diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,17 @@
 # Changelog for hs-opentelemetry-instrumentation-tasty
 
-## 0.0.1.0
+## Unreleased
+
+## 1.0.0.0 - 2026-05-29
+
+- Update to `hs-opentelemetry-api` 0.4.
+- Internal: `result.description` attribute key is now a typed `AttributeKey` constant.
+  Attribute name is unchanged.
+
+## 0.1.0.1
+
+- Relax `hs-opentelemetry-api` bounds to support 0.3.x
+
+## 0.1.0.0
 
 - Initial release
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright Ian Duncan (c) 2021
+Copyright Ian Duncan (c) 2021-2026
 
 All rights reserved.
 
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,13 +1,16 @@
 # hs-opentelemetry-instrumentation-tasty
 
-OpenTelemetry instrumentation library for Tasty.
-It creates spans for:
+[![hs-opentelemetry-instrumentation-tasty](https://img.shields.io/hackage/v/hs-opentelemetry-instrumentation-tasty?style=flat-square&logo=haskell&label=hs-opentelemetry-instrumentation-tasty&labelColor=5D4F85)](https://hackage.haskell.org/package/hs-opentelemetry-instrumentation-tasty)
 
+OpenTelemetry instrumentation for the [Tasty] test framework; it creates the following spans inside the instrumented `TestTree`:
+
 1. Individual test cases
 2. Test groups
 3. Resource setup and teardown
 
-The library should be robust to tests running in parallel.
+As Tasty executes all tests in parallel, this instrumentation should be robust in the presence of parallel execution.
+
+[Tasty]: https://hackage.haskell.org/package/tasty
 
 ## Usage
 
diff --git a/hs-opentelemetry-instrumentation-tasty.cabal b/hs-opentelemetry-instrumentation-tasty.cabal
--- a/hs-opentelemetry-instrumentation-tasty.cabal
+++ b/hs-opentelemetry-instrumentation-tasty.cabal
@@ -1,6 +1,8 @@
 cabal-version: 2.0
 name:          hs-opentelemetry-instrumentation-tasty
-version:       0.1
+version:       1.0.0.0
+synopsis:      OpenTelemetry instrumentation for the Tasty test framework
+category:      OpenTelemetry, Testing
 
 description:        Please see the README on GitHub at <https://github.com/iand675/hs-opentelemetry/tree/main/instrumentation/tasty#readme>
 homepage:           https://github.com/iand675/hs-opentelemetry#readme
@@ -13,6 +15,7 @@
 build-type:         Simple
 extra-source-files:
     README.md
+extra-doc-files:
     ChangeLog.md
 
 source-repository head
@@ -23,7 +26,8 @@
   default-language: Haskell2010
   build-depends:
     base >=4.7 && <5
-    , hs-opentelemetry-api ^>=0.2
+    , hs-opentelemetry-api ^>= 1.0
+    , hs-opentelemetry-semantic-conventions >= 1.40 && < 2
     , tagged ^>= 0.8
     , tasty ^>= 1.5
     , text
@@ -39,9 +43,9 @@
     async
     , base
     , containers
-    , hs-opentelemetry-api
-    , hs-opentelemetry-instrumentation-tasty
-    , hs-opentelemetry-sdk
+    , hs-opentelemetry-api ^>= 1.0
+    , hs-opentelemetry-instrumentation-tasty ^>= 1.0
+    , hs-opentelemetry-sdk ^>= 1.0
     , tasty
     , tasty-hunit
     , text
diff --git a/src/OpenTelemetry/Instrumentation/Tasty.hs b/src/OpenTelemetry/Instrumentation/Tasty.hs
--- a/src/OpenTelemetry/Instrumentation/Tasty.hs
+++ b/src/OpenTelemetry/Instrumentation/Tasty.hs
@@ -6,20 +6,34 @@
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TemplateHaskell #-}
 
+{- |
+Module      : OpenTelemetry.Instrumentation.Tasty
+Description : OpenTelemetry instrumentation for the Tasty test framework.
+Stability   : experimental
+
+Wraps test trees to emit spans for each test.
+-}
 module OpenTelemetry.Instrumentation.Tasty (instrumentTestTree, instrumentTestTreeWithTracer) where
 
 import Control.Exception (bracket)
 import Data.Tagged (Tagged, retag)
+import Data.Text (Text)
 import Data.Text qualified as T
+import OpenTelemetry.Attributes.Key (AttributeKey (..), unkey)
 import OpenTelemetry.Context (insertSpan, lookupSpan, removeSpan)
 import OpenTelemetry.Context.ThreadLocal (adjustContext, getContext)
 import OpenTelemetry.Trace.Core (Span, SpanStatus (Error, Ok), Tracer, addAttribute, createSpan, defaultSpanArguments, detectInstrumentationLibrary, endSpan, getGlobalTracerProvider, inSpan, makeTracer, setStatus, tracerOptions)
 import Test.Tasty (TestTree, withResource)
 import Test.Tasty.Options (OptionDescription)
 import Test.Tasty.Providers (IsTest (run, testOptions))
-import Test.Tasty.Runners (Outcome (Failure, Success), ResourceSpec (ResourceSpec), Result (Result, resultDescription, resultOutcome), TestTree (After, AskOptions, PlusTestOptions, SingleTest, TestGroup, WithResource))
+import Test.Tasty.Runners (FailureReason (..), Outcome (Failure, Success), ResourceSpec (ResourceSpec), Result (Result, resultDescription, resultOutcome), TestTree (After, AskOptions, PlusTestOptions, SingleTest, TestGroup, WithResource))
 
 
+-- | @result.description@ – human-readable description of the test result (custom attribute).
+resultDescriptionKey :: AttributeKey Text
+resultDescriptionKey = AttributeKey "result.description"
+
+
 {- | A test case with a wrapper function that can do some IO around the
 test. We use the wrapper to set up spans appropriately.
 -}
@@ -35,12 +49,12 @@
       res@Result {resultOutcome, resultDescription} <- run opts innerTest progress
       case mspan of
         Just s -> do
-          addAttribute s "result.description" (T.pack resultDescription)
+          addAttribute s (unkey resultDescriptionKey) (T.pack resultDescription)
           case resultOutcome of
             Success -> do
-              setStatus s $ Ok
+              setStatus s Ok
             Failure reason -> do
-              setStatus s $ Error $ T.pack $ show reason
+              setStatus s $ Error $ failureReasonText reason
         Nothing -> pure ()
 
       pure res
@@ -129,6 +143,14 @@
       pure (lookupSpan ctx, ctx)
     teardown (originalParentSpan, _ctx) = do
       adjustContext $ \ctx -> maybe (removeSpan ctx) (`insertSpan` ctx) originalParentSpan
+
+
+failureReasonText :: FailureReason -> T.Text
+failureReasonText = \case
+  TestFailed -> "TestFailed"
+  TestThrewException e -> T.pack $ "TestThrewException: " <> show e
+  TestTimedOut n -> T.pack $ "TestTimedOut: " <> show n
+  TestDepFailed -> "TestDepFailed"
 
 {- Note [Test parallelism]
 Tasty runs tests in parallel by default, and we don't want to disturb that.
diff --git a/tests/OpenTelemetry/Instrumentation/Tasty/Tests.hs b/tests/OpenTelemetry/Instrumentation/Tasty/Tests.hs
--- a/tests/OpenTelemetry/Instrumentation/Tasty/Tests.hs
+++ b/tests/OpenTelemetry/Instrumentation/Tasty/Tests.hs
@@ -8,7 +8,6 @@
 module OpenTelemetry.Instrumentation.Tasty.Tests (tests) where
 
 import Control.Concurrent (newEmptyMVar, putMVar, takeMVar)
-import Control.Concurrent.Async (async)
 import Control.Exception (bracket)
 import Data.Functor (void)
 import Data.IORef (atomicModifyIORef, newIORef, readIORef)
@@ -18,9 +17,9 @@
 import Data.Set qualified as Set
 import Data.Text (Text)
 import OpenTelemetry.Instrumentation.Tasty (instrumentTestTree)
-import OpenTelemetry.Processor.Span (ShutdownResult (ShutdownSuccess), SpanProcessor, spanProcessorForceFlush, spanProcessorOnEnd, spanProcessorOnStart, spanProcessorShutdown, pattern SpanProcessor)
-import OpenTelemetry.Trace (ImmutableSpan (ImmutableSpan, spanName, spanParent), createTracerProvider, defaultSpanArguments, emptyTracerProviderOptions, getGlobalTracerProvider, inSpan, makeTracer, setGlobalTracerProvider, shutdownTracerProvider, tracerOptions)
-import OpenTelemetry.Trace.Core (unsafeReadSpan)
+import OpenTelemetry.Processor.Span (FlushResult (FlushSuccess), ShutdownResult (ShutdownSuccess), SpanProcessor (..))
+import OpenTelemetry.Trace (ImmutableSpan (..), createTracerProvider, defaultSpanArguments, emptyTracerProviderOptions, getGlobalTracerProvider, inSpan, makeTracer, setGlobalTracerProvider, shutdownTracerProvider, tracerOptions)
+import OpenTelemetry.Trace.Core (hotName, spanHot, unsafeReadSpan)
 import Test.Tasty (DependencyType (AllFinish), TestTree, sequentialTestGroup, testGroup, withResource)
 import Test.Tasty.HUnit (testCase, (@?=))
 import Test.Tasty.Ingredients (tryIngredients)
@@ -130,7 +129,7 @@
 spanTrees :: IO a -> IO (a, Set.Set (Tree Text))
 spanTrees act = do
   (processor, readSpans) <- recordingProcessor
-  res <- bracket (setup processor) shutdownTracerProvider $ \_ -> do
+  res <- bracket (setup processor) (`shutdownTracerProvider` Nothing) $ \_ -> do
     act
   spans <- readSpans
   trees <- spansToTrees spans
@@ -142,14 +141,21 @@
       pure tp
 
 
+immutableSpanName :: ImmutableSpan -> IO Text
+immutableSpanName imm = hotName <$> readIORef (spanHot imm)
+
+
 toChildMap :: [ImmutableSpan] -> ([Text], Map Text [Text]) -> IO ([Text], Map Text [Text])
 toChildMap [] acc = pure acc
-toChildMap (ImmutableSpan {spanParent, spanName} : spans) (accRoots, accChildren) = case spanParent of
-  Just parent -> do
-    ImmutableSpan {spanName = parentName} <- unsafeReadSpan parent
-    let existingChildren = fromMaybe mempty $ Map.lookup parentName accChildren
-    toChildMap spans (accRoots, Map.insert parentName (existingChildren ++ [spanName]) accChildren)
-  Nothing -> toChildMap spans (spanName : accRoots, accChildren)
+toChildMap (imm : spans) (accRoots, accChildren) = do
+  name <- immutableSpanName imm
+  case spanParent imm of
+    Just parent -> do
+      parentImm <- unsafeReadSpan parent
+      parentName <- immutableSpanName parentImm
+      let existingChildren = fromMaybe mempty $ Map.lookup parentName accChildren
+      toChildMap spans (accRoots, Map.insert parentName (existingChildren ++ [name]) accChildren)
+    Nothing -> toChildMap spans (name : accRoots, accChildren)
 
 
 toTree :: (Ord a) => Map a [a] -> a -> Tree a
@@ -174,12 +180,11 @@
 
   let processor =
         SpanProcessor
-          { spanProcessorOnStart = mempty
-          , spanProcessorOnEnd = \spanRef -> do
-              immutableSpan <- readIORef spanRef
+          { spanProcessorOnStart = \_ _ -> pure ()
+          , spanProcessorOnEnd = \immutableSpan ->
               atomicModifyIORef spans $ \soFar -> (soFar ++ [immutableSpan], ())
-          , spanProcessorShutdown = async $ pure ShutdownSuccess
-          , spanProcessorForceFlush = mempty
+          , spanProcessorShutdown = pure ShutdownSuccess
+          , spanProcessorForceFlush = pure FlushSuccess
           }
 
   setGlobalTracerProvider