected Left" $ isLeft (parse Eval.singleLineEvalCommentP "" "-- $>")
+    , testCase "fails on the multi-line opening marker" do
+        assertBool "expected Left" $ isLeft (parse Eval.singleLineEvalCommentP "" "-- $$> expr -- <$$")
+    , testCase "fails on other text between comment start and eval marker" do
+        assertBool "expected Left" $ isLeft (parse Eval.singleLineEvalCommentP "" "-- foo $> 1 + 2")
+    , testCase "fails on unrelated text" do
+        assertBool "expected Left" $ isLeft (parse Eval.singleLineEvalCommentP "" "hello world")
+    ]
 
 
 --------------------------------------------------------------------------------
 -- multiLineEvalCommentP
 --------------------------------------------------------------------------------
 
-testMultiLine :: Spec
-testMultiLine = do
-    it "parses a single content line, stripping the -- prefix" do
+testMultiLine :: [TestTree]
+testMultiLine =
+    [ testCase "parses a single content line, stripping the -- prefix" do
         parse Eval.multiLineEvalCommentP "" "-- $$>\n-- expr\n-- <$$"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "expr"}
-
-    it "parses multiple content lines, stripping -- prefixes" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "expr"}
+    , testCase "parses multiple content lines, stripping -- prefixes" do
         parse Eval.multiLineEvalCommentP "" "-- $$>\n-- foo\n-- bar\n-- <$$"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "foo\nbar"}
-
-    it "preserves relative indentation after stripping -- prefix" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "foo\nbar"}
+    , testCase "preserves relative indentation after stripping -- prefix" do
         parse Eval.multiLineEvalCommentP "" "-- $$>\n-- let x = 1\n--     y = 2\n-- in x + y\n-- <$$"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "let x = 1\n    y = 2\nin x + y"}
-
-    it "handles -- with no trailing space" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "let x = 1\n    y = 2\nin x + y"}
+    , testCase "handles -- with no trailing space" do
         parse Eval.multiLineEvalCommentP "" "-- $$>\n--expr\n-- <$$"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "expr"}
-
-    it "parse multi-line eval comment in a single line" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "expr"}
+    , testCase "parse multi-line eval comment in a single line" do
         parse Eval.multiLineEvalCommentP "" "-- $$> expr <$$"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "expr"}
-
-    it "fails when the closing marker is absent" do
-        parse Eval.multiLineEvalCommentP "" "-- $$>\n-- expr" `shouldSatisfy` isLeft
-
-    it "fails on the single-line marker" do
-        parse Eval.multiLineEvalCommentP "" "-- $> expr" `shouldSatisfy` isLeft
-
-    it "fails on unrelated text" do
-        parse Eval.multiLineEvalCommentP "" "hello world" `shouldSatisfy` isLeft
+            @?= Right Eval.Comment {lineNumber = 1, expression = "expr"}
+    , testCase "fails when the closing marker is absent" do
+        assertBool "expected Left" $ isLeft (parse Eval.multiLineEvalCommentP "" "-- $$>\n-- expr")
+    , testCase "fails on the single-line marker" do
+        assertBool "expected Left" $ isLeft (parse Eval.multiLineEvalCommentP "" "-- $> expr")
+    , testCase "fails on unrelated text" do
+        assertBool "expected Left" $ isLeft (parse Eval.multiLineEvalCommentP "" "hello world")
+    ]
 
 
 --------------------------------------------------------------------------------
 -- blockCommentEvalP
 --------------------------------------------------------------------------------
 
-testBlockComment :: Spec
-testBlockComment = do
-    it "parses a single-line expression on its own line" do
+testBlockComment :: [TestTree]
+testBlockComment =
+    [ testCase "parses a single-line expression on its own line" do
         parse Eval.blockCommentEvalP "" "{- $$>\n2 + 2\n<$$ -}"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "2 + 2"}
-
-    it "parses an inline one-liner" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "2 + 2"}
+    , testCase "parses an inline one-liner" do
         parse Eval.blockCommentEvalP "" "{- $$> 2 + 2 <$$ -}"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "2 + 2"}
-
-    it "parses a multi-line expression preserving layout" do
+            @?= Right Eval.Comment {lineNumber = 1, expression = "2 + 2"}
+    , testCase "parses a multi-line expression preserving layout" do
         parse Eval.blockCommentEvalP "" "{- $$>\nlet x = 1\n    y = 2\nin x + y\n<$$ -}"
-            `shouldBe` Right Eval.Comment {lineNumber = 1, expression = "let x = 1\n    y = 2\nin x + y"}
-
-    it "fails when the closing marker is absent" do
-        parse Eval.blockCommentEvalP "" "{- $$>\nexpr" `shouldSatisfy` isLeft
-
-    it "fails on the line-comment multi-line eval marker" do
-        parse Eval.blockCommentEvalP "" "-- $$> expr" `shouldSatisfy` isLeft
-
-    it "fails on the single-line eval marker" do
-        parse Eval.blockCommentEvalP "" "{- $> expr -}" `shouldSatisfy` isLeft
-
-    it "fails on unrelated text" do
-        parse Eval.blockCommentEvalP "" "hello world" `shouldSatisfy` isLeft
+            @?= Right Eval.Comment {lineNumber = 1, expression = "let x = 1\n    y = 2\nin x + y"}
+    , testCase "fails when the closing marker is absent" do
+        assertBool "expected Left" $ isLeft (parse Eval.blockCommentEvalP "" "{- $$>\nexpr")
+    , testCase "fails on the line-comment multi-line eval marker" do
+        assertBool "expected Left" $ isLeft (parse Eval.blockCommentEvalP "" "-- $$> expr")
+    , testCase "fails on the single-line eval marker" do
+        assertBool "expected Left" $ isLeft (parse Eval.blockCommentEvalP "" "{- $> expr -}")
+    , testCase "fails on unrelated text" do
+        assertBool "expected Left" $ isLeft (parse Eval.blockCommentEvalP "" "hello world")
+    ]
 
 
 --------------------------------------------------------------------------------
 -- findComments
 --------------------------------------------------------------------------------
 
-testFindComments :: Spec
-testFindComments = do
-    it "returns empty list for empty text" do
-        Eval.findComments "" `shouldMatchList` []
-
-    it "returns empty list when there are no eval comments" do
-        Eval.findComments "hello world\nno comments here" `shouldMatchList` []
-
-    it "finds a single single-line eval comment" do
+testFindComments :: [TestTree]
+testFindComments =
+    [ testCase "returns empty list for empty text" do
+        Eval.findComments "" @?= []
+    , testCase "returns empty list when there are no eval comments" do
+        Eval.findComments "hello world\nno comments here" @?= []
+    , testCase "finds a single single-line eval comment" do
         Eval.findComments "x = 1\n-- $> x\ny = 2"
-            `shouldMatchList` [Eval.Comment {lineNumber = 2, expression = "x"}]
-
-    it "finds multiple single-line eval comments in source order" do
+            @?= [Eval.Comment {lineNumber = 2, expression = "x"}]
+    , testCase "finds multiple single-line eval comments in source order" do
         Eval.findComments "-- $> a\n-- $> b"
-            `shouldMatchList` [ Eval.Comment {lineNumber = 1, expression = "a"}
-                              , Eval.Comment {lineNumber = 2, expression = "b"}
-                              ]
-
-    it "reports correct line numbers" do
+            @?= [ Eval.Comment {lineNumber = 1, expression = "a"}
+                , Eval.Comment {lineNumber = 2, expression = "b"}
+                ]
+    , testCase "reports correct line numbers" do
         Eval.findComments "line1\nline2\n-- $> expr\nline4"
-            `shouldMatchList` [Eval.Comment {lineNumber = 3, expression = "expr"}]
-
-    it "ignores lines that look like partial markers" do
+            @?= [Eval.Comment {lineNumber = 3, expression = "expr"}]
+    , testCase "ignores lines that look like partial markers" do
         Eval.findComments "-- $\n-- $> expr"
-            `shouldMatchList` [Eval.Comment {lineNumber = 2, expression = "expr"}]
-
-    it "does not match an eval marker embedded in another comment" do
-        Eval.findComments "-- foo -- $> expr" `shouldMatchList` []
-
-    it "does not match an inline eval marker appearing after code" do
-        Eval.findComments "x = 1  -- $> x" `shouldMatchList` []
-
-    it "finds a multi-line eval comment, stripping -- prefixes" do
+            @?= [Eval.Comment {lineNumber = 2, expression = "expr"}]
+    , testCase "does not match an eval marker embedded in another comment" do
+        Eval.findComments "-- foo -- $> expr" @?= []
+    , testCase "does not match an inline eval marker appearing after code" do
+        Eval.findComments "x = 1  -- $> x" @?= []
+    , testCase "finds a multi-line eval comment, stripping -- prefixes" do
         Eval.findComments "-- $$>\n-- expr\n-- <$$"
-            `shouldMatchList` [Eval.Comment {lineNumber = 1, expression = "expr"}]
-
-    it "finds a block comment eval" do
+            @?= [Eval.Comment {lineNumber = 1, expression = "expr"}]
+    , testCase "finds a block comment eval" do
         Eval.findComments "{- $$>\nexpr\n<$$ -}"
-            `shouldMatchList` [Eval.Comment {lineNumber = 1, expression = "expr"}]
-
-    it "finds both single-line and multi-line eval comments" do
+            @?= [Eval.Comment {lineNumber = 1, expression = "expr"}]
+    , testCase "finds both single-line and multi-line eval comments" do
         Eval.findComments "-- $> a\n-- $$>\n-- b\n-- <$$"
-            `shouldMatchList` [ Eval.Comment {lineNumber = 1, expression = "a"}
-                              , Eval.Comment {lineNumber = 2, expression = "b"}
-                              ]
-
-    it "finds both single-line and block comment eval comments" do
+            @?= [ Eval.Comment {lineNumber = 1, expression = "a"}
+                , Eval.Comment {lineNumber = 2, expression = "b"}
+                ]
+    , testCase "finds both single-line and block comment eval comments" do
         Eval.findComments "-- $> a\n{- $$>\nb\n<$$ -}"
-            `shouldMatchList` [ Eval.Comment {lineNumber = 1, expression = "a"}
-                              , Eval.Comment {lineNumber = 2, expression = "b"}
-                              ]
+            @?= [ Eval.Comment {lineNumber = 1, expression = "a"}
+                , Eval.Comment {lineNumber = 2, expression = "b"}
+                ]
+    ]
diff --git a/test/Unit/Tricorder/CLI/RenderSpec.hs b/test/Unit/Tricorder/CLI/RenderSpec.hs
--- a/test/Unit/Tricorder/CLI/RenderSpec.hs
+++ b/test/Unit/Tricorder/CLI/RenderSpec.hs
@@ -1,30 +1,36 @@
-module Unit.Tricorder.CLI.RenderSpec (spec_Render) where
+module Unit.Tricorder.CLI.RenderSpec (test_Render) where
 
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (Assertion, assertBool, testCase)
 
+import Data.Text qualified as T
+
 import Tricorder.Build (Diagnostic (..), Severity (..))
 import Tricorder.CLI.Render (diagnosticBlock)
 
 
-spec_Render :: Spec
-spec_Render = do
-    describe "diagnosticBlock" do
-        it "includes the one-liner prefix for an error" do
-            diagnosticBlock errMsg `shouldContainT` "E Foo.hs:10 type mismatch"
-
-        it "includes the full text body after the first line" do
-            diagnosticBlock errMsg `shouldContainT` "\ntype mismatch"
-
-        it "uses 'W' prefix for warnings" do
-            diagnosticBlock warnMsg `shouldContainT` "W Bar.hs:3 unused import"
-
-        it "contains both title and text when they differ" do
-            let d = mixedMsg
-            diagnosticBlock d `shouldContainT` "short title"
-            diagnosticBlock d `shouldContainT` "full body of the message"
+test_Render :: TestTree
+test_Render =
+    testGroup
+        "Render"
+        [ testGroup
+            "diagnosticBlock"
+            [ testCase "includes the one-liner prefix for an error" do
+                diagnosticBlock errMsg `shouldContainT` "E Foo.hs:10 type mismatch"
+            , testCase "includes the full text body after the first line" do
+                diagnosticBlock errMsg `shouldContainT` "\ntype mismatch"
+            , testCase "uses 'W' prefix for warnings" do
+                diagnosticBlock warnMsg `shouldContainT` "W Bar.hs:3 unused import"
+            , testCase "contains both title and text when they differ" do
+                let d = mixedMsg
+                diagnosticBlock d `shouldContainT` "short title"
+                diagnosticBlock d `shouldContainT` "full body of the message"
+            ]
+        ]
   where
-    shouldContainT :: Text -> Text -> Expectation
-    shouldContainT a b = toString a `shouldContain` toString b
+    shouldContainT :: Text -> Text -> Assertion
+    shouldContainT a b =
+        assertBool (toString a <> "\ndoes not contain\n" <> toString b) $ b `T.isInfixOf` a
 
 
 --------------------------------------------------------------------------------
diff --git a/test/Unit/Tricorder/Daemon/BuildStateSpec.hs b/test/Unit/Tricorder/Daemon/BuildStateSpec.hs
--- a/test/Unit/Tricorder/Daemon/BuildStateSpec.hs
+++ b/test/Unit/Tricorder/Daemon/BuildStateSpec.hs
@@ -1,8 +1,9 @@
-module Unit.Tricorder.Daemon.BuildStateSpec (spec_BuildState) where
+module Unit.Tricorder.Daemon.BuildStateSpec (test_BuildState) where
 
 import Data.Aeson (eitherDecode, encode)
 import Data.Time (UTCTime (..), fromGregorian)
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Tricorder.Build
     ( BuildId (..)
@@ -13,74 +14,75 @@
     , Severity (..)
     )
 import Tricorder.Build.Duration (Duration (..))
-import Tricorder.Daemon.DaemonInfo (DaemonInfo (..))
 
 import Tricorder.Build qualified as Build
 import Tricorder.Build.EvalComment qualified as Eval
 
 
-spec_BuildState :: Spec
-spec_BuildState = do
-    describe "JSON round-trip" do
-        it "survives Unicode smart quotes in message text" do
-            let msg =
-                    Diagnostic
-                        { severity = SWarning
-                        , file = "<interactive>"
-                        , line = 2
-                        , col = 8
-                        , endLine = 2
-                        , endCol = 8
-                        , title = "Found \8216qualified\8217 in prepositive position"
-                        , text =
-                            "Found \8216qualified\8217 in prepositive position\n    Suggested fixes:\n      \8226 Place \8216qualified\8217 after the module name."
-                        }
-                bs = mkBuildState [msg]
-            eitherDecode (encode bs) `shouldBe` Right bs
-
-        it "survives control characters in message text" do
-            let msg =
-                    Diagnostic
-                        { severity = SWarning
-                        , file = "<interactive>"
-                        , line = 1
-                        , col = 1
-                        , endLine = 1
-                        , endCol = 1
-                        , title = "text with \CAN control \EM chars and \ESC[1m ANSI \ESC[0m codes"
-                        , text = "text with \CAN control \EM chars and \ESC[1m ANSI \ESC[0m codes"
-                        }
-                bs = mkBuildState [msg]
-            eitherDecode (encode bs) `shouldBe` Right bs
-
-        it "survives curly double quotes in message text" do
-            let msg =
-                    Diagnostic
-                        { severity = SWarning
-                        , file = "<interactive>"
-                        , line = 1
-                        , col = 1
-                        , endLine = 1
-                        , endCol = 1
-                        , title = "\8220Place qualified after the module name.\8221"
-                        , text = "\8220Place qualified after the module name.\8221"
-                        }
-                bs = mkBuildState [msg]
-            eitherDecode (encode bs) `shouldBe` Right bs
-
-        -- Guards the wire format for the BuildFailed phase: the captured
-        -- cabal/build error (multi-line, Unicode) must round-trip intact so
-        -- the CLI/UI clients can render it.
-        it "survives a BuildFailed phase with a multi-line message" do
-            let bs =
-                    mkBuildState [] :: BuildState
-                failed =
-                    bs
-                        { phase =
-                            Build.Failed
-                                "cabal: Could not resolve dependencies:\n[__0] trying: \8216base\8217\nrejecting: ..."
-                        }
-            eitherDecode (encode failed) `shouldBe` Right failed
+test_BuildState :: TestTree
+test_BuildState =
+    testGroup
+        "BuildState"
+        [ testGroup
+            "JSON round-trip"
+            [ testCase "survives Unicode smart quotes in message text" do
+                let msg =
+                        Diagnostic
+                            { severity = SWarning
+                            , file = "<interactive>"
+                            , line = 2
+                            , col = 8
+                            , endLine = 2
+                            , endCol = 8
+                            , title = "Found \8216qualified\8217 in prepositive position"
+                            , text =
+                                "Found \8216qualified\8217 in prepositive position\n    Suggested fixes:\n      \8226 Place \8216qualified\8217 after the module name."
+                            }
+                    bs = mkBuildState [msg]
+                eitherDecode (encode bs) @?= Right bs
+            , testCase "survives control characters in message text" do
+                let msg =
+                        Diagnostic
+                            { severity = SWarning
+                            , file = "<interactive>"
+                            , line = 1
+                            , col = 1
+                            , endLine = 1
+                            , endCol = 1
+                            , title = "text with \CAN control \EM chars and \ESC[1m ANSI \ESC[0m codes"
+                            , text = "text with \CAN control \EM chars and \ESC[1m ANSI \ESC[0m codes"
+                            }
+                    bs = mkBuildState [msg]
+                eitherDecode (encode bs) @?= Right bs
+            , testCase "survives curly double quotes in message text" do
+                let msg =
+                        Diagnostic
+                            { severity = SWarning
+                            , file = "<interactive>"
+                            , line = 1
+                            , col = 1
+                            , endLine = 1
+                            , endCol = 1
+                            , title = "\8220Place qualified after the module name.\8221"
+                            , text = "\8220Place qualified after the module name.\8221"
+                            }
+                    bs = mkBuildState [msg]
+                eitherDecode (encode bs) @?= Right bs
+            , -- Guards the wire format for the BuildFailed phase: the captured
+              -- cabal/build error (multi-line, Unicode) must round-trip intact so
+              -- the CLI/UI clients can render it.
+              testCase "survives a BuildFailed phase with a multi-line message" do
+                let bs =
+                        mkBuildState [] :: BuildState
+                    failed =
+                        bs
+                            { phase =
+                                Build.Failed
+                                    "cabal: Could not resolve dependencies:\n[__0] trying: \8216base\8217\nrejecting: ..."
+                            }
+                eitherDecode (encode failed) @?= Right failed
+            ]
+        ]
 
 
 mkBuildState :: [Diagnostic] -> BuildState
@@ -97,13 +99,6 @@
                     }
                 )
                 $ PostBuild mempty Eval.NoneFound
-        , daemonInfo =
-            DaemonInfo
-                { targets = []
-                , watchDirs = []
-                , sockPath = ""
-                , logFile = ""
-                }
         }
   where
     epoch = UTCTime (fromGregorian 1970 1 1) 0
diff --git a/test/Unit/Tricorder/Daemon/BuilderSpec.hs b/test/Unit/Tricorder/Daemon/BuilderSpec.hs
--- a/test/Unit/Tricorder/Daemon/BuilderSpec.hs
+++ b/test/Unit/Tricorder/Daemon/BuilderSpec.hs
@@ -1,7 +1,8 @@
-module Unit.Tricorder.Daemon.BuilderSpec (spec_Builder) where
+module Unit.Tricorder.Daemon.BuilderSpec (test_Builder) where
 
 import Data.Time (UTCTime (..), addUTCTime, fromGregorian)
-import Test.Hspec (Spec, describe, it, shouldBe)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Data.Map.Strict qualified as Map
 import Data.Set qualified as Set
@@ -19,20 +20,23 @@
 import Tricorder.Session.WatchDirs (WatchDirs (..))
 
 
-spec_Builder :: Spec
-spec_Builder = do
-    describe "extractTitle" testExtractTitle
-    describe "compileBuildResults" testCompileBuildResults
-    describe "resolveKnownTargets" testResolveKnownTargets
+test_Builder :: TestTree
+test_Builder =
+    testGroup
+        "Builder"
+        [ testGroup "extractTitle" testExtractTitle
+        , testGroup "compileBuildResults" testCompileBuildResults
+        , testGroup "resolveKnownTargets" testResolveKnownTargets
+        ]
 
 
 data StopSignal = StopSignal
     deriving stock (Show)
 
 
-testCompileBuildResults :: Spec
-testCompileBuildResults = do
-    it "uses NewLoadResult's times to calculate duration" do
+testCompileBuildResults :: [TestTree]
+testCompileBuildResults =
+    [ testCase "uses NewLoadResult's times to calculate duration" do
         let (_, r) =
                 compileBuildResults
                     root
@@ -50,8 +54,8 @@
                                 , diagnostics = []
                                 }
                         }
-        r.duration `shouldBe` Duration 10_000
-    it "merges with existing results" do
+        r.duration @?= Duration 10_000
+    , testCase "merges with existing results" do
         let (m, _) =
                 compileBuildResults root watchDirs (Map.fromList [(errMsg.file, [errMsg])])
                     $ NewLoadResult
@@ -67,12 +71,11 @@
                                 }
                         }
         m
-            `shouldBe` fromList
+            @?= fromList
                 [ (warnMsg.file, [warnMsg])
                 , (errMsg.file, [errMsg])
                 ]
-
-    it "returns a BuildResult" do
+    , testCase "returns a BuildResult" do
         let (_, r) =
                 compileBuildResults root watchDirs mempty
                     $ NewLoadResult
@@ -94,7 +97,8 @@
                     , moduleCount = 2
                     , diagnostics = [warnMsg]
                     }
-        r `shouldBe` expected
+        r @?= expected
+    ]
   where
     root = ProjectRoot "/"
     watchDirs = WatchDirs ["/src"]
@@ -104,9 +108,9 @@
 -- resolveKnownTargets tests
 --------------------------------------------------------------------------------
 
-testResolveKnownTargets :: Spec
-testResolveKnownTargets = do
-    it "uses :show modules as the primary source for path↔name mapping" do
+testResolveKnownTargets :: [TestTree]
+testResolveKnownTargets =
+    [ testCase "uses :show modules as the primary source for path↔name mapping" do
         let result =
                 emptyLr
                     { loadedModules =
@@ -119,19 +123,18 @@
                     , targetNames = ["Foo"]
                     }
         resolveKnownTargets Map.empty result
-            `shouldBe` Map.fromList
+            @?= Map.fromList
                 [
                     ( "/abs/src/Foo.hs"
                     , LoadedModule {relPath = "./src/Foo.hs", moduleName = "Foo"}
                     )
                 ]
-
-    -- Regression test for the stale-results bug. After a failed compile, the
-    -- module disappears from :show modules but stays in :show targets. The
-    -- prior state's entry must be carried over so the dispatcher continues to
-    -- see the file as "known" and issues :reload (not :add) when the user
-    -- fixes the error.
-    it "carries over prior state for targets that are no longer in :show modules" do
+    , -- Regression test for the stale-results bug. After a failed compile, the
+      -- module disappears from :show modules but stays in :show targets. The
+      -- prior state's entry must be carried over so the dispatcher continues to
+      -- see the file as "known" and issues :reload (not :add) when the user
+      -- fixes the error.
+      testCase "carries over prior state for targets that are no longer in :show modules" do
         let prev =
                 Map.fromList
                     [
@@ -144,9 +147,8 @@
                     { loadedModules = Map.empty -- Foo failed to compile
                     , targetNames = ["Foo"] -- but is still a target
                     }
-        resolveKnownTargets prev result `shouldBe` prev
-
-    it "drops targets that are no longer in :show targets" do
+        resolveKnownTargets prev result @?= prev
+    , testCase "drops targets that are no longer in :show targets" do
         let prev =
                 Map.fromList
                     [
@@ -155,13 +157,13 @@
                         )
                     ]
             result = emptyLr {loadedModules = Map.empty, targetNames = []}
-        resolveKnownTargets prev result `shouldBe` Map.empty
-
-    -- Dropped from the path-keyed map because we have no path↔name entry;
-    -- the dispatcher still handles them via 'KnownTargetNames'.
-    it "drops targets that have neither a current :show modules entry nor prior state" do
+        resolveKnownTargets prev result @?= Map.empty
+    , -- Dropped from the path-keyed map because we have no path↔name entry;
+      -- the dispatcher still handles them via 'KnownTargetNames'.
+      testCase "drops targets that have neither a current :show modules entry nor prior state" do
         let result = emptyLr {loadedModules = Map.empty, targetNames = ["BrandNew"]}
-        resolveKnownTargets Map.empty result `shouldBe` Map.empty
+        resolveKnownTargets Map.empty result @?= Map.empty
+    ]
   where
     emptyLr =
         LoadResult
@@ -177,14 +179,13 @@
 -- extractTitle tests
 --------------------------------------------------------------------------------
 
-testExtractTitle :: Spec
-testExtractTitle = do
-    it "returns empty string for empty message" do
-        extractTitle [] `shouldBe` ""
-
-    -- New GHC style: header ends with [GHC-XXXXX], content on body lines.
-    -- Captured from GHC 9.10.2 with -Weverything.
-    it "extracts first body line for error with [GHC-XXXXX] code" do
+testExtractTitle :: [TestTree]
+testExtractTitle =
+    [ testCase "returns empty string for empty message" do
+        extractTitle [] @?= ""
+    , -- New GHC style: header ends with [GHC-XXXXX], content on body lines.
+      -- Captured from GHC 9.10.2 with -Weverything.
+      testCase "extracts first body line for error with [GHC-XXXXX] code" do
         extractTitle
             [ "src/Tricorder/Config.hs:39:20: error: [GHC-83865]"
             , "    \8226 Couldn't match expected type 'Int' with actual type 'Bool'"
@@ -194,9 +195,8 @@
             , "39 | _deliberateError = True"
             , "   |                    ^^^^"
             ]
-            `shouldBe` "\8226 Couldn't match expected type 'Int' with actual type 'Bool'"
-
-    it "extracts first body line for warning with [GHC-XXXXX] [-Wfoo] codes" do
+            @?= "\8226 Couldn't match expected type 'Int' with actual type 'Bool'"
+    , testCase "extracts first body line for warning with [GHC-XXXXX] [-Wfoo] codes" do
         extractTitle
             [ "src/Tricorder/Config.hs:38:26: warning: [GHC-55631] [-Wmissing-deriving-strategies]"
             , "    No deriving strategy specified. Did you want stock, newtype, or anyclass?"
@@ -204,35 +204,30 @@
             , "38 | data TestWarn = TestWarn deriving (Eq)"
             , "   |                          ^^^^^^^^^^^^^"
             ]
-            `shouldBe` "No deriving strategy specified. Did you want stock, newtype, or anyclass?"
-
-    -- Old GHC style: message text is inline on the header line.
-    it "extracts inline content for old-style single-line error" do
+            @?= "No deriving strategy specified. Did you want stock, newtype, or anyclass?"
+    , -- Old GHC style: message text is inline on the header line.
+      testCase "extracts inline content for old-style single-line error" do
         extractTitle ["GHCi.hs:70:1: error: Parse error: naked expression at top level"]
-            `shouldBe` "Parse error: naked expression at top level"
-
-    it "extracts inline content for old-style Warning (capital W)" do
+            @?= "Parse error: naked expression at top level"
+    , testCase "extracts inline content for old-style Warning (capital W)" do
         extractTitle ["GHCi.hs:81:1: Warning: Defined but not used: \8216foo\8217"]
-            `shouldBe` "Defined but not used: \8216foo\8217"
-
-    -- Multi-line without any inline message: position-only or "Warning:" header.
-    it "extracts first body line when header has position only" do
+            @?= "Defined but not used: \8216foo\8217"
+    , -- Multi-line without any inline message: position-only or "Warning:" header.
+      testCase "extracts first body line when header has position only" do
         extractTitle
             [ "GHCi.hs:72:13:"
             , "    No instance for (Num ([String] -> [String]))"
             , "      arising from the literal '1'"
             ]
-            `shouldBe` "No instance for (Num ([String] -> [String]))"
-
-    it "extracts first body line when header ends with 'Warning:'" do
+            @?= "No instance for (Num ([String] -> [String]))"
+    , testCase "extracts first body line when header ends with 'Warning:'" do
         extractTitle
             [ "/src/TrieSpec.hs:(192,7)-(193,76): Warning:"
             , "    A do-notation statement discarded a result of type '[()]'"
             ]
-            `shouldBe` "A do-notation statement discarded a result of type '[()]'"
-
-    -- Source display lines (pipe/caret) must be skipped.
-    it "skips source display lines when scanning body" do
+            @?= "A do-notation statement discarded a result of type '[()]'"
+    , -- Source display lines (pipe/caret) must be skipped.
+      testCase "skips source display lines when scanning body" do
         extractTitle
             [ "file.hs:1:1: error: [GHC-12345]"
             , "   |"
@@ -240,15 +235,15 @@
             , "   |     ^^^"
             , "    actual content here"
             ]
-            `shouldBe` "actual content here"
-
-    -- ANSI-escaped header (colour output): strip escapes before searching.
-    it "handles ANSI-escaped headers" do
+            @?= "actual content here"
+    , -- ANSI-escaped header (colour output): strip escapes before searching.
+      testCase "handles ANSI-escaped headers" do
         extractTitle
             [ "\ESC[;1msrc/Types.hs:11:1: \ESC[35mwarning:\ESC[0m \ESC[35m[-Wunused-imports]\ESC[0m"
             , "    The import of 'Data.Data' is redundant"
             ]
-            `shouldBe` "The import of 'Data.Data' is redundant"
+            @?= "The import of 'Data.Data' is redundant"
+    ]
 
 
 --------------------------------------------------------------------------------
diff --git a/test/Unit/Tricorder/Daemon/DispatchSpec.hs b/test/Unit/Tricorder/Daemon/DispatchSpec.hs
--- a/test/Unit/Tricorder/Daemon/DispatchSpec.hs
+++ b/test/Unit/Tricorder/Daemon/DispatchSpec.hs
@@ -1,6 +1,7 @@
-module Unit.Tricorder.Daemon.DispatchSpec (spec_Dispatch) where
+module Unit.Tricorder.Daemon.DispatchSpec (test_Dispatch) where
 
-import Test.Hspec (Spec, describe, it, shouldBe, shouldMatchList, shouldSatisfy)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertBool, testCase, (@?=))
 
 import Data.Map.Strict qualified as Map
 import Data.Set qualified as Set
@@ -17,77 +18,74 @@
 import Tricorder.Session.WatchDirs (WatchDirs (..))
 
 
-spec_Dispatch :: Spec
-spec_Dispatch = do
-    describe "fileMatchesAnyTarget" testFileMatchesAnyTarget
-    describe "mergeDiagnostics" testMergeDiagnostics
-    describe "filterToWatchDirs" testFilterToWatchDirs
+test_Dispatch :: TestTree
+test_Dispatch =
+    testGroup
+        "Dispatch"
+        [ testGroup "fileMatchesAnyTarget" testFileMatchesAnyTarget
+        , testGroup "mergeDiagnostics" testMergeDiagnostics
+        , testGroup "filterToWatchDirs" testFilterToWatchDirs
+        ]
 
 
 --------------------------------------------------------------------------------
 -- fileMatchesAnyTarget tests
 --------------------------------------------------------------------------------
 
-testFileMatchesAnyTarget :: Spec
-testFileMatchesAnyTarget = do
-    it "matches when the path's uppercase-suffix equals a target" do
+testFileMatchesAnyTarget :: [TestTree]
+testFileMatchesAnyTarget =
+    [ testCase "matches when the path's uppercase-suffix equals a target" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "Tricorder.Version"))
             "./tricorder/src/Tricorder/Version.hs"
-            `shouldBe` True
-
-    it "matches a single-segment module" do
+            @?= True
+    , testCase "matches a single-segment module" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "Main"))
             "./app/Main.hs"
-            `shouldBe` True
-
-    it "does not match when no uppercase-suffix equals a target" do
+            @?= True
+    , testCase "does not match when no uppercase-suffix equals a target" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "Other.Module"))
             "./tricorder/src/Tricorder/Version.hs"
-            `shouldBe` False
-
-    it "does not match a lowercase-prefix even if textually contained" do
+            @?= False
+    , testCase "does not match a lowercase-prefix even if textually contained" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "src.Tricorder.Version"))
             "./tricorder/src/Tricorder/Version.hs"
-            `shouldBe` False
-
-    it "handles .lhs extension" do
+            @?= False
+    , testCase "handles .lhs extension" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "Foo.Bar"))
             "./src/Foo/Bar.lhs"
-            `shouldBe` True
-
-    -- GHCi renders a target whose module name is ambiguous across home units
-    -- (every executable/test 'Main') as its source path, e.g. "app/Main.hs".
-    it "matches a path-shaped target on directory-segment boundaries" do
+            @?= True
+    , -- GHCi renders a target whose module name is ambiguous across home units
+      -- (every executable/test 'Main') as its source path, e.g. "app/Main.hs".
+      testCase "matches a path-shaped target on directory-segment boundaries" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "app/Main.hs"))
             "./tricorder/app/Main.hs"
-            `shouldBe` True
-
-    it "does not match a path-shaped target on a partial segment" do
+            @?= True
+    , testCase "does not match a path-shaped target on a partial segment" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "pp/Main.hs"))
             "./tricorder/app/Main.hs"
-            `shouldBe` False
-
-    it "does not match a path-shaped target for a different file" do
+            @?= False
+    , testCase "does not match a path-shaped target for a different file" do
         fileMatchesAnyTarget
             (KnownTargetNames (Set.singleton "daemon/Main.hs"))
             "./tricorder/app/Main.hs"
-            `shouldBe` False
+            @?= False
+    ]
 
 
 --------------------------------------------------------------------------------
 -- mergeDiagnostics tests
 --------------------------------------------------------------------------------
 
-testMergeDiagnostics :: Spec
-testMergeDiagnostics = do
-    it "retains diagnostics from files not in compiledFiles" do
+testMergeDiagnostics :: [TestTree]
+testMergeDiagnostics =
+    [ testCase "retains diagnostics from files not in compiledFiles" do
         -- Foo has an error, Bar has a warning.
         -- Only Foo is recompiled (and fixed). Bar is unchanged, so Bar's
         -- warning must survive.
@@ -101,9 +99,8 @@
                     , diagnostics = []
                     }
         let merged = mergeDiagnostics prev result
-        Map.lookup warnMsg.file merged `shouldBe` Just [warnMsg]
-
-    it "clears diagnostics when a recompiled file now has no issues" do
+        Map.lookup warnMsg.file merged @?= Just [warnMsg]
+    , testCase "clears diagnostics when a recompiled file now has no issues" do
         let prev = Map.fromList [(errMsg.file, [errMsg])]
             result =
                 LoadResult
@@ -114,9 +111,8 @@
                     , diagnostics = []
                     }
         let merged = mergeDiagnostics prev result
-        Map.lookup errMsg.file merged `shouldBe` Nothing
-
-    it "replaces diagnostics for recompiled files" do
+        Map.lookup errMsg.file merged @?= Nothing
+    , testCase "replaces diagnostics for recompiled files" do
         let newErr = errMsg {title = "new error", text = "new error\n"}
             prev = Map.fromList [(errMsg.file, [errMsg])]
             result =
@@ -128,9 +124,8 @@
                     , diagnostics = [newErr]
                     }
         let merged = mergeDiagnostics prev result
-        Map.lookup errMsg.file merged `shouldBe` Just [newErr]
-
-    it "accumulates diagnostics for newly seen files" do
+        Map.lookup errMsg.file merged @?= Just [newErr]
+    , testCase "accumulates diagnostics for newly seen files" do
         let result =
                 LoadResult
                     { moduleCount = 1
@@ -140,26 +135,27 @@
                     , diagnostics = [warnMsg]
                     }
         let merged = mergeDiagnostics Map.empty result
-        Map.lookup warnMsg.file merged `shouldBe` Just [warnMsg]
-
-    describe "when the cycle reports none" $ it "clears a stale location-less diagnostic" do
-        -- <no location info> is never in compiledFiles, so without special
-        -- handling it would persist forever. A cycle with no location-less
-        -- diagnostic must evict it.
-        let noLoc = errMsg {file = "<no location info>"}
-            prev = Map.fromList [(noLoc.file, [noLoc])]
-            result =
-                LoadResult
-                    { moduleCount = 1
-                    , compiledFiles = Set.singleton errMsg.file
-                    , loadedModules = Map.empty
-                    , targetNames = []
-                    , diagnostics = []
-                    }
-        let merged = mergeDiagnostics prev result
-        Map.lookup noLoc.file merged `shouldBe` Nothing
-
-    it "refreshes a location-less diagnostic that is still present" do
+        Map.lookup warnMsg.file merged @?= Just [warnMsg]
+    , testGroup
+        "when the cycle reports none"
+        [ testCase "clears a stale location-less diagnostic" do
+            -- <no location info> is never in compiledFiles, so without special
+            -- handling it would persist forever. A cycle with no location-less
+            -- diagnostic must evict it.
+            let noLoc = errMsg {file = "<no location info>"}
+                prev = Map.fromList [(noLoc.file, [noLoc])]
+                result =
+                    LoadResult
+                        { moduleCount = 1
+                        , compiledFiles = Set.singleton errMsg.file
+                        , loadedModules = Map.empty
+                        , targetNames = []
+                        , diagnostics = []
+                        }
+            let merged = mergeDiagnostics prev result
+            Map.lookup noLoc.file merged @?= Nothing
+        ]
+    , testCase "refreshes a location-less diagnostic that is still present" do
         let noLoc = errMsg {file = "<no location info>"}
             prev = Map.fromList [(noLoc.file, [noLoc])]
             result =
@@ -171,83 +167,82 @@
                     , diagnostics = [noLoc]
                     }
         let merged = mergeDiagnostics prev result
-        Map.lookup noLoc.file merged `shouldBe` Just [noLoc]
+        Map.lookup noLoc.file merged @?= Just [noLoc]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- filterToWatchDirs tests
 --------------------------------------------------------------------------------
 
-testFilterToWatchDirs :: Spec
-testFilterToWatchDirs = do
-    let root = "/project"
-        watchDirs = WatchDirs ["/project/src"]
-
-    it "keeps diagnostics under a watched directory" do
+testFilterToWatchDirs :: [TestTree]
+testFilterToWatchDirs =
+    [ testCase "keeps diagnostics under a watched directory" do
         -- ./src/Foo.hs is what toRelative produces for an absolute project file
         let d = errMsg {file = "./src/Foo.hs"}
-        filterToWatchDirs root watchDirs [d] `shouldBe` [d]
-
-    it "keeps diagnostics under \".\" watched directory" do
+        filterToWatchDirs root watchDirs [d] @?= [d]
+    , testCase "keeps diagnostics under \".\" watched directory" do
         let d = errMsg {file = "src/Foo.hs"}
-        filterToWatchDirs root (WatchDirs ["."]) [d] `shouldMatchList` [d]
-
-    it "drops diagnostics from outside the project (e.g. Nix store .h files)" do
+        filterToWatchDirs root (WatchDirs ["."]) [d] @?= [d]
+    , testCase "drops diagnostics from outside the project (e.g. Nix store .h files)" do
         let d = errMsg {file = "/nix/store/abc123/ghcautoconf.h"}
-        filterToWatchDirs root watchDirs [d] `shouldBe` []
-
-    it "drops diagnostics with mangled CPP filenames" do
+        filterToWatchDirs root watchDirs [d] @?= []
+    , testCase "drops diagnostics with mangled CPP filenames" do
         -- The ghcid parser produces "In file included from <path>" as the file
         -- field for GCC-style CPP include-chain messages.
         let d = errMsg {file = "In file included from src/Foo.hs"}
-        filterToWatchDirs root watchDirs [d] `shouldBe` []
-
-    it "drops mangled CPP filenames when watchDirs is [\".\"] (project root)" do
+        filterToWatchDirs root watchDirs [d] @?= []
+    , testCase "drops mangled CPP filenames when watchDirs is [\".\"] (project root)" do
         -- With watchDirs=["."], the watch dir resolves to projectRoot itself.
         -- A mangled path joined onto projectRoot would incorrectly start with
         -- projectRoot+"/", so this case requires an explicit guard.
         let d = errMsg {file = "In file included from src/Foo.hs"}
-        filterToWatchDirs root (WatchDirs ["."]) [d] `shouldBe` []
-
-    it "passes everything through when watchDirs is empty" do
+        filterToWatchDirs root (WatchDirs ["."]) [d] @?= []
+    , testCase "passes everything through when watchDirs is empty" do
         let d = errMsg {file = "/nix/store/abc123/ghcautoconf.h"}
-        filterToWatchDirs root (WatchDirs []) [d] `shouldBe` [d]
-
-    it "works with the '.' fallback watch dir (whole project root)" do
+        filterToWatchDirs root (WatchDirs []) [d] @?= [d]
+    , testCase "works with the '.' fallback watch dir (whole project root)" do
         let d = errMsg {file = "./src/Foo.hs"}
             nixD = errMsg {file = "/nix/store/abc123/ghcautoconf.h"}
-        filterToWatchDirs root (WatchDirs ["."]) [d, nixD] `shouldBe` [d]
-
-    describe "when diagnostic has no path it" $ it "keeps location-less <no location info> errors" do
-        -- A home-unit GHC plugin that can't load under --enable-multi-repl
-        -- produces a <no location info> error. It has no path to test against a
-        -- watch dir, but must survive or the failed build reads as clean.
-        let d = errMsg {file = "<no location info>"}
-        filterToWatchDirs root watchDirs [d] `shouldBe` [d]
-
-    it "does not treat a real <-prefixed path as a location-less marker" do
+        filterToWatchDirs root (WatchDirs ["."]) [d, nixD] @?= [d]
+    , testGroup
+        "when diagnostic has no path it"
+        [ testCase "keeps location-less <no location info> errors" do
+            -- A home-unit GHC plugin that can't load under --enable-multi-repl
+            -- produces a <no location info> error. It has no path to test against a
+            -- watch dir, but must survive or the failed build reads as clean.
+            let d = errMsg {file = "<no location info>"}
+            filterToWatchDirs root watchDirs [d] @?= [d]
+        ]
+    , testCase "does not treat a real <-prefixed path as a location-less marker" do
         -- isLocationLess requires a closing '>'. A real (if exotic) path that
         -- merely starts with '<' is an ordinary out-of-watch file and must be
         -- dropped, not kept as a build-level marker.
         let d = errMsg {file = "<generated>/Foo.hs"}
-        filterToWatchDirs root watchDirs [d] `shouldBe` []
-
-    describe "when its only error is out of watch dirs" $ it "a failed load does not read as clean" do
-        -- collectResult only injects its synthetic failure when no SError is
-        -- present. Here GHCi Failed with a single *located* error in a file
-        -- outside the watch dirs, so collectResult adds no synthetic — and then
-        -- filterToWatchDirs drops the out-of-watch error, leaving nothing. The
-        -- Builder pipeline composes preserveFailureVisibility after filtering to
-        -- re-attach the failure, so a failed build never survives with zero
-        -- diagnostics.
-        let reloadOutput =
-                [ "/other/Dep.hs:5:1: error: boom"
-                , "Failed, 0 modules loaded."
-                ]
-            result = collectResult root reloadOutput [] []
-            filtered = filterToWatchDirs root watchDirs result.diagnostics
-        preserveFailureVisibility result.diagnostics filtered
-            `shouldSatisfy` (not . null)
+        filterToWatchDirs root watchDirs [d] @?= []
+    , testGroup
+        "when its only error is out of watch dirs"
+        [ testCase "a failed load does not read as clean" do
+            -- collectResult only injects its synthetic failure when no SError is
+            -- present. Here GHCi Failed with a single *located* error in a file
+            -- outside the watch dirs, so collectResult adds no synthetic — and then
+            -- filterToWatchDirs drops the out-of-watch error, leaving nothing. The
+            -- Builder pipeline composes preserveFailureVisibility after filtering to
+            -- re-attach the failure, so a failed build never survives with zero
+            -- diagnostics.
+            let reloadOutput =
+                    [ "/other/Dep.hs:5:1: error: boom"
+                    , "Failed, 0 modules loaded."
+                    ]
+                result = collectResult root reloadOutput [] []
+                filtered = filterToWatchDirs root watchDirs result.diagnostics
+            assertBool "expected at least one diagnostic"
+                $ not (null (preserveFailureVisibility result.diagnostics filtered))
+        ]
+    ]
+  where
+    root = "/project"
+    watchDirs = WatchDirs ["/project/src"]
 
 
 --------------------------------------------------------------------------------
diff --git a/test/Unit/Tricorder/Daemon/GhciSession/GhciParserSpec.hs b/test/Unit/Tricorder/Daemon/GhciSession/GhciParserSpec.hs
--- a/test/Unit/Tricorder/Daemon/GhciSession/GhciParserSpec.hs
+++ b/test/Unit/Tricorder/Daemon/GhciSession/GhciParserSpec.hs
@@ -1,6 +1,7 @@
-module Unit.Tricorder.Daemon.GhciSession.GhciParserSpec (spec_GhciParser) where
+module Unit.Tricorder.Daemon.GhciSession.GhciParserSpec (test_GhciParser) where
 
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertBool, testCase, (@?=))
 
 import Tricorder.Build (Diagnostic (..), Severity (..))
 import Tricorder.Daemon.GhciSession.GhciParser
@@ -19,35 +20,42 @@
     )
 
 
-spec_GhciParser :: Spec
-spec_GhciParser = do
-    describe "parseReload" do
-        describe "clean build" testCleanBuild
-        describe "with errors and warnings" testErrors
-        describe "with -fhide-source-paths (no Loading items)" testHideSourcePaths
-        describe "with <no location info> errors" testNoLocationInfo
-        describe "with Loaded GHCi configuration" testLoadedConfig
-
-    describe "parseShowModules" do
-        describe "typical output" testShowModules
-        describe "empty / blank input" testShowModulesEmpty
-
-    describe "parseShowTargets" testShowTargets
-
-    describe "collectResultCustom" do
-        describe "<no location info> plugin load failure" testPluginLoadFailure
-
-    describe "collectResult" do
-        describe "failed load with no located error" testUnattributedFailure
+test_GhciParser :: TestTree
+test_GhciParser =
+    testGroup
+        "GhciParser"
+        [ testGroup
+            "parseReload"
+            [ testGroup "clean build" testCleanBuild
+            , testGroup "with errors and warnings" testErrors
+            , testGroup "with -fhide-source-paths (no Loading items)" testHideSourcePaths
+            , testGroup "with <no location info> errors" testNoLocationInfo
+            , testGroup "with Loaded GHCi configuration" testLoadedConfig
+            ]
+        , testGroup
+            "parseShowModules"
+            [ testGroup "typical output" testShowModules
+            , testGroup "empty / blank input" testShowModulesEmpty
+            ]
+        , testGroup "parseShowTargets" testShowTargets
+        , testGroup
+            "collectResultCustom"
+            [ testGroup "<no location info> plugin load failure" testPluginLoadFailure
+            ]
+        , testGroup
+            "collectResult"
+            [ testGroup "failed load with no located error" testUnattributedFailure
+            ]
+        ]
 
 
 --------------------------------------------------------------------------------
 -- parseReload: clean build
 --------------------------------------------------------------------------------
 
-testCleanBuild :: Spec
-testCleanBuild = do
-    it "produces GLoading items for each compiled module" do
+testCleanBuild :: [TestTree]
+testCleanBuild =
+    [ testCase "produces GLoading items for each compiled module" do
         let input =
                 [ "[1 of 3] Compiling Tricorder.Build ( src/Tricorder.Build.hs, interpreted )"
                 , "[2 of 3] Compiling Tricorder.Session    ( src/Tricorder/Session.hs, interpreted )"
@@ -55,118 +63,115 @@
                 , "Ok, 3 modules loaded."
                 ]
         parseReload input
-            `shouldBe` [ GLoading
-                            GhciLoading
-                                { index = 1
-                                , total = 3
-                                , moduleName = "Tricorder.Build"
-                                , sourceFile = "src/Tricorder.Build.hs"
-                                }
-                       , GLoading
-                            GhciLoading
-                                { index = 2
-                                , total = 3
-                                , moduleName = "Tricorder.Session"
-                                , sourceFile = "src/Tricorder/Session.hs"
-                                }
-                       , GLoading GhciLoading {index = 3, total = 3, moduleName = "Main", sourceFile = "app/Main.hs"}
-                       , GSummary LoadSucceeded
-                       ]
-
-    it "handles padded module index (e.g. [ 1 of 47])" do
+            @?= [ GLoading
+                    GhciLoading
+                        { index = 1
+                        , total = 3
+                        , moduleName = "Tricorder.Build"
+                        , sourceFile = "src/Tricorder.Build.hs"
+                        }
+                , GLoading
+                    GhciLoading
+                        { index = 2
+                        , total = 3
+                        , moduleName = "Tricorder.Session"
+                        , sourceFile = "src/Tricorder/Session.hs"
+                        }
+                , GLoading GhciLoading {index = 3, total = 3, moduleName = "Main", sourceFile = "app/Main.hs"}
+                , GSummary LoadSucceeded
+                ]
+    , testCase "handles padded module index (e.g. [ 1 of 47])" do
         let input =
                 [ "[ 1 of 47] Compiling Main              ( app/Main.hs, interpreted )"
                 , "Ok, 1 module loaded."
                 ]
         parseReload input
-            `shouldBe` [ GLoading GhciLoading {index = 1, total = 47, moduleName = "Main", sourceFile = "app/Main.hs"}
-                       , GSummary LoadSucceeded
-                       ]
-
-    describe "when only summary line" $ it "returns the summary outcome" do
-        parseReload ["Ok, 0 modules loaded."] `shouldBe` [GSummary LoadSucceeded]
+            @?= [ GLoading GhciLoading {index = 1, total = 47, moduleName = "Main", sourceFile = "app/Main.hs"}
+                , GSummary LoadSucceeded
+                ]
+    , testGroup
+        "when only summary line"
+        [ testCase "returns the summary outcome" do
+            parseReload ["Ok, 0 modules loaded."] @?= [GSummary LoadSucceeded]
+        ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- parseReload: errors and warnings
 --------------------------------------------------------------------------------
 
-testErrors :: Spec
-testErrors = do
-    it "parses a single-line error" do
+testErrors :: [TestTree]
+testErrors =
+    [ testCase "parses a single-line error" do
         let input = ["src/Foo.hs:10:5: error: Variable not in scope: foo"]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Foo.hs"
-                                , startPos = Position 10 5
-                                , endPos = Position 10 5
-                                , messageLines = ["src/Foo.hs:10:5: error: Variable not in scope: foo"]
-                                }
-                       ]
-
-    it "parses a warning with continuation lines" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "src/Foo.hs"
+                        , startPos = Position 10 5
+                        , endPos = Position 10 5
+                        , messageLines = ["src/Foo.hs:10:5: error: Variable not in scope: foo"]
+                        }
+                ]
+    , testCase "parses a warning with continuation lines" do
         let input =
                 [ "src/Bar.hs:20:3: warning: [-Wunused-imports]"
                 , "    Redundant import: Data.List"
                 , "    Perhaps you want to remove it."
                 ]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GWarning
-                                , file = "src/Bar.hs"
-                                , startPos = Position 20 3
-                                , endPos = Position 20 3
-                                , messageLines =
-                                    [ "src/Bar.hs:20:3: warning: [-Wunused-imports]"
-                                    , "    Redundant import: Data.List"
-                                    , "    Perhaps you want to remove it."
-                                    ]
-                                }
-                       ]
-
-    it "parses a span position (L:C-C2:)" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GWarning
+                        , file = "src/Bar.hs"
+                        , startPos = Position 20 3
+                        , endPos = Position 20 3
+                        , messageLines =
+                            [ "src/Bar.hs:20:3: warning: [-Wunused-imports]"
+                            , "    Redundant import: Data.List"
+                            , "    Perhaps you want to remove it."
+                            ]
+                        }
+                ]
+    , testCase "parses a span position (L:C-C2:)" do
         let input = ["src/Baz.hs:5:1-10: error: Parse error"]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Baz.hs"
-                                , startPos = Position 5 1
-                                , endPos = Position 5 10
-                                , messageLines = ["src/Baz.hs:5:1-10: error: Parse error"]
-                                }
-                       ]
-
-    it "parses a span position ((L1,C1)-(L2,C2):)" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "src/Baz.hs"
+                        , startPos = Position 5 1
+                        , endPos = Position 5 10
+                        , messageLines = ["src/Baz.hs:5:1-10: error: Parse error"]
+                        }
+                ]
+    , testCase "parses a span position ((L1,C1)-(L2,C2):)" do
         let input = ["src/Qux.hs:(3,1)-(5,20): error: Multi-line error"]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Qux.hs"
-                                , startPos = Position 3 1
-                                , endPos = Position 5 20
-                                , messageLines = ["src/Qux.hs:(3,1)-(5,20): error: Multi-line error"]
-                                }
-                       ]
-
-    it "parses a span position with double-paren end ((L1,C1)-((L2,C2):)" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "src/Qux.hs"
+                        , startPos = Position 3 1
+                        , endPos = Position 5 20
+                        , messageLines = ["src/Qux.hs:(3,1)-(5,20): error: Multi-line error"]
+                        }
+                ]
+    , testCase "parses a span position with double-paren end ((L1,C1)-((L2,C2):)" do
         let input = ["src/Qux.hs:(3,1)-((5,20): error: Multi-line error"]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Qux.hs"
-                                , startPos = Position 3 1
-                                , endPos = Position 5 20
-                                , messageLines = ["src/Qux.hs:(3,1)-((5,20): error: Multi-line error"]
-                                }
-                       ]
-
-    it "parses source-display continuation lines (pipe format)" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "src/Qux.hs"
+                        , startPos = Position 3 1
+                        , endPos = Position 5 20
+                        , messageLines = ["src/Qux.hs:(3,1)-((5,20): error: Multi-line error"]
+                        }
+                ]
+    , testCase "parses source-display continuation lines (pipe format)" do
         let input =
                 [ "src/Foo.hs:10:5: error: Variable not in scope: foo"
                 , "   |"
@@ -175,49 +180,46 @@
                 , "    Suggested fix: import Foo"
                 ]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Foo.hs"
-                                , startPos = Position 10 5
-                                , endPos = Position 10 5
-                                , messageLines =
-                                    [ "src/Foo.hs:10:5: error: Variable not in scope: foo"
-                                    , "   |"
-                                    , "10 | foo bar"
-                                    , "   | ^^^"
-                                    , "    Suggested fix: import Foo"
-                                    ]
-                                }
-                       ]
-
-    it "strips ANSI codes from header for matching but stores original in glMessage" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "src/Foo.hs"
+                        , startPos = Position 10 5
+                        , endPos = Position 10 5
+                        , messageLines =
+                            [ "src/Foo.hs:10:5: error: Variable not in scope: foo"
+                            , "   |"
+                            , "10 | foo bar"
+                            , "   | ^^^"
+                            , "    Suggested fix: import Foo"
+                            ]
+                        }
+                ]
+    , testCase "strips ANSI codes from header for matching but stores original in glMessage" do
         let ansiHeader = "\ESC[1msrc/Foo.hs:10:5:\ESC[0m \ESC[91merror:\ESC[0m Variable not in scope: foo"
         parseReload [ansiHeader]
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Foo.hs"
-                                , startPos = Position 10 5
-                                , endPos = Position 10 5
-                                , messageLines = [ansiHeader]
-                                }
-                       ]
-
-    it "parses a Windows drive-letter path in a diagnostic" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "src/Foo.hs"
+                        , startPos = Position 10 5
+                        , endPos = Position 10 5
+                        , messageLines = [ansiHeader]
+                        }
+                ]
+    , testCase "parses a Windows drive-letter path in a diagnostic" do
         let input = ["C:\\path\\file.hs:10:5: error: Variable not in scope: foo"]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "C:\\path\\file.hs"
-                                , startPos = Position 10 5
-                                , endPos = Position 10 5
-                                , messageLines = ["C:\\path\\file.hs:10:5: error: Variable not in scope: foo"]
-                                }
-                       ]
-
-    it "parses mixed Loading, Message, and summary items" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "C:\\path\\file.hs"
+                        , startPos = Position 10 5
+                        , endPos = Position 10 5
+                        , messageLines = ["C:\\path\\file.hs:10:5: error: Variable not in scope: foo"]
+                        }
+                ]
+    , testCase "parses mixed Loading, Message, and summary items" do
         let input =
                 [ "[1 of 2] Compiling Lib ( src/Lib.hs, interpreted )"
                 , "src/Lib.hs:5:1: error: Oops"
@@ -225,185 +227,185 @@
                 , "Failed, 1 module loaded."
                 ]
         parseReload input
-            `shouldBe` [ GLoading GhciLoading {index = 1, total = 2, moduleName = "Lib", sourceFile = "src/Lib.hs"}
-                       , GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Lib.hs"
-                                , startPos = Position 5 1
-                                , endPos = Position 5 1
-                                , messageLines = ["src/Lib.hs:5:1: error: Oops"]
-                                }
-                       , GLoading GhciLoading {index = 2, total = 2, moduleName = "Main", sourceFile = "app/Main.hs"}
-                       , GSummary LoadFailed
-                       ]
+            @?= [ GLoading GhciLoading {index = 1, total = 2, moduleName = "Lib", sourceFile = "src/Lib.hs"}
+                , GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "src/Lib.hs"
+                        , startPos = Position 5 1
+                        , endPos = Position 5 1
+                        , messageLines = ["src/Lib.hs:5:1: error: Oops"]
+                        }
+                , GLoading GhciLoading {index = 2, total = 2, moduleName = "Main", sourceFile = "app/Main.hs"}
+                , GSummary LoadFailed
+                ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- parseReload: -fhide-source-paths output
 --------------------------------------------------------------------------------
 
-testHideSourcePaths :: Spec
-testHideSourcePaths = do
-    describe "when source paths are hidden" $ it "produces no GLoading items" do
-        let input =
-                [ "src/Foo.hs:10:5: error: Variable not in scope: foo"
-                , "    Perhaps you meant: 'bar'"
-                , "Failed, one module failed to load."
-                ]
-        parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "src/Foo.hs"
-                                , startPos = Position 10 5
-                                , endPos = Position 10 5
-                                , messageLines =
-                                    [ "src/Foo.hs:10:5: error: Variable not in scope: foo"
-                                    , "    Perhaps you meant: 'bar'"
-                                    ]
-                                }
-                       , GSummary LoadFailed
-                       ]
-
-    describe "when all modules are already up to date" $ it "returns the summary outcome" do
-        -- GHCi with -fhide-source-paths and nothing to recompile
-        parseReload ["Ok, 5 modules loaded."] `shouldBe` [GSummary LoadSucceeded]
+testHideSourcePaths :: [TestTree]
+testHideSourcePaths =
+    [ testGroup
+        "when source paths are hidden"
+        [ testCase "produces no GLoading items" do
+            let input =
+                    [ "src/Foo.hs:10:5: error: Variable not in scope: foo"
+                    , "    Perhaps you meant: 'bar'"
+                    , "Failed, one module failed to load."
+                    ]
+            parseReload input
+                @?= [ GMessage
+                        GhciMessage
+                            { severity = GError
+                            , file = "src/Foo.hs"
+                            , startPos = Position 10 5
+                            , endPos = Position 10 5
+                            , messageLines =
+                                [ "src/Foo.hs:10:5: error: Variable not in scope: foo"
+                                , "    Perhaps you meant: 'bar'"
+                                ]
+                            }
+                    , GSummary LoadFailed
+                    ]
+        ]
+    , testGroup
+        "when all modules are already up to date"
+        [ testCase "returns the summary outcome" do
+            -- GHCi with -fhide-source-paths and nothing to recompile
+            parseReload ["Ok, 5 modules loaded."] @?= [GSummary LoadSucceeded]
+        ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- parseReload: <no location info> errors
 --------------------------------------------------------------------------------
 
-testNoLocationInfo :: Spec
-testNoLocationInfo = do
-    it "handles <no location info>: error: with continuation" do
+testNoLocationInfo :: [TestTree]
+testNoLocationInfo =
+    [ testCase "handles <no location info>: error: with continuation" do
         let input =
                 [ "<no location info>: error:"
                 , "    Module `Tricorder.Missing' is not loaded."
                 ]
         parseReload input
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "<no location info>"
-                                , startPos = Position 0 0
-                                , endPos = Position 0 0
-                                , messageLines =
-                                    [ "<no location info>: error:"
-                                    , "    Module `Tricorder.Missing' is not loaded."
-                                    ]
-                                }
-                       ]
-
-    it "handles <no location info>: error: with no continuation" do
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "<no location info>"
+                        , startPos = Position 0 0
+                        , endPos = Position 0 0
+                        , messageLines =
+                            [ "<no location info>: error:"
+                            , "    Module `Tricorder.Missing' is not loaded."
+                            ]
+                        }
+                ]
+    , testCase "handles <no location info>: error: with no continuation" do
         parseReload ["<no location info>: error: some error"]
-            `shouldBe` [ GMessage
-                            GhciMessage
-                                { severity = GError
-                                , file = "<no location info>"
-                                , startPos = Position 0 0
-                                , endPos = Position 0 0
-                                , messageLines = ["<no location info>: error: some error"]
-                                }
-                       ]
+            @?= [ GMessage
+                    GhciMessage
+                        { severity = GError
+                        , file = "<no location info>"
+                        , startPos = Position 0 0
+                        , endPos = Position 0 0
+                        , messageLines = ["<no location info>: error: some error"]
+                        }
+                ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- parseReload: Loaded GHCi configuration
 --------------------------------------------------------------------------------
 
-testLoadedConfig :: Spec
-testLoadedConfig = do
-    it "parses a GHCi configuration line" do
+testLoadedConfig :: [TestTree]
+testLoadedConfig =
+    [ testCase "parses a GHCi configuration line" do
         parseReload ["Loaded GHCi configuration from /home/user/project/.ghci"]
-            `shouldBe` [GLoadConfig "/home/user/project/.ghci"]
-
-    it "parses a Windows-style GHCi configuration path" do
+            @?= [GLoadConfig "/home/user/project/.ghci"]
+    , testCase "parses a Windows-style GHCi configuration path" do
         parseReload ["Loaded GHCi configuration from C:\\Users\\user\\project\\.ghci"]
-            `shouldBe` [GLoadConfig "C:\\Users\\user\\project\\.ghci"]
-
-    it "handles config line mixed with other output" do
+            @?= [GLoadConfig "C:\\Users\\user\\project\\.ghci"]
+    , testCase "handles config line mixed with other output" do
         let input =
                 [ "Loaded GHCi configuration from .ghci"
                 , "[1 of 1] Compiling Main ( app/Main.hs, interpreted )"
                 , "Ok, 1 module loaded."
                 ]
         parseReload input
-            `shouldBe` [ GLoadConfig ".ghci"
-                       , GLoading GhciLoading {index = 1, total = 1, moduleName = "Main", sourceFile = "app/Main.hs"}
-                       , GSummary LoadSucceeded
-                       ]
+            @?= [ GLoadConfig ".ghci"
+                , GLoading GhciLoading {index = 1, total = 1, moduleName = "Main", sourceFile = "app/Main.hs"}
+                , GSummary LoadSucceeded
+                ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- parseShowModules
 --------------------------------------------------------------------------------
 
-testShowModules :: Spec
-testShowModules = do
-    it "parses typical :show modules output" do
+testShowModules :: [TestTree]
+testShowModules =
+    [ testCase "parses typical :show modules output" do
         let input =
                 [ "Tricorder.Build     ( src/Tricorder.Build.hs, interpreted )"
                 , "Tricorder.Session        ( src/Tricorder/Session.hs, interpreted )"
                 , "Main                     ( app/Main.hs, interpreted )"
                 ]
         parseShowModules input
-            `shouldBe` [ ("Tricorder.Build", "src/Tricorder.Build.hs")
-                       , ("Tricorder.Session", "src/Tricorder/Session.hs")
-                       , ("Main", "app/Main.hs")
-                       ]
-
-    it "parses absolute paths" do
+            @?= [ ("Tricorder.Build", "src/Tricorder.Build.hs")
+                , ("Tricorder.Session", "src/Tricorder/Session.hs")
+                , ("Main", "app/Main.hs")
+                ]
+    , testCase "parses absolute paths" do
         parseShowModules ["Lib ( /home/user/project/src/Lib.hs, interpreted )"]
-            `shouldBe` [("Lib", "/home/user/project/src/Lib.hs")]
-
-    it "strips ANSI codes before parsing" do
+            @?= [("Lib", "/home/user/project/src/Lib.hs")]
+    , testCase "strips ANSI codes before parsing" do
         parseShowModules ["\ESC[1mMain\ESC[0m                     ( app/Main.hs, interpreted )"]
-            `shouldBe` [("Main", "app/Main.hs")]
+            @?= [("Main", "app/Main.hs")]
+    ]
 
 
-testShowModulesEmpty :: Spec
-testShowModulesEmpty = do
-    it "returns empty list for empty input" do
-        parseShowModules [] `shouldBe` []
-
-    it "returns empty list for blank lines" do
-        parseShowModules ["", "   ", "\t"] `shouldBe` []
-
-    it "skips lines without '( '" do
-        parseShowModules ["just some random text"] `shouldBe` []
+testShowModulesEmpty :: [TestTree]
+testShowModulesEmpty =
+    [ testCase "returns empty list for empty input" do
+        parseShowModules [] @?= []
+    , testCase "returns empty list for blank lines" do
+        parseShowModules ["", "   ", "\t"] @?= []
+    , testCase "skips lines without '( '" do
+        parseShowModules ["just some random text"] @?= []
+    ]
 
 
 --------------------------------------------------------------------------------
 -- parseShowTargets
 --------------------------------------------------------------------------------
 
-testShowTargets :: Spec
-testShowTargets = do
-    it "parses module names emitted by cabal repl --enable-multi-repl" do
+testShowTargets :: [TestTree]
+testShowTargets =
+    [ testCase "parses module names emitted by cabal repl --enable-multi-repl" do
         parseShowTargets
             [ "Atelier.Effects.Cache"
             , "Atelier.Effects.Chan"
             , "Paths_tricorder"
             ]
-            `shouldBe` ["Atelier.Effects.Cache", "Atelier.Effects.Chan", "Paths_tricorder"]
-
-    it "parses file-path targets emitted by plain ghci" do
+            @?= ["Atelier.Effects.Cache", "Atelier.Effects.Chan", "Paths_tricorder"]
+    , testCase "parses file-path targets emitted by plain ghci" do
         parseShowTargets ["src/Foo.hs", "test/Bar.hs"]
-            `shouldBe` ["src/Foo.hs", "test/Bar.hs"]
-
-    it "strips the leading '*' marker for the active interactive target" do
-        parseShowTargets ["*Main", "Foo.Bar"] `shouldBe` ["Main", "Foo.Bar"]
-
-    it "strips ANSI escape sequences" do
-        parseShowTargets ["\ESC[1mFoo.Bar\ESC[0m"] `shouldBe` ["Foo.Bar"]
-
-    it "skips blank and whitespace-only lines" do
-        parseShowTargets ["", "   ", "\t", "Real.Target"] `shouldBe` ["Real.Target"]
-
-    it "returns empty list for empty input" do
-        parseShowTargets [] `shouldBe` []
+            @?= ["src/Foo.hs", "test/Bar.hs"]
+    , testCase "strips the leading '*' marker for the active interactive target" do
+        parseShowTargets ["*Main", "Foo.Bar"] @?= ["Main", "Foo.Bar"]
+    , testCase "strips ANSI escape sequences" do
+        parseShowTargets ["\ESC[1mFoo.Bar\ESC[0m"] @?= ["Foo.Bar"]
+    , testCase "skips blank and whitespace-only lines" do
+        parseShowTargets ["", "   ", "\t", "Real.Target"] @?= ["Real.Target"]
+    , testCase "returns empty list for empty input" do
+        parseShowTargets [] @?= []
+    ]
 
 
 --------------------------------------------------------------------------------
@@ -418,30 +420,31 @@
 -- failure with @\<no location info\>@ (it has no source span), and the load
 -- ends with @Failed, N modules loaded@. This output must still surface as an
 -- error diagnostic — otherwise the build is silently reported as clean.
-testPluginLoadFailure :: Spec
-testPluginLoadFailure = do
+testPluginLoadFailure :: [TestTree]
+testPluginLoadFailure =
     -- Shape of the GHCi output from `cabal repl --enable-multi-repl` when an
     -- executable loads a home-unit GHC plugin: the plugin package's modules
     -- compile, then the unit using the plugin fails with a location-less error.
-    let reloadOutput =
-            [ "[3 of 5] Compiling My.Plugin       ( src/My/Plugin.hs, interpreted )[plugin-pkg-1.0.0-inplace]"
-            , "<no location info>: error:"
-            , "    Could not load module \8216My.Plugin\8217."
-            , "It is a member of the hidden package \8216plugin-pkg-1.0.0\8217."
-            , "Perhaps you need to add \8216plugin-pkg\8217 to the build-depends in your .cabal file."
-            , "Use -v to see a list of the files searched for."
-            , ""
-            , "[5 of 5] Compiling Main            ( test/Tests.hs, interpreted )[app-pkg-0.1.0.0-inplace-test]"
-            , "Failed, 4 modules loaded."
-            ]
-        result = collectResultCustom "/project" (parseReload reloadOutput) [] []
-
-    it "surfaces the plugin load failure as an error diagnostic" do
-        map (.severity) result.diagnostics `shouldContain` [SError]
-
-    it "carries the plugin error message in the diagnostic title" do
-        map (.title) result.diagnostics
-            `shouldContain` ["Could not load module \8216My.Plugin\8217."]
+    [ testCase "surfaces the plugin load failure as an error diagnostic" do
+        assertBool "expected an error diagnostic"
+            $ SError `elem` map (.severity) result.diagnostics
+    , testCase "carries the plugin error message in the diagnostic title" do
+        assertBool "expected the plugin error message in a diagnostic title"
+            $ "Could not load module \8216My.Plugin\8217." `elem` map (.title) result.diagnostics
+    ]
+  where
+    reloadOutput =
+        [ "[3 of 5] Compiling My.Plugin       ( src/My/Plugin.hs, interpreted )[plugin-pkg-1.0.0-inplace]"
+        , "<no location info>: error:"
+        , "    Could not load module \8216My.Plugin\8217."
+        , "It is a member of the hidden package \8216plugin-pkg-1.0.0\8217."
+        , "Perhaps you need to add \8216plugin-pkg\8217 to the build-depends in your .cabal file."
+        , "Use -v to see a list of the files searched for."
+        , ""
+        , "[5 of 5] Compiling Main            ( test/Tests.hs, interpreted )[app-pkg-0.1.0.0-inplace-test]"
+        , "Failed, 4 modules loaded."
+        ]
+    result = collectResultCustom "/project" (parseReload reloadOutput) [] []
 
 
 --------------------------------------------------------------------------------
@@ -451,18 +454,20 @@
 -- 'collectResult' is the safety net: GHCi can end a load with @Failed, …@
 -- without emitting any error that carries a source span. The build must never
 -- read as clean in that case, so a synthetic error diagnostic is added.
-testUnattributedFailure :: Spec
-testUnattributedFailure = do
-    describe "when the load failed but no error was located" $ it "adds a synthetic error" do
-        let reloadOutput =
-                [ "[1 of 2] Compiling Lib  ( src/Lib.hs, interpreted )"
-                , "[2 of 2] Compiling Main ( app/Main.hs, interpreted )"
-                , "Failed, 1 module loaded."
-                ]
-            result = collectResult "/project" reloadOutput [] []
-        map (.severity) result.diagnostics `shouldBe` [SError]
-
-    it "does not duplicate a failure that already produced a located error" do
+testUnattributedFailure :: [TestTree]
+testUnattributedFailure =
+    [ testGroup
+        "when the load failed but no error was located"
+        [ testCase "adds a synthetic error" do
+            let reloadOutput =
+                    [ "[1 of 2] Compiling Lib  ( src/Lib.hs, interpreted )"
+                    , "[2 of 2] Compiling Main ( app/Main.hs, interpreted )"
+                    , "Failed, 1 module loaded."
+                    ]
+                result = collectResult "/project" reloadOutput [] []
+            map (.severity) result.diagnostics @?= [SError]
+        ]
+    , testCase "does not duplicate a failure that already produced a located error" do
         let reloadOutput =
                 [ "[1 of 1] Compiling Lib ( src/Lib.hs, interpreted )"
                 , "src/Lib.hs:5:1: error: Oops"
@@ -470,27 +475,29 @@
                 ]
             result = collectResult "/project" reloadOutput [] []
         -- Only the real, located diagnostic — no synthetic one appended.
-        map (.file) result.diagnostics `shouldBe` ["src/Lib.hs"]
-
-    it "adds nothing for a successful load" do
+        map (.file) result.diagnostics @?= ["src/Lib.hs"]
+    , testCase "adds nothing for a successful load" do
         let reloadOutput =
                 [ "[1 of 1] Compiling Main ( app/Main.hs, interpreted )"
                 , "Ok, 1 module loaded."
                 ]
             result = collectResult "/project" reloadOutput [] []
-        result.diagnostics `shouldBe` []
-
-    describe "when 'Failed,' appears off the summary line" $ it "does not flag a clean build" do
-        -- The load outcome lives on GHCi's single summary line
-        -- ("Ok, …" / "Failed, …"). Output printed *during* the load — e.g. a
-        -- Template Haskell splice or top-level IO run while interpreting — can
-        -- contain a line that happens to begin with "Failed,". That must not be
-        -- mistaken for a failed load: the summary here is "Ok," so no synthetic
-        -- error belongs.
-        let reloadOutput =
-                [ "[1 of 1] Compiling Main ( app/Main.hs, interpreted )"
-                , "Failed, retrying with fallback" -- printed by a TH splice
-                , "Ok, 1 module loaded."
-                ]
-            result = collectResult "/project" reloadOutput [] []
-        result.diagnostics `shouldBe` []
+        result.diagnostics @?= []
+    , testGroup
+        "when 'Failed,' appears off the summary line"
+        [ testCase "does not flag a clean build" do
+            -- The load outcome lives on GHCi's single summary line
+            -- ("Ok, …" / "Failed, …"). Output printed *during* the load — e.g. a
+            -- Template Haskell splice or top-level IO run while interpreting — can
+            -- contain a line that happens to begin with "Failed,". That must not be
+            -- mistaken for a failed load: the summary here is "Ok," so no synthetic
+            -- error belongs.
+            let reloadOutput =
+                    [ "[1 of 1] Compiling Main ( app/Main.hs, interpreted )"
+                    , "Failed, retrying with fallback" -- printed by a TH splice
+                    , "Ok, 1 module loaded."
+                    ]
+                result = collectResult "/project" reloadOutput [] []
+            result.diagnostics @?= []
+        ]
+    ]
diff --git a/test/Unit/Tricorder/Daemon/GhciSession/GhciProcessSpec.hs b/test/Unit/Tricorder/Daemon/GhciSession/GhciProcessSpec.hs
--- a/test/Unit/Tricorder/Daemon/GhciSession/GhciProcessSpec.hs
+++ b/test/Unit/Tricorder/Daemon/GhciSession/GhciProcessSpec.hs
@@ -1,4 +1,4 @@
-module Unit.Tricorder.Daemon.GhciSession.GhciProcessSpec (spec_GhciProcess) where
+module Unit.Tricorder.Daemon.GhciSession.GhciProcessSpec (test_GhciProcess) where
 
 import Atelier.Effects.Conc (runConc)
 import Atelier.Effects.Delay (runDelay)
@@ -34,7 +34,8 @@
     , stopProcess
     , waitExitCode
     )
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertFailure, testCase, (@?), (@?=))
 
 import Atelier.Effects.Conc qualified as Conc
 import Atelier.Effects.Delay qualified as Delay
@@ -49,6 +50,7 @@
     , GhciProcessError (..)
     , InterruptDecision (..)
     , SessionState (..)
+    , UnexpectedExit (..)
     , decideInterrupt
     , drainUntil
     , execGhci
@@ -56,16 +58,19 @@
     )
 
 
-spec_GhciProcess :: Spec
-spec_GhciProcess = do
-    describe "decideInterrupt" testDecideInterrupt
-    describe "drainUntil" testDrainUntil
-    describe "execGhci" testExecGhciScope
-    describe "execGhci (stale marker desync)" testExecGhciStaleMarker
-    describe "execGhci (sync marker scope independence)" testSyncMarkerScopeIndependent
-    describe "waitForBannerOrFail" testWaitForBannerOrFail
-    describe "withProcessGroup (process group)" testWithProcessGroupCleanup
-    describe "terminateProcessGroup (process group)" testTerminateProcessGroup
+test_GhciProcess :: TestTree
+test_GhciProcess =
+    testGroup
+        "GhciProcess"
+        [ testGroup "decideInterrupt" testDecideInterrupt
+        , testGroup "drainUntil" testDrainUntil
+        , testGroup "execGhci" testExecGhciScope
+        , testGroup "execGhci (stale marker desync)" testExecGhciStaleMarker
+        , testGroup "execGhci (sync marker scope independence)" testSyncMarkerScopeIndependent
+        , testGroup "waitForBannerOrFail" testWaitForBannerOrFail
+        , testGroup "withProcessGroup (process group)" testWithProcessGroupCleanup
+        , testGroup "terminateProcessGroup (process group)" testTerminateProcessGroup
+        ]
 
 
 -- | Mirrors the private 'markerFor' helper (not exported), using the same
@@ -74,9 +79,9 @@
 finishMarker n = "#~TRI-FINISH-" <> show n <> "~#"
 
 
-testDrainUntil :: Spec
-testDrainUntil = do
-    it "returns accumulated non-marker lines in order and stops at the marker" do
+testDrainUntil :: [TestTree]
+testDrainUntil =
+    [ testCase "returns accumulated non-marker lines in order and stops at the marker" do
         (r, w) <- Process.createPipe
         (result, _msgs) <-
             runEff
@@ -87,9 +92,8 @@
                     for_ ["line1", "line2", finishMarker 1, "line3"] (File.hPutTextLn w)
                     File.hClose w
                     drainUntil r (finishMarker 1) (\_ -> pure ())
-        result `shouldBe` ["line1", "line2"]
-
-    it "streams each non-marker line to onLine, in order, before returning" do
+        result @?= ["line1", "line2"]
+    , testCase "streams each non-marker line to onLine, in order, before returning" do
         (r, w) <- Process.createPipe
         seenRef <- newIORef []
         (result, _msgs) <-
@@ -102,10 +106,9 @@
                     File.hClose w
                     drainUntil r (finishMarker 2) (\l -> liftIO $ modifyIORef' seenRef (l :))
         seen <- reverse <$> readIORef seenRef
-        seen `shouldBe` ["a", "b", "c"]
-        result `shouldBe` seen
-
-    it "skips a stale marker with a different suffix and keeps draining" do
+        seen @?= ["a", "b", "c"]
+        result @?= seen
+    , testCase "skips a stale marker with a different suffix and keeps draining" do
         (r, w) <- Process.createPipe
         (result, _msgs) <-
             runEff
@@ -119,28 +122,29 @@
                     for_ ["before", finishMarker 5, "after", finishMarker 9] (File.hPutTextLn w)
                     File.hClose w
                     drainUntil r (finishMarker 9) (\_ -> pure ())
-        result `shouldBe` ["before", "after"]
-
-    it "throws UnexpectedExit with ALL accumulated lines (in order) on EOF, not just the last one" do
-        (r, w) <- Process.createPipe
-        (outcome, _msgs) <-
-            runEff
-                . runWriter @[Message]
-                . runLogWriter
-                . runFile
-                $ do
-                    for_ ["first", "second", "third"] (File.hPutTextLn w)
-                    File.hClose w -- EOF before the marker ever arrives
-                    trySync (drainUntil r (finishMarker 1) (\_ -> pure ()))
-        case outcome of
-            Right ls -> expectationFailure ("expected UnexpectedExit, got: " <> show ls)
-            Left ex -> case fromException ex of
-                Just (UnexpectedExit m ls) -> do
-                    m `shouldBe` finishMarker 1
-                    ls `shouldBe` Just "first\nsecond\nthird"
-                other -> expectationFailure ("expected UnexpectedExit, got: " <> show other)
-
-    it "throws UnexpectedExit with no lines when EOF is reached immediately" do
+        result @?= ["before", "after"]
+    , testCase
+        "throws UnexpectedExit with ALL accumulated lines (in order) on EOF, not just the last one"
+        do
+            (r, w) <- Process.createPipe
+            (outcome, _msgs) <-
+                runEff
+                    . runWriter @[Message]
+                    . runLogWriter
+                    . runFile
+                    $ do
+                        for_ ["first", "second", "third"] (File.hPutTextLn w)
+                        File.hClose w -- EOF before the marker ever arrives
+                        trySync (drainUntil r (finishMarker 1) (\_ -> pure ()))
+            case outcome of
+                Right ls -> assertFailure ("expected UnexpectedExit, got: " <> show ls)
+                Left ex -> case fromException ex of
+                    Just (UnexpectedExit (MkUnexpectedExit m ls)) -> do
+                        m @?= finishMarker 1
+                        ls
+                            @?= "Reached EOF before reading marker from GHCi.\nWas looking for marker '#~TRI-FINISH-1~#', but no such marker was found.\nAccumulated output from GHCi so far:\nfirst\nsecond\nthird"
+                    other -> assertFailure ("expected UnexpectedExit, got: " <> show other)
+    , testCase "throws UnexpectedExit with no lines when EOF is reached immediately" do
         (r, w) <- Process.createPipe
         (outcome, _msgs) <-
             runEff
@@ -151,14 +155,20 @@
                     File.hClose w
                     trySync (drainUntil r (finishMarker 1) (\_ -> pure ()))
         case outcome of
-            Right ls -> expectationFailure ("expected UnexpectedExit, got: " <> show ls)
+            Right ls -> assertFailure ("expected UnexpectedExit, got: " <> show ls)
             Left ex -> case fromException ex of
-                Just (UnexpectedExit m ls) -> do
-                    m `shouldBe` finishMarker 1
-                    ls `shouldBe` Nothing
-                other -> expectationFailure ("expected UnexpectedExit, got: " <> show other)
-
-    it
+                Just (UnexpectedExit (MkUnexpectedExit m ls)) -> do
+                    m @?= finishMarker 1
+                    let expected =
+                            "Reached EOF before reading marker from GHCi.\nWas looking for marker '#~TRI-FINISH-1~#', but no such marker was found.\nGHCi returned no output before we reached what we believe is EOF.\nGot the following exception when attempting to read from GHCi:\n<file descriptor:"
+                    (expected `T.isPrefixOf` ls)
+                        @? ( "error message does not start with expected prefix\nExpected:\n"
+                                <> show expected
+                                <> "\nActual:\n"
+                                <> show ls
+                           )
+                other -> assertFailure ("expected UnexpectedExit, got: " <> show other)
+    , testCase
         "logs an ERROR mentioning the missing marker and the exception when EOF is reached with no output"
         do
             (r, w) <- Process.createPipe
@@ -171,12 +181,11 @@
                         File.hClose w
                         trySync (drainUntil r (finishMarker 3) (\_ -> pure ()))
             case filter (\m -> m.severity == ERROR) msgs of
-                [] -> expectationFailure "expected an ERROR log message"
+                [] -> assertFailure "expected an ERROR log message"
                 (logMsg : _) -> do
-                    (finishMarker 3 `T.isInfixOf` logMsg.text) `shouldBe` True
-                    ("GHCi returned no output" `T.isInfixOf` logMsg.text) `shouldBe` True
-
-    it "logs an ERROR including the accumulated output when EOF is reached mid-output" do
+                    (finishMarker 3 `T.isInfixOf` logMsg.text) @?= True
+                    ("GHCi returned no output" `T.isInfixOf` logMsg.text) @?= True
+    , testCase "logs an ERROR including the accumulated output when EOF is reached mid-output" do
         (r, w) <- Process.createPipe
         (_outcome, msgs) <-
             runEff
@@ -188,11 +197,12 @@
                     File.hClose w
                     trySync (drainUntil r (finishMarker 4) (\_ -> pure ()))
         case filter (\m -> m.severity == ERROR) msgs of
-            [] -> expectationFailure "expected an ERROR log message"
+            [] -> assertFailure "expected an ERROR log message"
             (logMsg : _) -> do
-                (finishMarker 4 `T.isInfixOf` logMsg.text) `shouldBe` True
-                ("oops-line-1" `T.isInfixOf` logMsg.text) `shouldBe` True
-                ("oops-line-2" `T.isInfixOf` logMsg.text) `shouldBe` True
+                (finishMarker 4 `T.isInfixOf` logMsg.text) @?= True
+                ("oops-line-1" `T.isInfixOf` logMsg.text) @?= True
+                ("oops-line-2" `T.isInfixOf` logMsg.text) @?= True
+    ]
 
 
 -- | Regression for the touch-during-reload desync. Interrupting a *Busy* GHCi
@@ -202,9 +212,9 @@
 -- returned *before its command ran* — surfacing as @All good. (0 modules)@ (or,
 -- on the other timing, a hang). 'execGhci' must skip markers that aren't its
 -- own and stop only on the marker it is waiting for.
-testExecGhciStaleMarker :: Spec
+testExecGhciStaleMarker :: [TestTree]
 testExecGhciStaleMarker =
-    it "skips a stale leftover marker and returns the command's real output" do
+    [ testCase "skips a stale leftover marker and returns the command's real output" do
         (stdinR, stdinW) <- Process.createPipe
         (stdoutR, stdoutW) <- Process.createPipe
         (stderrR, stderrW) <- Process.createPipe
@@ -249,7 +259,8 @@
                     File.hClose stdinR
                     pure r
         _ <- (Right <$> stopProcess p) `catch` \(_ :: SomeException) -> pure (Left ())
-        result `shouldBe` ["out-line", "err-line"]
+        result @?= ["out-line", "err-line"]
+    ]
 
 
 -- | Root-cause regression for the "stuck Building…" stall. A SIGINT-interrupted
@@ -262,9 +273,9 @@
 -- emptied scope), one per stream, with no bare names or operators.
 --
 -- We assert on exactly what 'execGhci' writes to GHCi's stdin.
-testSyncMarkerScopeIndependent :: Spec
+testSyncMarkerScopeIndependent :: [TestTree]
 testSyncMarkerScopeIndependent =
-    it "writes the finish marker using only fully-qualified names (no bare putStrLn / >>)" do
+    [ testCase "writes the finish marker using only fully-qualified names (no bare putStrLn / >>)" do
         (stdinR, stdinW) <- Process.createPipe
         (stdoutR, stdoutW) <- Process.createPipe
         (stderrR, stderrW) <- Process.createPipe
@@ -309,9 +320,10 @@
                     readAll []
         _ <- (Right <$> stopProcess p) `catch` \(_ :: SomeException) -> pure (Left ())
         let blob = T.intercalate "\n" written
-        (" >> " `T.isInfixOf` blob) `shouldBe` False
-        ("System.IO.hPutStrLn System.IO.stdout" `T.isInfixOf` blob) `shouldBe` True
-        ("System.IO.hPutStrLn System.IO.stderr" `T.isInfixOf` blob) `shouldBe` True
+        (" >> " `T.isInfixOf` blob) @?= False
+        ("System.IO.hPutStrLn System.IO.stdout" `T.isInfixOf` blob) @?= True
+        ("System.IO.hPutStrLn System.IO.stderr" `T.isInfixOf` blob) @?= True
+    ]
 
 
 -- | Regression: when the build command exits before printing a GHCi banner,
@@ -320,9 +332,9 @@
 -- lines as soon as the process exited (it waited on 'waitExitCode'), racing
 -- the concurrent stderr drain — so a burst of error lines still buffered in
 -- the pipe was truncated, and the real cabal/build failure was lost.
-testWaitForBannerOrFail :: Spec
+testWaitForBannerOrFail :: [TestTree]
 testWaitForBannerOrFail =
-    it "captures the full stderr output when the command exits before the banner" do
+    [ testCase "captures the full stderr output when the command exits before the banner" do
         let lineCount = 200 :: Int
             lastLine = "err line " <> show lineCount
         -- The banner and error streams are pipes we drive ourselves, so the
@@ -352,12 +364,13 @@
                         File.hClose errW
                     trySync (waitForBannerOrFail (5 :: Second) bannerOut errR)
         case result of
-            Right () -> expectationFailure "expected waitForBannerOrFail to throw a startup error"
+            Right () -> assertFailure "expected waitForBannerOrFail to throw a startup error"
             Left ex -> case fromException ex of
                 Just (StartupFailed msg) ->
-                    (lastLine `T.isInfixOf` msg) `shouldBe` True
+                    (lastLine `T.isInfixOf` msg) @?= True
                 other ->
-                    expectationFailure ("expected StartupFailed, got: " <> show other)
+                    assertFailure ("expected StartupFailed, got: " <> show other)
+    ]
 
 
 -- | Regression for orphaned/zombie build subprocesses on restart and shutdown.
@@ -368,9 +381,9 @@
 -- gone. We simulate it with a leader that forks a long-lived child sharing its
 -- group and exits on stdin input (mirroring @:quit@); after 'withProcessGroup'
 -- returns, the child must be gone.
-testWithProcessGroupCleanup :: Spec
+testWithProcessGroupCleanup :: [TestTree]
 testWithProcessGroupCleanup =
-    it "terminates the whole group on exit, even after the leader has exited" do
+    [ testCase "terminates the whole group on exit, even after the leader has exited" do
         childPidRef <- newIORef (Nothing :: Maybe Int)
         let scenario =
                 runEff
@@ -393,15 +406,16 @@
         -- assertion, never as a hang that stalls the whole suite.
         outcome <- System.Timeout.timeout (8_000_000) scenario
         case outcome of
-            Nothing -> expectationFailure "test timed out (process did not settle)"
+            Nothing -> assertFailure "test timed out (process did not settle)"
             Just () ->
                 readIORef childPidRef >>= \case
-                    Nothing -> expectationFailure "could not capture the child pid"
+                    Nothing -> assertFailure "could not capture the child pid"
                     Just childPid -> do
                         died <- waitForProcessDeath childPid
                         -- Never leak the child if the assertion fails.
                         ignoring (signalProcess sigKILL (fromIntegral childPid))
-                        died `shouldBe` True
+                        died @?= True
+    ]
   where
     procConfig =
         setStdin createPipe
@@ -413,9 +427,9 @@
 -- | 'terminateProcessGroup' must kill the whole group when called mid-flight
 -- (the leader still alive) — the explicit early-termination path the test
 -- runner uses to abort a one-shot @cabal repl test:…@ from another thread.
-testTerminateProcessGroup :: Spec
+testTerminateProcessGroup :: [TestTree]
 testTerminateProcessGroup =
-    it "kills the whole group, not just the leader, mid-flight" do
+    [ testCase "kills the whole group, not just the leader, mid-flight" do
         outcome <- System.Timeout.timeout (8_000_000) do
             p <-
                 startProcess
@@ -428,15 +442,15 @@
             case parsePid childLine of
                 Nothing -> do
                     ignoring (stopProcess p)
-                    expectationFailure ("could not parse child pid from: " <> show childLine)
-                    pure False
+                    assertFailure ("could not parse child pid from: " <> show childLine)
                 Just childPid -> do
                     runEff . runProcessIO $ terminateProcessGroup (RunningProcess p)
                     died <- waitForProcessDeath childPid
                     -- Never leak the child if the assertion fails.
                     ignoring (signalProcess sigKILL (fromIntegral childPid))
                     pure died
-        outcome `shouldBe` Just True
+        outcome @?= Just True
+    ]
 
 
 -- | Parse a pid printed on its own line (tolerating surrounding whitespace).
@@ -464,24 +478,22 @@
             `catch` \(_ :: IOException) -> pure False
 
 
-testDecideInterrupt :: Spec
-testDecideInterrupt = do
+testDecideInterrupt :: [TestTree]
+testDecideInterrupt =
     -- Regression: an idle GHCi must not be SIGINT'd, since the matching
     -- sync-marker write would leave a stale marker line in stdout/stderr
     -- that the next 'execGhci' drain would match instead of the fresh one,
     -- desyncing the protocol and reporting "0 modules" or hanging.
-    it "is a no-op when the session is Idle" do
-        decideInterrupt (Idle 7) `shouldBe` (Idle 7, NoOpIdle)
-
-    it "preserves the counter for any Idle state" do
-        decideInterrupt (Idle 0) `shouldBe` (Idle 0, NoOpIdle)
-        decideInterrupt (Idle 42) `shouldBe` (Idle 42, NoOpIdle)
-
-    it "advances to Idle (n+1) and emits SendInterruptFor n when Busy" do
-        decideInterrupt (Busy 7) `shouldBe` (Idle 8, SendInterruptFor 7)
-
-    it "advances correctly from Busy 0" do
-        decideInterrupt (Busy 0) `shouldBe` (Idle 1, SendInterruptFor 0)
+    [ testCase "is a no-op when the session is Idle" do
+        decideInterrupt (Idle 7) @?= (Idle 7, NoOpIdle)
+    , testCase "preserves the counter for any Idle state" do
+        decideInterrupt (Idle 0) @?= (Idle 0, NoOpIdle)
+        decideInterrupt (Idle 42) @?= (Idle 42, NoOpIdle)
+    , testCase "advances to Idle (n+1) and emits SendInterruptFor n when Busy" do
+        decideInterrupt (Busy 7) @?= (Idle 8, SendInterruptFor 7)
+    , testCase "advances correctly from Busy 0" do
+        decideInterrupt (Busy 0) @?= (Idle 1, SendInterruptFor 0)
+    ]
 
 
 -- | Pins down the 'Conc.scoped' fix in 'execGhci': when the drain forks
@@ -496,13 +508,13 @@
 -- ambient scope is torn down — siblings die, the whole builder cycle
 -- unwinds, and the daemon ends up in the "Restarting builder..." state
 -- the user observed.
-testExecGhciScope :: Spec
+testExecGhciScope :: [TestTree]
 testExecGhciScope =
     -- Spawn a real subprocess that exits immediately ('true'). Its
     -- stdout/stderr pipes EOF as soon as the child exits, which makes
     -- 'drainUntil' inside 'execGhci' throw 'UnexpectedExit' — exactly the
     -- mid-command termination path the fix exists to handle.
-    it "contains drain exceptions inside its own scope so siblings survive" do
+    [ testCase "contains drain exceptions inside its own scope so siblings survive" do
         p <-
             startProcess
                 $ setStdin createPipe
@@ -550,7 +562,8 @@
         -- subprocess has long since exited; just swallow the cleanup error.
         _ <- (Right <$> stopProcess p) `catch` \(_ :: SomeException) -> pure (Left ())
         siblingDone <- readIORef siblingDoneRef
-        siblingDone `shouldBe` True
+        siblingDone @?= True
         case result of
+            Right _ -> assertFailure "expected execGhci to raise UnexpectedExit"
             Left _ -> pure ()
-            Right _ -> expectationFailure "expected execGhci to raise UnexpectedExit"
+    ]
diff --git a/test/Unit/Tricorder/Daemon/GhciSessionSpec.hs b/test/Unit/Tricorder/Daemon/GhciSessionSpec.hs
--- a/test/Unit/Tricorder/Daemon/GhciSessionSpec.hs
+++ b/test/Unit/Tricorder/Daemon/GhciSessionSpec.hs
@@ -1,10 +1,11 @@
-module Unit.Tricorder.Daemon.GhciSessionSpec (spec_GhciSession) where
+module Unit.Tricorder.Daemon.GhciSessionSpec (test_GhciSession) where
 
 import Atelier.Effects.Publishing.Pub (Pub)
 import Control.Exception (ErrorCall (..))
 import Effectful (IOE, runEff)
 import Effectful.Exception (try)
-import Test.Hspec (Spec, describe, it, shouldBe, shouldSatisfy)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertBool, testCase, (@?=))
 
 import Atelier.Effects.Publishing.Pub qualified as Pub
 import Data.Map.Strict qualified as Map
@@ -19,79 +20,86 @@
     , withGhci
     )
 import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.Command (Command (..), Repl (..))
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.Stage (Stage (..))
 
 
-spec_GhciSession :: Spec
-spec_GhciSession = do
-    describe "runGhciSessionScripted" testScripted
+test_GhciSession :: TestTree
+test_GhciSession =
+    testGroup
+        "GhciSession"
+        [ testGroup "runGhciSessionScripted" testScripted
+        ]
 
 
 --------------------------------------------------------------------------------
 -- Scripted interpreter tests
 --------------------------------------------------------------------------------
 
-testScripted :: Spec
-testScripted = do
-    describe "withGhci" do
-        describe "initial load" do
-            it "returns scripted messages" do
+testScripted :: [TestTree]
+testScripted =
+    [ testGroup
+        "withGhci"
+        [ testGroup
+            "initial load"
+            [ testCase "returns scripted messages" do
                 LoadResult {diagnostics = msgs} <-
                     runScripted [simpleResult [errMsg]]
                         $ withGhci cmd (ProjectRoot "/") \initial _ -> pure initial
-                msgs `shouldBe` [errMsg]
-
-            it "returns empty list when scripted result has no messages" do
+                msgs @?= [errMsg]
+            , testCase "returns empty list when scripted result has no messages" do
                 LoadResult {diagnostics = msgs} <-
                     runScripted [simpleResult []]
                         $ withGhci cmd (ProjectRoot "/") \initial _ -> pure initial
-                msgs `shouldBe` []
-
-            it "throws when scripted result is Left" do
+                msgs @?= []
+            , testCase "throws when scripted result is Left" do
                 result <-
                     runScripted [Left (toException boom)]
                         $ try @ErrorCall
                         $ withGhci cmd (ProjectRoot "/") \initial _ -> pure initial
-                result `shouldBe` Left boom
-
-        describe "reloading" do
-            it "returns scripted messages" do
+                result @?= Left boom
+            ]
+        , testGroup
+            "reloading"
+            [ testCase "returns scripted messages" do
                 LoadResult {diagnostics = msgs} <-
                     runScripted [simpleResult [warnMsg], simpleResult [errMsg]]
                         $ withGhci cmd (ProjectRoot "/") \_ controls -> controls.reload
-                msgs `shouldBe` [errMsg]
-
-            it "throws when scripted result is Left" do
+                msgs @?= [errMsg]
+            , testCase "throws when scripted result is Left" do
                 result <-
                     runScripted [Left (toException boom)]
                         $ try @ErrorCall
                         $ withGhci cmd (ProjectRoot "/") \_ controls -> controls.reload
-                result `shouldBe` Left boom
-
-    describe "sequencing" do
-        it "consumes results in order across mixed operations" do
+                result @?= Left boom
+            ]
+        ]
+    , testGroup
+        "sequencing"
+        [ testCase "consumes results in order across mixed operations" do
             (a, b) <- runScripted [simpleResult [errMsg], simpleResult [warnMsg]] do
                 withGhci cmd (ProjectRoot "/") \LoadResult {diagnostics = a} controls -> do
                     LoadResult {diagnostics = b} <- controls.reload
                     pure (a, b)
-            a `shouldBe` [errMsg]
-            b `shouldBe` [warnMsg]
-
-        it "recover scenario: error then success" do
+            a @?= [errMsg]
+            b @?= [warnMsg]
+        , testCase "recover scenario: error then success" do
             result <- runScripted [Left (toException boom), simpleResult []] do
                 r1 <- try @ErrorCall $ withGhci cmd (ProjectRoot "/") \i _ -> pure i
                 LoadResult {diagnostics = r2} <- withGhci cmd (ProjectRoot "/") \i _ -> pure i
                 pure (r1, r2)
-            fst result `shouldSatisfy` isLeft
-            snd result `shouldBe` []
+            assertBool "expected Left" $ isLeft (fst result)
+            snd result @?= []
+        ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- Helpers
 --------------------------------------------------------------------------------
 
-cmd :: Command
-cmd = Command Cabal [] []
+cmd :: RenderedCommand 'Build
+cmd = RenderedCommand "cabal repl lib:foo"
 
 
 boom :: ErrorCall
diff --git a/test/Unit/Tricorder/Daemon/TestRunnerSpec.hs b/test/Unit/Tricorder/Daemon/TestRunnerSpec.hs
--- a/test/Unit/Tricorder/Daemon/TestRunnerSpec.hs
+++ b/test/Unit/Tricorder/Daemon/TestRunnerSpec.hs
@@ -1,10 +1,12 @@
-module Unit.Tricorder.Daemon.TestRunnerSpec (spec_TestRunner) where
+module Unit.Tricorder.Daemon.TestRunnerSpec (test_TestRunner) where
 
 import Control.Exception (ErrorCall (..))
+import Data.Default (def)
 import Effectful (IOE, runEff)
 import Effectful.Concurrent (Concurrent, runConcurrent)
 import Effectful.Exception (try)
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Tricorder.Daemon.TestRunner
     ( GhciOutcome (..)
@@ -12,138 +14,156 @@
     , detectOutcome
     , runTestSuite
     )
-import Tricorder.Session.Command (Repl (..))
-import Tricorder.Session.Target (Target (..))
-import Tricorder.Session.TestTarget (TestTarget (..))
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.Stage.Test.Command (RenderedTestCommand (..))
 import Tricorder.Session.TestTimeout (TestTimeout (..))
 
 import Tricorder.Build.Test qualified as Test
 import Tricorder.Daemon.TestRunner qualified as TestRunner
+import Tricorder.Session.Stage qualified as Stage
 
 
-spec_TestRunner :: Spec
-spec_TestRunner = do
-    describe "detectOutcome" testDetectOutcome
-    describe "runScripted" testScripted
+test_TestRunner :: TestTree
+test_TestRunner =
+    testGroup
+        "TestRunner"
+        [ testGroup "detectOutcome" testDetectOutcome
+        , testGroup "runScripted" testScripted
+        ]
 
 
 --------------------------------------------------------------------------------
 -- detectOutcome tests
 --------------------------------------------------------------------------------
 
-testDetectOutcome :: Spec
-testDetectOutcome = do
-    describe "no exception line" do
-        it "treats empty output as pass" do
-            detectOutcome "" `shouldBe` GhciPassed
-
-        it "treats output with no exception as pass" do
-            detectOutcome "2 examples, 0 failures\n" `shouldBe` GhciPassed
-
-        it "does not match 'ExitSuccess' without the exception prefix" do
-            detectOutcome "ExitSuccess\n" `shouldBe` GhciPassed
-
-    describe "ExitSuccess" do
-        it "detects ExitSuccess as pass" do
-            detectOutcome "*** Exception: ExitSuccess\n" `shouldBe` GhciPassed
-
-        it "detects ExitSuccess anywhere in output" do
+testDetectOutcome :: [TestTree]
+testDetectOutcome =
+    [ testGroup
+        "no exception line"
+        [ testCase "treats empty output as pass" do
+            detectOutcome "" @?= GhciPassed
+        , testCase "treats output with no exception as pass" do
+            detectOutcome "2 examples, 0 failures\n" @?= GhciPassed
+        , testCase "does not match 'ExitSuccess' without the exception prefix" do
+            detectOutcome "ExitSuccess\n" @?= GhciPassed
+        ]
+    , testGroup
+        "ExitSuccess"
+        [ testCase "detects ExitSuccess as pass" do
+            detectOutcome "*** Exception: ExitSuccess\n" @?= GhciPassed
+        , testCase "detects ExitSuccess anywhere in output" do
             detectOutcome "All tests passed\n*** Exception: ExitSuccess\n"
-                `shouldBe` GhciPassed
-
-    describe "ExitFailure" do
-        it "detects ExitFailure 1 as fail" do
+                @?= GhciPassed
+        ]
+    , testGroup
+        "ExitFailure"
+        [ testCase "detects ExitFailure 1 as fail" do
             detectOutcome "1 failure\n*** Exception: ExitFailure 1\n"
-                `shouldBe` GhciFailed
-
-        it "detects ExitFailure with any exit code as fail" do
-            detectOutcome "*** Exception: ExitFailure 42\n" `shouldBe` GhciFailed
-
-        it "detects ExitFailure anywhere in output" do
+                @?= GhciFailed
+        , testCase "detects ExitFailure with any exit code as fail" do
+            detectOutcome "*** Exception: ExitFailure 42\n" @?= GhciFailed
+        , testCase "detects ExitFailure anywhere in output" do
             detectOutcome "Some output\n*** Exception: ExitFailure 1\nMore output\n"
-                `shouldBe` GhciFailed
-
-    describe "other exception" do
-        it "classifies unknown exception as error with message" do
+                @?= GhciFailed
+        ]
+    , testGroup
+        "other exception"
+        [ testCase "classifies unknown exception as error with message" do
             detectOutcome "*** Exception: SomeException \"oops\"\n"
-                `shouldBe` GhciCrashed "SomeException \"oops\""
-
-        it "trims trailing whitespace from the error message" do
+                @?= GhciCrashed "SomeException \"oops\""
+        , testCase "trims trailing whitespace from the error message" do
             detectOutcome "*** Exception: Crashed  \n"
-                `shouldBe` GhciCrashed "Crashed"
-
-    describe "compile failure (no exception line, but GHC errors present)" do
-        it "flags ':main not in scope' as crashed" do
+                @?= GhciCrashed "Crashed"
+        ]
+    , testGroup
+        "compile failure (no exception line, but GHC errors present)"
+        [ testCase "flags ':main not in scope' as crashed" do
             detectOutcome "<interactive>:1:1: error: [GHC-76037] Not in scope: 'main'\n"
-                `shouldBe` GhciCrashed
+                @?= GhciCrashed
                     "<interactive>:1:1: error: [GHC-76037] Not in scope: 'main'"
-
-        it "flags a source-file compile error as crashed" do
+        , testCase "flags a source-file compile error as crashed" do
             detectOutcome "src/Foo.hs:42:5: error: Variable not in scope: foo\n"
-                `shouldBe` GhciCrashed "src/Foo.hs:42:5: error: Variable not in scope: foo"
-
-        it "reports the first error line when multiple are present" do
+                @?= GhciCrashed "src/Foo.hs:42:5: error: Variable not in scope: foo"
+        , testCase "reports the first error line when multiple are present" do
             detectOutcome
                 "src/Foo.hs:42:5: error: Variable not in scope: foo\nsrc/Bar.hs:10:1: error: Parse error\n"
-                `shouldBe` GhciCrashed "src/Foo.hs:42:5: error: Variable not in scope: foo"
-
-        it "prefers exit exception over compile-error heuristic when both appear" do
+                @?= GhciCrashed "src/Foo.hs:42:5: error: Variable not in scope: foo"
+        , testCase "prefers exit exception over compile-error heuristic when both appear" do
             -- A real failing run could plausibly mention 'error:' in its
             -- captured output (e.g. logged messages); the ExitFailure line
             -- still wins.
             detectOutcome "log: error: something happened\n*** Exception: ExitFailure 1\n"
-                `shouldBe` GhciFailed
+                @?= GhciFailed
+        ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- Scripted interpreter tests
 --------------------------------------------------------------------------------
 
-testScripted :: Spec
-testScripted = do
-    it "returns scripted TestRun" do
+testScripted :: [TestTree]
+testScripted =
+    [ testCase "returns scripted TestRun" do
         result <-
             runScripted [Right passingRun]
-                $ runTestSuite noProgress Nothing Cabal testTimeout
-                $ mkTestTarget "test:foo"
-        result `shouldBe` passingRun
-
-    it "ignores the target name argument" do
+                $ runTestSuite noProgress testTimeout
+                $ mkResolved
+                $ RenderedCommand
+                $ "cabal repl test:foo"
+        result @?= passingRun
+    , testCase "ignores the target name argument" do
         result <-
             runScripted [Right failingRun]
-                $ runTestSuite noProgress Nothing Cabal testTimeout
-                $ mkTestTarget "test:anything"
-        result `shouldBe` failingRun
-
-    it "throws when scripted result is Left" do
+                $ runTestSuite noProgress testTimeout
+                $ mkResolved
+                $ RenderedCommand
+                $ "cabal repl test:anything"
+        result @?= failingRun
+    , testCase "throws when scripted result is Left" do
         result <-
             runScripted [Left (toException boom)]
                 $ try @ErrorCall
-                $ runTestSuite noProgress Nothing Cabal testTimeout
-                $ mkTestTarget "test:foo"
-        result `shouldBe` Left boom
-
-    describe "sequencing" do
-        it "consumes results in order across multiple calls" do
+                $ runTestSuite noProgress testTimeout
+                $ mkResolved
+                $ RenderedCommand
+                $ "cabal repl test:foo"
+        result @?= Left boom
+    , testGroup
+        "sequencing"
+        [ testCase "consumes results in order across multiple calls" do
             (a, b) <- runScripted [Right passingRun, Right failingRun] do
-                a <- runTestSuite noProgress Nothing Cabal testTimeout $ mkTestTarget "test:foo"
-                b <- runTestSuite noProgress Nothing Cabal testTimeout $ mkTestTarget "test:bar"
+                a <-
+                    runTestSuite noProgress testTimeout
+                        $ mkResolved
+                        $ RenderedCommand
+                        $ "cabal repl test:foo"
+                b <-
+                    runTestSuite noProgress testTimeout
+                        $ mkResolved
+                        $ RenderedCommand
+                        $ "cabal repl test:bar"
                 pure (a, b)
-            a `shouldBe` passingRun
-            b `shouldBe` failingRun
-
-        it "recover scenario: error then success" do
+            a @?= passingRun
+            b @?= failingRun
+        , testCase "recover scenario: error then success" do
             result <- runScripted [Left (toException boom), Right passingRun] do
                 r1 <-
                     try @ErrorCall
-                        $ runTestSuite noProgress Nothing Cabal testTimeout
-                        $ mkTestTarget "test:foo"
+                        $ runTestSuite noProgress testTimeout
+                        $ mkResolved
+                        $ RenderedCommand
+                        $ "cabal repl test:foo"
                 r2 <-
-                    runTestSuite noProgress Nothing Cabal testTimeout
-                        $ mkTestTarget "test:bar"
+                    runTestSuite noProgress testTimeout
+                        $ mkResolved
+                        $ RenderedCommand
+                        $ "cabal repl test:bar"
                 pure (r1, r2)
-            fst result `shouldBe` Left boom
-            snd result `shouldBe` passingRun
+            fst result @?= Left boom
+            snd result @?= passingRun
+        ]
+    ]
 
 
 --------------------------------------------------------------------------------
@@ -180,8 +200,8 @@
 runScripted results = runEff . runConcurrent . TestRunner.runScripted results
 
 
-mkTestTarget :: Text -> TestTarget
-mkTestTarget = TestTarget . Bare
+mkResolved :: RenderedCommand 'Stage.Test -> RenderedTestCommand
+mkResolved cmd = RenderedTestCommand cmd def
 
 
 testTimeout :: TestTimeout
diff --git a/test/Unit/Tricorder/Daemon/WatchSpec.hs b/test/Unit/Tricorder/Daemon/WatchSpec.hs
--- a/test/Unit/Tricorder/Daemon/WatchSpec.hs
+++ b/test/Unit/Tricorder/Daemon/WatchSpec.hs
@@ -1,9 +1,10 @@
-module Unit.Tricorder.Daemon.WatchSpec (spec_Watch) where
+module Unit.Tricorder.Daemon.WatchSpec (test_Watch) where
 
 import Atelier.Effects.FileWatcher (FileEvent (..), matchesAny)
 import Effectful (runEff)
 import Effectful.Writer.Static.Shared (execWriter, runWriter)
-import Test.Hspec (Spec, describe, it, shouldBe, shouldMatchList)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 import Text.Regex.TDFA.ReadRegex (parseRegex)
 
 import Atelier.Effects.Publishing.Pub qualified as Pub
@@ -20,21 +21,30 @@
 import Tricorder.Daemon.Watch qualified as Watch
 
 
-spec_Watch :: Spec
-spec_Watch = do
-    describe "publishChange" testPublishChange
-    describe "specs" testSpecs
+test_Watch :: TestTree
+test_Watch =
+    testGroup
+        "Watch"
+        [ testGroup "publishChange" testPublishChange
+        , testGroup "specs" testSpecs
+        ]
 
 
-testPublishChange :: Spec
-testPublishChange = do
-    describe "with non-cabal file change" $ it "should publish SourceChangeDetected" do
-        (_, sourceChanges) <- runTest "foo"
-        sourceChanges `shouldMatchList` [SourceChangeDetected "foo" Modified]
-
-    describe "with cabal file change" $ it "should publish CabalChangeDetected" do
-        (cabalChanges, _) <- runTest "foo.cabal"
-        cabalChanges `shouldMatchList` [CabalChangeDetected "foo.cabal" Modified]
+testPublishChange :: [TestTree]
+testPublishChange =
+    [ testGroup
+        "with non-cabal file change"
+        [ testCase "should publish SourceChangeDetected" do
+            (_, sourceChanges) <- runTest "foo"
+            sourceChanges @?= [SourceChangeDetected "foo" Modified]
+        ]
+    , testGroup
+        "with cabal file change"
+        [ testCase "should publish CabalChangeDetected" do
+            (cabalChanges, _) <- runTest "foo.cabal"
+            cabalChanges @?= [CabalChangeDetected "foo.cabal" Modified]
+        ]
+    ]
   where
     runTest =
         runEff
@@ -46,105 +56,100 @@
             . (`WatchedFile` Modified)
 
 
-testSpecs :: Spec
-testSpecs = do
-    describe "source watches" do
-        it "matches .hs files in configured watch dirs" do
+testSpecs :: [TestTree]
+testSpecs =
+    [ testGroup
+        "source watches"
+        [ testCase "matches .hs files in configured watch dirs" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs ["/proj/src"])
-            matchesAny watches "/proj/src/Foo.hs" `shouldBe` True
-
-        it "does not match non-.hs files" do
+            matchesAny watches "/proj/src/Foo.hs" @?= True
+        , testCase "does not match non-.hs files" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs ["/proj/src"])
-            matchesAny watches "/proj/src/Foo.txt" `shouldBe` False
-
-        it "excludes paths containing dist-newstyle" do
+            matchesAny watches "/proj/src/Foo.txt" @?= False
+        , testCase "excludes paths containing dist-newstyle" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs ["/proj/src"])
-            matchesAny watches "/proj/src/dist-newstyle/Foo.hs" `shouldBe` False
-
-        it "excludes paths matching an exclusion pattern" do
+            matchesAny watches "/proj/src/dist-newstyle/Foo.hs" @?= False
+        , testCase "excludes paths matching an exclusion pattern" do
             let pat = parsePattern "vendor"
                 watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [pat])
                         (WatchDirs ["/proj/src"])
-            matchesAny watches "/proj/src/vendor/Foo.hs" `shouldBe` False
-            matchesAny watches "/proj/src/Foo.hs" `shouldBe` True
-
-        it "matches .hs files across multiple watch dirs" do
+            matchesAny watches "/proj/src/vendor/Foo.hs" @?= False
+            matchesAny watches "/proj/src/Foo.hs" @?= True
+        , testCase "matches .hs files across multiple watch dirs" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs ["/proj/src", "/proj/test"])
-            matchesAny watches "/proj/src/Foo.hs" `shouldBe` True
-            matchesAny watches "/proj/test/FooSpec.hs" `shouldBe` True
-
-        -- Second line of defense: 'cabalWatches' registers the whole project
-        -- root, and 'deduplicateDirs' collapses the narrow source dirs into it,
-        -- so the OS watches the entire repo recursively. 'matchesAny' is what
-        -- re-scopes events back to the configured dirs — a .hs file in a sibling
-        -- package must not match.
-        it "does not match a .hs file in a sibling package outside the watch dirs" do
+            matchesAny watches "/proj/src/Foo.hs" @?= True
+            matchesAny watches "/proj/test/FooSpec.hs" @?= True
+        , -- Second line of defense: 'cabalWatches' registers the whole project
+          -- root, and 'deduplicateDirs' collapses the narrow source dirs into it,
+          -- so the OS watches the entire repo recursively. 'matchesAny' is what
+          -- re-scopes events back to the configured dirs — a .hs file in a sibling
+          -- package must not match.
+          testCase "does not match a .hs file in a sibling package outside the watch dirs" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs ["/proj/pkg-a/src"])
-            matchesAny watches "/proj/pkg-a/src/Foo.hs" `shouldBe` True
-            matchesAny watches "/proj/pkg-b/src/Foo.hs" `shouldBe` False
-
-    describe "cabal watches" do
-        it "matches .cabal files under project root" do
+            matchesAny watches "/proj/pkg-a/src/Foo.hs" @?= True
+            matchesAny watches "/proj/pkg-b/src/Foo.hs" @?= False
+        ]
+    , testGroup
+        "cabal watches"
+        [ testCase "matches .cabal files under project root" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs [])
-            matchesAny watches "/proj/foo.cabal" `shouldBe` True
-
-        it "matches cabal.project under project root" do
+            matchesAny watches "/proj/foo.cabal" @?= True
+        , testCase "matches cabal.project under project root" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs [])
-            matchesAny watches "/proj/cabal.project" `shouldBe` True
-
-        it "matches package.yaml under project root" do
+            matchesAny watches "/proj/cabal.project" @?= True
+        , testCase "matches package.yaml under project root" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs [])
-            matchesAny watches "/proj/package.yaml" `shouldBe` True
-
-        it "does not match non-cabal files" do
+            matchesAny watches "/proj/package.yaml" @?= True
+        , testCase "does not match non-cabal files" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs [])
-            matchesAny watches "/proj/README.md" `shouldBe` False
-
-        it "excludes cabal files under dist-newstyle" do
+            matchesAny watches "/proj/README.md" @?= False
+        , testCase "excludes cabal files under dist-newstyle" do
             let watches =
                     Watch.specs
                         (ProjectRoot "/proj")
                         (WatchExclusionPatterns [])
                         (WatchDirs [])
-            matchesAny watches "/proj/dist-newstyle/foo.cabal" `shouldBe` False
+            matchesAny watches "/proj/dist-newstyle/foo.cabal" @?= False
+        ]
+    ]
   where
     parsePattern p = fromRight (error . toText $ "bad test pattern: " <> p) (parseRegex p)
diff --git a/test/Unit/Tricorder/Session/CabalFileSpec.hs b/test/Unit/Tricorder/Session/CabalFileSpec.hs
--- a/test/Unit/Tricorder/Session/CabalFileSpec.hs
+++ b/test/Unit/Tricorder/Session/CabalFileSpec.hs
@@ -1,23 +1,37 @@
-module Unit.Tricorder.Session.CabalFileSpec (spec_CabalFile) where
+module Unit.Tricorder.Session.CabalFileSpec (test_CabalFile) where
 
 import Atelier.Effects.Env (runEnvConst)
 import Atelier.Effects.FileSystem (runFileSystemState)
+import Atelier.Effects.Input (runInputConst)
+import Atelier.Effects.Log (runLogNoOp)
 import Effectful (runPureEff)
 import Effectful.Reader.Static (runReader)
 import Effectful.State.Static.Shared (evalState)
-import Test.Hspec (Spec, describe, it, shouldBe, shouldMatchList)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Atelier.Effects.FileSystem.Glob qualified as Glob
 import Data.Map.Strict qualified as Map
 
 import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.CabalFile (discoverCabalFiles)
+import Tricorder.Session.CabalFile
+    ( CabalFile (..)
+    , discoverCabalPackages
+    , discoverStackPackages
+    , readProjectFile
+    )
+import Tricorder.Session.StackProject (StackProject (..))
 import Unit.Tricorder.Session.Helpers (cabalFixture, multiPackageCabalFs, multiPackageFs)
 
 
-spec_CabalFile :: Spec
-spec_CabalFile = do
-    describe "discoverCabalFiles" testDiscoverCabalFiles
+test_CabalFile :: TestTree
+test_CabalFile =
+    testGroup
+        "CabalFile"
+        [ testGroup "discoverCabalPackages" testDiscoverCabalPackages
+        , testGroup "discoverStackPackages" testDiscoverStackPackages
+        , testGroup "readProjectFile" testReadProjectFile
+        ]
 
 
 -- | Pins the discovery contract: a @cabal.project@ (or @.local@/@.freeze@
@@ -25,109 +39,118 @@
 -- otherwise the @.cabal@ files in the project root are used. Falls back
 -- further to @$HOME/.cabal/config@'s @packages:@ stanza if none of the
 -- project-root files exist.
-testDiscoverCabalFiles :: Spec
-testDiscoverCabalFiles = do
-    describe "when there is no cabal.project" do
-        it "finds the .cabal files in the project root" do
+testDiscoverCabalPackages :: [TestTree]
+testDiscoverCabalPackages =
+    [ testGroup
+        "when there is no cabal.project"
+        [ testCase "finds the .cabal files in the project root" do
             let actual =
                     runDiscovery (Map.singleton "/myapp.cabal" cabalFixture) []
-                        $ discoverCabalFiles
-            actual `shouldBe` ["/myapp.cabal"]
-
-        it "returns no files when the root has no cabal file" do
-            let actual = runDiscovery mempty [] discoverCabalFiles
-            actual `shouldBe` []
-
-    describe "when there is a multi-package cabal.project" do
-        it "resolves each listed package to its .cabal (regression: was root-only)" do
-            let actual = runDiscovery multiPackageFs [] discoverCabalFiles
-            actual `shouldBe` ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
-
-    describe "priority among cabal.project.local, cabal.project.freeze, and cabal.project" do
-        it "prefers cabal.project.local over cabal.project" do
+                        $ discoverCabalPackages
+            actual @?= Right ["/myapp.cabal"]
+        , testCase "returns no files when the root has no cabal file" do
+            let actual = runDiscovery mempty [] discoverCabalPackages
+            actual @?= Right []
+        ]
+    , testGroup
+        "when there is a multi-package cabal.project"
+        [ testCase "resolves each listed package to its .cabal (regression: was root-only)" do
+            let actual = runDiscovery multiPackageFs [] discoverCabalPackages
+            actual @?= Right ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
+        ]
+    , testGroup
+        "priority among cabal.project.local, cabal.project.freeze, and cabal.project"
+        [ testCase "prefers cabal.project.local over cabal.project" do
             let fs =
                     Map.fromList
                         [ ("/cabal.project.local", "packages: pkg-a\n")
                         , ("/cabal.project", "packages: pkg-b\n")
                         ]
                         `Map.union` multiPackageCabalFs
-                actual = runDiscovery fs [] discoverCabalFiles
-            actual `shouldBe` ["/pkg-a/pkg-a.cabal"]
-
-        it "prefers cabal.project.freeze over cabal.project" do
+                actual = runDiscovery fs [] discoverCabalPackages
+            actual @?= Right ["/pkg-a/pkg-a.cabal"]
+        , testCase "prefers cabal.project.freeze over cabal.project" do
             let fs =
                     Map.fromList
                         [ ("/cabal.project.freeze", "packages: pkg-a\n")
                         , ("/cabal.project", "packages: pkg-b\n")
                         ]
                         `Map.union` multiPackageCabalFs
-                actual = runDiscovery fs [] discoverCabalFiles
-            actual `shouldBe` ["/pkg-a/pkg-a.cabal"]
-
-        describe "when a higher-priority file lists no packages" do
-            it "falls through to the next file in priority order" do
+                actual = runDiscovery fs [] discoverCabalPackages
+            actual @?= Right ["/pkg-a/pkg-a.cabal"]
+        , testGroup
+            "when a higher-priority file lists no packages"
+            [ testCase "falls through to the next file in priority order" do
                 let fs =
                         Map.fromList
                             [ ("/cabal.project.local", "tests: True\n")
                             , ("/cabal.project", "packages: pkg-b\n")
                             ]
                             `Map.union` multiPackageCabalFs
-                    actual = runDiscovery fs [] discoverCabalFiles
-                actual `shouldBe` ["/pkg-b/pkg-b.cabal"]
-
-    describe "packages: entry resolution" do
-        it "uses a direct .cabal path entry verbatim, without scanning a directory" do
+                    actual = runDiscovery fs [] discoverCabalPackages
+                actual @?= Right ["/pkg-b/pkg-b.cabal"]
+            ]
+        ]
+    , testGroup
+        "packages: entry resolution"
+        [ testCase "uses a direct .cabal path entry verbatim, without scanning a directory" do
             let fs = Map.singleton "/cabal.project" "packages: sub/foo.cabal\n"
-                actual = runDiscovery fs [] discoverCabalFiles
-            actual `shouldBe` ["/sub/foo.cabal"]
-
-        it "expands a glob entry matching .cabal files directly" do
+                actual = runDiscovery fs [] discoverCabalPackages
+            actual @?= Right ["/sub/foo.cabal"]
+        , testCase "expands a glob entry matching .cabal files directly" do
             let fs = Map.singleton "/cabal.project" "packages: */*.cabal\n"
                 script = [Glob.NextGlobDir1 ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]]
-                actual = runDiscoveryGlob fs [] script discoverCabalFiles
-            actual `shouldMatchList` ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
-
-        it "expands a glob entry matching package directories" do
+                actual = runDiscoveryGlob fs [] script discoverCabalPackages
+            fromRight [] actual @?= ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
+        , testCase "expands a glob entry matching package directories" do
             let fs =
                     Map.singleton "/cabal.project" "packages: */\n"
                         `Map.union` multiPackageCabalFs
                 script = [Glob.NextGlobDir1 ["/pkg-a", "/pkg-b"]]
-                actual = runDiscoveryGlob fs [] script discoverCabalFiles
-            actual `shouldMatchList` ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
-
-        it "returns no files when a glob entry matches nothing" do
+                actual = runDiscoveryGlob fs [] script discoverCabalPackages
+            fromRight [] actual @?= ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
+        , testCase "returns no files when a glob entry matches nothing" do
             let fs = Map.singleton "/cabal.project" "packages: */*.cabal\n"
                 script = [Glob.NextGlobDir1 []]
-                actual = runDiscoveryGlob fs [] script discoverCabalFiles
-            actual `shouldBe` []
-
-    describe "$HOME/.cabal/config fallback" do
-        describe "when no cabal.project files exist" do
-            it "uses $HOME/.cabal/config as a last-resort packages source" do
+                actual = runDiscoveryGlob fs [] script discoverCabalPackages
+            actual @?= Right []
+        ]
+    , testGroup
+        "$HOME/.cabal/config fallback"
+        [ testGroup
+            "when no cabal.project files exist"
+            [ testCase "uses $HOME/.cabal/config as a last-resort packages source" do
                 let fs =
                         Map.singleton "/home/user/.cabal/config" "packages: pkg-a\n"
                             `Map.union` multiPackageCabalFs
-                    actual = runDiscovery fs [("HOME", "/home/user")] discoverCabalFiles
-                actual `shouldBe` ["/pkg-a/pkg-a.cabal"]
-
-        describe "when $HOME/.cabal/config exists but lists no packages" do
-            it "falls back to scanning the project root" do
+                    actual = runDiscovery fs [("HOME", "/home/user")] discoverCabalPackages
+                actual @?= Right ["/pkg-a/pkg-a.cabal"]
+            ]
+        , testGroup
+            "when $HOME/.cabal/config exists but lists no packages"
+            [ testCase "falls back to scanning the project root" do
                 let fs =
                         Map.fromList
                             [ ("/home/user/.cabal/config", "")
                             , ("/myapp.cabal", cabalFixture)
                             ]
-                    actual = runDiscovery fs [("HOME", "/home/user")] discoverCabalFiles
-                actual `shouldBe` ["/myapp.cabal"]
-
-    describe "packages: single-line list" do
-        describe "when package list is comma-separated" do
-            it "parses package names correctly" do
+                    actual = runDiscovery fs [("HOME", "/home/user")] discoverCabalPackages
+                actual @?= Right ["/myapp.cabal"]
+            ]
+        ]
+    , testGroup
+        "packages: single-line list"
+        [ testGroup
+            "when package list is comma-separated"
+            [ testCase "parses package names correctly" do
                 let fs =
                         Map.singleton "/cabal.project" "packages: pkg-a, pkg-b\n"
                             `Map.union` multiPackageCabalFs
-                    actual = runDiscovery fs [] discoverCabalFiles
-                actual `shouldMatchList` ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
+                    actual = runDiscovery fs [] discoverCabalPackages
+                fromRight [] actual @?= ["/pkg-a/pkg-a.cabal", "/pkg-b/pkg-b.cabal"]
+            ]
+        ]
+    ]
   where
     pr = ProjectRoot "/"
     runDiscovery fs env = runDiscoveryGlob fs env []
@@ -138,3 +161,49 @@
             . runFileSystemState
             . Glob.runScripted script
             . runReader pr
+
+
+-- | Pins the discovery contract: with a @stack.yaml@, package paths come
+-- straight from its @packages:@ list, resolved against the project root.
+testDiscoverStackPackages :: [TestTree]
+testDiscoverStackPackages =
+    [ testCase "resolves each package path against the project root" do
+        let actual = runStack (StackProject ["pkg-a", "pkg-b"]) discoverStackPackages
+        actual @?= Right ["/pkg-a", "/pkg-b"]
+    , testCase "normalises resolved paths" do
+        let actual = runStack (StackProject ["./pkg-a"]) discoverStackPackages
+        actual @?= Right ["/pkg-a"]
+    , testCase "returns no packages when the list is empty" do
+        let actual = runStack (StackProject []) discoverStackPackages
+        actual @?= Right []
+    ]
+  where
+    pr = ProjectRoot "/"
+    runStack result =
+        runPureEff
+            . runReader pr
+            . runLogNoOp
+            . runInputConst result
+
+
+-- | Pins how a package path resolves to a @.cabal@ file: a directory path
+-- (as listed in @stack.yaml@) reads the @.cabal@ file inside it.
+testReadProjectFile :: [TestTree]
+testReadProjectFile =
+    [ testGroup
+        "when the path is a directory"
+        [ testCase "reads the .cabal file inside it" do
+            let actual = runRead multiPackageCabalFs $ readProjectFile "/pkg-a"
+            actual @?= Right "/pkg-a/pkg-a.cabal"
+        , testCase "fails with the directory path when it contains no .cabal file" do
+            let fs = Map.singleton "/pkg-a/package.yaml" "name: pkg-a\n"
+                actual = runRead fs $ readProjectFile "/pkg-a"
+            actual @?= Left "/pkg-a"
+        ]
+    ]
+  where
+    runRead fs =
+        fmap (.projectFilePath)
+            . runPureEff
+            . evalState fs
+            . runFileSystemState
diff --git a/test/Unit/Tricorder/Session/CommandSpec.hs b/test/Unit/Tricorder/Session/CommandSpec.hs
deleted file mode 100644
--- a/test/Unit/Tricorder/Session/CommandSpec.hs
+++ /dev/null
@@ -1,123 +0,0 @@
-module Unit.Tricorder.Session.CommandSpec (spec_Command) where
-
-import Atelier.Effects.FileSystem (runFileSystemState)
-import Data.Default (def)
-import Effectful (runPureEff)
-import Effectful.State.Static.Shared (evalState)
-import Test.Hspec (Spec, describe, it, shouldBe)
-
-import Data.Map.Strict qualified as Map
-
-import Tricorder.Runtime (ProjectRoot (..))
-import Tricorder.Session.Command (resolveCommand)
-import Tricorder.Session.Config (Config (..))
-import Tricorder.Session.Target (parseTarget)
-import Tricorder.Session.TestTarget (parseTestTargets)
-
-import Tricorder.Session.Command qualified as Command
-import Tricorder.Session.Config qualified as Config
-
-
-spec_Command :: Spec
-spec_Command = do
-    describe "resolveCommand" testResolveCommand
-
-
-testResolveCommand :: Spec
-testResolveCommand = do
-    describe "when config has a command" do
-        it "should use specified command" do
-            let actual =
-                    Command.render
-                        . runPureEff
-                        . evalState mempty
-                        . runFileSystemState
-                        $ resolveCommand pr def {command = Just "foo"} [] testTargets
-            actual `shouldBe` "foo"
-
-    describe "when config has explicit targets" do
-        it "should spell them out verbatim, ignoring discovered test targets" do
-            let actual =
-                    Command.render
-                        . runPureEff
-                        . evalState (Map.singleton "/cabal.project" "")
-                        . runFileSystemState
-                        $ resolveCommand pr cfg (parseTarget <$> ["lib:foo"]) testTargets
-            actual `shouldBe` "cabal repl --enable-multi-repl --builddir /replbuild lib:foo"
-
-    describe "when config does not have a command or targets" do
-        describe "and there is a cabal.project file" do
-            it "should use cabal 'all' plus the discovered test targets" do
-                let actual =
-                        Command.render
-                            . runPureEff
-                            . evalState (Map.singleton "/cabal.project" "")
-                            . runFileSystemState
-                            $ resolveCommand pr cfg [] testTargets
-                actual
-                    `shouldBe` "cabal repl --enable-multi-repl --builddir /replbuild all test:foo"
-
-        describe "and there is at least one *.cabal file" do
-            it "should use cabal 'all' plus the discovered test targets" do
-                let actual =
-                        Command.render
-                            . runPureEff
-                            . evalState (Map.singleton "/foo.cabal" "")
-                            . runFileSystemState
-                            $ resolveCommand pr cfg [] testTargets
-                actual
-                    `shouldBe` "cabal repl --enable-multi-repl --builddir /replbuild all test:foo"
-
-        describe "and there is a stack.yaml file" do
-            it "should use stack ghci with 'all' plus test targets" do
-                let actual =
-                        Command.render
-                            . runPureEff
-                            . evalState (Map.singleton "/stack.yaml" "")
-                            . runFileSystemState
-                            $ resolveCommand pr cfg [] testTargets
-                actual `shouldBe` "stack ghci all foo"
-
-        describe "and there is both a stack.yaml and a cabal.project file" do
-            it "should prefer stack ghci over cabal" do
-                let actual =
-                        Command.render
-                            . runPureEff
-                            . evalState (Map.fromList [("/stack.yaml", ""), ("/cabal.project", "")])
-                            . runFileSystemState
-                            $ resolveCommand pr cfg [] testTargets
-                actual `shouldBe` "stack ghci all foo"
-
-        describe "and there is both a stack.yaml and a *.cabal file" do
-            it "should prefer stack ghci over cabal" do
-                let actual =
-                        Command.render
-                            . runPureEff
-                            . evalState (Map.fromList [("/stack.yaml", ""), ("/foo.cabal", "")])
-                            . runFileSystemState
-                            $ resolveCommand pr cfg [] testTargets
-                actual `shouldBe` "stack ghci all foo"
-
-        describe "but there are no project files" do
-            it "should use default cabal repl with 'all' plus test targets" do
-                let actual =
-                        Command.render
-                            . runPureEff
-                            . evalState mempty
-                            . runFileSystemState
-                            $ resolveCommand pr cfg [] testTargets
-                actual `shouldBe` "cabal repl --builddir /replbuild all test:foo"
-
-        describe "and no test targets are discovered" do
-            it "should fall back to plain 'all'" do
-                let actual =
-                        Command.render
-                            . runPureEff
-                            . evalState (Map.singleton "/cabal.project" "")
-                            . runFileSystemState
-                            $ resolveCommand pr cfg [] (parseTestTargets [])
-                actual `shouldBe` "cabal repl --enable-multi-repl --builddir /replbuild all"
-  where
-    pr = ProjectRoot "/"
-    cfg = def {Config.replBuildDir = "/replbuild"}
-    testTargets = parseTestTargets ["test:foo"]
diff --git a/test/Unit/Tricorder/Session/CommandTemplateSpec.hs b/test/Unit/Tricorder/Session/CommandTemplateSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/Session/CommandTemplateSpec.hs
@@ -0,0 +1,58 @@
+module Unit.Tricorder.Session.CommandTemplateSpec (test_Command) where
+
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
+
+import Tricorder.Session.CommandTemplate
+    ( hasPlaceholder
+    , renderTargetsFor
+    , targetPlaceholder
+    , targetsPlaceholder
+    )
+import Tricorder.Session.Repl (Repl (..))
+import Tricorder.Session.Target (ComponentKind (..), Target (..))
+
+
+test_Command :: TestTree
+test_Command =
+    testGroup
+        "Command"
+        [ testGroup "renderTargetsFor" testRenderTargetsFor
+        , testGroup "hasPlaceholder" testHasPlaceholder
+        ]
+
+
+--------------------------------------------------------------------------------
+-- renderTargetsFor
+--------------------------------------------------------------------------------
+
+testRenderTargetsFor :: [TestTree]
+testRenderTargetsFor =
+    [ testCase "renders bare component names for plain Stack, deduplicated" do
+        renderTargetsFor Stack [Qualified Test "foo", PackageQualified "pkg" Test "foo"]
+            @?= ["foo"]
+    , testCase "renders fully qualified targets for StackMulti" do
+        renderTargetsFor StackMulti [PackageQualified "pkg" Test "foo"]
+            @?= ["pkg:test:foo"]
+    , testCase "renders fully qualified targets for Cabal" do
+        renderTargetsFor Cabal [Qualified Test "foo"] @?= ["test:foo"]
+    ]
+
+
+--------------------------------------------------------------------------------
+-- hasPlaceholder
+--------------------------------------------------------------------------------
+
+testHasPlaceholder :: [TestTree]
+testHasPlaceholder =
+    [ testCase "is True when {targets} is present and checking for targetsPlaceholder" do
+        hasPlaceholder targetsPlaceholder "cabal repl {targets}" @?= True
+    , testCase "is True when only the escaped \\{targets} is present" do
+        hasPlaceholder targetsPlaceholder "echo \\{targets}" @?= True
+    , testCase "is False when neither form is present" do
+        hasPlaceholder targetsPlaceholder "cabal repl test:foo" @?= False
+    , testCase "is True when {target} is present and checking for targetPlaceholder" do
+        hasPlaceholder targetPlaceholder "cabal repl {target}" @?= True
+    , testCase "is False for {targets} (plural) when checking for targetPlaceholder" do
+        hasPlaceholder targetPlaceholder "cabal repl {targets}" @?= False
+    ]
diff --git a/test/Unit/Tricorder/Session/ReplSpec.hs b/test/Unit/Tricorder/Session/ReplSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/Session/ReplSpec.hs
@@ -0,0 +1,52 @@
+module Unit.Tricorder.Session.ReplSpec (test_Repl) where
+
+import Atelier.Effects.FileSystem (FileSystem, runFileSystemState)
+import Effectful (runPureEff)
+import Effectful.State.Static.Shared (State, evalState)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
+
+import Data.Map.Strict qualified as Map
+
+import Tricorder.Runtime (ProjectRoot (..))
+import Tricorder.Session.Repl (Repl (..), resolveRepl)
+
+
+test_Repl :: TestTree
+test_Repl =
+    testGroup
+        "Repl"
+        [ testGroup "resolveRepl" testResolveRepl
+        ]
+
+
+testResolveRepl :: [TestTree]
+testResolveRepl =
+    [ testCase "resolves Stack for a single-package stack.yaml" do
+        withFiles [("/stack.yaml", "")] (resolveRepl pr) @?= Stack
+    , testCase "resolves StackMulti for a multi-package stack.yaml" do
+        withFiles
+            [("/stack.yaml", "packages:\n  - foo\n  - bar\n")]
+            (resolveRepl pr)
+            @?= StackMulti
+    , testCase "resolves Cabal when there is a cabal.project file" do
+        withFiles [("/cabal.project", "")] (resolveRepl pr) @?= Cabal
+    , testCase "resolves Cabal when there is at least one *.cabal file" do
+        withFiles [("/foo.cabal", "")] (resolveRepl pr) @?= Cabal
+    , testCase "prefers Stack over Cabal when both are present" do
+        withFiles [("/stack.yaml", ""), ("/cabal.project", "")] (resolveRepl pr) @?= Stack
+    , testCase "falls back to Cabal when there are no project files at all" do
+        withFiles [] (resolveRepl pr) @?= Cabal
+    ]
+
+
+-- | Run a 'FileSystem'-using computation against a faked in-memory
+-- filesystem seeded with the given files (content is irrelevant except for
+-- @stack.yaml@, which is parsed for its @packages@ key).
+withFiles :: [(FilePath, ByteString)] -> Eff '[FileSystem, State (Map FilePath ByteString)] a -> a
+withFiles files action =
+    runPureEff $ evalState (Map.fromList files) $ runFileSystemState action
+
+
+pr :: ProjectRoot
+pr = ProjectRoot "/"
diff --git a/test/Unit/Tricorder/Session/Stage/Build/CommandSpec.hs b/test/Unit/Tricorder/Session/Stage/Build/CommandSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/Session/Stage/Build/CommandSpec.hs
@@ -0,0 +1,193 @@
+module Unit.Tricorder.Session.Stage.Build.CommandSpec (test_Command) where
+
+import Atelier.Effects.FileSystem (FileSystem, runFileSystemState)
+import Data.Default (def)
+import Effectful (runPureEff)
+import Effectful.State.Static.Shared (State, evalState)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
+
+import Data.Map.Strict qualified as Map
+
+import Tricorder.Runtime (ProjectRoot (..))
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..), targetsPlaceholder)
+import Tricorder.Session.Config (Config (..))
+import Tricorder.Session.Repl (Repl (..), resolveRepl)
+import Tricorder.Session.Stage (Stage (..))
+import Tricorder.Session.Stage.Build.Command (render, resolve)
+import Tricorder.Session.Target (Target)
+
+import Tricorder.Session.Config qualified as Config
+import Tricorder.Session.Target qualified as Target
+
+
+test_Command :: TestTree
+test_Command =
+    testGroup
+        "Tricorder.Session.Stage.Build.Command"
+        [ testGroup "resolveBuildCommand" testResolveBuildCommand
+        , testGroup "renderBuild" testRenderBuild
+        ]
+
+
+testRenderBuild :: [TestTree]
+testRenderBuild =
+    [ testCase "substitutes {targets} with the rendered target list" do
+        build (CommandTemplate Cabal "cabal repl {targets}" [] targetsPlaceholder) [Target.parse "lib:foo"]
+            @?= "cabal repl lib:foo"
+    , testCase "substitutes every occurrence of {targets}" do
+        build
+            (CommandTemplate Cabal "echo {targets} && cabal repl {targets}" [] targetsPlaceholder)
+            [Target.parse "lib:foo"]
+            @?= "echo lib:foo && cabal repl lib:foo"
+    , testCase "leaves a template with no placeholder untouched, but still appends arguments" do
+        build
+            (CommandTemplate Cabal "my-wrapper --repl" ["--flag"] targetsPlaceholder)
+            [Target.parse "lib:foo"]
+            @?= "my-wrapper --repl --flag"
+    , testCase "renders \\{targets} as a literal {targets}, without substitution" do
+        build (CommandTemplate Cabal "echo \\{targets}" [] targetsPlaceholder) [Target.parse "lib:foo"]
+            @?= "echo {targets}"
+    , testCase "substitutes an unescaped {targets} while leaving an escaped one literal" do
+        build
+            (CommandTemplate Cabal "echo \\{targets} && cabal repl {targets}" [] targetsPlaceholder)
+            [Target.parse "lib:foo"]
+            @?= "echo {targets} && cabal repl lib:foo"
+    , testCase "substitutes {targets} with nothing when the target list is empty" do
+        build (CommandTemplate Cabal "cabal repl {targets}" [] targetsPlaceholder) []
+            @?= "cabal repl"
+    , testCase "appends arguments after the rendered template" do
+        build
+            (CommandTemplate Cabal "cabal repl {targets}" ["--flag", "value"] targetsPlaceholder)
+            [Target.parse "lib:foo"]
+            @?= "cabal repl lib:foo --flag value"
+    , testCase "does not substitute {target} (singular) when the command uses targetsPlaceholder" do
+        build (CommandTemplate Cabal "cabal repl {target}" [] targetsPlaceholder) [Target.parse "lib:foo"]
+            @?= "cabal repl {target}"
+    ]
+  where
+    build template targets = (render template targets).getRenderedCommand
+
+
+testResolveBuildCommand :: [TestTree]
+testResolveBuildCommand =
+    [ testGroup
+        "deprecated top-level command"
+        [ testCase "is used as the build template when build.command_template is unset" do
+            renderBuildFor [] def {command = Just "foo"} [] @?= "foo"
+        ]
+    , testGroup
+        "build.command_template"
+        [ testCase "overrides the deprecated top-level command" do
+            let cfg =
+                    cfg0
+                        { command = Just "should be ignored"
+                        , build = cfg0.build {commandTemplate = Just "cabal repl {targets}"}
+                        }
+            renderBuildFor [("/cabal.project", "")] cfg (Target.parse <$> ["lib:foo"])
+                @?= "cabal repl lib:foo"
+        ]
+    , testGroup
+        "explicit targets"
+        [ testCase "spell them out verbatim" do
+            renderBuildFor [("/cabal.project", "")] cfg0 (Target.parse <$> ["lib:foo"])
+                @?= "cabal repl --enable-multi-repl --builddir /replbuild lib:foo"
+        ]
+    , testGroup
+        "no command or targets configured"
+        [ testGroup
+            "and there is a cabal.project file"
+            [ testCase "uses cabal 'all'" do
+                renderBuildFor [("/cabal.project", "")] cfg0 []
+                    @?= "cabal repl --enable-multi-repl --builddir /replbuild all"
+            ]
+        , testGroup
+            "and there is at least one *.cabal file"
+            [ testCase "uses cabal 'all'" do
+                renderBuildFor [("/foo.cabal", "")] cfg0 []
+                    @?= "cabal repl --enable-multi-repl --builddir /replbuild all"
+            ]
+        , testGroup
+            "and there is a stack.yaml file"
+            [ testCase "uses stack ghci with 'all'" do
+                renderBuildFor [("/stack.yaml", "")] cfg0 []
+                    @?= "stack ghci all"
+            ]
+        , testGroup
+            "and there is both a stack.yaml and a cabal.project file"
+            [ testCase "prefers stack ghci over cabal" do
+                renderBuildFor [("/stack.yaml", ""), ("/cabal.project", "")] cfg0 []
+                    @?= "stack ghci all"
+            ]
+        , testGroup
+            "but there are no project files"
+            [ testCase "uses default cabal repl with 'all'" do
+                renderBuildFor [] cfg0 []
+                    @?= "cabal repl --builddir /replbuild all"
+            ]
+        ]
+    , testGroup
+        "build.extra_auto_arguments"
+        [ testCase "is appended after the rendered automatically resolved template" do
+            let cfg = cfg0 {build = cfg0.build {extraAutoArguments = ["--extra-flag"]}}
+            renderBuildFor [("/cabal.project", "")] cfg (Target.parse <$> ["lib:foo"])
+                @?= "cabal repl --enable-multi-repl --builddir /replbuild lib:foo --extra-flag"
+        , testCase "is ignored when build.command_template is set" do
+            let cfg =
+                    cfg0
+                        { build =
+                            cfg0.build
+                                { commandTemplate = Just "cabal repl {targets}"
+                                , extraAutoArguments = ["--extra-flag"]
+                                }
+                        }
+            renderBuildFor [("/cabal.project", "")] cfg (Target.parse <$> ["lib:foo"])
+                @?= "cabal repl lib:foo"
+        , testCase "is ignored when the deprecated top-level command is set" do
+            let cfg =
+                    cfg0
+                        { command = Just "cabal repl {targets}"
+                        , build = cfg0.build {extraAutoArguments = ["--extra-flag"]}
+                        }
+            renderBuildFor [("/cabal.project", "")] cfg (Target.parse <$> ["lib:foo"])
+                @?= "cabal repl lib:foo"
+        ]
+    ]
+
+
+-- | Resolve and fully render the build command against a faked filesystem —
+-- the composition 'Tricorder.Session.loadSession' and 'Tricorder.Daemon.Core'
+-- perform between them (resolve a 'CommandTemplate' plus its target list,
+-- then 'renderBuild' the two together).
+renderBuildFor :: [(FilePath, ByteString)] -> Config -> [Target] -> Text
+renderBuildFor files cfg targets =
+    (uncurry render $ withFiles files $ resolveBuild cfg targets).getRenderedCommand
+
+
+-- | Run a 'FileSystem'-using computation against a faked in-memory
+-- filesystem seeded with the given files (content is irrelevant except for
+-- @stack.yaml@, which is parsed for its @packages@ key).
+withFiles :: [(FilePath, ByteString)] -> Eff '[FileSystem, State (Map FilePath ByteString)] a -> a
+withFiles files action =
+    runPureEff $ evalState (Map.fromList files) $ runFileSystemState action
+
+
+cfg0 :: Config
+cfg0 = def {Config.replBuildDir = "/replbuild"}
+
+
+-- | Resolve 'Repl' from the faked filesystem, then resolve the build
+-- command from it — mirrors how 'Tricorder.Session.loadSession' chains the
+-- two steps.
+resolveBuild
+    :: (FileSystem :> es)
+    => Config -> [Target] -> Eff es (CommandTemplate 'Build, [Target])
+resolveBuild cfg targets = do
+    repl <- resolveRepl pr
+    resolve pr cfg repl targets
+
+
+pr :: ProjectRoot
+pr = ProjectRoot "/"
diff --git a/test/Unit/Tricorder/Session/Stage/Eval/CommandSpec.hs b/test/Unit/Tricorder/Session/Stage/Eval/CommandSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/Session/Stage/Eval/CommandSpec.hs
@@ -0,0 +1,62 @@
+module Unit.Tricorder.Session.Stage.Eval.CommandSpec (test_Command) where
+
+import Data.Default (def)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
+
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..), targetPlaceholder)
+import Tricorder.Session.Config (Config (..))
+import Tricorder.Session.Repl (Repl (..))
+import Tricorder.Session.Stage (Stage (..))
+import Tricorder.Session.Stage.Eval.Command (render, resolve)
+import Tricorder.Session.Target (Target (..))
+
+
+test_Command :: TestTree
+test_Command =
+    testGroup
+        "Tricorder.Session.Stage.Eval.Command"
+        [ testGroup "resolveEvalCommand" testResolveEvalCommand
+        , testGroup "renderEval" testRenderEval
+        ]
+
+
+testRenderEval :: [TestTree]
+testRenderEval =
+    [ testCase "substitutes {target} (singular) with the module being evaluated" do
+        eval (CommandTemplate Cabal "cabal repl {target}" [] targetPlaceholder) [Bare "Tricorder.Foo"]
+            @?= "cabal repl Tricorder.Foo"
+    , testCase "does not substitute {targets} (plural) when the command uses targetPlaceholder" do
+        eval (CommandTemplate Cabal "cabal repl {targets}" [] targetPlaceholder) [Bare "Tricorder.Foo"]
+            @?= "cabal repl {targets}"
+    ]
+  where
+    eval template targets = (render template targets).getRenderedCommand
+
+
+testResolveEvalCommand :: [TestTree]
+testResolveEvalCommand =
+    [ testCase "uses the built-in default template for Cabal when eval.command_template is unset" do
+        (resolve Cabal def).template @?= "cabal repl {target}"
+    , testCase "uses eval.command_template when set" do
+        let cfg =
+                def
+                    { eval = (def :: CommandConfig 'Eval) {commandTemplate = Just "cabal repl --builddir /tmp {target}"}
+                    }
+        (resolve Cabal cfg).template @?= "cabal repl --builddir /tmp {target}"
+    , testCase "carries eval.extra_auto_arguments when eval.command_template is unset" do
+        let cfg = def {eval = (def :: CommandConfig 'Eval) {extraAutoArguments = ["--flag"]}}
+        (resolve Cabal cfg).arguments @?= ["--flag"]
+    , testCase "ignores eval.extra_auto_arguments when eval.command_template is set" do
+        let cfg =
+                def
+                    { eval =
+                        (def :: CommandConfig 'Eval)
+                            { commandTemplate = Just "cabal repl {target}"
+                            , extraAutoArguments = ["--flag"]
+                            }
+                    }
+        (resolve Cabal cfg).arguments @?= []
+    ]
diff --git a/test/Unit/Tricorder/Session/Stage/Test/CommandSpec.hs b/test/Unit/Tricorder/Session/Stage/Test/CommandSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/Session/Stage/Test/CommandSpec.hs
@@ -0,0 +1,106 @@
+module Unit.Tricorder.Session.Stage.Test.CommandSpec (test_Command) where
+
+import Data.Default (def)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
+
+import Tricorder.Build.ByteSize (ByteSize (..), Unit (..))
+import Tricorder.Session.Command.RenderedCommand (RenderedCommand (..))
+import Tricorder.Session.CommandConfig (CommandConfig (..))
+import Tricorder.Session.CommandTemplate (CommandTemplate (..), targetPlaceholder)
+import Tricorder.Session.Config (Config (..))
+import Tricorder.Session.Repl (Repl (..))
+import Tricorder.Session.Stage.Test.Command
+    ( RenderedTestCommand (..)
+    , render
+    )
+import Tricorder.Session.Stage.Test.Config (TestConfig (..))
+import Tricorder.Session.Stage.Test.Session (TestSession (..), resolve)
+import Tricorder.Session.TestTarget (TestTarget (..))
+
+import Tricorder.Session.CommandConfig qualified as CommandConfig
+import Tricorder.Session.Stage qualified as Stage
+import Tricorder.Session.Target qualified as Target
+
+
+test_Command :: TestTree
+test_Command =
+    testGroup
+        "Tricorder.Session.Stage.Test.Command"
+        [ testResolveTestSession
+        , testGroup "renderTest" testRenderTest
+        ]
+
+
+testRenderTest :: [TestTree]
+testRenderTest =
+    [ testCase "substitutes {target} (singular) with the single test target" do
+        test (CommandTemplate Cabal "cabal repl {target}" [] targetPlaceholder) Nothing testTarget
+            @?= "cabal repl test:foo"
+    , testCase "does not substitute {targets} (plural) when the command uses targetPlaceholder" do
+        test (CommandTemplate Cabal "cabal repl {targets}" [] targetPlaceholder) Nothing testTarget
+            @?= "cabal repl {targets}"
+    , testCase "adds no memory-limit flag when no limit is configured" do
+        test (CommandTemplate Cabal "cabal repl {target}" [] targetPlaceholder) Nothing testTarget
+            @?= "cabal repl test:foo"
+    , testCase "appends a --repl-options memory-limit RTS flag for Cabal" do
+        test (CommandTemplate Cabal "cabal repl {target}" [] targetPlaceholder) (Just oneByte) testTarget
+            @?= "cabal repl test:foo --repl-options +RTS -M1 -RTS"
+    , testCase "appends a --ghc-options memory-limit RTS flag for Stack" do
+        -- Plain (single-package) Stack renders bare component names, not
+        -- the fully qualified target — see 'testRenderTargetsFor'.
+        test (CommandTemplate Stack "stack ghci {target}" [] targetPlaceholder) (Just oneByte) testTarget
+            @?= "stack ghci foo --ghc-options +RTS -M1 -RTS"
+    , testCase "appends the memory-limit flag after the user's configured arguments" do
+        test
+            (CommandTemplate Cabal "cabal repl {target}" ["--flag"] targetPlaceholder)
+            (Just oneByte)
+            testTarget
+            @?= "cabal repl test:foo --flag --repl-options +RTS -M1 -RTS"
+    ]
+  where
+    test :: CommandTemplate 'Stage.Test -> Maybe ByteSize -> TestTarget -> Text
+    test template mMemoryLimit target =
+        (render (TestSession template [] def) mMemoryLimit target).command.getRenderedCommand
+    testTarget = TestTarget (Target.parse "test:foo")
+    oneByte = ByteSize 1 B
+
+
+testResolveTestSession :: TestTree
+testResolveTestSession =
+    testGroup
+        "resolveTestSession"
+        [ testCase "uses the built-in default template for Cabal when test.command_template is unset" do
+            (resolve Cabal [] def).commandTemplate.template @?= "cabal repl {target}"
+        , testCase "uses the built-in default template for Stack when test.command_template is unset" do
+            (resolve Stack [] def).commandTemplate.template @?= "stack ghci {target}"
+        , testCase "uses test.command_template when set" do
+            let cfg =
+                    def
+                        { test =
+                            def
+                                { commandConfig =
+                                    def
+                                        { CommandConfig.commandTemplate = Just "cabal repl --repl-options=-fno-code {target}"
+                                        }
+                                }
+                        }
+            (resolve Cabal [] cfg).commandTemplate.template
+                @?= "cabal repl --repl-options=-fno-code {target}"
+        , testCase "carries test.extra_auto_arguments when test.command_template is unset" do
+            let cfg = def {test = def {commandConfig = def {extraAutoArguments = ["--flag"]}}}
+            (resolve Cabal [] cfg).commandTemplate.arguments @?= ["--flag"]
+        , testCase "ignores test.extra_auto_arguments when test.command_template is set" do
+            let cfg =
+                    def
+                        { test =
+                            def
+                                { commandConfig =
+                                    def
+                                        { commandTemplate = Just "cabal repl {target}"
+                                        , extraAutoArguments = ["--flag"]
+                                        }
+                                }
+                        }
+            (resolve Cabal [] cfg).commandTemplate.arguments @?= []
+        ]
diff --git a/test/Unit/Tricorder/Session/TargetSpec.hs b/test/Unit/Tricorder/Session/TargetSpec.hs
--- a/test/Unit/Tricorder/Session/TargetSpec.hs
+++ b/test/Unit/Tricorder/Session/TargetSpec.hs
@@ -1,24 +1,19 @@
-module Unit.Tricorder.Session.TargetSpec (spec_Target) where
+module Unit.Tricorder.Session.TargetSpec (test_Target) where
 
 import Distribution.PackageDescription.Parsec (parseGenericPackageDescriptionMaybe)
-import Test.Hspec
-    ( Spec
-    , describe
-    , it
-    , shouldBe
-    , shouldContain
-    , shouldMatchList
-    )
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertBool, testCase, (@?=))
+import Prelude hiding (compare)
 
 import Tricorder.Session.CabalFile (CabalFile (..))
 import Tricorder.Session.Target
     ( ComponentKind (..)
     , Target (..)
     , allComponentTargets
-    , compareTargets
+    , compare
     , definesCustomPrelude
-    , parseTarget
-    , resolveTargets
+    , parse
+    , resolve
     )
 import Unit.Tricorder.Session.Helpers
     ( gpd
@@ -29,211 +24,246 @@
     )
 
 
-spec_Target :: Spec
-spec_Target = do
-    describe "resolveTargets" testResolveTargets
-    describe "parseTarget" testParseTarget
-    describe "compareTargets" testCompareTargets
-    describe "allComponentTargets" testAllComponentTargets
-    describe "definesCustomPrelude" testDefinesCustomPrelude
+test_Target :: TestTree
+test_Target =
+    testGroup
+        "Target"
+        [ testGroup "resolve" testResolveTargets
+        , testGroup "parse" testParseTarget
+        , testGroup "compare" testCompareTargets
+        , testGroup "allComponentTargets" testAllComponentTargets
+        , testGroup "definesCustomPrelude" testDefinesCustomPrelude
+        ]
 
 
-testParseTarget :: Spec
-testParseTarget = do
-    describe "qualified targets" do
-        it "parses lib: as the main library (empty name)" do
-            parseTarget "lib:" `shouldBe` Qualified Lib ""
-
-        it "parses a named lib: target" do
-            parseTarget "lib:myapp-utils" `shouldBe` Qualified Lib "myapp-utils"
-
-        it "parses an flib: target" do
-            parseTarget "flib:myapp-flib" `shouldBe` Qualified FLib "myapp-flib"
-
-        it "parses an exe: target" do
-            parseTarget "exe:myapp-exe" `shouldBe` Qualified Exe "myapp-exe"
-
-        it "parses a test: target" do
-            parseTarget "test:myapp-test" `shouldBe` Qualified Test "myapp-test"
-
-        it "parses a bench: target" do
-            parseTarget "bench:myapp-bench" `shouldBe` Qualified Bench "myapp-bench"
-
-    describe "a name with no kind prefix" do
-        it "parses as bare" do
-            parseTarget "myapp" `shouldBe` Bare "myapp"
-
-    describe "unrecognized targets" do
-        it "rejects an unknown kind" do
-            parseTarget "bogus:myapp" `shouldBe` Unrecognized "bogus:myapp"
-
-        it "rejects a form with extra colons" do
-            parseTarget "lib:a:b" `shouldBe` Unrecognized "lib:a:b"
+testParseTarget :: [TestTree]
+testParseTarget =
+    [ testGroup
+        "qualified targets"
+        [ testCase "parses lib: as the main library (empty name)" do
+            parse "lib:" @?= Qualified Lib ""
+        , testCase "parses a named lib: target" do
+            parse "lib:myapp-utils" @?= Qualified Lib "myapp-utils"
+        , testCase "parses an flib: target" do
+            parse "flib:myapp-flib" @?= Qualified FLib "myapp-flib"
+        , testCase "parses an exe: target" do
+            parse "exe:myapp-exe" @?= Qualified Exe "myapp-exe"
+        , testCase "parses a test: target" do
+            parse "test:myapp-test" @?= Qualified Test "myapp-test"
+        , testCase "parses a bench: target" do
+            parse "bench:myapp-bench" @?= Qualified Bench "myapp-bench"
+        ]
+    , testGroup
+        "a name with no kind prefix"
+        [ testCase "parses as bare" do
+            parse "myapp" @?= Bare "myapp"
+        ]
+    , testGroup
+        "unrecognized targets"
+        [ testCase "rejects an unknown kind" do
+            parse "bogus:myapp" @?= Unrecognized "bogus:myapp"
+        , testCase "rejects a form with extra colons" do
+            parse "lib:a:b" @?= Unrecognized "lib:a:b"
+        ]
+    ]
 
 
-testResolveTargets :: Spec
-testResolveTargets = do
-    describe "when targets are configured" do
-        it "parses and sorts configured targets" do
-            let actual = resolveTargets [] ["lib:foo", "test:foo-test"]
-            actual `shouldBe` [Qualified Lib "foo", Qualified Test "foo-test"]
-
-    describe "when no targets are configured" do
-        it "auto-detects all components from the cabal file" do
+testResolveTargets :: [TestTree]
+testResolveTargets =
+    [ testGroup
+        "when targets are configured"
+        [ testCase "parses and sorts configured targets" do
+            let actual = resolve [] ["lib:foo", "test:foo-test"]
+            actual @?= [Qualified Lib "foo", Qualified Test "foo-test"]
+        ]
+    , testGroup
+        "when no targets are configured"
+        [ testCase "auto-detects all components from the cabal file" do
             -- cabalFixture exposes no Prelude module, so all components sort
             -- alphabetically by their rendered form.
-            let actual = resolveTargets singleCabalFile []
+            let actual = resolve singleCabalFile []
             actual
-                `shouldBe` [ PackageQualified "myapp" Bench "myapp-bench"
-                           , PackageQualified "myapp" Exe "myapp-exe"
-                           , PackageQualified "myapp" FLib "myapp-flib"
-                           , PackageQualified "myapp" Lib "myapp"
-                           , PackageQualified "myapp" Lib "myapp-utils"
-                           , PackageQualified "myapp" Test "myapp-test"
-                           ]
-
-        it "surfaces test-suite components so they can be run after a build" do
-            let actual = resolveTargets singleCabalFile []
-            actual `shouldContain` [PackageQualified "myapp" Test "myapp-test"]
-
-        it "returns no targets when there are no cabal files" do
-            let actual = resolveTargets [] []
-            actual `shouldBe` []
-
-        -- [tag: test_resolve_targest_aggregate]
-        it "aggregates components across every package (regression: was 0)" do
-            let actual = resolveTargets multiCabalFiles []
+                @?= [ PackageQualified "myapp" Bench "myapp-bench"
+                    , PackageQualified "myapp" Exe "myapp-exe"
+                    , PackageQualified "myapp" FLib "myapp-flib"
+                    , PackageQualified "myapp" Lib "myapp"
+                    , PackageQualified "myapp" Lib "myapp-utils"
+                    , PackageQualified "myapp" Test "myapp-test"
+                    ]
+        , testCase "surfaces test-suite components so they can be run after a build" do
+            let actual = resolve singleCabalFile []
+            assertBool "expected myapp-test among the targets"
+                $ PackageQualified "myapp" Test "myapp-test" `elem` actual
+        , testCase "returns no targets when there are no cabal files" do
+            let actual = resolve [] []
+            actual @?= []
+        , -- [tag: test_resolve_targest_aggregate]
+          testCase "aggregates components across every package (regression: was 0)" do
+            let actual = resolve multiCabalFiles []
             actual
-                `shouldMatchList` [ PackageQualified "pkg-a" Test "pkg-a-test"
-                                  , PackageQualified "pkg-b" Test "pkg-b-test"
-                                  , PackageQualified "pkg-a" Lib "pkg-a"
-                                  , PackageQualified "pkg-b" Lib "pkg-b"
-                                  ]
-
-        it "sorts a library exposing a custom Prelude last" do
+                @?= [ PackageQualified "pkg-a" Lib "pkg-a"
+                    , PackageQualified "pkg-a" Test "pkg-a-test"
+                    , PackageQualified "pkg-b" Lib "pkg-b"
+                    , PackageQualified "pkg-b" Test "pkg-b-test"
+                    ]
+        , testCase "sorts a library exposing a custom Prelude last" do
             let cabalFile =
                     CabalFile "/myprelude.cabal"
                         $ fromMaybe (error "libWithPreludeCabal failed to parse")
                         $ parseGenericPackageDescriptionMaybe (libWithPreludeCabal "myprelude")
-            let actual = resolveTargets [cabalFile] []
+            let actual = resolve [cabalFile] []
             actual
-                `shouldBe` [ PackageQualified "myprelude" Exe "myprelude-exe"
-                           , PackageQualified "myprelude" Lib "myprelude"
-                           ]
+                @?= [ PackageQualified "myprelude" Exe "myprelude-exe"
+                    , PackageQualified "myprelude" Lib "myprelude"
+                    ]
+        ]
+    ]
 
 
-testCompareTargets :: Spec
-testCompareTargets = do
+testCompareTargets :: [TestTree]
+testCompareTargets =
     -- A predicate that stands in for 'definesCustomPrelude': marks lib: targets
     -- as "defines custom Prelude" so the comparison contract is exercised
     -- independently of cabal-file parsing.
-    let defPred (Qualified Lib _) = True
-        defPred _ = False
-
-    describe "Ord" do
-        describe "only first target matches the predicate" do
-            describe "first target's render normally sorts as LT" do
-                it "should return GT" do
-                    compareTargets defPred (Qualified Lib "a") (Qualified Exe "b") `shouldBe` GT
-            describe "both targets have the same render" do
-                it "should return GT" do
-                    compareTargets defPred (Qualified Lib "a") (Qualified Exe "a") `shouldBe` GT
-            describe "first target's render normally sorts as GT" do
-                it "should return GT" do
-                    compareTargets defPred (Qualified Lib "b") (Qualified Exe "a") `shouldBe` GT
-
-        describe "only second target matches the predicate" do
-            describe "first target's render normally sorts as LT" do
-                it "should return LT" do
-                    compareTargets defPred (Qualified Exe "a") (Qualified Lib "b") `shouldBe` LT
-            describe "both targets have the same render" do
-                it "should return LT" do
-                    compareTargets defPred (Qualified Exe "a") (Qualified Lib "a") `shouldBe` LT
-            describe "first target's render normally sorts as GT" do
-                it "should return LT" do
-                    compareTargets defPred (Qualified Exe "b") (Qualified Lib "a") `shouldBe` LT
-
-        describe "both targets match the predicate" do
-            describe "first target's render normally sorts as LT" do
-                it "should sort normally" do
-                    compareTargets defPred (Qualified Lib "a") (Qualified Lib "b") `shouldBe` LT
-            describe "both targets have the same render" do
-                it "should sort normally" do
-                    compareTargets defPred (Qualified Lib "a") (Qualified Lib "a") `shouldBe` EQ
-            describe "first target's render normally sorts as GT" do
-                it "should sort normally" do
-                    compareTargets defPred (Qualified Lib "b") (Qualified Lib "a") `shouldBe` GT
-
-        describe "neither target matches the predicate" do
-            describe "first target's render normally sorts as LT" do
-                it "should sort normally" do
-                    compareTargets defPred (Qualified Exe "a") (Qualified Exe "b") `shouldBe` LT
-            describe "both targets have the same render" do
-                it "should sort normally" do
-                    compareTargets defPred (Qualified Exe "a") (Qualified Exe "a") `shouldBe` EQ
-            describe "first target's render normally sorts as GT" do
-                it "should sort normally" do
-                    compareTargets defPred (Qualified Exe "b") (Qualified Exe "a") `shouldBe` GT
+    [ testGroup
+        "Ord"
+        [ testGroup
+            "only first target matches the predicate"
+            [ testGroup
+                "first target's render normally sorts as LT"
+                [ testCase "should return GT" do
+                    compare defPred (Qualified Lib "a") (Qualified Exe "b") @?= GT
+                ]
+            , testGroup
+                "both targets have the same render"
+                [ testCase "should return GT" do
+                    compare defPred (Qualified Lib "a") (Qualified Exe "a") @?= GT
+                ]
+            , testGroup
+                "first target's render normally sorts as GT"
+                [ testCase "should return GT" do
+                    compare defPred (Qualified Lib "b") (Qualified Exe "a") @?= GT
+                ]
+            ]
+        , testGroup
+            "only second target matches the predicate"
+            [ testGroup
+                "first target's render normally sorts as LT"
+                [ testCase "should return LT" do
+                    compare defPred (Qualified Exe "a") (Qualified Lib "b") @?= LT
+                ]
+            , testGroup
+                "both targets have the same render"
+                [ testCase "should return LT" do
+                    compare defPred (Qualified Exe "a") (Qualified Lib "a") @?= LT
+                ]
+            , testGroup
+                "first target's render normally sorts as GT"
+                [ testCase "should return LT" do
+                    compare defPred (Qualified Exe "b") (Qualified Lib "a") @?= LT
+                ]
+            ]
+        , testGroup
+            "both targets match the predicate"
+            [ testGroup
+                "first target's render normally sorts as LT"
+                [ testCase "should sort normally" do
+                    compare defPred (Qualified Lib "a") (Qualified Lib "b") @?= LT
+                ]
+            , testGroup
+                "both targets have the same render"
+                [ testCase "should sort normally" do
+                    compare defPred (Qualified Lib "a") (Qualified Lib "a") @?= EQ
+                ]
+            , testGroup
+                "first target's render normally sorts as GT"
+                [ testCase "should sort normally" do
+                    compare defPred (Qualified Lib "b") (Qualified Lib "a") @?= GT
+                ]
+            ]
+        , testGroup
+            "neither target matches the predicate"
+            [ testGroup
+                "first target's render normally sorts as LT"
+                [ testCase "should sort normally" do
+                    compare defPred (Qualified Exe "a") (Qualified Exe "b") @?= LT
+                ]
+            , testGroup
+                "both targets have the same render"
+                [ testCase "should sort normally" do
+                    compare defPred (Qualified Exe "a") (Qualified Exe "a") @?= EQ
+                ]
+            , testGroup
+                "first target's render normally sorts as GT"
+                [ testCase "should sort normally" do
+                    compare defPred (Qualified Exe "b") (Qualified Exe "a") @?= GT
+                ]
+            ]
+        ]
+    ]
+  where
+    defPred (Qualified Lib _) = True
+    defPred _ = False
 
 
-testAllComponentTargets :: Spec
-testAllComponentTargets = do
-    it "returns every component for the fixture" do
+testAllComponentTargets :: [TestTree]
+testAllComponentTargets =
+    [ testCase "returns every component for the fixture" do
         allComponentTargets gpd
-            `shouldMatchList` [ PackageQualified "myapp" Lib "myapp"
-                              , PackageQualified "myapp" Lib "myapp-utils"
-                              , PackageQualified "myapp" FLib "myapp-flib"
-                              , PackageQualified "myapp" Exe "myapp-exe"
-                              , PackageQualified "myapp" Test "myapp-test"
-                              , PackageQualified "myapp" Bench "myapp-bench"
-                              ]
-    -- This test ensures `allComponentTargets`' part of the aggregate test.
-    -- [ref:test_resolve_targest_aggregate]
-    it "returns every component for test fixures" do
+            @?= [ PackageQualified "myapp" Lib "myapp"
+                , PackageQualified "myapp" Lib "myapp-utils"
+                , PackageQualified "myapp" FLib "myapp-flib"
+                , PackageQualified "myapp" Exe "myapp-exe"
+                , PackageQualified "myapp" Test "myapp-test"
+                , PackageQualified "myapp" Bench "myapp-bench"
+                ]
+    , -- This test ensures `allComponentTargets`' part of the aggregate test.
+      -- [ref:test_resolve_targest_aggregate]
+      testCase "returns every component for test fixures" do
         let actual =
                 allComponentTargets
                     $ fromMaybe (error "failed to parse cabal")
                     $ parseGenericPackageDescriptionMaybe
                     $ libTestCabal "pkg-a"
         actual
-            `shouldMatchList` [ PackageQualified "pkg-a" Lib "pkg-a"
-                              , PackageQualified "pkg-a" Test "pkg-a-test"
-                              ]
+            @?= [ PackageQualified "pkg-a" Lib "pkg-a"
+                , PackageQualified "pkg-a" Test "pkg-a-test"
+                ]
+    ]
 
 
-testDefinesCustomPrelude :: Spec
-testDefinesCustomPrelude = do
-    let preludeCF =
-            CabalFile "/myprelude.cabal"
-                $ fromMaybe (error "libWithPreludeCabal failed to parse")
-                $ parseGenericPackageDescriptionMaybe (libWithPreludeCabal "myprelude")
-
-    describe "when the main library exposes Prelude" do
-        it "returns True for Qualified Lib \"\" (unnamed main lib)" do
-            definesCustomPrelude [preludeCF] (Qualified Lib "") `shouldBe` True
-
-        it "returns True for Qualified Lib matching the package name" do
-            definesCustomPrelude [preludeCF] (Qualified Lib "myprelude") `shouldBe` True
-
-        it "returns True for Bare matching the package name" do
-            definesCustomPrelude [preludeCF] (Bare "myprelude") `shouldBe` True
-
-    describe "when no library exposes Prelude" do
-        it "returns False for a lib target in a normal package" do
-            definesCustomPrelude singleCabalFile (Qualified Lib "myapp") `shouldBe` False
-
-        it "returns False for Bare matching the package name" do
-            definesCustomPrelude singleCabalFile (Bare "myapp") `shouldBe` False
-
-    describe "for non-library targets" do
-        it "returns False for Qualified Exe" do
-            definesCustomPrelude [preludeCF] (Qualified Exe "myprelude-exe") `shouldBe` False
-
-        it "returns False for Qualified Test" do
-            definesCustomPrelude singleCabalFile (Qualified Test "myapp-test") `shouldBe` False
-
-        it "returns False for Unrecognized" do
-            definesCustomPrelude [preludeCF] (Unrecognized "library:myprelude") `shouldBe` False
-
-    it "returns False when the cabal file list is empty" do
-        definesCustomPrelude [] (Qualified Lib "anything") `shouldBe` False
+testDefinesCustomPrelude :: [TestTree]
+testDefinesCustomPrelude =
+    [ testGroup
+        "when the main library exposes Prelude"
+        [ testCase "returns True for Qualified Lib \"\" (unnamed main lib)" do
+            definesCustomPrelude [preludeCF] (Qualified Lib "") @?= True
+        , testCase "returns True for Qualified Lib matching the package name" do
+            definesCustomPrelude [preludeCF] (Qualified Lib "myprelude") @?= True
+        , testCase "returns True for Bare matching the package name" do
+            definesCustomPrelude [preludeCF] (Bare "myprelude") @?= True
+        ]
+    , testGroup
+        "when no library exposes Prelude"
+        [ testCase "returns False for a lib target in a normal package" do
+            definesCustomPrelude singleCabalFile (Qualified Lib "myapp") @?= False
+        , testCase "returns False for Bare matching the package name" do
+            definesCustomPrelude singleCabalFile (Bare "myapp") @?= False
+        ]
+    , testGroup
+        "for non-library targets"
+        [ testCase "returns False for Qualified Exe" do
+            definesCustomPrelude [preludeCF] (Qualified Exe "myprelude-exe") @?= False
+        , testCase "returns False for Qualified Test" do
+            definesCustomPrelude singleCabalFile (Qualified Test "myapp-test") @?= False
+        , testCase "returns False for Unrecognized" do
+            definesCustomPrelude [preludeCF] (Unrecognized "library:myprelude") @?= False
+        ]
+    , testCase "returns False when the cabal file list is empty" do
+        definesCustomPrelude [] (Qualified Lib "anything") @?= False
+    ]
+  where
+    preludeCF =
+        CabalFile "/myprelude.cabal"
+            $ fromMaybe (error "libWithPreludeCabal failed to parse")
+            $ parseGenericPackageDescriptionMaybe (libWithPreludeCabal "myprelude")
diff --git a/test/Unit/Tricorder/Session/TestTargetSpec.hs b/test/Unit/Tricorder/Session/TestTargetSpec.hs
--- a/test/Unit/Tricorder/Session/TestTargetSpec.hs
+++ b/test/Unit/Tricorder/Session/TestTargetSpec.hs
@@ -1,43 +1,45 @@
-module Unit.Tricorder.Session.TestTargetSpec (spec_TestTarget) where
+module Unit.Tricorder.Session.TestTargetSpec (test_TestTarget) where
 
 import Data.Default (def)
-import Test.Hspec (Spec, describe, it, shouldBe)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Tricorder.Session.Config (Config (..))
-import Tricorder.Session.Target (parseTarget)
-import Tricorder.Session.TestTarget (parseTestTargets, resolveTestTargets)
 
+import Tricorder.Session.Target qualified as Target
+import Tricorder.Session.TestTarget qualified as TestTarget
 
-spec_TestTarget :: Spec
-spec_TestTarget = do
-    describe "resolveTestTargets" testResolveTestTargets
 
+test_TestTarget :: TestTree
+test_TestTarget =
+    testGroup
+        "TestTarget"
+        [ testGroup "resolveTestTargets" testResolveTestTargets
+        ]
 
-testResolveTestTargets :: Spec
-testResolveTestTargets = do
-    it "infers test: components from targets when testTargets is absent" do
-        let cfg = def :: Config
-        resolveTestTargets cfg (mkTargets ["lib:mylib", "test:mylib-test"])
-            `shouldBe` parseTestTargets ["test:mylib-test"]
 
-    it "returns empty list when no test: components in targets" do
+testResolveTestTargets :: [TestTree]
+testResolveTestTargets =
+    [ testCase "infers test: components from targets when testTargets is absent" do
         let cfg = def :: Config
-        resolveTestTargets cfg (mkTargets ["lib:mylib", "exe:myapp"])
-            `shouldBe` parseTestTargets []
-
-    it "uses explicit testTargets list when set" do
+        TestTarget.resolve cfg (mkTargets ["lib:mylib", "test:mylib-test"])
+            @?= TestTarget.parse ["test:mylib-test"]
+    , testCase "returns empty list when no test: components in targets" do
+        let cfg = def :: Config
+        TestTarget.resolve cfg (mkTargets ["lib:mylib", "exe:myapp"])
+            @?= TestTarget.parse []
+    , testCase "uses explicit testTargets list when set" do
         let cfg = def {testTargets = Just ["test:b-test"]} :: Config
-        resolveTestTargets cfg (mkTargets ["lib:a", "test:a-test", "test:b-test"])
-            `shouldBe` parseTestTargets ["test:b-test"]
-
-    it "returns empty list when testTargets is explicitly empty" do
+        TestTarget.resolve cfg (mkTargets ["lib:a", "test:a-test", "test:b-test"])
+            @?= TestTarget.parse ["test:b-test"]
+    , testCase "returns empty list when testTargets is explicitly empty" do
         let cfg = def {testTargets = Just []} :: Config
-        resolveTestTargets cfg (mkTargets ["lib:a", "test:a-test"])
-            `shouldBe` parseTestTargets []
-
-    it "infers multiple test: components" do
+        TestTarget.resolve cfg (mkTargets ["lib:a", "test:a-test"])
+            @?= TestTarget.parse []
+    , testCase "infers multiple test: components" do
         let cfg = def :: Config
-        resolveTestTargets cfg (mkTargets ["lib:a", "test:a-test", "test:b-test"])
-            `shouldBe` parseTestTargets ["test:a-test", "test:b-test"]
+        TestTarget.resolve cfg (mkTargets ["lib:a", "test:a-test", "test:b-test"])
+            @?= TestTarget.parse ["test:a-test", "test:b-test"]
+    ]
   where
-    mkTargets = fmap parseTarget
+    mkTargets = fmap Target.parse
diff --git a/test/Unit/Tricorder/Session/WatchDirsSpec.hs b/test/Unit/Tricorder/Session/WatchDirsSpec.hs
--- a/test/Unit/Tricorder/Session/WatchDirsSpec.hs
+++ b/test/Unit/Tricorder/Session/WatchDirsSpec.hs
@@ -1,142 +1,167 @@
-module Unit.Tricorder.Session.WatchDirsSpec (spec_WatchDirs) where
+module Unit.Tricorder.Session.WatchDirsSpec (test_WatchDirs) where
 
 import Data.Default (def)
-import Test.Hspec (Spec, context, describe, it, shouldBe)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Tricorder.Runtime (ProjectRoot (..))
 import Tricorder.Session.Config (Config (..))
-import Tricorder.Session.Target (ComponentKind (..), Target (..), parseTarget)
-import Tricorder.Session.WatchDirs (WatchDirs (..), resolveWatchDirs, sourceDirsForTarget)
+import Tricorder.Session.Target (ComponentKind (..), Target (..))
+import Tricorder.Session.WatchDirs (WatchDirs (..), sourceDirsForTarget)
 import Unit.Tricorder.Session.Helpers (gpd, multiCabalFiles, singleCabalFile)
 
+import Tricorder.Session.Target qualified as Target
+import Tricorder.Session.WatchDirs qualified as WatchDirs
 
-spec_WatchDirs :: Spec
-spec_WatchDirs = do
-    describe "resolveWatchDirs" testResolveWatchDirs
-    describe "sourceDirsForTarget" testSourceDirsForTarget
 
+test_WatchDirs :: TestTree
+test_WatchDirs =
+    testGroup
+        "WatchDirs"
+        [ testGroup "resolveWatchDirs" testResolveWatchDirs
+        , testGroup "sourceDirsForTarget" testSourceDirsForTarget
+        ]
 
-testResolveWatchDirs :: Spec
-testResolveWatchDirs = do
-    describe "when watch_dirs is set in config" do
-        it "uses config dirs relative to project root" do
-            let WatchDirs actual =
-                    resolveWatchDirs pr [] def {watchDirs = ["src", "test"]} []
-            actual `shouldBe` ["/src", "/test"]
 
-    describe "when watch_dirs is not set" do
-        it "falls back to [\".\"] when targets list is empty" do
-            let WatchDirs actual = resolveWatchDirs pr [] def []
-            actual `shouldBe` ["."]
-
-        it "infers source dirs from resolved targets" do
+testResolveWatchDirs :: [TestTree]
+testResolveWatchDirs =
+    [ testGroup
+        "when watch_dirs is set in config"
+        [ testCase "uses config dirs relative to project root" do
             let WatchDirs actual =
-                    resolveWatchDirs pr singleCabalFile def (mkTargets ["lib:myapp", "test:myapp-test"])
-            actual `shouldBe` ["/src", "/test"]
-
-        it "falls back to [\".\"] when there are no cabal files" do
+                    WatchDirs.resolve pr [] def {watchDirs = ["src", "test"]} []
+            actual @?= ["/src", "/test"]
+        ]
+    , testGroup
+        "when watch_dirs is not set"
+        [ testCase "falls back to [\".\"] when targets list is empty" do
+            let WatchDirs actual = WatchDirs.resolve pr [] def []
+            actual @?= ["."]
+        , testCase "infers source dirs from resolved targets" do
             let WatchDirs actual =
-                    resolveWatchDirs pr [] def (mkTargets ["lib:myapp"])
-            actual `shouldBe` ["."]
-
-        -- Sharp edge: an unparseable .cabal yields no source dirs, so resolution
-        -- falls back to watching the whole project root. This pins the current
-        -- behavior; if it ever changes to something narrower, update this test.
-        it "falls back to [\".\"] when no cabal files are found or parsed" do
+                    WatchDirs.resolve pr singleCabalFile def (mkTargets ["lib:myapp", "test:myapp-test"])
+            actual @?= ["/src", "/test"]
+        , testCase "falls back to [\".\"] when there are no cabal files" do
             let WatchDirs actual =
-                    resolveWatchDirs pr [] def (mkTargets ["lib:myapp"])
-            actual `shouldBe` ["."]
-
-    describe "when the project is a multi-package cabal.project" do
-        it "infers per-package source dirs, scoped to each package's directory" do
+                    WatchDirs.resolve pr [] def (mkTargets ["lib:myapp"])
+            actual @?= ["."]
+        , -- Sharp edge: an unparseable .cabal yields no source dirs, so resolution
+          -- falls back to watching the whole project root. This pins the current
+          -- behavior; if it ever changes to something narrower, update this test.
+          testCase "falls back to [\".\"] when no cabal files are found or parsed" do
             let WatchDirs actual =
-                    resolveWatchDirs
+                    WatchDirs.resolve pr [] def (mkTargets ["lib:myapp"])
+            actual @?= ["."]
+        ]
+    , testGroup
+        "when the project is a multi-package cabal.project"
+        [ testCase "infers per-package source dirs, scoped to each package's directory" do
+            let WatchDirs actual =
+                    WatchDirs.resolve
                         pr
                         multiCabalFiles
                         def
                         (mkTargets ["lib:pkg-a", "test:pkg-a-test", "lib:pkg-b", "test:pkg-b-test"])
             actual
-                `shouldBe` ["/pkg-a/src", "/pkg-a/test", "/pkg-b/src", "/pkg-b/test"]
-
-        it "scopes a bare package-name target to that package, ignoring siblings" do
+                @?= ["/pkg-a/src", "/pkg-a/test", "/pkg-b/src", "/pkg-b/test"]
+        , testCase "scopes a bare package-name target to that package, ignoring siblings" do
             let WatchDirs actual =
-                    resolveWatchDirs pr multiCabalFiles def (mkTargets ["pkg-a"])
-            actual `shouldBe` ["/pkg-a/src", "/pkg-a/test"]
+                    WatchDirs.resolve pr multiCabalFiles def (mkTargets ["pkg-a"])
+            actual @?= ["/pkg-a/src", "/pkg-a/test"]
+        ]
+    ]
   where
     pr = ProjectRoot "/"
 
 
 -- | These exercise the 'Target' -> dirs resolution directly with constructed
 -- 'Target' values; the string -> 'Target' parsing is covered by 'testParseTarget'.
-testSourceDirsForTarget :: Spec
-testSourceDirsForTarget = do
-    describe "Qualified Lib" do
-        context "when the name is empty" do
-            it "returns the main library source dirs" do
-                sourceDirsForTarget gpd (Qualified Lib "") `shouldBe` ["src"]
-
-        context "when the name matches the package name" do
-            it "returns the main library source dirs" do
-                sourceDirsForTarget gpd (Qualified Lib "myapp") `shouldBe` ["src"]
-
-        context "when the name matches a sub-library" do
-            it "returns the sub-library source dirs" do
-                sourceDirsForTarget gpd (Qualified Lib "myapp-utils") `shouldBe` ["utils"]
-
-        context "when the sub-library is unknown" do
-            it "returns an empty list" do
-                sourceDirsForTarget gpd (Qualified Lib "nonexistent") `shouldBe` []
-
-    describe "Qualified FLib" do
-        it "returns the foreign-library source dirs" do
-            sourceDirsForTarget gpd (Qualified FLib "myapp-flib") `shouldBe` ["flib"]
-
-    describe "Qualified Exe" do
-        it "returns the executable source dirs" do
-            sourceDirsForTarget gpd (Qualified Exe "myapp-exe") `shouldBe` ["app"]
-
-    describe "Qualified Test" do
-        it "returns the test suite source dirs" do
-            sourceDirsForTarget gpd (Qualified Test "myapp-test") `shouldBe` ["test"]
-
-    describe "Qualified Bench" do
-        it "returns the benchmark source dirs" do
-            sourceDirsForTarget gpd (Qualified Bench "myapp-bench") `shouldBe` ["bench"]
-
-    describe "Bare (package name)" do
-        it "returns every component's source dirs" do
-            sourceDirsForTarget gpd (Bare "myapp") `shouldBe` ["src", "utils", "flib", "app", "test", "bench"]
-
-    describe "Bare (component name)" do
-        context "when it names a sub-library" do
-            it "returns the sub-library source dirs" do
-                sourceDirsForTarget gpd (Bare "myapp-utils") `shouldBe` ["utils"]
-
-        context "when it names an executable" do
-            it "returns the executable source dirs" do
-                sourceDirsForTarget gpd (Bare "myapp-exe") `shouldBe` ["app"]
-
-        context "when it names a test suite" do
-            it "returns the test suite source dirs" do
-                sourceDirsForTarget gpd (Bare "myapp-test") `shouldBe` ["test"]
-
-        context "when it matches no component" do
-            it "returns an empty list" do
-                sourceDirsForTarget gpd (Bare "unknown") `shouldBe` []
-
-    describe "Unrecognized" do
-        it "matches an aliased kind prefix by trailing name" do
-            sourceDirsForTarget gpd (Unrecognized "executable:myapp-exe") `shouldBe` ["app"]
-
-        it "matches a case-variant kind prefix by trailing name" do
-            sourceDirsForTarget gpd (Unrecognized "Test-Suite:myapp-test") `shouldBe` ["test"]
-
-        it "matches the main library when the trailing name is the package name" do
-            sourceDirsForTarget gpd (Unrecognized "library:myapp") `shouldBe` ["src"]
-
-        it "returns an empty list when the trailing name matches no component" do
-            sourceDirsForTarget gpd (Unrecognized "bogus:x") `shouldBe` []
+testSourceDirsForTarget :: [TestTree]
+testSourceDirsForTarget =
+    [ testGroup
+        "Qualified Lib"
+        [ testGroup
+            "when the name is empty"
+            [ testCase "returns the main library source dirs" do
+                sourceDirsForTarget gpd (Qualified Lib "") @?= ["src"]
+            ]
+        , testGroup
+            "when the name matches the package name"
+            [ testCase "returns the main library source dirs" do
+                sourceDirsForTarget gpd (Qualified Lib "myapp") @?= ["src"]
+            ]
+        , testGroup
+            "when the name matches a sub-library"
+            [ testCase "returns the sub-library source dirs" do
+                sourceDirsForTarget gpd (Qualified Lib "myapp-utils") @?= ["utils"]
+            ]
+        , testGroup
+            "when the sub-library is unknown"
+            [ testCase "returns an empty list" do
+                sourceDirsForTarget gpd (Qualified Lib "nonexistent") @?= []
+            ]
+        ]
+    , testGroup
+        "Qualified FLib"
+        [ testCase "returns the foreign-library source dirs" do
+            sourceDirsForTarget gpd (Qualified FLib "myapp-flib") @?= ["flib"]
+        ]
+    , testGroup
+        "Qualified Exe"
+        [ testCase "returns the executable source dirs" do
+            sourceDirsForTarget gpd (Qualified Exe "myapp-exe") @?= ["app"]
+        ]
+    , testGroup
+        "Qualified Test"
+        [ testCase "returns the test suite source dirs" do
+            sourceDirsForTarget gpd (Qualified Test "myapp-test") @?= ["test"]
+        ]
+    , testGroup
+        "Qualified Bench"
+        [ testCase "returns the benchmark source dirs" do
+            sourceDirsForTarget gpd (Qualified Bench "myapp-bench") @?= ["bench"]
+        ]
+    , testGroup
+        "Bare (package name)"
+        [ testCase "returns every component's source dirs" do
+            sourceDirsForTarget gpd (Bare "myapp") @?= ["src", "utils", "flib", "app", "test", "bench"]
+        ]
+    , testGroup
+        "Bare (component name)"
+        [ testGroup
+            "when it names a sub-library"
+            [ testCase "returns the sub-library source dirs" do
+                sourceDirsForTarget gpd (Bare "myapp-utils") @?= ["utils"]
+            ]
+        , testGroup
+            "when it names an executable"
+            [ testCase "returns the executable source dirs" do
+                sourceDirsForTarget gpd (Bare "myapp-exe") @?= ["app"]
+            ]
+        , testGroup
+            "when it names a test suite"
+            [ testCase "returns the test suite source dirs" do
+                sourceDirsForTarget gpd (Bare "myapp-test") @?= ["test"]
+            ]
+        , testGroup
+            "when it matches no component"
+            [ testCase "returns an empty list" do
+                sourceDirsForTarget gpd (Bare "unknown") @?= []
+            ]
+        ]
+    , testGroup
+        "Unrecognized"
+        [ testCase "matches an aliased kind prefix by trailing name" do
+            sourceDirsForTarget gpd (Unrecognized "executable:myapp-exe") @?= ["app"]
+        , testCase "matches a case-variant kind prefix by trailing name" do
+            sourceDirsForTarget gpd (Unrecognized "Test-Suite:myapp-test") @?= ["test"]
+        , testCase "matches the main library when the trailing name is the package name" do
+            sourceDirsForTarget gpd (Unrecognized "library:myapp") @?= ["src"]
+        , testCase "returns an empty list when the trailing name matches no component" do
+            sourceDirsForTarget gpd (Unrecognized "bogus:x") @?= []
+        ]
+    ]
 
 
 mkTargets :: [Text] -> [Target]
-mkTargets = fmap parseTarget
+mkTargets = fmap Target.parse
diff --git a/test/Unit/Tricorder/SessionSpec.hs b/test/Unit/Tricorder/SessionSpec.hs
--- a/test/Unit/Tricorder/SessionSpec.hs
+++ b/test/Unit/Tricorder/SessionSpec.hs
@@ -1,4 +1,4 @@
-module Unit.Tricorder.SessionSpec (spec_Session) where
+module Unit.Tricorder.SessionSpec (test_Session) where
 
 import Atelier.Config (LoadedConfig (..))
 import Atelier.Effects.FileSystem (runFileSystemState)
@@ -10,7 +10,8 @@
 import Effectful.Reader.Static (runReader)
 import Effectful.State.Static.Shared (evalState)
 import Effectful.Writer.Static.Shared (execWriter)
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Tricorder.Runtime (ProjectRoot (..))
 import Tricorder.Session (Session (..), loadSession)
@@ -19,27 +20,36 @@
 import Unit.Tricorder.Session.Helpers (libWithPreludeCabal, preludeOnlyLibCabal)
 
 
-spec_Session :: Spec
-spec_Session = do
-    describe "loadSession" testLoadSession
-    describe "loadSession idleTimeout" testIdleTimeout
+test_Session :: TestTree
+test_Session =
+    testGroup
+        "Session"
+        [ testLoadSession
+        , testIdleTimeout
+        , testMissingTargetPlaceholder
+        ]
 
 
-testLoadSession :: Spec
-testLoadSession = do
-    describe "when every resolved target exposes a custom Prelude module" do
-        it "emits a WARN" do
-            let msgs = captureSessionLogs [preludeOnlyCF]
-            any (\m -> m.severity == WARN) msgs `shouldBe` True
-
-    describe "when not every resolved target exposes a custom Prelude module" do
-        it "does not emit a WARN" do
-            -- libWithPreludeCabal has both a lib (custom Prelude) and an exe (no Prelude)
-            let msgs = captureSessionLogs [mixedCF]
-            any (\m -> m.severity == WARN) msgs `shouldBe` False
-
-    it "does not emit a WARN when there are no resolved targets" do
-        any (\m -> m.severity == WARN) (captureSessionLogs []) `shouldBe` False
+testLoadSession :: TestTree
+testLoadSession =
+    testGroup
+        "loadSession"
+        [ testGroup
+            "when every resolved target exposes a custom Prelude module"
+            [ testCase "emits a WARN" do
+                let msgs = captureSessionLogs [preludeOnlyCF]
+                any (\m -> m.severity == WARN) msgs @?= True
+            ]
+        , testGroup
+            "when not every resolved target exposes a custom Prelude module"
+            [ testCase "does not emit a WARN" do
+                -- libWithPreludeCabal has both a lib (custom Prelude) and an exe (no Prelude)
+                let msgs = captureSessionLogs [mixedCF]
+                any (\m -> m.severity == WARN) msgs @?= False
+            ]
+        , testCase "does not emit a WARN when there are no resolved targets" do
+            any (\m -> m.severity == WARN) (captureSessionLogs []) @?= False
+        ]
   where
     preludeOnlyCF =
         CabalFile "/p.cabal"
@@ -61,14 +71,59 @@
             $ loadSession
 
 
-testIdleTimeout :: Spec
-testIdleTimeout = do
-    it "defaults to 300 seconds when unset" do
-        (loadSessionWith (LoadedConfig Null)).idleTimeout `shouldBe` IdleTimeout 300
+testMissingTargetPlaceholder :: TestTree
+testMissingTargetPlaceholder =
+    testGroup
+        "loadSession missing {target} placeholder"
+        [ testGroup
+            "test.command_template"
+            [ testCase "emits a WARN when it has no {target} placeholder" do
+                let cfg = sessionCfg ["test" .= object ["command_template" .= ("cabal repl test:foo" :: Text)]]
+                any (\m -> m.severity == WARN) (captureLogsFor cfg) @?= True
+            , testCase "does not emit a WARN when it has the {target} placeholder" do
+                let cfg = sessionCfg ["test" .= object ["command_template" .= ("cabal repl {target}" :: Text)]]
+                any (\m -> m.severity == WARN) (captureLogsFor cfg) @?= False
+            ]
+        , testGroup
+            "eval.command_template"
+            [ testCase "emits a WARN when it has no {target} placeholder" do
+                let cfg = sessionCfg ["eval" .= object ["command_template" .= ("cabal repl Tricorder.Foo" :: Text)]]
+                any (\m -> m.severity == WARN) (captureLogsFor cfg) @?= True
+            , testCase "does not emit a WARN when it has the {target} placeholder" do
+                let cfg = sessionCfg ["eval" .= object ["command_template" .= ("cabal repl {target}" :: Text)]]
+                any (\m -> m.severity == WARN) (captureLogsFor cfg) @?= False
+            ]
+        , testGroup
+            "build.command_template"
+            [ testCase "does not emit a WARN when it has no {targets} placeholder" do
+                let cfg = sessionCfg ["build" .= object ["command_template" .= ("cabal repl lib:foo" :: Text)]]
+                any (\m -> m.severity == WARN) (captureLogsFor cfg) @?= False
+            ]
+        ]
+  where
+    sessionCfg session = LoadedConfig $ object ["session" .= object session]
+    captureLogsFor cfg =
+        runPureEff
+            . execWriter @[Message]
+            . runLogWriter
+            . evalState @(Map FilePath ByteString) mempty
+            . runFileSystemState
+            . runInputConst ([] :: [CabalFile])
+            . runReader (ProjectRoot "/")
+            . runInputConst cfg
+            $ loadSession
 
-    it "reads idle_timeout_seconds from the session config" do
-        let cfg = LoadedConfig $ object ["session" .= object ["idle_timeout_seconds" .= (5 :: Int)]]
-        (loadSessionWith cfg).idleTimeout `shouldBe` IdleTimeout 5
+
+testIdleTimeout :: TestTree
+testIdleTimeout =
+    testGroup
+        "loadSession idleTimeout"
+        [ testCase "defaults to 300 seconds when unset" do
+            (loadSessionWith (LoadedConfig Null)).idleTimeout @?= IdleTimeout 300
+        , testCase "reads idle_timeout_seconds from the session config" do
+            let cfg = LoadedConfig $ object ["session" .= object ["idle_timeout_seconds" .= (5 :: Int)]]
+            (loadSessionWith cfg).idleTimeout @?= IdleTimeout 5
+        ]
   where
     loadSessionWith cfg =
         runPureEff
diff --git a/test/Unit/Tricorder/SocketSpec.hs b/test/Unit/Tricorder/SocketSpec.hs
--- a/test/Unit/Tricorder/SocketSpec.hs
+++ b/test/Unit/Tricorder/SocketSpec.hs
@@ -1,9 +1,10 @@
-module Unit.Tricorder.SocketSpec (spec_Socket) where
+module Unit.Tricorder.SocketSpec (test_Socket) where
 
 import Atelier.Effects.File (File, runFile)
 import Effectful (IOE, runEff)
 import System.IO (hClose, hGetLine, openFile, writeFile)
-import Test.Hspec (Spec, describe, it, shouldBe)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Tricorder.Socket.Client (isDaemonReady)
 import Tricorder.Socket.UnixSocket
@@ -18,34 +19,39 @@
     )
 
 
-spec_Socket :: Spec
-spec_Socket = do
-    describe "runUnixSocketScripted" testScripted
-    describe "isDaemonReady" testReady
+test_Socket :: TestTree
+test_Socket =
+    testGroup
+        "Socket"
+        [ testGroup "runUnixSocketScripted" testScripted
+        , testGroup "isDaemonReady" testReady
+        ]
 
 
 --------------------------------------------------------------------------------
 -- Scripted interpreter tests
 --------------------------------------------------------------------------------
 
-testScripted :: Spec
-testScripted = do
-    describe "socketFileExists" do
-        it "returns True when scripted" do
+testScripted :: [TestTree]
+testScripted =
+    [ testGroup
+        "socketFileExists"
+        [ testCase "returns True when scripted" do
             result <- runScripted [NextFileCheck True] $ socketFileExists "/"
-            result `shouldBe` True
-
-        it "returns False when scripted" do
+            result @?= True
+        , testCase "returns False when scripted" do
             result <- runScripted [NextFileCheck False] $ socketFileExists "/"
-            result `shouldBe` False
-
-    describe "removeSocketFile" do
-        it "is always a no-op" do
+            result @?= False
+        ]
+    , testGroup
+        "removeSocketFile"
+        [ testCase "is always a no-op" do
             -- No NextFileCheck/NextAccept needed; just returns ()
             runScripted [] $ removeSocketFile "/nonexistent/path"
-
-    describe "acceptHandle" do
-        it "returns the scripted handle, readable from a file" do
+        ]
+    , testGroup
+        "acceptHandle"
+        [ testCase "returns the scripted handle, readable from a file" do
             let tmpPath = "/tmp/tricorder-socket-accept-test.txt"
             writeFile tmpPath "hello from test\n"
             h <- liftIO $ openFile tmpPath ReadMode
@@ -54,29 +60,31 @@
                 h' <- acceptHandle sock
                 liftIO $ hGetLine h'
             liftIO $ hClose h
-            line `shouldBe` "hello from test"
+            line @?= "hello from test"
+        ]
+    ]
 
 
 --------------------------------------------------------------------------------
 -- isDaemonReady (real IO interpreter)
 --------------------------------------------------------------------------------
 
-testReady :: Spec
-testReady = do
-    it "returns False when nothing is listening on the path" do
+testReady :: [TestTree]
+testReady =
+    [ testCase "returns False when nothing is listening on the path" do
         -- A connect to a non-existent socket must be caught, not thrown: this is
         -- the race the start/status path hit before the socket was bound.
         result <- runIO' $ isDaemonReady "/tmp/tricorder-isdaemonready-absent.sock"
-        result `shouldBe` False
-
-    it "returns True once a socket is bound and listening" do
+        result @?= False
+    , testCase "returns True once a socket is bound and listening" do
         let path = "/tmp/tricorder-isdaemonready-bound.sock"
         result <- runIO' do
             removeSocketFile path
             _ <- bindSocket path
             isDaemonReady path
         runIO' $ removeSocketFile path
-        result `shouldBe` True
+        result @?= True
+    ]
 
 
 --------------------------------------------------------------------------------
diff --git a/test/Unit/Tricorder/SourceLookup/GhcPkgSpec.hs b/test/Unit/Tricorder/SourceLookup/GhcPkgSpec.hs
--- a/test/Unit/Tricorder/SourceLookup/GhcPkgSpec.hs
+++ b/test/Unit/Tricorder/SourceLookup/GhcPkgSpec.hs
@@ -1,32 +1,35 @@
-module Unit.Tricorder.SourceLookup.GhcPkgSpec (spec_GhcPkg) where
+module Unit.Tricorder.SourceLookup.GhcPkgSpec (test_GhcPkg) where
 
 import Effectful (runPureEff)
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
-import Tricorder.Session.Command (Repl (..))
+import Tricorder.Session.Repl (Repl (..))
 import Tricorder.SourceLookup.GhcPkg (GhcPkg, GhcPkgScript (..), findModule, runGhcPkgScripted)
 
 
-spec_GhcPkg :: Spec
-spec_GhcPkg = do
-    describe "findModule" testFindModule
+test_GhcPkg :: TestTree
+test_GhcPkg =
+    testGroup
+        "GhcPkg"
+        [ testGroup "findModule" testFindModule
+        ]
 
 
-testFindModule :: Spec
-testFindModule = do
-    it "returns Just pkgId when module is known" do
+testFindModule :: [TestTree]
+testFindModule =
+    [ testCase "returns Just pkgId when module is known" do
         let result = runScripted [NextFindModule (Just "base-4.18")] $ findModule Cabal "Prelude"
-        result `shouldBe` Just "base-4.18"
-
-    it "returns Nothing for an unknown module" do
+        result @?= Just "base-4.18"
+    , testCase "returns Nothing for an unknown module" do
         let result = runScripted [NextFindModule Nothing] $ findModule Cabal "No.Such.Module"
-        result `shouldBe` Nothing
-
-    it "returns the first scripted result" do
+        result @?= Nothing
+    , testCase "returns the first scripted result" do
         let result =
                 runScripted [NextFindModule (Just "pkg-1.0"), NextFindModule (Just "pkg-2.0")]
                     $ findModule Cabal "Foo"
-        result `shouldBe` Just "pkg-1.0"
+        result @?= Just "pkg-1.0"
+    ]
 
 
 runScripted :: [GhcPkgScript] -> Eff '[GhcPkg] a -> a
diff --git a/test/Unit/Tricorder/SourceLookup/SliceSpec.hs b/test/Unit/Tricorder/SourceLookup/SliceSpec.hs
--- a/test/Unit/Tricorder/SourceLookup/SliceSpec.hs
+++ b/test/Unit/Tricorder/SourceLookup/SliceSpec.hs
@@ -1,20 +1,27 @@
-module Unit.Tricorder.SourceLookup.SliceSpec (spec_Slice) where
+module Unit.Tricorder.SourceLookup.SliceSpec (test_Slice) where
 
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertBool, testCase, (@?=))
 
 import Data.Text qualified as T
 
 import Tricorder.SourceLookup.Slice (sliceSymbol)
 
 
-spec_Slice :: Spec
-spec_Slice = describe "sliceSymbol" do
-    valueBindings
-    typeDeclarations
-    constructors
-    compactDeclarations
-    robustness
-    capturePrecision
+test_Slice :: TestTree
+test_Slice =
+    testGroup
+        "Slice"
+        [ testGroup
+            "sliceSymbol"
+            [ valueBindings
+            , typeDeclarations
+            , constructors
+            , compactDeclarations
+            , robustness
+            , capturePrecision
+            ]
+        ]
 
 
 -- | Build a source fixture from individual lines.
@@ -22,321 +29,314 @@
 src = T.unlines
 
 
-valueBindings :: Spec
-valueBindings = describe "value bindings" do
-    it "slices a function with its signature and doc block" do
-        let source =
-                src
-                    [ "-- | The answer to everything."
-                    , "answer :: Int"
-                    , "answer = 42"
-                    , ""
-                    , "other :: Bool"
-                    , "other = True"
-                    ]
-        sliceSymbol "answer" source
-            `shouldBe` Just "-- | The answer to everything.\nanswer :: Int\nanswer = 42"
-
-    it "slices a binding with no signature" do
-        let source = src ["foo = 1", "", "bar = 2"]
-        sliceSymbol "foo" source `shouldBe` Just "foo = 1"
-
-    it "captures every equation of a multi-equation binding" do
-        let source =
-                src
-                    [ "isJust :: Maybe a -> Bool"
-                    , "isJust (Just _) = True"
-                    , "isJust Nothing = False"
-                    , ""
-                    , "next = ()"
-                    ]
-        sliceSymbol "isJust" source
-            `shouldBe` Just "isJust :: Maybe a -> Bool\nisJust (Just _) = True\nisJust Nothing = False"
-
-    it "keeps a multi-line line-comment doc block" do
-        let source =
-                src
-                    [ "-- | The answer to everything,"
-                    , "-- computed once."
-                    , "answer :: Int"
-                    , "answer = 42"
-                    ]
-        sliceSymbol "answer" source
-            `shouldBe` Just "-- | The answer to everything,\n-- computed once.\nanswer :: Int\nanswer = 42"
-
-    it "slices an operator binding in (op) form" do
-        let source =
-                src
-                    [ "(<+>) :: Int -> Int -> Int"
-                    , "a <+> b = a + b"
-                    ]
-        sliceSymbol "<+>" source
-            `shouldBe` Just "(<+>) :: Int -> Int -> Int\na <+> b = a + b"
-
-    it "does not match a different binding with a shared prefix" do
-        let source = src ["answer = 1", "", "answerable = 2"]
-        sliceSymbol "answerable" source `shouldBe` Just "answerable = 2"
+valueBindings :: TestTree
+valueBindings =
+    testGroup
+        "value bindings"
+        [ testCase "slices a function with its signature and doc block" do
+            let source =
+                    src
+                        [ "-- | The answer to everything."
+                        , "answer :: Int"
+                        , "answer = 42"
+                        , ""
+                        , "other :: Bool"
+                        , "other = True"
+                        ]
+            sliceSymbol "answer" source
+                @?= Just "-- | The answer to everything.\nanswer :: Int\nanswer = 42"
+        , testCase "slices a binding with no signature" do
+            let source = src ["foo = 1", "", "bar = 2"]
+            sliceSymbol "foo" source @?= Just "foo = 1"
+        , testCase "captures every equation of a multi-equation binding" do
+            let source =
+                    src
+                        [ "isJust :: Maybe a -> Bool"
+                        , "isJust (Just _) = True"
+                        , "isJust Nothing = False"
+                        , ""
+                        , "next = ()"
+                        ]
+            sliceSymbol "isJust" source
+                @?= Just "isJust :: Maybe a -> Bool\nisJust (Just _) = True\nisJust Nothing = False"
+        , testCase "keeps a multi-line line-comment doc block" do
+            let source =
+                    src
+                        [ "-- | The answer to everything,"
+                        , "-- computed once."
+                        , "answer :: Int"
+                        , "answer = 42"
+                        ]
+            sliceSymbol "answer" source
+                @?= Just "-- | The answer to everything,\n-- computed once.\nanswer :: Int\nanswer = 42"
+        , testCase "slices an operator binding in (op) form" do
+            let source =
+                    src
+                        [ "(<+>) :: Int -> Int -> Int"
+                        , "a <+> b = a + b"
+                        ]
+            sliceSymbol "<+>" source
+                @?= Just "(<+>) :: Int -> Int -> Int\na <+> b = a + b"
+        , testCase "does not match a different binding with a shared prefix" do
+            let source = src ["answer = 1", "", "answerable = 2"]
+            sliceSymbol "answerable" source @?= Just "answerable = 2"
+        ]
 
 
 -- | Real Hackage source frequently packs top-level declarations together with
 -- no blank line between them. The slice must stop at the neighbouring
 -- declaration, not swallow it.
-compactDeclarations :: Spec
-compactDeclarations = describe "adjacent declarations without blank lines" do
-    it "does not swallow the following binding" do
-        sliceSymbol "bar" (src ["foo = 1", "bar = 2", "baz = 3"])
-            `shouldBe` Just "bar = 2"
-
-    it "does not swallow the preceding binding and its signature" do
-        let source =
-                src
-                    [ "foo :: Int"
-                    , "foo = 1"
-                    , "bar :: Int"
-                    , "bar = 2"
-                    ]
-        sliceSymbol "bar" source `shouldBe` Just "bar :: Int\nbar = 2"
-
-    it "keeps the doc block but not a preceding declaration" do
-        let source =
-                src
-                    [ "foo = 1"
-                    , "-- | doc for bar"
-                    , "bar = 2"
-                    ]
-        sliceSymbol "bar" source `shouldBe` Just "-- | doc for bar\nbar = 2"
-
-    it "keeps a multi-line doc block but not a preceding declaration" do
-        let source =
-                src
-                    [ "foo = 1"
-                    , "-- | doc for bar,"
-                    , "-- second line."
-                    , "bar = 2"
-                    ]
-        sliceSymbol "bar" source
-            `shouldBe` Just "-- | doc for bar,\n-- second line.\nbar = 2"
+compactDeclarations :: TestTree
+compactDeclarations =
+    testGroup
+        "adjacent declarations without blank lines"
+        [ testCase "does not swallow the following binding" do
+            sliceSymbol "bar" (src ["foo = 1", "bar = 2", "baz = 3"])
+                @?= Just "bar = 2"
+        , testCase "does not swallow the preceding binding and its signature" do
+            let source =
+                    src
+                        [ "foo :: Int"
+                        , "foo = 1"
+                        , "bar :: Int"
+                        , "bar = 2"
+                        ]
+            sliceSymbol "bar" source @?= Just "bar :: Int\nbar = 2"
+        , testCase "keeps the doc block but not a preceding declaration" do
+            let source =
+                    src
+                        [ "foo = 1"
+                        , "-- | doc for bar"
+                        , "bar = 2"
+                        ]
+            sliceSymbol "bar" source @?= Just "-- | doc for bar\nbar = 2"
+        , testCase "keeps a multi-line doc block but not a preceding declaration" do
+            let source =
+                    src
+                        [ "foo = 1"
+                        , "-- | doc for bar,"
+                        , "-- second line."
+                        , "bar = 2"
+                        ]
+            sliceSymbol "bar" source
+                @?= Just "-- | doc for bar,\n-- second line.\nbar = 2"
+        ]
 
 
-typeDeclarations :: Spec
-typeDeclarations = describe "type declarations" do
-    it "slices a data declaration with doc and deriving clause" do
-        let source =
-                src
-                    [ "-- | A JSON value."
-                    , "data Value = Null | Bool Bool"
-                    , "    deriving (Show)"
-                    , ""
-                    , "instance Eq Value"
-                    ]
-        sliceSymbol "Value" source
-            `shouldBe` Just "-- | A JSON value.\ndata Value = Null | Bool Bool\n    deriving (Show)"
-
-    it "keeps a multi-line block doc comment on a data declaration" do
-        let source =
-                src
-                    [ "{- | A JSON value,"
-                    , "   as parsed. -}"
-                    , "data Value = Null | Bool Bool"
-                    , ""
-                    ]
-        sliceSymbol "Value" source
-            `shouldBe` Just "{- | A JSON value,\n   as parsed. -}\ndata Value = Null | Bool Bool"
-
-    it "slices a newtype" do
-        sliceSymbol "Age" (src ["newtype Age = Age Int", ""])
-            `shouldBe` Just "newtype Age = Age Int"
-
-    it "slices a type alias" do
-        sliceSymbol "Name" (src ["type Name = Text"])
-            `shouldBe` Just "type Name = Text"
-
-    it "slices a type family" do
-        sliceSymbol "Elem" (src ["type family Elem c"])
-            `shouldBe` Just "type family Elem c"
-
-    it "slices a class with its methods" do
-        let source =
-                src
-                    [ "class Eq a => Container a where"
-                    , "    empty :: a"
-                    , ""
-                    , "foo = ()"
-                    ]
-        sliceSymbol "Container" source
-            `shouldBe` Just "class Eq a => Container a where\n    empty :: a"
-
-    it "slices a record declaration including all fields" do
-        let source =
-                src
-                    [ "data Person = Person"
-                    , "    { name :: Text"
-                    , "    , age :: Int"
-                    , "    }"
-                    , "    deriving (Show)"
-                    , ""
-                    ]
-        sliceSymbol "Person" source
-            `shouldBe` Just
-                ( "data Person = Person\n"
-                    <> "    { name :: Text\n"
-                    <> "    , age :: Int\n"
-                    <> "    }\n"
-                    <> "    deriving (Show)"
-                )
-
-    it "slices a GADT declaration" do
-        let source =
-                src
-                    [ "data Expr a where"
-                    , "    Lit :: Int -> Expr Int"
-                    , "    Add :: Expr Int -> Expr Int -> Expr Int"
-                    , ""
-                    ]
-        sliceSymbol "Expr" source
-            `shouldBe` Just
-                ( "data Expr a where\n"
-                    <> "    Lit :: Int -> Expr Int\n"
-                    <> "    Add :: Expr Int -> Expr Int -> Expr Int"
-                )
+typeDeclarations :: TestTree
+typeDeclarations =
+    testGroup
+        "type declarations"
+        [ testCase "slices a data declaration with doc and deriving clause" do
+            let source =
+                    src
+                        [ "-- | A JSON value."
+                        , "data Value = Null | Bool Bool"
+                        , "    deriving (Show)"
+                        , ""
+                        , "instance Eq Value"
+                        ]
+            sliceSymbol "Value" source
+                @?= Just "-- | A JSON value.\ndata Value = Null | Bool Bool\n    deriving (Show)"
+        , testCase "keeps a multi-line block doc comment on a data declaration" do
+            let source =
+                    src
+                        [ "{- | A JSON value,"
+                        , "   as parsed. -}"
+                        , "data Value = Null | Bool Bool"
+                        , ""
+                        ]
+            sliceSymbol "Value" source
+                @?= Just "{- | A JSON value,\n   as parsed. -}\ndata Value = Null | Bool Bool"
+        , testCase "slices a newtype" do
+            sliceSymbol "Age" (src ["newtype Age = Age Int", ""])
+                @?= Just "newtype Age = Age Int"
+        , testCase "slices a type alias" do
+            sliceSymbol "Name" (src ["type Name = Text"])
+                @?= Just "type Name = Text"
+        , testCase "slices a type family" do
+            sliceSymbol "Elem" (src ["type family Elem c"])
+                @?= Just "type family Elem c"
+        , testCase "slices a class with its methods" do
+            let source =
+                    src
+                        [ "class Eq a => Container a where"
+                        , "    empty :: a"
+                        , ""
+                        , "foo = ()"
+                        ]
+            sliceSymbol "Container" source
+                @?= Just "class Eq a => Container a where\n    empty :: a"
+        , testCase "slices a record declaration including all fields" do
+            let source =
+                    src
+                        [ "data Person = Person"
+                        , "    { name :: Text"
+                        , "    , age :: Int"
+                        , "    }"
+                        , "    deriving (Show)"
+                        , ""
+                        ]
+            sliceSymbol "Person" source
+                @?= Just
+                    ( "data Person = Person\n"
+                        <> "    { name :: Text\n"
+                        <> "    , age :: Int\n"
+                        <> "    }\n"
+                        <> "    deriving (Show)"
+                    )
+        , testCase "slices a GADT declaration" do
+            let source =
+                    src
+                        [ "data Expr a where"
+                        , "    Lit :: Int -> Expr Int"
+                        , "    Add :: Expr Int -> Expr Int -> Expr Int"
+                        , ""
+                        ]
+            sliceSymbol "Expr" source
+                @?= Just
+                    ( "data Expr a where\n"
+                        <> "    Lit :: Int -> Expr Int\n"
+                        <> "    Add :: Expr Int -> Expr Int -> Expr Int"
+                    )
+        ]
 
 
-constructors :: Spec
-constructors = describe "constructor queries" do
-    it "returns the enclosing data block for a constructor" do
-        let source =
-                src
-                    [ "-- | Optionality."
-                    , "data Maybe a = Nothing | Just a"
-                    , ""
-                    , "foo = ()"
-                    ]
-        sliceSymbol "Just" source
-            `shouldBe` Just "-- | Optionality.\ndata Maybe a = Nothing | Just a"
-
-    it "keeps a multi-line doc block above the enclosing data block" do
-        let source =
-                src
-                    [ "-- | Optionality,"
-                    , "-- the Maybe type."
-                    , "data Maybe a = Nothing | Just a"
-                    , ""
-                    ]
-        sliceSymbol "Just" source
-            `shouldBe` Just "-- | Optionality,\n-- the Maybe type.\ndata Maybe a = Nothing | Just a"
-
-    it "returns the enclosing GADT block for a GADT constructor" do
-        let source =
-                src
-                    [ "data Expr a where"
-                    , "    Lit :: Int -> Expr Int"
-                    , "    Add :: Expr Int -> Expr Int -> Expr Int"
-                    , ""
-                    ]
-        sliceSymbol "Lit" source
-            `shouldBe` Just
-                ( "data Expr a where\n"
-                    <> "    Lit :: Int -> Expr Int\n"
-                    <> "    Add :: Expr Int -> Expr Int -> Expr Int"
-                )
+constructors :: TestTree
+constructors =
+    testGroup
+        "constructor queries"
+        [ testCase "returns the enclosing data block for a constructor" do
+            let source =
+                    src
+                        [ "-- | Optionality."
+                        , "data Maybe a = Nothing | Just a"
+                        , ""
+                        , "foo = ()"
+                        ]
+            sliceSymbol "Just" source
+                @?= Just "-- | Optionality.\ndata Maybe a = Nothing | Just a"
+        , testCase "keeps a multi-line doc block above the enclosing data block" do
+            let source =
+                    src
+                        [ "-- | Optionality,"
+                        , "-- the Maybe type."
+                        , "data Maybe a = Nothing | Just a"
+                        , ""
+                        ]
+            sliceSymbol "Just" source
+                @?= Just "-- | Optionality,\n-- the Maybe type.\ndata Maybe a = Nothing | Just a"
+        , testCase "returns the enclosing GADT block for a GADT constructor" do
+            let source =
+                    src
+                        [ "data Expr a where"
+                        , "    Lit :: Int -> Expr Int"
+                        , "    Add :: Expr Int -> Expr Int -> Expr Int"
+                        , ""
+                        ]
+            sliceSymbol "Lit" source
+                @?= Just
+                    ( "data Expr a where\n"
+                        <> "    Lit :: Int -> Expr Int\n"
+                        <> "    Add :: Expr Int -> Expr Int -> Expr Int"
+                    )
+        ]
 
 
-robustness :: Spec
-robustness = describe "robustness" do
-    it "returns Nothing for a missing symbol" do
-        sliceSymbol "nope" (src ["foo = 1", "bar = 2"]) `shouldBe` Nothing
-
-    it "returns Nothing for an empty query" do
-        sliceSymbol "" (src ["foo = 1"]) `shouldBe` Nothing
-
-    it "does not choke on CPP-laden source" do
-        let source =
-                src
-                    [ "#if MIN_VERSION_base(4,18,0)"
-                    , "answer :: Int"
-                    , "#else"
-                    , "answer :: Integer"
-                    , "#endif"
-                    , "answer = 42"
-                    ]
-        let result = sliceSymbol "answer" source
-        result `shouldSatisfy` isJust
-        fmap (T.isInfixOf "answer = 42") result `shouldBe` Just True
+robustness :: TestTree
+robustness =
+    testGroup
+        "robustness"
+        [ testCase "returns Nothing for a missing symbol" do
+            sliceSymbol "nope" (src ["foo = 1", "bar = 2"]) @?= Nothing
+        , testCase "returns Nothing for an empty query" do
+            sliceSymbol "" (src ["foo = 1"]) @?= Nothing
+        , testCase "does not choke on CPP-laden source" do
+            let source =
+                    src
+                        [ "#if MIN_VERSION_base(4,18,0)"
+                        , "answer :: Int"
+                        , "#else"
+                        , "answer :: Integer"
+                        , "#endif"
+                        , "answer = 42"
+                        ]
+            let result = sliceSymbol "answer" source
+            assertBool "expected Just" $ isJust (result)
+            fmap (T.isInfixOf "answer = 42") result @?= Just True
+        ]
 
 
 -- | The slice must span exactly the queried declaration: not truncating it
 -- early, not swallowing a neighbour, and not anchoring on the wrong entity.
 -- These are the over-/under-capture shapes real Hackage source triggers.
-capturePrecision :: Spec
-capturePrecision = describe "capture precision" do
-    it "keeps a where-clause that contains a blank line" do
-        let source =
-                src
-                    [ "foo x = go x"
-                    , "  where"
-                    , "    go y = y + 1"
-                    , ""
-                    , "    helper = 2"
-                    , ""
-                    , "bar = 3"
-                    ]
-        sliceSymbol "foo" source
-            `shouldBe` Just "foo x = go x\n  where\n    go y = y + 1\n\n    helper = 2"
-
-    it "does not swallow a following binding that merely uses the operator" do
-        let source =
-                src
-                    [ "(<+>) :: Int -> Int -> Int"
-                    , "a <+> b = a + b"
-                    , "merge x y = x <+> y"
-                    ]
-        sliceSymbol "<+>" source
-            `shouldBe` Just "(<+>) :: Int -> Int -> Int\na <+> b = a + b"
-
-    it "does not anchor on a superclass name in a class head" do
-        let source =
-                src
-                    [ "class Eq a => Ord a where"
-                    , "    compare :: a -> a -> Ordering"
-                    ]
-        sliceSymbol "Eq" source `shouldBe` Nothing
-
-    it "slices a class that has a superclass context by its own name" do
-        let source =
-                src
-                    [ "class Eq a => Ord a where"
-                    , "    compare :: a -> a -> Ordering"
-                    ]
-        sliceSymbol "Ord" source
-            `shouldBe` Just "class Eq a => Ord a where\n    compare :: a -> a -> Ordering"
-
-    it "picks the data block that actually defines the constructor" do
-        let source =
-                src
-                    [ "-- | Uses Just internally."
-                    , "data Wrapper = Wrap Int"
-                    , ""
-                    , "data Maybe a = Nothing | Just a"
-                    ]
-        sliceSymbol "Just" source
-            `shouldBe` Just "data Maybe a = Nothing | Just a"
-
-    it "does not anchor on a constructor name used as a field type elsewhere" do
-        let source =
-                src
-                    [ "data Holder = Holder Bar"
-                    , ""
-                    , "data Thing = Bar | Baz"
-                    ]
-        sliceSymbol "Bar" source `shouldBe` Just "data Thing = Bar | Baz"
-
-    it "keeps a multi-line {- | -} block doc comment" do
-        let source =
-                src
-                    [ "{- | This does X"
-                    , "   over multiple lines. -}"
-                    , "foo :: Int"
-                    , "foo = 1"
-                    ]
-        sliceSymbol "foo" source
-            `shouldBe` Just "{- | This does X\n   over multiple lines. -}\nfoo :: Int\nfoo = 1"
+capturePrecision :: TestTree
+capturePrecision =
+    testGroup
+        "capture precision"
+        [ testCase "keeps a where-clause that contains a blank line" do
+            let source =
+                    src
+                        [ "foo x = go x"
+                        , "  where"
+                        , "    go y = y + 1"
+                        , ""
+                        , "    helper = 2"
+                        , ""
+                        , "bar = 3"
+                        ]
+            sliceSymbol "foo" source
+                @?= Just "foo x = go x\n  where\n    go y = y + 1\n\n    helper = 2"
+        , testCase "does not swallow a following binding that merely uses the operator" do
+            let source =
+                    src
+                        [ "(<+>) :: Int -> Int -> Int"
+                        , "a <+> b = a + b"
+                        , "merge x y = x <+> y"
+                        ]
+            sliceSymbol "<+>" source
+                @?= Just "(<+>) :: Int -> Int -> Int\na <+> b = a + b"
+        , testCase "does not anchor on a superclass name in a class head" do
+            let source =
+                    src
+                        [ "class Eq a => Ord a where"
+                        , "    compare :: a -> a -> Ordering"
+                        ]
+            sliceSymbol "Eq" source @?= Nothing
+        , testCase "slices a class that has a superclass context by its own name" do
+            let source =
+                    src
+                        [ "class Eq a => Ord a where"
+                        , "    compare :: a -> a -> Ordering"
+                        ]
+            sliceSymbol "Ord" source
+                @?= Just "class Eq a => Ord a where\n    compare :: a -> a -> Ordering"
+        , testCase "picks the data block that actually defines the constructor" do
+            let source =
+                    src
+                        [ "-- | Uses Just internally."
+                        , "data Wrapper = Wrap Int"
+                        , ""
+                        , "data Maybe a = Nothing | Just a"
+                        ]
+            sliceSymbol "Just" source
+                @?= Just "data Maybe a = Nothing | Just a"
+        , testCase "does not anchor on a constructor name used as a field type elsewhere" do
+            let source =
+                    src
+                        [ "data Holder = Holder Bar"
+                        , ""
+                        , "data Thing = Bar | Baz"
+                        ]
+            sliceSymbol "Bar" source @?= Just "data Thing = Bar | Baz"
+        , testCase "keeps a multi-line {- | -} block doc comment" do
+            let source =
+                    src
+                        [ "{- | This does X"
+                        , "   over multiple lines. -}"
+                        , "foo :: Int"
+                        , "foo = 1"
+                        ]
+            sliceSymbol "foo" source
+                @?= Just "{- | This does X\n   over multiple lines. -}\nfoo :: Int\nfoo = 1"
+        ]
diff --git a/test/Unit/Tricorder/SourceLookup/TarballSpec.hs b/test/Unit/Tricorder/SourceLookup/TarballSpec.hs
--- a/test/Unit/Tricorder/SourceLookup/TarballSpec.hs
+++ b/test/Unit/Tricorder/SourceLookup/TarballSpec.hs
@@ -1,7 +1,8 @@
-module Unit.Tricorder.SourceLookup.TarballSpec (spec_Tarball) where
+module Unit.Tricorder.SourceLookup.TarballSpec (test_Tarball) where
 
 import System.FilePath (isAbsolute, (</>))
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Codec.Archive.Tar qualified as Tar
 import Codec.Archive.Tar.Entry qualified as Tar
@@ -17,68 +18,65 @@
     )
 
 
-spec_Tarball :: Spec
-spec_Tarball = do
-    describe "splitPackageId" do
-        it "splits a simple package id" do
-            splitPackageId "aeson-2.2.5.0" `shouldBe` ("aeson", "2.2.5.0")
-
-        it "keeps hyphens inside the package name" do
-            splitPackageId "list-t-1.0.5.7" `shouldBe` ("list-t", "1.0.5.7")
-
-    describe "tarballPath" do
-        it "derives the cache path for a package id" do
-            tarballPath "/c" "hackage.haskell.org" "aeson-2.2.5.0"
-                `shouldBe` "/c" </> "hackage.haskell.org/aeson/2.2.5.0/aeson-2.2.5.0.tar.gz"
-
-    describe "cabalPackagesDirs" do
-        it "honors CABAL_DIR" do
-            cabalPackagesDirs [("CABAL_DIR", "/cd")] `shouldBe` ["/cd/packages"]
-
-        it "includes the legacy ~/.cabal location alongside the XDG one" do
-            cabalPackagesDirs [("HOME", "/h")]
-                `shouldBe` ["/h/.cache/cabal/packages", "/h/.cabal/packages"]
-
-        it "yields no candidates (never a relative path) when HOME is unset" do
-            cabalPackagesDirs [] `shouldBe` []
-
-        it "only ever produces absolute candidates" do
-            all isAbsolute (cabalPackagesDirs [("HOME", "/h"), ("XDG_CACHE_HOME", "/x")])
-                `shouldBe` True
-
-    describe "matchesModule" do
-        it "matches a src/ layout entry" do
-            matchesModule "Data.Aeson" "aeson-2.2.5.0/src/Data/Aeson.hs" `shouldBe` True
-
-        it "matches a lib/ layout entry" do
-            matchesModule "Data.Aeson" "aeson-2.2.5.0/lib/Data/Aeson.hs" `shouldBe` True
-
-        it "matches a flat layout entry" do
-            matchesModule "Data.Aeson" "aeson-2.2.5.0/Data/Aeson.hs" `shouldBe` True
-
-        it "does not match a different module under the same prefix" do
-            matchesModule "Data.Aeson" "aeson-2.2.5.0/src/Data/Aeson/Types.hs" `shouldBe` False
-
-        it "does not match a deeper module whose final component coincides" do
-            -- Module `Lens` must not resolve to the file for `Control.Lens`.
-            matchesModule "Lens" "pkg-1.0/Control/Lens.hs" `shouldBe` False
-
-        it "matches a preprocessed .hsc entry" do
-            matchesModule "System.Posix.Files" "unix-2.8.5.0/System/Posix/Files.hsc" `shouldBe` True
-
-        it "matches a literate .lhs entry" do
-            matchesModule "Data.Ratio" "base-4.19.0.0/src/Data/Ratio.lhs" `shouldBe` True
-
-    describe "extractModule" do
-        it "extracts a member by module name" do
-            extractModule "Data.Aeson" fixtureTarball `shouldBe` Just "module Data.Aeson where\n"
-
-        it "returns Nothing when the module is absent" do
-            extractModule "Data.Missing" fixtureTarball `shouldBe` Nothing
-
-        it "prefers a library source path over a same-named test path" do
-            extractModule "Data.Aeson" dupModuleTarball
-                `shouldBe` Just "module Data.Aeson (lib) where\n"
+test_Tarball :: TestTree
+test_Tarball =
+    testGroup
+        "Tarball"
+        [ testGroup
+            "splitPackageId"
+            [ testCase "splits a simple package id" do
+                splitPackageId "aeson-2.2.5.0" @?= ("aeson", "2.2.5.0")
+            , testCase "keeps hyphens inside the package name" do
+                splitPackageId "list-t-1.0.5.7" @?= ("list-t", "1.0.5.7")
+            ]
+        , testGroup
+            "tarballPath"
+            [ testCase "derives the cache path for a package id" do
+                tarballPath "/c" "hackage.haskell.org" "aeson-2.2.5.0"
+                    @?= "/c" </> "hackage.haskell.org/aeson/2.2.5.0/aeson-2.2.5.0.tar.gz"
+            ]
+        , testGroup
+            "cabalPackagesDirs"
+            [ testCase "honors CABAL_DIR" do
+                cabalPackagesDirs [("CABAL_DIR", "/cd")] @?= ["/cd/packages"]
+            , testCase "includes the legacy ~/.cabal location alongside the XDG one" do
+                cabalPackagesDirs [("HOME", "/h")]
+                    @?= ["/h/.cache/cabal/packages", "/h/.cabal/packages"]
+            , testCase "yields no candidates (never a relative path) when HOME is unset" do
+                cabalPackagesDirs [] @?= []
+            , testCase "only ever produces absolute candidates" do
+                all isAbsolute (cabalPackagesDirs [("HOME", "/h"), ("XDG_CACHE_HOME", "/x")])
+                    @?= True
+            ]
+        , testGroup
+            "matchesModule"
+            [ testCase "matches a src/ layout entry" do
+                matchesModule "Data.Aeson" "aeson-2.2.5.0/src/Data/Aeson.hs" @?= True
+            , testCase "matches a lib/ layout entry" do
+                matchesModule "Data.Aeson" "aeson-2.2.5.0/lib/Data/Aeson.hs" @?= True
+            , testCase "matches a flat layout entry" do
+                matchesModule "Data.Aeson" "aeson-2.2.5.0/Data/Aeson.hs" @?= True
+            , testCase "does not match a different module under the same prefix" do
+                matchesModule "Data.Aeson" "aeson-2.2.5.0/src/Data/Aeson/Types.hs" @?= False
+            , testCase "does not match a deeper module whose final component coincides" do
+                -- Module `Lens` must not resolve to the file for `Control.Lens`.
+                matchesModule "Lens" "pkg-1.0/Control/Lens.hs" @?= False
+            , testCase "matches a preprocessed .hsc entry" do
+                matchesModule "System.Posix.Files" "unix-2.8.5.0/System/Posix/Files.hsc" @?= True
+            , testCase "matches a literate .lhs entry" do
+                matchesModule "Data.Ratio" "base-4.19.0.0/src/Data/Ratio.lhs" @?= True
+            ]
+        , testGroup
+            "extractModule"
+            [ testCase "extracts a member by module name" do
+                extractModule "Data.Aeson" fixtureTarball @?= Just "module Data.Aeson where\n"
+            , testCase "returns Nothing when the module is absent" do
+                extractModule "Data.Missing" fixtureTarball @?= Nothing
+            , testCase "prefers a library source path over a same-named test path" do
+                extractModule "Data.Aeson" dupModuleTarball
+                    @?= Just "module Data.Aeson (lib) where\n"
+            ]
+        ]
 
 
 -- | A gzipped tar with a single source member.
diff --git a/test/Unit/Tricorder/SourceLookupSpec.hs b/test/Unit/Tricorder/SourceLookupSpec.hs
--- a/test/Unit/Tricorder/SourceLookupSpec.hs
+++ b/test/Unit/Tricorder/SourceLookupSpec.hs
@@ -1,4 +1,4 @@
-module Unit.Tricorder.SourceLookupSpec (spec_SourceLookup) where
+module Unit.Tricorder.SourceLookupSpec (test_SourceLookup) where
 
 import Atelier.Effects.Cache (Cache, runCacheForever)
 import Atelier.Effects.Env (Env, runEnvConst)
@@ -10,7 +10,8 @@
 import Effectful.Dispatch.Dynamic (interpret_)
 import Effectful.State.Static.Shared (State, evalState, gets, modify)
 import System.FilePath ((</>))
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 import Tricorder.SourceLookup.SourceQuery (ModuleName, SourceQuery (..))
 
 import Codec.Archive.Tar qualified as Tar
@@ -22,7 +23,7 @@
 import Data.Map.Strict qualified as Map
 import Data.Text qualified as T
 
-import Tricorder.Session.Command (Repl (..))
+import Tricorder.Session.Repl (Repl (..))
 import Tricorder.SourceLookup
     ( ModuleSourceResult (..)
     , lookupModuleSource
@@ -35,104 +36,101 @@
 import Tricorder.SourceLookup.PackageStore qualified as PackageStore
 
 
-spec_SourceLookup :: Spec
-spec_SourceLookup = describe "lookupModuleSource" do
-    it "reads the whole module from a cached tarball" do
-        result <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch
-                $ lookupModuleSource (wholeModule "Data.Aeson")
-        result `shouldBe` SourceFound (wholeModule "Data.Aeson") moduleSource
-
-    it "slices a symbol (with its doc block) from a cached tarball" do
-        result <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch
-                $ lookupModuleSource (symbol "Data.Aeson" "encode")
-        result
-            `shouldBe` SourceFound
-                (symbol "Data.Aeson" "encode")
-                "-- | Encode a value as JSON.\nencode :: Value -> ByteString\nencode = undefined"
-
-    it "returns FunctionNotFound for a symbol absent from the module" do
-        result <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch
-                $ lookupModuleSource (symbol "Data.Aeson" "nope")
-        result `shouldBe` FunctionNotFound (symbol "Data.Aeson" "nope")
-
-    it "returns SourceNotFound when the module is in no package" do
-        result <-
-            runTest [NextFindModule Nothing] Map.empty noFetch
-                $ lookupModuleSource (wholeModule "Data.Unknown")
-        result `shouldBe` SourceNotFound (wholeModule "Data.Unknown")
-
-    it "fetches from Hackage on a cache miss, then reads the now-fetched tarball" do
-        result <-
-            runTest
-                [NextFindModule (Just "aeson-2.2.5.0")]
-                Map.empty
-                (pure (Success (BSL.toStrict tarballBytes)))
-                $ lookupModuleSource (wholeModule "Data.Aeson")
-        result `shouldBe` SourceFound (wholeModule "Data.Aeson") moduleSource
-
-    it "returns SourceUnavailable when the package is not found on Hackage" do
-        result <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] Map.empty noFetch
-                $ lookupModuleSource (wholeModule "Data.Aeson")
-        result `shouldBe` SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
-
-    it "caches the result so a second lookup needs no further resolution" do
-        -- Only one NextFindModule is scripted; the second lookup must be served
-        -- entirely from cache (module→package and package→source).
-        (r1, r2) <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch $ do
-                r1 <- lookupModuleSource (wholeModule "Data.Aeson")
-                r2 <- lookupModuleSource (wholeModule "Data.Aeson")
-                pure (r1, r2)
-        r1 `shouldBe` SourceFound (wholeModule "Data.Aeson") moduleSource
-        r2 `shouldBe` SourceFound (wholeModule "Data.Aeson") moduleSource
-
-    it "caches an unavailable result and does not re-fetch on a repeat lookup" do
-        -- The tarball is absent and every fetch reports the package as not
-        -- found, so the first lookup is SourceUnavailable. A repeat lookup must
-        -- be served from cache — no second Hackage fetch on the (network)
-        -- request path.
-        fetchCount <- IORef.newIORef (0 :: Int)
-        let countingFetch = do
-                liftIO (IORef.modifyIORef' fetchCount (+ 1))
-                noFetch
-        (r1, r2) <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] Map.empty countingFetch $ do
-                r1 <- lookupModuleSource (wholeModule "Data.Aeson")
-                r2 <- lookupModuleSource (wholeModule "Data.Aeson")
-                pure (r1, r2)
-        r1 `shouldBe` SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
-        r2 `shouldBe` SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
-        fetches <- IORef.readIORef fetchCount
-        fetches `shouldBe` 1
-
-    it "re-fetches after a failed fetch rather than caching the failure" do
-        -- A failed Hackage fetch (offline, DNS failure, 5xx) is transient, so
-        -- the resulting SourceUnavailable must NOT be cached: a repeat lookup
-        -- has to retry the fetch, or a brief network blip pins unavailability
-        -- for the whole cache window.
-        fetchCount <- IORef.newIORef (0 :: Int)
-        let failingFetch = do
-                liftIO (IORef.modifyIORef' fetchCount (+ 1))
-                pure (Failure "network unreachable")
-        (r1, r2) <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] Map.empty failingFetch $ do
-                r1 <- lookupModuleSource (wholeModule "Data.Aeson")
-                r2 <- lookupModuleSource (wholeModule "Data.Aeson")
-                pure (r1, r2)
-        r1 `shouldBe` SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
-        r2 `shouldBe` SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
-        fetches <- IORef.readIORef fetchCount
-        fetches `shouldBe` 2
-
-    it "finds a tarball in the legacy ~/.cabal cache location" do
-        result <-
-            runTest [NextFindModule (Just "aeson-2.2.5.0")] withLegacyTarball noFetch
-                $ lookupModuleSource (wholeModule "Data.Aeson")
-        result `shouldBe` SourceFound (wholeModule "Data.Aeson") moduleSource
+test_SourceLookup :: TestTree
+test_SourceLookup =
+    testGroup
+        "SourceLookup"
+        [ testGroup
+            "lookupModuleSource"
+            [ testCase "reads the whole module from a cached tarball" do
+                result <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch
+                        $ lookupModuleSource (wholeModule "Data.Aeson")
+                result @?= SourceFound (wholeModule "Data.Aeson") moduleSource
+            , testCase "slices a symbol (with its doc block) from a cached tarball" do
+                result <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch
+                        $ lookupModuleSource (symbol "Data.Aeson" "encode")
+                result
+                    @?= SourceFound
+                        (symbol "Data.Aeson" "encode")
+                        "-- | Encode a value as JSON.\nencode :: Value -> ByteString\nencode = undefined"
+            , testCase "returns FunctionNotFound for a symbol absent from the module" do
+                result <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch
+                        $ lookupModuleSource (symbol "Data.Aeson" "nope")
+                result @?= FunctionNotFound (symbol "Data.Aeson" "nope")
+            , testCase "returns SourceNotFound when the module is in no package" do
+                result <-
+                    runTest [NextFindModule Nothing] Map.empty noFetch
+                        $ lookupModuleSource (wholeModule "Data.Unknown")
+                result @?= SourceNotFound (wholeModule "Data.Unknown")
+            , testCase "fetches from Hackage on a cache miss, then reads the now-fetched tarball" do
+                result <-
+                    runTest
+                        [NextFindModule (Just "aeson-2.2.5.0")]
+                        Map.empty
+                        (pure (Success (BSL.toStrict tarballBytes)))
+                        $ lookupModuleSource (wholeModule "Data.Aeson")
+                result @?= SourceFound (wholeModule "Data.Aeson") moduleSource
+            , testCase "returns SourceUnavailable when the package is not found on Hackage" do
+                result <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] Map.empty noFetch
+                        $ lookupModuleSource (wholeModule "Data.Aeson")
+                result @?= SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
+            , testCase "caches the result so a second lookup needs no further resolution" do
+                -- Only one NextFindModule is scripted; the second lookup must be served
+                -- entirely from cache (module→package and package→source).
+                (r1, r2) <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] withTarball noFetch $ do
+                        r1 <- lookupModuleSource (wholeModule "Data.Aeson")
+                        r2 <- lookupModuleSource (wholeModule "Data.Aeson")
+                        pure (r1, r2)
+                r1 @?= SourceFound (wholeModule "Data.Aeson") moduleSource
+                r2 @?= SourceFound (wholeModule "Data.Aeson") moduleSource
+            , testCase "caches an unavailable result and does not re-fetch on a repeat lookup" do
+                -- The tarball is absent and every fetch reports the package as not
+                -- found, so the first lookup is SourceUnavailable. A repeat lookup must
+                -- be served from cache — no second Hackage fetch on the (network)
+                -- request path.
+                fetchCount <- IORef.newIORef (0 :: Int)
+                let countingFetch = do
+                        liftIO (IORef.modifyIORef' fetchCount (+ 1))
+                        noFetch
+                (r1, r2) <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] Map.empty countingFetch $ do
+                        r1 <- lookupModuleSource (wholeModule "Data.Aeson")
+                        r2 <- lookupModuleSource (wholeModule "Data.Aeson")
+                        pure (r1, r2)
+                r1 @?= SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
+                r2 @?= SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
+                fetches <- IORef.readIORef fetchCount
+                fetches @?= 1
+            , testCase "re-fetches after a failed fetch rather than caching the failure" do
+                -- A failed Hackage fetch (offline, DNS failure, 5xx) is transient, so
+                -- the resulting SourceUnavailable must NOT be cached: a repeat lookup
+                -- has to retry the fetch, or a brief network blip pins unavailability
+                -- for the whole cache window.
+                fetchCount <- IORef.newIORef (0 :: Int)
+                let failingFetch = do
+                        liftIO (IORef.modifyIORef' fetchCount (+ 1))
+                        pure (Failure "network unreachable")
+                (r1, r2) <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] Map.empty failingFetch $ do
+                        r1 <- lookupModuleSource (wholeModule "Data.Aeson")
+                        r2 <- lookupModuleSource (wholeModule "Data.Aeson")
+                        pure (r1, r2)
+                r1 @?= SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
+                r2 @?= SourceUnavailable (wholeModule "Data.Aeson") "aeson-2.2.5.0"
+                fetches <- IORef.readIORef fetchCount
+                fetches @?= 2
+            , testCase "finds a tarball in the legacy ~/.cabal cache location" do
+                result <-
+                    runTest [NextFindModule (Just "aeson-2.2.5.0")] withLegacyTarball noFetch
+                        $ lookupModuleSource (wholeModule "Data.Aeson")
+                result @?= SourceFound (wholeModule "Data.Aeson") moduleSource
+            ]
+        ]
 
 
 --------------------------------------------------------------------------------
diff --git a/test/Unit/Tricorder/TestOutputSpec.hs b/test/Unit/Tricorder/TestOutputSpec.hs
--- a/test/Unit/Tricorder/TestOutputSpec.hs
+++ b/test/Unit/Tricorder/TestOutputSpec.hs
@@ -1,6 +1,7 @@
-module Unit.Tricorder.TestOutputSpec (spec_TestOutput) where
+module Unit.Tricorder.TestOutputSpec (test_TestOutput) where
 
-import Test.Hspec
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertFailure, testCase, (@?=))
 
 import Tricorder.Build.Duration (Duration (..))
 import Tricorder.TestOutput (parseHspecDuration, parseHspecOutput, stripGhciNoise)
@@ -8,182 +9,168 @@
 import Tricorder.Build.Test qualified as Test
 
 
-spec_TestOutput :: Spec
-spec_TestOutput = do
-    describe "parseHspecOutput" do
-        it "returns empty list for empty output" do
-            parseHspecOutput "" `shouldBe` []
-
-        it "parses a passing test" do
-            let output = "  foo\n    bar baz:                                      OK\n"
-            parseHspecOutput output
-                `shouldBe` [Test.Case {description = "bar baz:", outcome = Test.Passed}]
-
-        it "parses a failing test" do
-            let output = "  foo\n    bar baz:                                      FAIL\n"
-            parseHspecOutput output
-                `shouldBe` [Test.Case {description = "bar baz:", outcome = Test.Failed ""}]
-
-        it "captures failure details" do
-            let output =
-                    "    a test:                                            FAIL\n"
-                        <> "      expected: 1\n"
-                        <> "       but got: 2\n"
-                        <> "    another test:                                       OK\n"
-            parseHspecOutput output
-                `shouldBe` [ Test.Case
-                                { description = "a test:"
-                                , outcome = Test.Failed "expected: 1\nbut got: 2"
-                                }
-                           , Test.Case {description = "another test:", outcome = Test.Passed}
-                           ]
-
-        it "stops collecting details when indentation returns to test level" do
-            let output =
-                    "    failing:                                           FAIL\n"
-                        <> "      detail line\n"
-                        <> "    passing:                                          OK\n"
-            let cases = parseHspecOutput output
-            length cases `shouldBe` 2
-            case cases of
-                (c : _) -> c.outcome `shouldBe` Test.Failed "detail line"
-                [] -> expectationFailure "expected at least one test case"
-
-        it "skips group header lines" do
-            let output =
-                    "  MyModule\n"
-                        <> "    someFunction\n"
-                        <> "      does the thing:                                  OK\n"
-            parseHspecOutput output
-                `shouldBe` [Test.Case {description = "does the thing:", outcome = Test.Passed}]
-
-        it "parses mixed passing and failing tests" do
-            let output =
-                    "  Suite\n"
-                        <> "    passes:                                            OK\n"
-                        <> "    fails:                                             FAIL\n"
-                        <> "      reason\n"
-                        <> "    also passes:                                       OK\n"
-            parseHspecOutput output
-                `shouldBe` [ Test.Case {description = "passes:", outcome = Test.Passed}
-                           , Test.Case {description = "fails:", outcome = Test.Failed "reason"}
-                           , Test.Case {description = "also passes:", outcome = Test.Passed}
-                           ]
-
-        it "parses a passing test with a timing annotation" do
-            let output = "  slow test:                                          OK (0.05s)\n"
-            parseHspecOutput output
-                `shouldBe` [Test.Case {description = "slow test:", outcome = Test.Passed}]
-
-        it "parses a passing test with a millisecond annotation" do
-            let output = "  fast property:                                      OK (12ms)\n"
-            parseHspecOutput output
-                `shouldBe` [Test.Case {description = "fast property:", outcome = Test.Passed}]
-
-        it "parses a failing test with a timing annotation" do
-            let output = "  slow fail:                                          FAIL (0.03s)\n"
-            parseHspecOutput output
-                `shouldBe` [Test.Case {description = "slow fail:", outcome = Test.Failed ""}]
-
-        it "does not strip a non-timing parenthetical in the description" do
-            let output = "  test (corner case):                                 OK\n"
-            parseHspecOutput output
-                `shouldBe` [Test.Case {description = "test (corner case):", outcome = Test.Passed}]
-
-    describe "parseHspecDuration" do
-        it "returns Nothing for empty output" do
-            parseHspecDuration "" `shouldBe` Nothing
-
-        it "returns Nothing when no timing line is present" do
-            parseHspecDuration "2 examples, 0 failures\n" `shouldBe` Nothing
-
-        it "parses duration from passing summary line" do
-            parseHspecDuration "All 177 tests passed (0.05s)\n"
-                `shouldBe` Just (Duration 50)
-
-        it "parses duration from failing summary line" do
-            parseHspecDuration "1 out of 177 tests failed (0.06s)\n"
-                `shouldBe` Just (Duration 60)
-
-        it "does not match indented individual test timing lines" do
-            parseHspecDuration "      entry is evicted after cleanup thread fires past TTL:  OK (0.05s)\n"
-                `shouldBe` Nothing
-
-        it "parses duration embedded in full hspec output" do
-            let output =
-                    "  Suite\n"
-                        <> "    passes:                                          OK\n"
-                        <> "    slow test:                                       OK (0.05s)\n"
-                        <> "\n"
-                        <> "All 2 tests passed (0.5s)\n"
-            parseHspecDuration output `shouldBe` Just (Duration 500)
-
-    describe "stripGhciNoise" do
-        it "passes through empty list" do
-            stripGhciNoise [] `shouldBe` []
-
-        it "passes through output with no ghci prompt" do
-            let ls = ["line one", "line two", "line three"]
-            stripGhciNoise ls `shouldBe` ls
-
-        it "strips cabal build preamble" do
-            let ls =
-                    [ "Resolving dependencies..."
-                    , "Build profile: -w ghc-9.6.3 -O1"
-                    , "ghci> :reload"
-                    , "  test one:                                          OK"
-                    , "  test two:                                          OK"
-                    ]
-            stripGhciNoise ls
-                `shouldBe` [ "  test one:                                          OK"
-                           , "  test two:                                          OK"
-                           ]
-
-        it "strips trailing ghci prompt" do
-            let ls =
-                    [ "ghci> :reload"
-                    , "  a test:                                            OK"
-                    , "ghci> "
-                    ]
-            stripGhciNoise ls `shouldBe` ["  a test:                                            OK"]
-
-        it "strips trailing \"Leaving GHCi.\" line" do
-            let ls =
-                    [ "ghci> :reload"
-                    , "  a test:                                            OK"
-                    , "Leaving GHCi."
-                    ]
-            stripGhciNoise ls `shouldBe` ["  a test:                                            OK"]
-
-        it "strips trailing \"*** Exception: ...\" lines" do
-            let ls =
-                    [ "ghci> :reload"
-                    , "  a test:                                            OK"
-                    , "*** Exception: ExitSuccess"
-                    ]
-            stripGhciNoise ls `shouldBe` ["  a test:                                            OK"]
-
-        it "full round-trip strips build noise, keeps test output" do
-            let ls =
-                    [ "Resolving dependencies..."
-                    , "Build profile: -w ghc-9.6.3 -O1"
-                    , "Preprocessing test suite 'spec' for tricorder-0.1.0.0..."
-                    , "ghci> :reload"
-                    , "  Suite"
-                    , "    passes:                                          OK"
-                    , "    fails:                                           FAIL"
-                    , "      some detail"
-                    , ""
-                    , "Finished in 0.0001 seconds"
-                    , "ghci> "
-                    , "Leaving GHCi."
-                    , "*** Exception: ExitFailure 1"
-                    ]
-            stripGhciNoise ls
-                `shouldBe` [ "  Suite"
-                           , "    passes:                                          OK"
-                           , "    fails:                                           FAIL"
-                           , "      some detail"
-                           , ""
-                           , "Finished in 0.0001 seconds"
-                           ]
+test_TestOutput :: TestTree
+test_TestOutput =
+    testGroup
+        "TestOutput"
+        [ testGroup
+            "parseHspecOutput"
+            [ testCase "returns empty list for empty output" do
+                parseHspecOutput "" @?= []
+            , testCase "parses a passing test" do
+                let output = "  foo\n    bar baz:                                      OK\n"
+                parseHspecOutput output
+                    @?= [Test.Case {description = "bar baz:", outcome = Test.Passed}]
+            , testCase "parses a failing test" do
+                let output = "  foo\n    bar baz:                                      FAIL\n"
+                parseHspecOutput output
+                    @?= [Test.Case {description = "bar baz:", outcome = Test.Failed ""}]
+            , testCase "captures failure details" do
+                let output =
+                        "    a test:                                            FAIL\n"
+                            <> "      expected: 1\n"
+                            <> "       but got: 2\n"
+                            <> "    another test:                                       OK\n"
+                parseHspecOutput output
+                    @?= [ Test.Case
+                            { description = "a test:"
+                            , outcome = Test.Failed "expected: 1\nbut got: 2"
+                            }
+                        , Test.Case {description = "another test:", outcome = Test.Passed}
+                        ]
+            , testCase "stops collecting details when indentation returns to test level" do
+                let output =
+                        "    failing:                                           FAIL\n"
+                            <> "      detail line\n"
+                            <> "    passing:                                          OK\n"
+                let cases = parseHspecOutput output
+                length cases @?= 2
+                case cases of
+                    (c : _) -> c.outcome @?= Test.Failed "detail line"
+                    [] -> assertFailure "expected at least one test case"
+            , testCase "skips group header lines" do
+                let output =
+                        "  MyModule\n"
+                            <> "    someFunction\n"
+                            <> "      does the thing:                                  OK\n"
+                parseHspecOutput output
+                    @?= [Test.Case {description = "does the thing:", outcome = Test.Passed}]
+            , testCase "parses mixed passing and failing tests" do
+                let output =
+                        "  Suite\n"
+                            <> "    passes:                                            OK\n"
+                            <> "    fails:                                             FAIL\n"
+                            <> "      reason\n"
+                            <> "    also passes:                                       OK\n"
+                parseHspecOutput output
+                    @?= [ Test.Case {description = "passes:", outcome = Test.Passed}
+                        , Test.Case {description = "fails:", outcome = Test.Failed "reason"}
+                        , Test.Case {description = "also passes:", outcome = Test.Passed}
+                        ]
+            , testCase "parses a passing test with a timing annotation" do
+                let output = "  slow test:                                          OK (0.05s)\n"
+                parseHspecOutput output
+                    @?= [Test.Case {description = "slow test:", outcome = Test.Passed}]
+            , testCase "parses a passing test with a millisecond annotation" do
+                let output = "  fast property:                                      OK (12ms)\n"
+                parseHspecOutput output
+                    @?= [Test.Case {description = "fast property:", outcome = Test.Passed}]
+            , testCase "parses a failing test with a timing annotation" do
+                let output = "  slow fail:                                          FAIL (0.03s)\n"
+                parseHspecOutput output
+                    @?= [Test.Case {description = "slow fail:", outcome = Test.Failed ""}]
+            , testCase "does not strip a non-timing parenthetical in the description" do
+                let output = "  test (corner case):                                 OK\n"
+                parseHspecOutput output
+                    @?= [Test.Case {description = "test (corner case):", outcome = Test.Passed}]
+            ]
+        , testGroup
+            "parseHspecDuration"
+            [ testCase "returns Nothing for empty output" do
+                parseHspecDuration "" @?= Nothing
+            , testCase "returns Nothing when no timing line is present" do
+                parseHspecDuration "2 examples, 0 failures\n" @?= Nothing
+            , testCase "parses duration from passing summary line" do
+                parseHspecDuration "All 177 tests passed (0.05s)\n"
+                    @?= Just (Duration 50)
+            , testCase "parses duration from failing summary line" do
+                parseHspecDuration "1 out of 177 tests failed (0.06s)\n"
+                    @?= Just (Duration 60)
+            , testCase "does not match indented individual test timing lines" do
+                parseHspecDuration "      entry is evicted after cleanup thread fires past TTL:  OK (0.05s)\n"
+                    @?= Nothing
+            , testCase "parses duration embedded in full hspec output" do
+                let output =
+                        "  Suite\n"
+                            <> "    passes:                                          OK\n"
+                            <> "    slow test:                                       OK (0.05s)\n"
+                            <> "\n"
+                            <> "All 2 tests passed (0.5s)\n"
+                parseHspecDuration output @?= Just (Duration 500)
+            ]
+        , testGroup
+            "stripGhciNoise"
+            [ testCase "passes through empty list" do
+                stripGhciNoise [] @?= []
+            , testCase "passes through output with no ghci prompt" do
+                let ls = ["line one", "line two", "line three"]
+                stripGhciNoise ls @?= ls
+            , testCase "strips cabal build preamble" do
+                let ls =
+                        [ "Resolving dependencies..."
+                        , "Build profile: -w ghc-9.6.3 -O1"
+                        , "ghci> :reload"
+                        , "  test one:                                          OK"
+                        , "  test two:                                          OK"
+                        ]
+                stripGhciNoise ls
+                    @?= [ "  test one:                                          OK"
+                        , "  test two:                                          OK"
+                        ]
+            , testCase "strips trailing ghci prompt" do
+                let ls =
+                        [ "ghci> :reload"
+                        , "  a test:                                            OK"
+                        , "ghci> "
+                        ]
+                stripGhciNoise ls @?= ["  a test:                                            OK"]
+            , testCase "strips trailing \"Leaving GHCi.\" line" do
+                let ls =
+                        [ "ghci> :reload"
+                        , "  a test:                                            OK"
+                        , "Leaving GHCi."
+                        ]
+                stripGhciNoise ls @?= ["  a test:                                            OK"]
+            , testCase "strips trailing \"*** Exception: ...\" lines" do
+                let ls =
+                        [ "ghci> :reload"
+                        , "  a test:                                            OK"
+                        , "*** Exception: ExitSuccess"
+                        ]
+                stripGhciNoise ls @?= ["  a test:                                            OK"]
+            , testCase "full round-trip strips build noise, keeps test output" do
+                let ls =
+                        [ "Resolving dependencies..."
+                        , "Build profile: -w ghc-9.6.3 -O1"
+                        , "Preprocessing test suite 'spec' for tricorder-0.1.0.0..."
+                        , "ghci> :reload"
+                        , "  Suite"
+                        , "    passes:                                          OK"
+                        , "    fails:                                           FAIL"
+                        , "      some detail"
+                        , ""
+                        , "Finished in 0.0001 seconds"
+                        , "ghci> "
+                        , "Leaving GHCi."
+                        , "*** Exception: ExitFailure 1"
+                        ]
+                stripGhciNoise ls
+                    @?= [ "  Suite"
+                        , "    passes:                                          OK"
+                        , "    fails:                                           FAIL"
+                        , "      some detail"
+                        , ""
+                        , "Finished in 0.0001 seconds"
+                        ]
+            ]
+        ]
diff --git a/test/Unit/Tricorder/WaitersSpec.hs b/test/Unit/Tricorder/WaitersSpec.hs
--- a/test/Unit/Tricorder/WaitersSpec.hs
+++ b/test/Unit/Tricorder/WaitersSpec.hs
@@ -1,11 +1,13 @@
-module Unit.Tricorder.WaitersSpec (spec_Waiters) where
+module Unit.Tricorder.WaitersSpec (test_Waiters) where
 
 import Atelier.Effects.Conc (Conc, runConc)
+import Control.Exception (try)
 import Effectful (IOE, runEff)
 import Effectful.Concurrent (Concurrent, runConcurrent)
 import Effectful.Exception (catch, throwIO)
 import Effectful.State.Static.Shared (State, get, modify, runState)
-import Test.Hspec (Spec, describe, it, shouldBe, shouldMatchList, shouldThrow)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
 
 import Atelier.Effects.Conc qualified as Conc
 import Atelier.Types.Semaphore qualified as Sem
@@ -37,104 +39,110 @@
 logEvent name = modify (<> [name])
 
 
-spec_Waiters :: Spec
-spec_Waiters = do
-    describe "Waiters.without" do
-        describe "with waiters" $ it "skips the action" do
-            (_, events) <- runWaitersTest do
-                proceed <- Sem.new
-                started <- Sem.new
-                waiter <- Conc.fork $ Waiters.with do
-                    void $ Sem.set started
-                    Sem.wait proceed
-                    logEvent "waiter"
-                Sem.wait started
-                -- Called directly (not forked): Without never blocks, so
-                -- forking it here would race its no-waiters check against
-                -- the `Sem.set proceed` below, making the test flaky.
-                Waiters.without (logEvent "without")
-                void $ Sem.set proceed
-                Conc.await waiter
-            events `shouldBe` ["waiter"]
-        it "runs its action immediately when there are no active waiters" do
-            (_, events) <- runWaitersTest $ Waiters.without (logEvent "ran")
-            events `shouldBe` ["ran"]
-
-    describe "Waiters.with" do
-        it "runs its action" do
-            (_, events) <- runWaitersTest $ Waiters.with (logEvent "ran")
-            events `shouldBe` ["ran"]
-
-        it "lets a subsequent Waiters.wait proceed once it has completed" do
-            (_, events) <- runWaitersTest do
-                Waiters.with (logEvent "waiter")
-                Waiters.wait (logEvent "quiesced")
-            events `shouldBe` ["waiter", "quiesced"]
-
-        it "blocks a concurrent Waiters.wait until its action finishes" do
-            (_, events) <- runWaitersTest do
-                started <- Sem.new
-                proceed <- Sem.new
-                waiter <- Conc.fork $ Waiters.with do
-                    _ <- Sem.set started
-                    Sem.wait proceed
-                    logEvent "waiter-end"
-                Sem.wait started
-                quiescent <- Conc.fork $ Waiters.wait (logEvent "quiesced")
-                _ <- Sem.set proceed
-                Conc.await waiter
-                Conc.await quiescent
-            -- Blocking is guaranteed by the STM retry on the waiter count,
-            -- not by scheduling luck, so this order holds on every run.
-            events `shouldBe` ["waiter-end", "quiesced"]
-
-        it "blocks wait until every concurrent waiter finishes" do
-            (afterFirst, events) <- runWaitersTest do
-                started1 <- Sem.new
-                proceed1 <- Sem.new
-                waiter1 <- Conc.fork $ Waiters.with do
-                    _ <- Sem.set started1
-                    Sem.wait proceed1
-                    logEvent "waiter1-end"
-                Sem.wait started1
-
-                quiescent <- Conc.fork $ Waiters.wait (logEvent "quiesced")
-
-                started2 <- Sem.new
-                proceed2 <- Sem.new
-                waiter2 <- Conc.fork $ Waiters.with do
-                    _ <- Sem.set started2
-                    Sem.wait proceed2
-                    logEvent "waiter2-end"
-                Sem.wait started2
+test_Waiters :: TestTree
+test_Waiters =
+    testGroup
+        "Waiters"
+        [ testGroup
+            "Waiters.without"
+            [ testGroup
+                "with waiters"
+                [ testCase "skips the action" do
+                    (_, events) <- runWaitersTest do
+                        proceed <- Sem.new
+                        started <- Sem.new
+                        waiter <- Conc.fork $ Waiters.with do
+                            void $ Sem.set started
+                            Sem.wait proceed
+                            logEvent "waiter"
+                        Sem.wait started
+                        -- Called directly (not forked): Without never blocks, so
+                        -- forking it here would race its no-waiters check against
+                        -- the `Sem.set proceed` below, making the test flaky.
+                        Waiters.without (logEvent "without")
+                        void $ Sem.set proceed
+                        Conc.await waiter
+                    events @?= ["waiter"]
+                ]
+            , testCase "runs its action immediately when there are no active waiters" do
+                (_, events) <- runWaitersTest $ Waiters.without (logEvent "ran")
+                events @?= ["ran"]
+            ]
+        , testGroup
+            "Waiters.with"
+            [ testCase "runs its action" do
+                (_, events) <- runWaitersTest $ Waiters.with (logEvent "ran")
+                events @?= ["ran"]
+            , testCase "lets a subsequent Waiters.wait proceed once it has completed" do
+                (_, events) <- runWaitersTest do
+                    Waiters.with (logEvent "waiter")
+                    Waiters.wait (logEvent "quiesced")
+                events @?= ["waiter", "quiesced"]
+            , testCase "blocks a concurrent Waiters.wait until its action finishes" do
+                (_, events) <- runWaitersTest do
+                    started <- Sem.new
+                    proceed <- Sem.new
+                    waiter <- Conc.fork $ Waiters.with do
+                        _ <- Sem.set started
+                        Sem.wait proceed
+                        logEvent "waiter-end"
+                    Sem.wait started
+                    quiescent <- Conc.fork $ Waiters.wait (logEvent "quiesced")
+                    _ <- Sem.set proceed
+                    Conc.await waiter
+                    Conc.await quiescent
+                -- Blocking is guaranteed by the STM retry on the waiter count,
+                -- not by scheduling luck, so this order holds on every run.
+                events @?= ["waiter-end", "quiesced"]
+            , testCase "blocks wait until every concurrent waiter finishes" do
+                (afterFirst, events) <- runWaitersTest do
+                    started1 <- Sem.new
+                    proceed1 <- Sem.new
+                    waiter1 <- Conc.fork $ Waiters.with do
+                        _ <- Sem.set started1
+                        Sem.wait proceed1
+                        logEvent "waiter1-end"
+                    Sem.wait started1
 
-                _ <- Sem.set proceed1
-                Conc.await waiter1
-                -- waiter2 is still active here, so the waiter count cannot
-                -- have reached zero yet: quiescent is still blocked, not
-                -- just "hasn't been scheduled".
-                afterFirst <- get
-                _ <- Sem.set proceed2
-                Conc.await waiter2
-                -- No snapshot is taken here: once waiter2's slot is released,
-                -- quiescent's STM retry can wake and log concurrently with
-                -- this thread, so there is no deterministic in-between state
-                -- to observe. Only the final, fully-awaited state is safe to
-                -- assert on.
-                Conc.await quiescent
-                pure afterFirst
-            afterFirst `shouldMatchList` ["waiter1-end"]
-            events `shouldMatchList` ["waiter1-end", "waiter2-end", "quiesced"]
+                    quiescent <- Conc.fork $ Waiters.wait (logEvent "quiesced")
 
-    describe "exception safety" do
-        it "propagates an exception raised by the waiter's action" do
-            let action = runWaitersTest $ Waiters.with (throwIO $ TestException "boom")
-            action `shouldThrow` \(TestException msg) -> msg == "boom"
+                    started2 <- Sem.new
+                    proceed2 <- Sem.new
+                    waiter2 <- Conc.fork $ Waiters.with do
+                        _ <- Sem.set started2
+                        Sem.wait proceed2
+                        logEvent "waiter2-end"
+                    Sem.wait started2
 
-        it "releases the waiter slot even when the action throws" do
-            (_, events) <- runWaitersTest do
-                _ <-
-                    Waiters.with (throwIO $ TestException "boom")
-                        `catch` \(_ :: TestException) -> pure ()
-                Waiters.without (logEvent "quiesced")
-            events `shouldBe` ["quiesced"]
+                    _ <- Sem.set proceed1
+                    Conc.await waiter1
+                    -- waiter2 is still active here, so the waiter count cannot
+                    -- have reached zero yet: quiescent is still blocked, not
+                    -- just "hasn't been scheduled".
+                    afterFirst <- get
+                    _ <- Sem.set proceed2
+                    Conc.await waiter2
+                    -- No snapshot is taken here: once waiter2's slot is released,
+                    -- quiescent's STM retry can wake and log concurrently with
+                    -- this thread, so there is no deterministic in-between state
+                    -- to observe. Only the final, fully-awaited state is safe to
+                    -- assert on.
+                    Conc.await quiescent
+                    pure afterFirst
+                afterFirst @?= ["waiter1-end"]
+                events @?= ["waiter1-end", "waiter2-end", "quiesced"]
+            ]
+        , testGroup
+            "exception safety"
+            [ testCase "propagates an exception raised by the waiter's action" do
+                res <- try $ runWaitersTest $ Waiters.with (throwIO $ TestException "boom")
+                res @?= (Left (TestException "boom") :: Either TestException ((), [Text]))
+            , testCase "releases the waiter slot even when the action throws" do
+                (_, events) <- runWaitersTest do
+                    _ <-
+                        Waiters.with (throwIO $ TestException "boom")
+                            `catch` \(_ :: TestException) -> pure ()
+                    Waiters.without (logEvent "quiesced")
+                events @?= ["quiesced"]
+            ]
+        ]
diff --git a/tricorder.cabal b/tricorder.cabal
--- a/tricorder.cabal
+++ b/tricorder.cabal
@@ -5,13 +5,13 @@
 -- see: https://github.com/sol/hpack
 
 name:            tricorder
-version:         0.4.1.1
+version:         0.5.0.0
 synopsis:        Continuous Haskell build status, diagnostics, and tests via a shared daemon
 description:     tricorder rebuilds your Haskell project continuously and surfaces build status, diagnostics, test results, and documentation - for developers and LLM coding agents. Like ghcid and ghciwatch it reloads on every change, but builds run in a background daemon so multiple clients (an interactive TUI, a status CLI, an agent skill) share a single build state without triggering redundant rebuilds. It discovers components across multi-package cabal.project workspaces automatically and ships context-friendly output for agentic use via the CLI.
 category:        Development
 homepage:        https://github.com/tweag/tricorder#readme
 bug-reports:     https://github.com/tweag/tricorder/issues
-author:          Victor Nascimento Bakke
+author:          Christian Georgii
 maintainer:      victor.bakke@tweag.io
 license:         MIT
 license-file:    LICENSE
@@ -40,6 +40,8 @@
       Tricorder.Build.Test
       Tricorder.CLI.App
       Tricorder.CLI.Arguments
+      Tricorder.CLI.Arguments.Daemon
+      Tricorder.CLI.Arguments.OutputFormat
       Tricorder.CLI.Daemon
       Tricorder.CLI.Main
       Tricorder.CLI.Operations
@@ -72,15 +74,28 @@
       Tricorder.Runtime
       Tricorder.Session
       Tricorder.Session.CabalFile
-      Tricorder.Session.Command
+      Tricorder.Session.Command.RenderedCommand
+      Tricorder.Session.CommandConfig
+      Tricorder.Session.CommandTemplate
       Tricorder.Session.Config
       Tricorder.Session.GenerateWithHpack
       Tricorder.Session.Hooks
       Tricorder.Session.IdleTimeout
+      Tricorder.Session.Repl
       Tricorder.Session.ReplBuildDir
+      Tricorder.Session.StackProject
+      Tricorder.Session.Stage
+      Tricorder.Session.Stage.Build.Command
+      Tricorder.Session.Stage.Build.Session
+      Tricorder.Session.Stage.Eval.Command
+      Tricorder.Session.Stage.Eval.Session
+      Tricorder.Session.Stage.Test.Command
+      Tricorder.Session.Stage.Test.Config
+      Tricorder.Session.Stage.Test.Session
       Tricorder.Session.Target
       Tricorder.Session.TestTarget
       Tricorder.Session.TestTimeout
+      Tricorder.Session.Util
       Tricorder.Session.WatchDirs
       Tricorder.Session.WatchExclusionPatterns
       Tricorder.Socket.Client
@@ -129,7 +144,7 @@
     , atelier-core ==0.7.*
     , atelier-prelude ==0.4.*
     , base >=4.18 && <4.23
-    , brick >=2.10 && <2.14
+    , brick ==3.0.*
     , bytestring >=0.11 && <0.13
     , casing ==0.1.*
     , containers >=0.6 && <0.9
@@ -258,8 +273,12 @@
       Unit.Tricorder.Daemon.TestRunnerSpec
       Unit.Tricorder.Daemon.WatchSpec
       Unit.Tricorder.Session.CabalFileSpec
-      Unit.Tricorder.Session.CommandSpec
+      Unit.Tricorder.Session.CommandTemplateSpec
       Unit.Tricorder.Session.Helpers
+      Unit.Tricorder.Session.ReplSpec
+      Unit.Tricorder.Session.Stage.Build.CommandSpec
+      Unit.Tricorder.Session.Stage.Eval.CommandSpec
+      Unit.Tricorder.Session.Stage.Test.CommandSpec
       Unit.Tricorder.Session.TargetSpec
       Unit.Tricorder.Session.TestTargetSpec
       Unit.Tricorder.Session.WatchDirsSpec
@@ -309,7 +328,6 @@
     , effectful-core ==2.7.*
     , effectful-plugin ==2.2.*
     , filepath >=1.4 && <1.6
-    , hspec ==2.11.*
     , megaparsec >=9.7 && <9.9
     , process ==1.6.*
     , regex-tdfa >=1.3.2.5 && <1.4
@@ -317,7 +335,7 @@
     , tar >=0.6 && <0.8
     , tasty ==1.5.*
     , tasty-discover ==5.2.*
-    , tasty-hspec ==1.2.*
+    , tasty-hunit >=0.10.2 && <0.11
     , text ==2.1.*
     , time >=1.12 && <1.17
     , time-units ==1.0.*