diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,21 @@
 
 ## [Unreleased]
 
+## [0.6.0.0] - 2026-10-23
+
+### Added
+
+- Moved all argument parsing functionality from `tricorder` to
+  `tricorder-types` for module locality.
+
+### Changed
+
+- `Tricorder.API.Daemon.Command.DaemonCommand` renamed to
+  `Tricorder.API.Daemon.Command.Command`.
+- `Tricorder.API` moved to `Tricorder.API.Command`.
+- `Tricorder.API.Args` moved to `Tricorder.API.Command.Args`.
+- `Tricorder.API.Command.commandToArgs` renamed to `Tricorder.API.Command.toArgs`.
+
 ## [0.5.0.0] - 2026-10-20
 
 ### Added
diff --git a/src/Tricorder/API/Args/Deprecated.hs b/src/Tricorder/API/Args/Deprecated.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Args/Deprecated.hs
@@ -0,0 +1,76 @@
+module Tricorder.API.Args.Deprecated (parser) where
+
+import Options.Applicative
+    ( Parser
+    , command
+    , commandGroup
+    , flag
+    , help
+    , hidden
+    , hsubparser
+    , info
+    , long
+    , progDescDoc
+    )
+
+import Options.Applicative.Help qualified as Doc
+
+import Tricorder.API.Command (Command (..), TestOptions (..))
+
+import Tricorder.API.Daemon.Args qualified as Daemon.Args
+import Tricorder.API.Daemon.Command qualified as Daemon.Command
+import Tricorder.API.WaitMode.Args qualified as WaitMode.Args
+
+
+parser :: Parser Command
+parser =
+    hsubparser
+        $ mconcat
+            [ hidden
+            , commandGroup "Deprecated:"
+            , command
+                "start"
+                $ info (pure $ Daemon Daemon.Command.Start)
+                $ progDescDoc
+                $ Just
+                $ "Start the daemon (no-op if already running.)"
+                    <> Doc.line
+                    <> "Use 'daemon start' instead."
+            , command
+                "stop"
+                $ info (Daemon <$> Daemon.Args.stopParser)
+                $ progDescDoc
+                $ Just
+                $ "Stop the daemon."
+                    <> Doc.line
+                    <> "Use 'daemon stop' instead."
+            , command
+                "restart"
+                $ info (Daemon <$> Daemon.Args.restartParser)
+                $ progDescDoc
+                $ Just
+                $ "Restart the daemon."
+                    <> Doc.line
+                    <> "Use 'daemon restart' instead."
+            , command "test-results"
+                $ info testResultsParser
+                $ progDescDoc
+                $ Just
+                $ "Show output from the latest test run"
+                    <> Doc.line
+                    <> "Use `test suites` instead."
+            ]
+
+
+testResultsParser :: Parser Command
+testResultsParser =
+    TestResults
+        <$> ( TestOptions
+                <$> flag
+                    False
+                    True
+                    ( long "failed"
+                        <> help "Only show output from failed test suites"
+                    )
+                <*> WaitMode.Args.parser
+            )
diff --git a/src/Tricorder/API/Command.hs b/src/Tricorder/API/Command.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Command.hs
@@ -0,0 +1,114 @@
+module Tricorder.API.Command
+    ( Command (..)
+    , EvalCommentsOptions (..)
+    , LogMode (..)
+    , SourceOptions (..)
+    , StatusOptions (..)
+    , TestOptions (..)
+    , Verbosity (..)
+    , toArgs
+    )
+where
+
+import Tricorder.API.IfDaemonIsStopped (IfDaemonIsStopped)
+import Tricorder.API.OutputFormat (OutputFormat (..))
+import Tricorder.API.WaitMode (WaitMode)
+import Tricorder.SourceLookup.SourceQuery (SourceQuery, renderSourceQuery)
+
+import Tricorder.API.Daemon.Command qualified as Daemon (Command)
+import Tricorder.API.Daemon.Command qualified as Daemon.Command
+import Tricorder.API.OutputFormat qualified as OutputFormat
+import Tricorder.API.Test qualified as Test
+import Tricorder.API.WaitMode qualified as WaitMode
+
+
+data Verbosity
+    = Concise
+    | Verbose
+    deriving stock (Eq)
+
+
+data LogMode = ShowLog | ShowLogPath
+
+
+data StatusOptions = StatusOptions
+    { wait :: WaitMode
+    , format :: OutputFormat
+    , verbosity :: Verbosity
+    , expand :: Maybe Int
+    , ifDaemonIsStopped :: IfDaemonIsStopped
+    }
+
+
+data TestOptions = TestOptions
+    { failedOnly :: Bool
+    , wait :: WaitMode
+    }
+
+
+data EvalCommentsOptions = EvalCommentsOptions
+    { wait :: WaitMode
+    , format :: OutputFormat
+    , ifDaemonIsStopped :: IfDaemonIsStopped
+    }
+
+
+data SourceOptions = SourceOptions
+    { queries :: [SourceQuery]
+    , maxDepth :: Maybe Word
+    -- ^ Most re-export hops to follow for a symbol query; 'Nothing' is the default.
+    , maxModules :: Maybe Word
+    -- ^ Most modules to read while following re-exports; 'Nothing' is the default.
+    }
+
+
+data Command
+    = Status StatusOptions
+    | -- | DEPRECATED: Use 'Test' instead.
+      TestResults TestOptions
+    | Test Test.Command
+    | UI
+    | Log LogMode
+    | Source SourceOptions
+    | EvalComments EvalCommentsOptions
+    | Daemon Daemon.Command
+
+
+-- | Render a 'Command' to the argument list the @tricorder@ CLI expects
+-- (subcommand name followed by flags) — the inverse of the parser in
+-- "Tricorder.CLI.Arguments". Kept next to 'Command' so a new field or
+-- constructor forces both the parser and this renderer to be updated
+-- together; this is what @tricorder-mcp@ uses to invoke @tricorder@ without
+-- duplicating flag names.
+toArgs :: Command -> [String]
+toArgs = \case
+    Status (StatusOptions {wait, format, verbosity, expand}) ->
+        "status"
+            : WaitMode.toArgs wait
+                <> OutputFormat.toArgs format
+                <> verbosityArgs verbosity
+                <> maybe [] (\n -> ["--expand", show n]) expand
+    TestResults (TestOptions {failedOnly, wait}) ->
+        "test-results" : failedArgs failedOnly <> WaitMode.toArgs wait
+    Test testCommand -> "test" : Test.toArgs testCommand
+    UI -> ["ui"]
+    Log ShowLogPath -> ["log", "--print-path"]
+    Log ShowLog -> ["log"]
+    Source (SourceOptions {queries, maxDepth, maxModules}) ->
+        "source"
+            : maybe [] (\n -> ["--max-depth", show n]) maxDepth
+                <> maybe [] (\n -> ["--max-modules", show n]) maxModules
+                <> map renderSourceQuery queries
+    EvalComments (EvalCommentsOptions {wait, format}) ->
+        "eval-comments" : WaitMode.toArgs wait <> OutputFormat.toArgs format
+    Daemon daemonCommand -> "daemon" : Daemon.Command.toArgs daemonCommand
+
+
+verbosityArgs :: Verbosity -> [String]
+verbosityArgs Verbose = ["--verbose"]
+verbosityArgs Concise = []
+
+
+failedArgs :: Bool -> [String]
+failedArgs True = ["--failed"]
+failedArgs False = []
diff --git a/src/Tricorder/API/Command/Args.hs b/src/Tricorder/API/Command/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Command/Args.hs
@@ -0,0 +1,158 @@
+module Tricorder.API.Command.Args
+    ( parser
+    )
+where
+
+import Options.Applicative
+    ( Parser
+    , ReadM
+    , argument
+    , auto
+    , command
+    , eitherReader
+    , flag
+    , help
+    , hsubparser
+    , info
+    , long
+    , metavar
+    , option
+    , progDesc
+    , readerError
+    , short
+    )
+
+import Tricorder.API.Command
+    ( Command (..)
+    , EvalCommentsOptions (..)
+    , LogMode (..)
+    , SourceOptions (..)
+    , StatusOptions (..)
+    , Verbosity (..)
+    )
+import Tricorder.SourceLookup.ReexportLimits (ReexportLimits (..), defaultReexportLimits)
+import Tricorder.SourceLookup.SourceQuery (SourceQuery, parseSourceQuery)
+
+import Tricorder.API.Args.Deprecated qualified as Args.Deprecated
+import Tricorder.API.Daemon.Args qualified as Daemon.Args
+import Tricorder.API.IfDaemonIsStopped.Args qualified as IfDaemonIsStopped.Args
+import Tricorder.API.OutputFormat.Args qualified as OutputFormat.Args
+import Tricorder.API.Test.Args qualified as Test.Args
+import Tricorder.API.WaitMode.Args qualified as WaitMode.Args
+
+
+parser :: Parser Command
+parser =
+    asum
+        [ hsubparser
+            $ mconcat
+                [ command "ui"
+                    $ info (pure UI)
+                    $ progDesc "Auto-refreshing terminal display."
+                , command "status"
+                    $ info statusParser
+                    $ progDesc "Print build diagnostics (--json for machine-readable output.)"
+                , command "test" $ Test <$> Test.Args.parser
+                , command "source"
+                    $ info sourceParser
+                    $ progDesc "Print the Haskell source of one or more project or installed modules."
+                , command "eval-comments"
+                    $ info evalCommentsParser
+                    $ progDesc "Show eval comments from the latest build."
+                , command "daemon" $ Daemon <$> Daemon.Args.parser
+                , command "log"
+                    $ info logParser
+                    $ progDesc "Show daemon log output."
+                ]
+        , Args.Deprecated.parser
+        ]
+
+
+logParser :: Parser Command
+logParser =
+    Log <$> pathFlag
+  where
+    pathFlag =
+        flag
+            ShowLog
+            ShowLogPath
+            $ long "print-path"
+                <> help "Print the path to the log file instead of its contents"
+
+
+statusParser :: Parser Command
+statusParser =
+    Status
+        <$> ( StatusOptions
+                <$> WaitMode.Args.parser
+                <*> OutputFormat.Args.parser
+                <*> flag
+                    Concise
+                    Verbose
+                    ( long "verbose"
+                        <> short 'v'
+                        <> help "Print full GHC message body under each diagnostic, and full test suite error messages"
+                    )
+                <*> optional
+                    ( option
+                        auto
+                        ( long "expand"
+                            <> metavar "N"
+                            <> help "Print full GHC message body for diagnostic #N"
+                        )
+                    )
+                <*> IfDaemonIsStopped.Args.parser
+            )
+
+
+sourceParser :: Parser Command
+sourceParser =
+    Source
+        <$> ( SourceOptions
+                <$> some
+                    ( argument
+                        queryReader
+                        $ metavar "Module[#function]"
+                            <> help "Module or Module#function"
+                    )
+                <*> optional
+                    ( option
+                        nonNegative
+                        $ long "max-depth"
+                            <> metavar "N"
+                            <> help
+                                ( "Follow at most N re-export hops when a symbol is not defined in the queried module (default: "
+                                    <> show defaultReexportLimits.maxDepth
+                                    <> ")"
+                                )
+                    )
+                <*> optional
+                    ( option
+                        nonNegative
+                        $ long "max-modules"
+                            <> metavar "N"
+                            <> help
+                                ( "Read at most N modules while following re-exports (default: "
+                                    <> show defaultReexportLimits.maxModules
+                                    <> ")"
+                                )
+                    )
+            )
+  where
+    nonNegative = do
+        n <- auto
+        if n < 0 then readerError "must be a non-negative integer" else pure n
+
+
+evalCommentsParser :: Parser Command
+evalCommentsParser =
+    EvalComments
+        <$> ( EvalCommentsOptions
+                <$> WaitMode.Args.parser
+                <*> OutputFormat.Args.parser
+                <*> IfDaemonIsStopped.Args.parser
+            )
+
+
+queryReader :: ReadM SourceQuery
+queryReader = eitherReader $ Right . parseSourceQuery . toText
diff --git a/src/Tricorder/API/Daemon/Args.hs b/src/Tricorder/API/Daemon/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Daemon/Args.hs
@@ -0,0 +1,56 @@
+module Tricorder.API.Daemon.Args
+    ( parser
+    , infoParser
+    , startParser
+    , stopParser
+    , restartParser
+    )
+where
+
+import Options.Applicative (Parser, ParserInfo, command, hsubparser, info, progDesc)
+
+import Tricorder.API.Daemon.Command (Command (..))
+
+import Tricorder.API.Force.Args qualified as Force.Args
+import Tricorder.API.OutputFormat.Args qualified as OutputFormat.Args
+
+
+parser :: ParserInfo Command
+parser = info subParser $ progDesc "Manage the daemon itself."
+
+
+subParser :: Parser Command
+subParser =
+    hsubparser
+        $ mconcat
+            [ command "info"
+                $ info infoParser
+                $ progDesc "Information about the daemon."
+            , command "start"
+                $ info startParser
+                $ progDesc "Start the daemon (no-op if already running.)"
+            , command "stop"
+                $ info stopParser
+                $ progDesc "Stop the daemon."
+            , command "restart"
+                $ info restartParser
+                $ progDesc "Restart the daemon."
+            ]
+
+
+infoParser :: Parser Command
+infoParser = Info <$> OutputFormat.Args.parser
+
+
+startParser :: Parser Command
+startParser = pure Start
+
+
+stopParser :: Parser Command
+stopParser =
+    Stop <$> Force.Args.parser "Ignore waiting queries when stopping the daemon."
+
+
+restartParser :: Parser Command
+restartParser =
+    Restart <$> Force.Args.parser "Ignore watiting queries when restarting the daemon."
diff --git a/src/Tricorder/API/Daemon/Command.hs b/src/Tricorder/API/Daemon/Command.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Daemon/Command.hs
@@ -0,0 +1,22 @@
+module Tricorder.API.Daemon.Command (Command (..), toArgs) where
+
+import Tricorder.API.Force (Force)
+import Tricorder.API.OutputFormat (OutputFormat)
+
+import Tricorder.API.Force qualified as Force
+import Tricorder.API.OutputFormat qualified as OutputFormat
+
+
+data Command
+    = Start
+    | Stop Force
+    | Restart Force
+    | Info OutputFormat
+
+
+toArgs :: Command -> [String]
+toArgs = \case
+    Start -> ["start"]
+    Stop force' -> "stop" : Force.toArgs force'
+    Restart force' -> "restart" : Force.toArgs force'
+    Info format -> "info" : OutputFormat.toArgs format
diff --git a/src/Tricorder/API/FieldMask.hs b/src/Tricorder/API/FieldMask.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/FieldMask.hs
@@ -0,0 +1,42 @@
+module Tricorder.API.FieldMask
+    ( FieldMask (..)
+    , Field (..)
+    , render
+    , toArgs
+    , fieldsFlagName
+    )
+where
+
+import Data.Text qualified as T
+
+
+-- | A selection of fields to include in a response, in the style of Google's
+-- partial-response @fields@ parameter:
+--
+-- @
+-- name,status,cases(description,failure)
+-- @
+newtype FieldMask = FieldMask {getFields :: NonEmpty Field}
+    deriving stock (Eq, Show)
+
+
+data Field = Field
+    { name :: Text
+    , subFields :: Maybe FieldMask
+    -- ^ 'Nothing' selects the field's whole value.
+    }
+    deriving stock (Eq, Show)
+
+
+render :: FieldMask -> Text
+render (FieldMask fields) = T.intercalate "," $ renderField <$> toList fields
+  where
+    renderField field = field.name <> maybe "" (\sub -> "(" <> render sub <> ")") field.subFields
+
+
+toArgs :: Maybe FieldMask -> [String]
+toArgs = maybe [] \mask -> ["--" <> fieldsFlagName, toString $ render mask]
+
+
+fieldsFlagName :: String
+fieldsFlagName = "fields"
diff --git a/src/Tricorder/API/FieldMask/Args.hs b/src/Tricorder/API/FieldMask/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/FieldMask/Args.hs
@@ -0,0 +1,41 @@
+module Tricorder.API.FieldMask.Args (parser, parse) where
+
+import Options.Applicative (Mod, OptionFields, Parser, eitherReader, long, metavar, option)
+import Text.Megaparsec (Parsec, between, eof, errorBundlePretty, takeWhile1P)
+import Text.Megaparsec.Char (space)
+
+import Data.Char qualified as Char
+import Text.Megaparsec qualified as Megaparsec
+import Text.Megaparsec.Char.Lexer qualified as Lexer
+
+import Tricorder.API.FieldMask (Field (..), FieldMask (..), fieldsFlagName)
+
+
+parser :: Mod OptionFields FieldMask -> Parser (Maybe FieldMask)
+parser extraMods =
+    optional
+        $ option (eitherReader $ first toString . parse . toText)
+        $ long fieldsFlagName
+            <> metavar "FIELDS"
+            <> extraMods
+
+
+-- | Parse a field mask such as @name,status,cases(description,failure)@.
+parse :: Text -> Either Text FieldMask
+parse =
+    first (toText . errorBundlePretty)
+        . Megaparsec.parse (space *> fieldMask <* eof) "fields"
+  where
+    fieldMask :: TParser FieldMask
+    fieldMask = FieldMask <$> ((:|) <$> field <*> many (symbol "," *> field))
+
+    field :: TParser Field
+    field = Field <$> lexeme fieldName <*> optional (between (symbol "(") (symbol ")") fieldMask)
+
+    fieldName = takeWhile1P (Just "field name") \c -> Char.isAlphaNum c || c == '_'
+
+    lexeme = Lexer.lexeme space
+    symbol = Lexer.symbol space
+
+
+type TParser = Parsec Void Text
diff --git a/src/Tricorder/API/FieldMask/Projection.hs b/src/Tricorder/API/FieldMask/Projection.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/FieldMask/Projection.hs
@@ -0,0 +1,68 @@
+-- | Parsing field masks, checking them against the shape of a response, and
+-- projecting response values down to the selected fields.
+module Tricorder.API.FieldMask.Projection
+    ( Projection (..)
+    , project
+    , renderYaml
+    )
+where
+
+import Data.Aeson (ToJSON (..), Value (..), object, pairs, (.=))
+
+import Data.Aeson.Key qualified as Key
+import Data.Aeson.KeyMap qualified as KeyMap
+import Data.Yaml.Builder qualified as Yaml
+
+import Tricorder.API.FieldMask.Schema (Schema (..))
+
+
+-- | A JSON value cut down to the fields of a 'Schema', with its fields in
+-- schema order.
+data Projection
+    = PObject [(Text, Projection)]
+    | PArray [Projection]
+    | PScalar Value
+    deriving stock (Eq, Show)
+
+
+instance ToJSON Projection where
+    toJSON = \case
+        PObject fields -> object [Key.fromText name .= value | (name, value) <- fields]
+        PArray values -> toJSON values
+        PScalar value -> value
+    toEncoding = \case
+        PObject fields -> pairs $ foldMap (\(name, value) -> Key.fromText name .= value) fields
+        PArray values -> toEncoding values
+        PScalar value -> toEncoding value
+
+
+-- | Keep only the fields in the 'Schema'. Arrays are projected element-wise,
+-- and fields that are missing or @null@ are left out.
+project :: Schema -> Value -> Projection
+project schema@(Schema fields) = \case
+    Array values -> PArray $ project schema <$> toList values
+    Object obj ->
+        PObject
+            [ (name, maybe PScalar project sub value)
+            | (name, sub) <- fields
+            , Just value <- [KeyMap.lookup (Key.fromText name) obj]
+            , value /= Null
+            ]
+    value -> PScalar value
+
+
+renderYaml :: Projection -> Text
+renderYaml = decodeUtf8 . Yaml.toByteString . toYaml
+  where
+    toYaml = \case
+        PObject fields -> Yaml.mapping $ second toYaml <$> fields
+        PArray values -> Yaml.array $ toYaml <$> values
+        PScalar value -> valueToYaml value
+
+    valueToYaml = \case
+        Object obj -> Yaml.mapping $ bimap Key.toText valueToYaml <$> KeyMap.toList obj
+        Array values -> Yaml.array $ valueToYaml <$> toList values
+        String text -> Yaml.string text
+        Number number -> Yaml.scientific number
+        Bool b -> Yaml.bool b
+        Null -> Yaml.null
diff --git a/src/Tricorder/API/FieldMask/Schema.hs b/src/Tricorder/API/FieldMask/Schema.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/FieldMask/Schema.hs
@@ -0,0 +1,77 @@
+module Tricorder.API.FieldMask.Schema
+    ( Schema (..)
+    , leaf
+    , nested
+    , select
+    , render
+    )
+where
+
+import Options.Applicative.Help (Doc)
+
+import Data.List qualified as List
+import Data.Text qualified as T
+import Options.Applicative.Help qualified as Doc
+
+import Tricorder.API.FieldMask (Field (..), FieldMask (..))
+
+
+-- | The fields available in a response, in the order they are shown by
+-- default. Fields without a nested 'Schema' are shown as-is.
+--
+-- A 'Schema' narrowed down by 'select' describes exactly what to show.
+newtype Schema = Schema [(Text, Maybe Schema)]
+    deriving stock (Eq, Show)
+
+
+leaf :: Text -> (Text, Maybe Schema)
+leaf name = (name, Nothing)
+
+
+nested :: Text -> [(Text, Maybe Schema)] -> (Text, Maybe Schema)
+nested name fields = (name, Just $ Schema fields)
+
+
+-- | Narrow a 'Schema' down to the fields of a 'FieldMask', keeping the order
+-- the fields were requested in. Fails on fields the schema does not have.
+select :: Schema -> FieldMask -> Either Text Schema
+select = go []
+  where
+    go path (Schema available) (FieldMask requested) =
+        Schema <$> traverse (selectField path available) (toList requested)
+
+    selectField path available field =
+        case (field.subFields, List.lookup field.name available) of
+            (_, Nothing) ->
+                Left
+                    $ "unknown field "
+                        <> quote (fieldPath path field.name)
+                        <> ", expected one of: "
+                        <> T.intercalate ", " (fst <$> available)
+            (Nothing, Just schema) -> Right (field.name, schema)
+            (Just mask, Just (Just schema)) -> (field.name,) . Just <$> go (field.name : path) schema mask
+            (Just _, Just Nothing) ->
+                Left $ "field " <> quote (fieldPath path field.name) <> " has no sub-fields"
+
+    fieldPath path name = T.intercalate "." $ reverse $ name : path
+    quote name = "'" <> name <> "'"
+
+
+render :: Schema -> [Doc]
+render (Schema fields) = renderField <$> fields
+
+
+renderField :: (Text, Maybe Schema) -> Doc
+renderField (name, sub) =
+    Doc.pretty name
+        <> maybe
+            Doc.emptyDoc
+            ( \nestedSchema ->
+                Doc.enclose
+                    "("
+                    ")"
+                    $ Doc.sep
+                    $ Doc.punctuate ","
+                    $ render nestedSchema
+            )
+            sub
diff --git a/src/Tricorder/API/Force.hs b/src/Tricorder/API/Force.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Force.hs
@@ -0,0 +1,18 @@
+module Tricorder.API.Force
+    ( Force (..)
+    , toArgs
+    , forceFlagName
+    )
+where
+
+
+data Force = Force | NoForce
+
+
+toArgs :: Force -> [String]
+toArgs Force = ["--" <> forceFlagName]
+toArgs NoForce = []
+
+
+forceFlagName :: String
+forceFlagName = "force"
diff --git a/src/Tricorder/API/Force/Args.hs b/src/Tricorder/API/Force/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Force/Args.hs
@@ -0,0 +1,26 @@
+module Tricorder.API.Force.Args
+    ( parser
+    , forceFlagName
+    , forceShortFlagName
+    )
+where
+
+import Options.Applicative (Parser, flag, help, long, short)
+
+import Tricorder.API.Force (Force)
+
+import Tricorder.API.Force qualified as Force
+
+
+parser :: String -> Parser Force
+parser helpText =
+    flag Force.NoForce Force.Force
+        $ short forceShortFlagName <> long forceFlagName <> help helpText
+
+
+forceFlagName :: String
+forceFlagName = "force"
+
+
+forceShortFlagName :: Char
+forceShortFlagName = 'f'
diff --git a/src/Tricorder/API/IfDaemonIsStopped.hs b/src/Tricorder/API/IfDaemonIsStopped.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/IfDaemonIsStopped.hs
@@ -0,0 +1,22 @@
+module Tricorder.API.IfDaemonIsStopped
+    ( IfDaemonIsStopped (..)
+    , toArgs
+    , startDaemonFlagName
+    )
+where
+
+
+data IfDaemonIsStopped
+    = StartDaemon
+    | DoNothing
+    deriving stock (Eq)
+
+
+toArgs :: IfDaemonIsStopped -> [String]
+toArgs = \case
+    StartDaemon -> ["--" <> startDaemonFlagName]
+    DoNothing -> []
+
+
+startDaemonFlagName :: String
+startDaemonFlagName = "start-daemon"
diff --git a/src/Tricorder/API/IfDaemonIsStopped/Args.hs b/src/Tricorder/API/IfDaemonIsStopped/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/IfDaemonIsStopped/Args.hs
@@ -0,0 +1,15 @@
+module Tricorder.API.IfDaemonIsStopped.Args (parser) where
+
+import Options.Applicative (Parser, flag, help, long, short)
+
+import Tricorder.API.IfDaemonIsStopped (IfDaemonIsStopped (..), startDaemonFlagName)
+
+
+parser :: Parser IfDaemonIsStopped
+parser =
+    flag
+        DoNothing
+        StartDaemon
+        $ long startDaemonFlagName
+            <> short 'd'
+            <> help "Start the daemon if it is not already running."
diff --git a/src/Tricorder/API/OutputFormat.hs b/src/Tricorder/API/OutputFormat.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/OutputFormat.hs
@@ -0,0 +1,21 @@
+module Tricorder.API.OutputFormat
+    ( OutputFormat (..)
+    , toArgs
+    , jsonOutputFlagName
+    )
+where
+
+
+data OutputFormat
+    = TextOutput
+    | JsonOutput
+    deriving stock (Eq, Show)
+
+
+toArgs :: OutputFormat -> [String]
+toArgs JsonOutput = ["--" <> jsonOutputFlagName]
+toArgs TextOutput = []
+
+
+jsonOutputFlagName :: String
+jsonOutputFlagName = "json"
diff --git a/src/Tricorder/API/OutputFormat/Args.hs b/src/Tricorder/API/OutputFormat/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/OutputFormat/Args.hs
@@ -0,0 +1,15 @@
+module Tricorder.API.OutputFormat.Args (parser) where
+
+import Options.Applicative (Parser, flag, help, long, short)
+
+import Tricorder.API.OutputFormat (OutputFormat (..), jsonOutputFlagName)
+
+
+parser :: Parser OutputFormat
+parser =
+    flag
+        TextOutput
+        JsonOutput
+        $ long jsonOutputFlagName
+            <> short 'j'
+            <> help "Output full build state as JSON"
diff --git a/src/Tricorder/API/Test.hs b/src/Tricorder/API/Test.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Test.hs
@@ -0,0 +1,52 @@
+module Tricorder.API.Test
+    ( Command (..)
+    , SuitesOptions (..)
+    , SuiteName
+    , toArgs
+    )
+where
+
+import Prelude hiding (All, filter)
+
+import Tricorder.API.FieldMask (FieldMask)
+import Tricorder.API.IfDaemonIsStopped (IfDaemonIsStopped)
+import Tricorder.API.OutputFormat (OutputFormat)
+import Tricorder.API.TestFilter (TestFilter)
+import Tricorder.API.WaitMode (WaitMode)
+
+import Tricorder.API.FieldMask qualified as FieldMask
+import Tricorder.API.IfDaemonIsStopped qualified as IfDaemonIsStopped
+import Tricorder.API.OutputFormat qualified as OutputFormat
+import Tricorder.API.TestFilter qualified as TestFilter
+import Tricorder.API.WaitMode qualified as WaitMode
+
+
+data Command
+    = Suites SuitesOptions
+
+
+data SuitesOptions = SuitesOptions
+    { suiteNames :: [SuiteName]
+    -- ^ Test suites to show. Empty means all of them.
+    , testFilter :: TestFilter
+    , fields :: Maybe FieldMask
+    -- ^ Fields to show for each test suite. 'Nothing' uses the default fields.
+    , format :: OutputFormat
+    , wait :: WaitMode
+    , ifDaemonIsStopped :: IfDaemonIsStopped
+    }
+
+
+type SuiteName = Text
+
+
+toArgs :: Command -> [String]
+toArgs = \case
+    Suites (SuitesOptions {suiteNames, testFilter, fields, format, wait, ifDaemonIsStopped}) ->
+        "suites"
+            : fmap toString suiteNames
+                <> TestFilter.toArgs testFilter
+                <> FieldMask.toArgs fields
+                <> OutputFormat.toArgs format
+                <> WaitMode.toArgs wait
+                <> IfDaemonIsStopped.toArgs ifDaemonIsStopped
diff --git a/src/Tricorder/API/Test/Args.hs b/src/Tricorder/API/Test/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Test/Args.hs
@@ -0,0 +1,93 @@
+module Tricorder.API.Test.Args (parser) where
+
+import Options.Applicative
+    ( Parser
+    , ParserInfo
+    , command
+    , footer
+    , help
+    , helpDoc
+    , hsubparser
+    , info
+    , metavar
+    , progDesc
+    , strArgument
+    )
+
+import Data.Text qualified as T
+import Options.Applicative.Help.Pretty qualified as Doc
+
+import Tricorder.API.Test (Command)
+
+import Tricorder.API.FieldMask qualified as FieldMask
+import Tricorder.API.FieldMask.Args qualified as FieldMask.Args
+import Tricorder.API.FieldMask.Schema qualified as FieldMask (Schema (..))
+import Tricorder.API.FieldMask.Schema qualified as FieldMask.Schema
+import Tricorder.API.IfDaemonIsStopped.Args qualified as IfDaemonIsStopped.Args
+import Tricorder.API.OutputFormat.Args qualified as OutputFormat.Args
+import Tricorder.API.Test qualified as Test
+import Tricorder.API.Test.SuiteView.Schema qualified as SuiteView.Schema
+import Tricorder.API.TestFilter.Args qualified as TestFilter.Args
+import Tricorder.API.WaitMode.Args qualified as WaitMode.Args
+
+
+parser :: ParserInfo Command
+parser =
+    info commandParser (progDesc "See statuses and information on configured test suites.")
+
+
+commandParser :: Parser Command
+commandParser =
+    hsubparser
+        $ command
+            "suites"
+            ( info
+                suitesParser
+                ( progDesc "Show test suites, their test cases and output."
+                    <> footer suitesFooter
+                )
+            )
+
+
+suitesParser :: Parser Command
+suitesParser =
+    fmap Test.Suites
+        $ Test.SuitesOptions
+            <$> many (strArgument (metavar "TEST-TARGET..." <> help "Test suites to show (default: all)"))
+            <*> TestFilter.Args.parser (help "Show only failed test suites, and only their failed test cases")
+            <*> FieldMask.Args.parser
+                ( helpDoc
+                    $ Just
+                    $ (<> Doc.line)
+                    $ mconcat
+                    $ Doc.punctuate
+                        (Doc.line <> Doc.line)
+                        [ "Comma-separated list of fields to return for each test suite."
+                        , "Available fields:"
+                            <> Doc.line
+                            <> Doc.indent 4 (Doc.vsep $ FieldMask.Schema.render SuiteView.Schema.schema)
+                        , "Select nested fields with parentheses,"
+                            <> Doc.line
+                            <> "e.g. --fields 'name,cases(description,failure)'."
+                            <> Doc.line
+                            <> "A field without parentheses shows all of its nested fields."
+                        , "Default fields:"
+                            <> Doc.line
+                            <> Doc.pretty (FieldMask.render SuiteView.Schema.defaultFields)
+                        ]
+                )
+            <*> OutputFormat.Args.parser
+            <*> WaitMode.Args.parser
+            <*> IfDaemonIsStopped.Args.parser
+
+
+suitesFooter :: String
+suitesFooter =
+    toString
+        $ "Available fields:\n"
+            <> renderSchema SuiteView.Schema.schema
+            <> "\nSelect nested fields with parentheses, e.g. --fields 'name,cases(description,failure)'."
+            <> " A field without parentheses shows all of its nested fields."
+  where
+    renderSchema (FieldMask.Schema fields) = T.intercalate ", " $ renderField <$> fields
+    renderField (name, sub) = name <> maybe "" (\nestedSchema -> "(" <> renderSchema nestedSchema <> ")") sub
diff --git a/src/Tricorder/API/Test/SuiteView.hs b/src/Tricorder/API/Test/SuiteView.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Test/SuiteView.hs
@@ -0,0 +1,51 @@
+module Tricorder.API.Test.SuiteView
+    ( SuiteView (..)
+    , Status (..)
+    , CaseView (..)
+    , Outcome (..)
+    )
+where
+
+import Atelier.Time (AsRawUnit, Millisecond)
+import Atelier.Types.JSON.QuietSnake (QuietSnake (..))
+import Data.Aeson (ToJSON (..))
+
+
+-- | Fields that do not apply to a suite's 'Status' are 'Nothing', and are
+-- left out of the output.
+data SuiteView = SuiteView
+    { name :: Text
+    , status :: Status
+    , error :: Maybe Text
+    , passedCases :: Maybe Int
+    , totalCases :: Maybe Int
+    , durationMs :: Maybe (AsRawUnit Millisecond)
+    , output :: Maybe Text
+    , cases :: Maybe [CaseView]
+    }
+    deriving stock (Eq, Generic, Show)
+    deriving (ToJSON) via QuietSnake SuiteView
+
+
+data Status = Running | Errored | Passed | Failed
+    deriving stock (Eq, Generic, Show)
+    deriving (ToJSON) via QuietSnake Status
+
+
+data CaseView = CaseView
+    { description :: Text
+    , outcome :: Outcome
+    , failure :: Maybe Text
+    }
+    deriving stock (Eq, Generic, Show)
+    deriving (ToJSON) via QuietSnake CaseView
+
+
+data Outcome = CasePassed | CaseFailed
+    deriving stock (Eq, Generic, Show)
+
+
+instance ToJSON Outcome where
+    toJSON = \case
+        CasePassed -> "passed"
+        CaseFailed -> "failed"
diff --git a/src/Tricorder/API/Test/SuiteView/Schema.hs b/src/Tricorder/API/Test/SuiteView/Schema.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/Test/SuiteView/Schema.hs
@@ -0,0 +1,36 @@
+module Tricorder.API.Test.SuiteView.Schema (defaultFields, schema) where
+
+import Tricorder.API.FieldMask (FieldMask (..))
+
+import Tricorder.API.FieldMask qualified as FieldMask
+import Tricorder.API.FieldMask.Schema qualified as FieldMask (Schema (..))
+import Tricorder.API.FieldMask.Schema qualified as FieldMask.Schema
+
+
+-- | Every field of a 'SuiteView', as named in its JSON encoding.
+schema :: FieldMask.Schema
+schema =
+    FieldMask.Schema
+        [ FieldMask.Schema.leaf "name"
+        , FieldMask.Schema.leaf "status"
+        , FieldMask.Schema.leaf "error"
+        , FieldMask.Schema.leaf "passed_cases"
+        , FieldMask.Schema.leaf "total_cases"
+        , FieldMask.Schema.leaf "duration_ms"
+        , FieldMask.Schema.leaf "output"
+        , FieldMask.Schema.nested
+            "cases"
+            [ FieldMask.Schema.leaf "description"
+            , FieldMask.Schema.leaf "outcome"
+            , FieldMask.Schema.leaf "failure"
+            ]
+        ]
+
+
+-- | A summary of each suite, leaving out the (potentially large) test output
+-- and test cases.
+defaultFields :: FieldMask
+defaultFields =
+    FieldMask
+        $ (\name -> FieldMask.Field name Nothing)
+            <$> "name" :| ["status", "error", "passed_cases", "total_cases", "duration_ms"]
diff --git a/src/Tricorder/API/TestFilter.hs b/src/Tricorder/API/TestFilter.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/TestFilter.hs
@@ -0,0 +1,26 @@
+module Tricorder.API.TestFilter
+    ( TestFilter (..)
+    , toArgs
+    , failedOnlyFlagName
+    , failedOnlyFlagShortName
+    )
+where
+
+import Prelude hiding (All (..))
+
+
+data TestFilter = All | FailedOnly
+    deriving stock (Bounded, Enum, Eq)
+
+
+toArgs :: TestFilter -> [String]
+toArgs All = []
+toArgs FailedOnly = ["--" <> failedOnlyFlagName]
+
+
+failedOnlyFlagName :: String
+failedOnlyFlagName = "failed-only"
+
+
+failedOnlyFlagShortName :: Char
+failedOnlyFlagShortName = 'f'
diff --git a/src/Tricorder/API/TestFilter/Args.hs b/src/Tricorder/API/TestFilter/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/TestFilter/Args.hs
@@ -0,0 +1,19 @@
+module Tricorder.API.TestFilter.Args (parser) where
+
+import Options.Applicative (FlagFields, Mod, Parser, flag, long, short)
+
+import Tricorder.API.TestFilter
+    ( TestFilter (..)
+    , failedOnlyFlagName
+    , failedOnlyFlagShortName
+    )
+
+import Tricorder.API.TestFilter qualified as TestFilter
+
+
+parser :: Mod FlagFields TestFilter -> Parser TestFilter
+parser extraMods =
+    flag TestFilter.All TestFilter.FailedOnly
+        $ long failedOnlyFlagName
+            <> short failedOnlyFlagShortName
+            <> extraMods
diff --git a/src/Tricorder/API/WaitMode.hs b/src/Tricorder/API/WaitMode.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/WaitMode.hs
@@ -0,0 +1,21 @@
+module Tricorder.API.WaitMode
+    ( WaitMode (..)
+    , toArgs
+    , waitForBuildFlagName
+    )
+where
+
+
+data WaitMode
+    = ShowCurrent
+    | WaitForBuild
+    deriving stock (Eq)
+
+
+toArgs :: WaitMode -> [String]
+toArgs WaitForBuild = ["--" <> waitForBuildFlagName]
+toArgs ShowCurrent = []
+
+
+waitForBuildFlagName :: String
+waitForBuildFlagName = "wait"
diff --git a/src/Tricorder/API/WaitMode/Args.hs b/src/Tricorder/API/WaitMode/Args.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/API/WaitMode/Args.hs
@@ -0,0 +1,13 @@
+module Tricorder.API.WaitMode.Args (parser) where
+
+import Options.Applicative (Parser, flag, help, long, short)
+
+import Tricorder.API.WaitMode (WaitMode (..), waitForBuildFlagName)
+
+
+parser :: Parser WaitMode
+parser =
+    flag ShowCurrent WaitForBuild
+        $ long waitForBuildFlagName
+            <> short 'w'
+            <> help "Block until the current build cycle completes"
diff --git a/src/Tricorder/CLI/Command.hs b/src/Tricorder/CLI/Command.hs
deleted file mode 100644
--- a/src/Tricorder/CLI/Command.hs
+++ /dev/null
@@ -1,125 +0,0 @@
-module Tricorder.CLI.Command
-    ( Command (..)
-    , EvalCommentsOptions (..)
-    , Force (..)
-    , LogMode (..)
-    , SourceOptions (..)
-    , StatusOptions (..)
-    , TestOptions (..)
-    , Verbosity (..)
-    , commandToArgs
-    )
-where
-
-import Tricorder.CLI.Command.Daemon (DaemonCommand)
-import Tricorder.CLI.Command.OutputFormat (OutputFormat (..))
-import Tricorder.CLI.Command.WaitMode (WaitMode)
-import Tricorder.SourceLookup.SourceQuery (SourceQuery, renderSourceQuery)
-
-import Tricorder.CLI.Command.Daemon qualified as Daemon
-import Tricorder.CLI.Command.OutputFormat qualified as OutputFormat
-import Tricorder.CLI.Command.Test qualified as Test
-import Tricorder.CLI.Command.WaitMode qualified as WaitMode
-
-
-data Force = Force | NoForce
-
-
-data Verbosity
-    = Concise
-    | Verbose
-    deriving stock (Eq)
-
-
-data LogMode = ShowLog | ShowLogPath
-
-
-data StatusOptions = StatusOptions
-    { wait :: WaitMode
-    , format :: OutputFormat
-    , verbosity :: Verbosity
-    , expand :: Maybe Int
-    }
-
-
-data TestOptions = TestOptions
-    { failedOnly :: Bool
-    , wait :: WaitMode
-    }
-
-
-data EvalCommentsOptions = EvalCommentsOptions
-    { wait :: WaitMode
-    , format :: OutputFormat
-    }
-
-
-data SourceOptions = SourceOptions
-    { queries :: [SourceQuery]
-    , maxDepth :: Maybe Word
-    -- ^ Most re-export hops to follow for a symbol query; 'Nothing' is the default.
-    , maxModules :: Maybe Word
-    -- ^ Most modules to read while following re-exports; 'Nothing' is the default.
-    }
-
-
-data Command
-    = Start
-    | Stop Force
-    | Status StatusOptions
-    | -- | DEPRECATED: Use 'Test' instead.
-      TestResults TestOptions
-    | Test Test.Command
-    | UI
-    | Log LogMode
-    | Source SourceOptions
-    | Restart Force
-    | EvalComments EvalCommentsOptions
-    | Daemon DaemonCommand
-
-
--- | Render a 'Command' to the argument list the @tricorder@ CLI expects
--- (subcommand name followed by flags) — the inverse of the parser in
--- "Tricorder.CLI.Arguments". Kept next to 'Command' so a new field or
--- constructor forces both the parser and this renderer to be updated
--- together; this is what @tricorder-mcp@ uses to invoke @tricorder@ without
--- duplicating flag names.
-commandToArgs :: Command -> [String]
-commandToArgs Start = ["start"]
-commandToArgs (Stop doForce) = "stop" : forceArgs doForce
-commandToArgs (Status (StatusOptions {wait, format, verbosity, expand})) =
-    "status"
-        : WaitMode.toArgs wait
-            <> OutputFormat.toArgs format
-            <> verbosityArgs verbosity
-            <> maybe [] (\n -> ["--expand", show n]) expand
-commandToArgs (TestResults (TestOptions {failedOnly, wait})) =
-    "test-results" : failedArgs failedOnly <> WaitMode.toArgs wait
-commandToArgs (Test testCommand) = "test" : Test.toArgs testCommand
-commandToArgs UI = ["ui"]
-commandToArgs (Log ShowLogPath) = ["log", "--print-path"]
-commandToArgs (Log ShowLog) = ["log"]
-commandToArgs (Source (SourceOptions {queries, maxDepth, maxModules})) =
-    "source"
-        : maybe [] (\n -> ["--max-depth", show n]) maxDepth
-            <> maybe [] (\n -> ["--max-modules", show n]) maxModules
-            <> map renderSourceQuery queries
-commandToArgs (Restart doForce) = "restart" : forceArgs doForce
-commandToArgs (EvalComments (EvalCommentsOptions {wait, format})) =
-    "eval-comments" : WaitMode.toArgs wait <> OutputFormat.toArgs format
-commandToArgs (Daemon daemonCommand) = "daemon" : Daemon.toArgs daemonCommand
-
-
-forceArgs :: Force -> [String]
-forceArgs Force = ["--force"]
-forceArgs NoForce = []
-
-
-verbosityArgs :: Verbosity -> [String]
-verbosityArgs Verbose = ["--verbose"]
-verbosityArgs Concise = []
-
-
-failedArgs :: Bool -> [String]
-failedArgs True = ["--failed"]
-failedArgs False = []
diff --git a/src/Tricorder/CLI/Command/Daemon.hs b/src/Tricorder/CLI/Command/Daemon.hs
deleted file mode 100644
--- a/src/Tricorder/CLI/Command/Daemon.hs
+++ /dev/null
@@ -1,14 +0,0 @@
-module Tricorder.CLI.Command.Daemon (DaemonCommand (..), toArgs) where
-
-import Tricorder.CLI.Command.OutputFormat (OutputFormat)
-
-import Tricorder.CLI.Command.OutputFormat qualified as OutputFormat
-
-
-data DaemonCommand
-    = Info OutputFormat
-
-
-toArgs :: DaemonCommand -> [String]
-toArgs = \case
-    Info format -> "info" : OutputFormat.toArgs format
diff --git a/src/Tricorder/CLI/Command/IfDaemonIsStopped.hs b/src/Tricorder/CLI/Command/IfDaemonIsStopped.hs
deleted file mode 100644
--- a/src/Tricorder/CLI/Command/IfDaemonIsStopped.hs
+++ /dev/null
@@ -1,21 +0,0 @@
-module Tricorder.CLI.Command.IfDaemonIsStopped
-    ( IfDaemonIsStopped (..)
-    , toArgs
-    , startDaemonFlagName
-    )
-where
-
-
-data IfDaemonIsStopped
-    = StartDaemon
-    | Fail
-
-
-toArgs :: IfDaemonIsStopped -> [String]
-toArgs = \case
-    StartDaemon -> ["--" <> startDaemonFlagName]
-    Fail -> []
-
-
-startDaemonFlagName :: String
-startDaemonFlagName = "start-daemon"
diff --git a/src/Tricorder/CLI/Command/OutputFormat.hs b/src/Tricorder/CLI/Command/OutputFormat.hs
deleted file mode 100644
--- a/src/Tricorder/CLI/Command/OutputFormat.hs
+++ /dev/null
@@ -1,21 +0,0 @@
-module Tricorder.CLI.Command.OutputFormat
-    ( OutputFormat (..)
-    , toArgs
-    , jsonOutputFlagName
-    )
-where
-
-
-data OutputFormat
-    = TextOutput
-    | JsonOutput
-    deriving stock (Eq, Show)
-
-
-toArgs :: OutputFormat -> [String]
-toArgs JsonOutput = ["--" <> jsonOutputFlagName]
-toArgs TextOutput = []
-
-
-jsonOutputFlagName :: String
-jsonOutputFlagName = "json"
diff --git a/src/Tricorder/CLI/Command/Test.hs b/src/Tricorder/CLI/Command/Test.hs
deleted file mode 100644
--- a/src/Tricorder/CLI/Command/Test.hs
+++ /dev/null
@@ -1,52 +0,0 @@
-module Tricorder.CLI.Command.Test
-    ( Command (..)
-    , SuitesOptions (..)
-    , SuiteName
-    , toArgs
-    )
-where
-
-import Prelude hiding (All, filter)
-
-import Tricorder.CLI.Command.IfDaemonIsStopped (IfDaemonIsStopped)
-import Tricorder.CLI.Command.OutputFormat (OutputFormat)
-import Tricorder.CLI.Command.TestFilter (TestFilter)
-import Tricorder.CLI.Command.WaitMode (WaitMode)
-import Tricorder.FieldMask (FieldMask)
-
-import Tricorder.CLI.Command.IfDaemonIsStopped qualified as IfDaemonIsStopped
-import Tricorder.CLI.Command.OutputFormat qualified as OutputFormat
-import Tricorder.CLI.Command.TestFilter qualified as TestFilter
-import Tricorder.CLI.Command.WaitMode qualified as WaitMode
-import Tricorder.FieldMask qualified as FieldMask
-
-
-data Command
-    = Suites SuitesOptions
-
-
-data SuitesOptions = SuitesOptions
-    { suiteNames :: [SuiteName]
-    -- ^ Test suites to show. Empty means all of them.
-    , testFilter :: TestFilter
-    , fields :: Maybe FieldMask
-    -- ^ Fields to show for each test suite. 'Nothing' uses the default fields.
-    , format :: OutputFormat
-    , wait :: WaitMode
-    , ifDaemonIsStopped :: IfDaemonIsStopped
-    }
-
-
-type SuiteName = Text
-
-
-toArgs :: Command -> [String]
-toArgs = \case
-    Suites (SuitesOptions {suiteNames, testFilter, fields, format, wait, ifDaemonIsStopped}) ->
-        "suites"
-            : fmap toString suiteNames
-                <> TestFilter.toArgs testFilter
-                <> FieldMask.toArgs fields
-                <> OutputFormat.toArgs format
-                <> WaitMode.toArgs wait
-                <> IfDaemonIsStopped.toArgs ifDaemonIsStopped
diff --git a/src/Tricorder/CLI/Command/TestFilter.hs b/src/Tricorder/CLI/Command/TestFilter.hs
deleted file mode 100644
--- a/src/Tricorder/CLI/Command/TestFilter.hs
+++ /dev/null
@@ -1,25 +0,0 @@
-module Tricorder.CLI.Command.TestFilter
-    ( TestFilter (..)
-    , toArgs
-    , failedOnlyFlagName
-    , failedOnlyFlagShortName
-    )
-where
-
-import Prelude hiding (All (..))
-
-
-data TestFilter = All | FailedOnly
-
-
-toArgs :: TestFilter -> [String]
-toArgs All = []
-toArgs FailedOnly = ["--" <> failedOnlyFlagName]
-
-
-failedOnlyFlagName :: String
-failedOnlyFlagName = "failed-only"
-
-
-failedOnlyFlagShortName :: Char
-failedOnlyFlagShortName = 'f'
diff --git a/src/Tricorder/CLI/Command/WaitMode.hs b/src/Tricorder/CLI/Command/WaitMode.hs
deleted file mode 100644
--- a/src/Tricorder/CLI/Command/WaitMode.hs
+++ /dev/null
@@ -1,21 +0,0 @@
-module Tricorder.CLI.Command.WaitMode
-    ( WaitMode (..)
-    , toArgs
-    , waitForBuildFlagName
-    )
-where
-
-
-data WaitMode
-    = ShowCurrent
-    | WaitForBuild
-    deriving stock (Eq)
-
-
-toArgs :: WaitMode -> [String]
-toArgs WaitForBuild = ["--" <> waitForBuildFlagName]
-toArgs ShowCurrent = []
-
-
-waitForBuildFlagName :: String
-waitForBuildFlagName = "wait"
diff --git a/src/Tricorder/FieldMask.hs b/src/Tricorder/FieldMask.hs
deleted file mode 100644
--- a/src/Tricorder/FieldMask.hs
+++ /dev/null
@@ -1,42 +0,0 @@
-module Tricorder.FieldMask
-    ( FieldMask (..)
-    , Field (..)
-    , render
-    , toArgs
-    , fieldsFlagName
-    )
-where
-
-import Data.Text qualified as T
-
-
--- | A selection of fields to include in a response, in the style of Google's
--- partial-response @fields@ parameter:
---
--- @
--- name,status,cases(description,failure)
--- @
-newtype FieldMask = FieldMask {getFields :: NonEmpty Field}
-    deriving stock (Eq, Show)
-
-
-data Field = Field
-    { name :: Text
-    , subFields :: Maybe FieldMask
-    -- ^ 'Nothing' selects the field's whole value.
-    }
-    deriving stock (Eq, Show)
-
-
-render :: FieldMask -> Text
-render (FieldMask fields) = T.intercalate "," $ renderField <$> toList fields
-  where
-    renderField field = field.name <> maybe "" (\sub -> "(" <> render sub <> ")") field.subFields
-
-
-toArgs :: Maybe FieldMask -> [String]
-toArgs = maybe [] \mask -> ["--" <> fieldsFlagName, toString $ render mask]
-
-
-fieldsFlagName :: String
-fieldsFlagName = "fields"
diff --git a/src/Tricorder/FieldMask/Args.hs b/src/Tricorder/FieldMask/Args.hs
deleted file mode 100644
--- a/src/Tricorder/FieldMask/Args.hs
+++ /dev/null
@@ -1,41 +0,0 @@
-module Tricorder.FieldMask.Args (parser, parse) where
-
-import Options.Applicative (Mod, OptionFields, Parser, eitherReader, long, metavar, option)
-import Text.Megaparsec (Parsec, between, eof, errorBundlePretty, takeWhile1P)
-import Text.Megaparsec.Char (space)
-
-import Data.Char qualified as Char
-import Text.Megaparsec qualified as Megaparsec
-import Text.Megaparsec.Char.Lexer qualified as Lexer
-
-import Tricorder.FieldMask (Field (..), FieldMask (..), fieldsFlagName)
-
-
-parser :: Mod OptionFields FieldMask -> Parser (Maybe FieldMask)
-parser extraMods =
-    optional
-        $ option (eitherReader $ first toString . parse . toText)
-        $ long fieldsFlagName
-            <> metavar "FIELDS"
-            <> extraMods
-
-
--- | Parse a field mask such as @name,status,cases(description,failure)@.
-parse :: Text -> Either Text FieldMask
-parse =
-    first (toText . errorBundlePretty)
-        . Megaparsec.parse (space *> fieldMask <* eof) "fields"
-  where
-    fieldMask :: TParser FieldMask
-    fieldMask = FieldMask <$> ((:|) <$> field <*> many (symbol "," *> field))
-
-    field :: TParser Field
-    field = Field <$> lexeme fieldName <*> optional (between (symbol "(") (symbol ")") fieldMask)
-
-    fieldName = takeWhile1P (Just "field name") \c -> Char.isAlphaNum c || c == '_'
-
-    lexeme = Lexer.lexeme space
-    symbol = Lexer.symbol space
-
-
-type TParser = Parsec Void Text
diff --git a/src/Tricorder/FieldMask/Projection.hs b/src/Tricorder/FieldMask/Projection.hs
deleted file mode 100644
--- a/src/Tricorder/FieldMask/Projection.hs
+++ /dev/null
@@ -1,68 +0,0 @@
--- | Parsing field masks, checking them against the shape of a response, and
--- projecting response values down to the selected fields.
-module Tricorder.FieldMask.Projection
-    ( Projection (..)
-    , project
-    , renderYaml
-    )
-where
-
-import Data.Aeson (ToJSON (..), Value (..), object, pairs, (.=))
-
-import Data.Aeson.Key qualified as Key
-import Data.Aeson.KeyMap qualified as KeyMap
-import Data.Yaml.Builder qualified as Yaml
-
-import Tricorder.FieldMask.Schema (Schema (..))
-
-
--- | A JSON value cut down to the fields of a 'Schema', with its fields in
--- schema order.
-data Projection
-    = PObject [(Text, Projection)]
-    | PArray [Projection]
-    | PScalar Value
-    deriving stock (Eq, Show)
-
-
-instance ToJSON Projection where
-    toJSON = \case
-        PObject fields -> object [Key.fromText name .= value | (name, value) <- fields]
-        PArray values -> toJSON values
-        PScalar value -> value
-    toEncoding = \case
-        PObject fields -> pairs $ foldMap (\(name, value) -> Key.fromText name .= value) fields
-        PArray values -> toEncoding values
-        PScalar value -> toEncoding value
-
-
--- | Keep only the fields in the 'Schema'. Arrays are projected element-wise,
--- and fields that are missing or @null@ are left out.
-project :: Schema -> Value -> Projection
-project schema@(Schema fields) = \case
-    Array values -> PArray $ project schema <$> toList values
-    Object obj ->
-        PObject
-            [ (name, maybe PScalar project sub value)
-            | (name, sub) <- fields
-            , Just value <- [KeyMap.lookup (Key.fromText name) obj]
-            , value /= Null
-            ]
-    value -> PScalar value
-
-
-renderYaml :: Projection -> Text
-renderYaml = decodeUtf8 . Yaml.toByteString . toYaml
-  where
-    toYaml = \case
-        PObject fields -> Yaml.mapping $ second toYaml <$> fields
-        PArray values -> Yaml.array $ toYaml <$> values
-        PScalar value -> valueToYaml value
-
-    valueToYaml = \case
-        Object obj -> Yaml.mapping $ bimap Key.toText valueToYaml <$> KeyMap.toList obj
-        Array values -> Yaml.array $ valueToYaml <$> toList values
-        String text -> Yaml.string text
-        Number number -> Yaml.scientific number
-        Bool b -> Yaml.bool b
-        Null -> Yaml.null
diff --git a/src/Tricorder/FieldMask/Schema.hs b/src/Tricorder/FieldMask/Schema.hs
deleted file mode 100644
--- a/src/Tricorder/FieldMask/Schema.hs
+++ /dev/null
@@ -1,53 +0,0 @@
-module Tricorder.FieldMask.Schema
-    ( Schema (..)
-    , leaf
-    , nested
-    , select
-    )
-where
-
-import Data.List qualified as List
-import Data.Text qualified as T
-
-import Tricorder.FieldMask (Field (..), FieldMask (..))
-
-
--- | The fields available in a response, in the order they are shown by
--- default. Fields without a nested 'Schema' are shown as-is.
---
--- A 'Schema' narrowed down by 'select' describes exactly what to show.
-newtype Schema = Schema [(Text, Maybe Schema)]
-    deriving stock (Eq, Show)
-
-
-leaf :: Text -> (Text, Maybe Schema)
-leaf name = (name, Nothing)
-
-
-nested :: Text -> [(Text, Maybe Schema)] -> (Text, Maybe Schema)
-nested name fields = (name, Just $ Schema fields)
-
-
--- | Narrow a 'Schema' down to the fields of a 'FieldMask', keeping the order
--- the fields were requested in. Fails on fields the schema does not have.
-select :: Schema -> FieldMask -> Either Text Schema
-select = go []
-  where
-    go path (Schema available) (FieldMask requested) =
-        Schema <$> traverse (selectField path available) (toList requested)
-
-    selectField path available field =
-        case (field.subFields, List.lookup field.name available) of
-            (_, Nothing) ->
-                Left
-                    $ "unknown field "
-                        <> quote (fieldPath path field.name)
-                        <> ", expected one of: "
-                        <> T.intercalate ", " (fst <$> available)
-            (Nothing, Just schema) -> Right (field.name, schema)
-            (Just mask, Just (Just schema)) -> (field.name,) . Just <$> go (field.name : path) schema mask
-            (Just _, Just Nothing) ->
-                Left $ "field " <> quote (fieldPath path field.name) <> " has no sub-fields"
-
-    fieldPath path name = T.intercalate "." $ reverse $ name : path
-    quote name = "'" <> name <> "'"
diff --git a/src/Tricorder/SourceLookup/ModuleSourceResult.hs b/src/Tricorder/SourceLookup/ModuleSourceResult.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/SourceLookup/ModuleSourceResult.hs
@@ -0,0 +1,25 @@
+module Tricorder.SourceLookup.ModuleSourceResult (ModuleSourceResult (..)) where
+
+import Data.Aeson (FromJSON, ToJSON)
+import GHC.Generics (Generically (..))
+
+import Tricorder.SourceLookup.PackageId (PackageId)
+import Tricorder.SourceLookup.SourceQuery (ModuleName, SourceQuery)
+
+
+-- | The result of a source lookup for a single module.
+data ModuleSourceResult
+    = -- | Source was found; contains the module (or single-symbol) source text.
+      SourceFound SourceQuery Text
+    | -- | The module is neither in the project nor in any installed package.
+      SourceNotFound SourceQuery
+    | -- | The package was resolved but no source tarball could be located or
+      -- fetched (no index, offline, yanked, or the archive could not be read).
+      SourceUnavailable SourceQuery PackageId
+    | -- | The symbol is not defined in the queried module but re-exported by
+      -- it; contains the module that defines it and the symbol's source there.
+      SourceReexported SourceQuery ModuleName Text
+    | -- | The module source was found but the requested symbol was not in it.
+      FunctionNotFound SourceQuery
+    deriving stock (Eq, Generic, Show)
+    deriving (FromJSON, ToJSON) via Generically ModuleSourceResult
diff --git a/src/Tricorder/SourceLookup/PackageId.hs b/src/Tricorder/SourceLookup/PackageId.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/SourceLookup/PackageId.hs
@@ -0,0 +1,25 @@
+module Tricorder.SourceLookup.PackageId
+    ( PackageId (..)
+    , splitPackageId
+    )
+where
+
+import Data.Aeson (FromJSON, ToJSON)
+
+import Data.Text qualified as T
+
+
+-- | A @ghc-pkg@ package identifier, e.g. @"containers-0.6.8"@.
+newtype PackageId = PackageId {unPackageId :: Text}
+    deriving stock (Eq, Ord, Show)
+    deriving (FromJSON, Hashable, IsString, ToJSON) via Text
+
+
+-- | Split a 'PackageId' into its package name and version. The version is the
+-- final hyphen-delimited component (versions are dot-, not hyphen-separated),
+-- so @"list-t-1.0.5.7"@ → @("list-t", "1.0.5.7")@.
+splitPackageId :: PackageId -> (Text, Text)
+splitPackageId (PackageId pid) =
+    case reverse (T.splitOn "-" pid) of
+        (ver : nameParts@(_ : _)) -> (T.intercalate "-" (reverse nameParts), ver)
+        _ -> (pid, "")
diff --git a/src/Tricorder/SourceLookup/ReexportLimits.hs b/src/Tricorder/SourceLookup/ReexportLimits.hs
new file mode 100644
--- /dev/null
+++ b/src/Tricorder/SourceLookup/ReexportLimits.hs
@@ -0,0 +1,22 @@
+module Tricorder.SourceLookup.ReexportLimits
+    ( ReexportLimits (..)
+    , defaultReexportLimits
+    )
+where
+
+
+-- | Bounds on the re-export search for a symbol the queried module does not
+-- define itself (see 'followReexports').
+data ReexportLimits = ReexportLimits
+    { maxDepth :: Word
+    -- ^ Most re-export hops to follow; @0@ disables following re-exports.
+    , maxModules :: Word
+    -- ^ Most modules to read during the search.
+    }
+    deriving stock (Eq, Show)
+
+
+-- | Enough for the deepest chains seen in practice (@Prelude#Maybe@ takes 3
+-- hops through @ghc-internal@) while keeping a miss cheap.
+defaultReexportLimits :: ReexportLimits
+defaultReexportLimits = ReexportLimits {maxDepth = 5, maxModules = 24}
diff --git a/test/Unit/Tricorder/API/FieldMask/ArgsSpec.hs b/test/Unit/Tricorder/API/FieldMask/ArgsSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/API/FieldMask/ArgsSpec.hs
@@ -0,0 +1,55 @@
+module Unit.Tricorder.API.FieldMask.ArgsSpec (test_Args) where
+
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertFailure, testCase, (@?=))
+
+import Tricorder.API.FieldMask (Field (..), FieldMask (..))
+import Tricorder.API.FieldMask.Args (parse)
+
+import Tricorder.API.FieldMask qualified as FieldMask
+
+
+test_Args :: TestTree
+test_Args =
+    testGroup
+        "Tricorder.API.FieldMask.Args"
+        [ testGroup "parse" testParse
+        ]
+
+
+testParse :: [TestTree]
+testParse =
+    [ testCase "parses a flat list of fields" do
+        parse "name,status" @?= Right (mask [field "name", field "status"])
+    , testCase "parses nested fields" do
+        parse "name,cases(description,failure)"
+            @?= Right (mask [field "name", Field "cases" $ Just $ mask [field "description", field "failure"]])
+    , testCase "allows whitespace between tokens" do
+        parse " name , cases ( description ) "
+            @?= Right (mask [field "name", Field "cases" $ Just $ mask [field "description"]])
+    , testCase "rejects an empty mask" do
+        assertLeft $ parse ""
+    , testCase "rejects a trailing comma" do
+        assertLeft $ parse "name,"
+    , testCase "rejects empty parentheses" do
+        assertLeft $ parse "cases()"
+    , testCase "rejects unbalanced parentheses" do
+        assertLeft $ parse "cases(description"
+    , testCase "round-trips through render" do
+        let input = "name,cases(description,failure),output"
+        (FieldMask.render <$> parse input) @?= Right input
+    ]
+
+
+mask :: [Field] -> FieldMask
+mask = maybe (error "mask: no fields") FieldMask . nonEmpty
+
+
+field :: Text -> Field
+field name = Field name Nothing
+
+
+assertLeft :: (Show a) => Either Text a -> IO ()
+assertLeft = \case
+    Left _ -> pass
+    Right a -> assertFailure $ "expected Left, got Right " <> show a
diff --git a/test/Unit/Tricorder/API/FieldMask/ProjectionSpec.hs b/test/Unit/Tricorder/API/FieldMask/ProjectionSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/API/FieldMask/ProjectionSpec.hs
@@ -0,0 +1,50 @@
+module Unit.Tricorder.API.FieldMask.ProjectionSpec (test_Projection) where
+
+import Data.Aeson (Value (..), object, (.=))
+import Data.Aeson.Text (encodeToLazyText)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
+
+import Tricorder.API.FieldMask.Projection (Projection (..), project, renderYaml)
+import Tricorder.API.FieldMask.Schema (Schema (..), leaf, nested)
+
+
+test_Projection :: TestTree
+test_Projection =
+    testGroup
+        "Tricorder.API.FieldMask.Projection"
+        [ testGroup "project" testProject
+        ]
+
+
+testProject :: [TestTree]
+testProject =
+    [ testCase "keeps only the selected fields, in selection order" do
+        project (Schema [leaf "status", leaf "name"]) suite
+            @?= PObject [("status", PScalar "failed"), ("name", PScalar "suite")]
+    , testCase "projects every element of an array" do
+        project (Schema [nested "cases" [leaf "outcome"]]) suite
+            @?= PObject
+                [ ("cases", PArray [PObject [("outcome", PScalar "passed")], PObject [("outcome", PScalar "failed")]])
+                ]
+    , testCase "leaves out missing and null fields" do
+        project (Schema [leaf "name", leaf "missing", leaf "error"]) suite
+            @?= PObject [("name", PScalar "suite")]
+    , testCase "encodes JSON objects in selection order" do
+        encodeToLazyText (project (Schema [leaf "status", leaf "name"]) suite)
+            @?= "{\"status\":\"failed\",\"name\":\"suite\"}"
+    , testCase "renders YAML in selection order" do
+        renderYaml (project (Schema [leaf "status", leaf "name"]) suite)
+            @?= "status: failed\nname: suite\n"
+    ]
+  where
+    suite =
+        object
+            [ "name" .= ("suite" :: Text)
+            , "status" .= ("failed" :: Text)
+            , "error" .= Null
+            , "cases"
+                .= [ object ["description" .= ("a" :: Text), "outcome" .= ("passed" :: Text)]
+                   , object ["description" .= ("b" :: Text), "outcome" .= ("failed" :: Text)]
+                   ]
+            ]
diff --git a/test/Unit/Tricorder/API/FieldMask/SchemaSpec.hs b/test/Unit/Tricorder/API/FieldMask/SchemaSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/API/FieldMask/SchemaSpec.hs
@@ -0,0 +1,50 @@
+module Unit.Tricorder.API.FieldMask.SchemaSpec (test_Schema) where
+
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (assertBool, assertFailure, testCase, (@?=))
+
+import Data.Text qualified as T
+
+import Tricorder.API.FieldMask.Args (parse)
+import Tricorder.API.FieldMask.Schema (Schema (..), leaf, nested, select)
+
+
+test_Schema :: TestTree
+test_Schema =
+    testGroup
+        "Tricorder.API.FieldMask.Schema"
+        [ testGroup "select" testSelect
+        ]
+
+
+testSelect :: [TestTree]
+testSelect =
+    [ testCase "keeps the requested fields in the requested order" do
+        select' "status,name" @?= Right (Schema [leaf "status", leaf "name"])
+    , testCase "a field without sub-fields keeps its whole nested schema" do
+        select' "cases" @?= Right (Schema [casesSchema])
+    , testCase "narrows nested fields" do
+        select' "cases(outcome)" @?= Right (Schema [nested "cases" [leaf "outcome"]])
+    , testCase "rejects unknown fields" do
+        assertLeftContaining "unknown field 'nope'" $ select' "name,nope"
+    , testCase "names the path of unknown nested fields" do
+        assertLeftContaining "unknown field 'cases.nope'" $ select' "cases(nope)"
+    , testCase "rejects sub-fields of a field without any" do
+        assertLeftContaining "field 'name' has no sub-fields" $ select' "name(x)"
+    ]
+  where
+    select' input = select schema =<< parse input
+
+
+schema :: Schema
+schema = Schema [leaf "name", leaf "status", casesSchema]
+
+
+casesSchema :: (Text, Maybe Schema)
+casesSchema = nested "cases" [leaf "description", leaf "outcome"]
+
+
+assertLeftContaining :: (Show a) => Text -> Either Text a -> IO ()
+assertLeftContaining needle = \case
+    Left err -> assertBool (toString $ err <> "\ndoes not contain\n" <> needle) $ needle `T.isInfixOf` err
+    Right a -> assertFailure $ "expected Left, got Right " <> show a
diff --git a/test/Unit/Tricorder/API/SuiteView/SchemaSpec.hs b/test/Unit/Tricorder/API/SuiteView/SchemaSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Unit/Tricorder/API/SuiteView/SchemaSpec.hs
@@ -0,0 +1,60 @@
+module Unit.Tricorder.API.SuiteView.SchemaSpec (test_Schema) where
+
+import Atelier.Time (AsRawUnit (..))
+import Data.Aeson (Value (..), toJSON)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.HUnit (testCase, (@?=))
+
+import Data.Aeson.Key qualified as Key
+import Data.Aeson.KeyMap qualified as KeyMap
+
+import Tricorder.API.Test.SuiteView (CaseView (..), Outcome (..), Status (..), SuiteView (..))
+import Tricorder.API.Test.SuiteView.Schema (defaultFields, schema)
+
+import Tricorder.API.FieldMask.Schema qualified as FieldMask (Schema (..))
+import Tricorder.API.FieldMask.Schema qualified as FieldMask.Schema
+
+
+test_Schema :: TestTree
+test_Schema =
+    testGroup
+        "Tricorder.API.SuiteView.Schema"
+        [ testCase "schema lists every field of the JSON encoding" do
+            schemaKeys schema @?= jsonKeys (toJSON fullView)
+        , testCase "default fields are in the schema" do
+            void (FieldMask.Schema.select schema defaultFields) @?= Right ()
+        ]
+
+
+-- | Keys of a JSON value, nested keys of arrays taken from their first element.
+data Keys = Keys [(Text, Maybe Keys)]
+    deriving stock (Eq, Show)
+
+
+schemaKeys :: FieldMask.Schema -> Keys
+schemaKeys (FieldMask.Schema fields) = Keys $ sortOn fst $ second (fmap schemaKeys) <$> fields
+
+
+jsonKeys :: Value -> Keys
+jsonKeys = \case
+    Object obj -> Keys $ sortOn fst [(Key.toText key, nestedKeys value) | (key, value) <- KeyMap.toList obj]
+    _ -> Keys []
+  where
+    nestedKeys = \case
+        Array values | Just element <- viaNonEmpty head (toList values) -> Just $ jsonKeys element
+        _ -> Nothing
+
+
+-- | A view with every field set, so every field shows up in its JSON.
+fullView :: SuiteView
+fullView =
+    SuiteView
+        { name = "test:suite"
+        , status = Failed
+        , error = Just "error"
+        , passedCases = Just 0
+        , totalCases = Just 1
+        , durationMs = Just $ AsRawUnit 5
+        , output = Just "output"
+        , cases = Just [CaseView "case" CaseFailed (Just "failure")]
+        }
diff --git a/test/Unit/Tricorder/FieldMask/ArgsSpec.hs b/test/Unit/Tricorder/FieldMask/ArgsSpec.hs
deleted file mode 100644
--- a/test/Unit/Tricorder/FieldMask/ArgsSpec.hs
+++ /dev/null
@@ -1,55 +0,0 @@
-module Unit.Tricorder.FieldMask.ArgsSpec (test_Args) where
-
-import Test.Tasty (TestTree, testGroup)
-import Test.Tasty.HUnit (assertFailure, testCase, (@?=))
-
-import Tricorder.FieldMask (Field (..), FieldMask (..))
-import Tricorder.FieldMask.Args (parse)
-
-import Tricorder.FieldMask qualified as FieldMask
-
-
-test_Args :: TestTree
-test_Args =
-    testGroup
-        "Tricorder.FieldMask.Args"
-        [ testGroup "parse" testParse
-        ]
-
-
-testParse :: [TestTree]
-testParse =
-    [ testCase "parses a flat list of fields" do
-        parse "name,status" @?= Right (mask [field "name", field "status"])
-    , testCase "parses nested fields" do
-        parse "name,cases(description,failure)"
-            @?= Right (mask [field "name", Field "cases" $ Just $ mask [field "description", field "failure"]])
-    , testCase "allows whitespace between tokens" do
-        parse " name , cases ( description ) "
-            @?= Right (mask [field "name", Field "cases" $ Just $ mask [field "description"]])
-    , testCase "rejects an empty mask" do
-        assertLeft $ parse ""
-    , testCase "rejects a trailing comma" do
-        assertLeft $ parse "name,"
-    , testCase "rejects empty parentheses" do
-        assertLeft $ parse "cases()"
-    , testCase "rejects unbalanced parentheses" do
-        assertLeft $ parse "cases(description"
-    , testCase "round-trips through render" do
-        let input = "name,cases(description,failure),output"
-        (FieldMask.render <$> parse input) @?= Right input
-    ]
-
-
-mask :: [Field] -> FieldMask
-mask = maybe (error "mask: no fields") FieldMask . nonEmpty
-
-
-field :: Text -> Field
-field name = Field name Nothing
-
-
-assertLeft :: (Show a) => Either Text a -> IO ()
-assertLeft = \case
-    Left _ -> pass
-    Right a -> assertFailure $ "expected Left, got Right " <> show a
diff --git a/test/Unit/Tricorder/FieldMask/ProjectionSpec.hs b/test/Unit/Tricorder/FieldMask/ProjectionSpec.hs
deleted file mode 100644
--- a/test/Unit/Tricorder/FieldMask/ProjectionSpec.hs
+++ /dev/null
@@ -1,50 +0,0 @@
-module Unit.Tricorder.FieldMask.ProjectionSpec (test_Projection) where
-
-import Data.Aeson (Value (..), object, (.=))
-import Data.Aeson.Text (encodeToLazyText)
-import Test.Tasty (TestTree, testGroup)
-import Test.Tasty.HUnit (testCase, (@?=))
-
-import Tricorder.FieldMask.Projection (Projection (..), project, renderYaml)
-import Tricorder.FieldMask.Schema (Schema (..), leaf, nested)
-
-
-test_Projection :: TestTree
-test_Projection =
-    testGroup
-        "Tricorder.FieldMask.Projection"
-        [ testGroup "project" testProject
-        ]
-
-
-testProject :: [TestTree]
-testProject =
-    [ testCase "keeps only the selected fields, in selection order" do
-        project (Schema [leaf "status", leaf "name"]) suite
-            @?= PObject [("status", PScalar "failed"), ("name", PScalar "suite")]
-    , testCase "projects every element of an array" do
-        project (Schema [nested "cases" [leaf "outcome"]]) suite
-            @?= PObject
-                [ ("cases", PArray [PObject [("outcome", PScalar "passed")], PObject [("outcome", PScalar "failed")]])
-                ]
-    , testCase "leaves out missing and null fields" do
-        project (Schema [leaf "name", leaf "missing", leaf "error"]) suite
-            @?= PObject [("name", PScalar "suite")]
-    , testCase "encodes JSON objects in selection order" do
-        encodeToLazyText (project (Schema [leaf "status", leaf "name"]) suite)
-            @?= "{\"status\":\"failed\",\"name\":\"suite\"}"
-    , testCase "renders YAML in selection order" do
-        renderYaml (project (Schema [leaf "status", leaf "name"]) suite)
-            @?= "status: failed\nname: suite\n"
-    ]
-  where
-    suite =
-        object
-            [ "name" .= ("suite" :: Text)
-            , "status" .= ("failed" :: Text)
-            , "error" .= Null
-            , "cases"
-                .= [ object ["description" .= ("a" :: Text), "outcome" .= ("passed" :: Text)]
-                   , object ["description" .= ("b" :: Text), "outcome" .= ("failed" :: Text)]
-                   ]
-            ]
diff --git a/test/Unit/Tricorder/FieldMask/SchemaSpec.hs b/test/Unit/Tricorder/FieldMask/SchemaSpec.hs
deleted file mode 100644
--- a/test/Unit/Tricorder/FieldMask/SchemaSpec.hs
+++ /dev/null
@@ -1,50 +0,0 @@
-module Unit.Tricorder.FieldMask.SchemaSpec (test_Schema) where
-
-import Test.Tasty (TestTree, testGroup)
-import Test.Tasty.HUnit (assertBool, assertFailure, testCase, (@?=))
-
-import Data.Text qualified as T
-
-import Tricorder.FieldMask.Args (parse)
-import Tricorder.FieldMask.Schema (Schema (..), leaf, nested, select)
-
-
-test_Schema :: TestTree
-test_Schema =
-    testGroup
-        "Unit.Tricorder.FieldMask.Schema"
-        [ testGroup "select" testSelect
-        ]
-
-
-testSelect :: [TestTree]
-testSelect =
-    [ testCase "keeps the requested fields in the requested order" do
-        select' "status,name" @?= Right (Schema [leaf "status", leaf "name"])
-    , testCase "a field without sub-fields keeps its whole nested schema" do
-        select' "cases" @?= Right (Schema [casesSchema])
-    , testCase "narrows nested fields" do
-        select' "cases(outcome)" @?= Right (Schema [nested "cases" [leaf "outcome"]])
-    , testCase "rejects unknown fields" do
-        assertLeftContaining "unknown field 'nope'" $ select' "name,nope"
-    , testCase "names the path of unknown nested fields" do
-        assertLeftContaining "unknown field 'cases.nope'" $ select' "cases(nope)"
-    , testCase "rejects sub-fields of a field without any" do
-        assertLeftContaining "field 'name' has no sub-fields" $ select' "name(x)"
-    ]
-  where
-    select' input = select schema =<< parse input
-
-
-schema :: Schema
-schema = Schema [leaf "name", leaf "status", casesSchema]
-
-
-casesSchema :: (Text, Maybe Schema)
-casesSchema = nested "cases" [leaf "description", leaf "outcome"]
-
-
-assertLeftContaining :: (Show a) => Text -> Either Text a -> IO ()
-assertLeftContaining needle = \case
-    Left err -> assertBool (toString $ err <> "\ndoes not contain\n" <> needle) $ needle `T.isInfixOf` err
-    Right a -> assertFailure $ "expected Left, got Right " <> show a
diff --git a/tricorder-types.cabal b/tricorder-types.cabal
--- a/tricorder-types.cabal
+++ b/tricorder-types.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           tricorder-types
-version:        0.5.0.0
+version:        0.6.0.0
 synopsis:       Shared domain types for various Tricorder components
 description:    Shared domain types for various Tricorder components like
                 [Tricorder itself](https://hackage.haskell.org/package/tricorder) and
@@ -34,17 +34,32 @@
 
 library
   exposed-modules:
-      Tricorder.CLI.Command
-      Tricorder.CLI.Command.Daemon
-      Tricorder.CLI.Command.IfDaemonIsStopped
-      Tricorder.CLI.Command.OutputFormat
-      Tricorder.CLI.Command.Test
-      Tricorder.CLI.Command.TestFilter
-      Tricorder.CLI.Command.WaitMode
-      Tricorder.FieldMask
-      Tricorder.FieldMask.Args
-      Tricorder.FieldMask.Projection
-      Tricorder.FieldMask.Schema
+      Tricorder.API.Args.Deprecated
+      Tricorder.API.Command
+      Tricorder.API.Command.Args
+      Tricorder.API.Daemon.Args
+      Tricorder.API.Daemon.Command
+      Tricorder.API.FieldMask
+      Tricorder.API.FieldMask.Args
+      Tricorder.API.FieldMask.Projection
+      Tricorder.API.FieldMask.Schema
+      Tricorder.API.Force
+      Tricorder.API.Force.Args
+      Tricorder.API.IfDaemonIsStopped
+      Tricorder.API.IfDaemonIsStopped.Args
+      Tricorder.API.OutputFormat
+      Tricorder.API.OutputFormat.Args
+      Tricorder.API.Test
+      Tricorder.API.Test.Args
+      Tricorder.API.Test.SuiteView
+      Tricorder.API.Test.SuiteView.Schema
+      Tricorder.API.TestFilter
+      Tricorder.API.TestFilter.Args
+      Tricorder.API.WaitMode
+      Tricorder.API.WaitMode.Args
+      Tricorder.SourceLookup.ModuleSourceResult
+      Tricorder.SourceLookup.PackageId
+      Tricorder.SourceLookup.ReexportLimits
       Tricorder.SourceLookup.SourceQuery
   other-modules:
       Paths_tricorder_types
@@ -72,8 +87,10 @@
   ghc-options: -Weverything -Wno-unsafe -Wno-missing-safe-haskell-mode -Wno-monomorphism-restriction -Wno-missing-kind-signatures -Wno-missing-local-signatures -Wno-missing-import-lists -Wno-implicit-prelude -Wno-unticked-promoted-constructors -Wno-unused-packages -Wno-all-missed-specialisations -Wno-missed-specialisations
   build-depends:
       aeson >=2.2 && <2.4
+    , atelier-core ==0.8.*
     , atelier-prelude ==0.4.*
     , base >=4.18 && <4.23
+    , effectful ==2.7.*
     , megaparsec >=9.7 && <9.9
     , optparse-applicative ==0.19.*
     , text ==2.1.*
@@ -88,9 +105,10 @@
   type: exitcode-stdio-1.0
   main-is: Driver.hs
   other-modules:
-      Unit.Tricorder.FieldMask.ArgsSpec
-      Unit.Tricorder.FieldMask.ProjectionSpec
-      Unit.Tricorder.FieldMask.SchemaSpec
+      Unit.Tricorder.API.FieldMask.ArgsSpec
+      Unit.Tricorder.API.FieldMask.ProjectionSpec
+      Unit.Tricorder.API.FieldMask.SchemaSpec
+      Unit.Tricorder.API.SuiteView.SchemaSpec
       Paths_tricorder_types
   autogen-modules:
       Paths_tricorder_types