diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,91 @@
 
 ## [Unreleased]
 
+## [baikai 0.9.0.0] - 2026-10-25
+
+### Added
+
+- `Baikai.Judgment` compiles closed-set schemas into ordered questions, refuses
+  generation controls and validates neutral answers without normalizing provider
+  probabilities or deriving confidence and expected scores.
+- `UserData`, `AssistantData`/`DataContent`, user-data message helpers, atomic
+  data events, and named full-response JSON codecs preserve structured answers.
+- `TypeSafeSystemOne`, catalog-owned `OutputKind`/`isJudgmentOnly`, `InputData`,
+  and `typesafe_jev_latest`/`typesafe_jev_preview`. Legacy model JSON defaults to
+  generative output. Register the new `baikai-typesafe` provider explicitly.
+
+### Changed (breaking)
+
+- Public content/event sums and model, error, trace and log records gain fields
+  or constructors. Update exhaustive matches and record construction on upgrade.
+- Terminal traces and both call-log paths preserve structured answer payloads.
+  Evidence schema 2.6 includes structured response commitments and typed request
+  problems; existing digest rules are unchanged.
+
+## [baikai-typesafe 0.1.0.0] - 2026-10-25
+
+### Added
+
+- Initial explicitly registered TypeSafe System One provider using the released
+  `typesafe-hs ^>=0.1.0.0` wire client. Strict request and response validation,
+  atomic synthetic streaming, truthful call evidence, bounded HTTP calls and an
+  opt-in live test. No retry policy is embedded.
+- Installation, schema, refusal and consumer migration guide, plus CAP-27.
+
+## [baikai-claude 0.7.2.0] - 2026-10-25
+
+### Changed
+
+- Require `baikai ^>=0.9.0`, encode user data as canonical JSON text, and refuse
+  structured assistant history before dispatch with a typed field path.
+
+### Fixed
+
+- The offline cancellation fixture waits until the response reader is active
+  before cancelling, eliminating a fixed-startup-delay race under build load.
+
+## [baikai-openai 0.7.2.0] - 2026-10-25
+
+### Changed
+
+- Require `baikai ^>=0.9.0`, encode user data as canonical JSON text, and refuse
+  structured assistant history before dispatch with a typed field path across
+  Chat Completions, Responses and batch CLI calls.
+
+### Fixed
+
+- The offline cancellation fixture waits until the response reader is active
+  before cancelling, eliminating a fixed-startup-delay race under build load.
+
+## [baikai-trace-otel 0.4.1.0] - 2026-10-25
+
+### Added
+
+- Export structured answer data as canonical JSON under
+  `baikai.response.structured_data`, on success and failure terminals.
+
+### Changed
+
+- Require `baikai ^>=0.9.0` for the expanded trace protocol.
+
+## [baikai-effectful 0.4.0.4] - 2026-10-25
+
+### Changed
+
+- Require `baikai ^>=0.9.0`. Dependency-only update; no package API change.
+
+## [baikai-kit 0.4.0.2] - 2026-10-25
+
+### Changed
+
+- Require `baikai ^>=0.9.0`. Dependency-only update; no package API change.
+
+## [baikai-agent 0.2.0.3] - 2026-10-25
+
+### Changed
+
+- Require `baikai ^>=0.9.0`. Dependency-only update; no package API change.
+
 ## [baikai 0.8.0.0] - 2026-10-10
 
 ### Added
diff --git a/baikai-claude.cabal b/baikai-claude.cabal
--- a/baikai-claude.cabal
+++ b/baikai-claude.cabal
@@ -1,6 +1,6 @@
 cabal-version: 3.4
 name: baikai-claude
-version: 0.7.1.1
+version: 0.7.2.0
 synopsis: Anthropic Claude providers for the baikai abstraction
 description:
   Anthropic backends for baikai: the Messages API over SSE, the claude -p batch
@@ -72,7 +72,7 @@
   autogen-modules: Paths_baikai_claude
   build-depends:
     aeson ^>=2.2,
-    baikai ^>=0.8.0,
+    baikai ^>=0.9.0,
     base >=4.20 && <5,
     base16-bytestring ^>=1.0,
     base64-bytestring ^>=1.2,
@@ -106,6 +106,7 @@
     CliEvidenceSpec
     CliProcessFixture
     Contract
+    DataInputSpec
     ErrorClassSpec
     EvidenceSpec
     FableContractsSpec
@@ -125,7 +126,7 @@
 
   build-depends:
     aeson,
-    baikai ^>=0.8.0,
+    baikai ^>=0.9.0,
     baikai-claude,
     base >=4.20 && <5,
     bytestring,
diff --git a/src/Baikai/Provider/Claude/Cli.hs b/src/Baikai/Provider/Claude/Cli.hs
--- a/src/Baikai/Provider/Claude/Cli.hs
+++ b/src/Baikai/Provider/Claude/Cli.hs
@@ -50,6 +50,7 @@
 import Baikai.Api (Api (..))
 import Baikai.Content (AssistantContent (..), TextContent (..))
 import Baikai.Context (Context)
+import Baikai.Context qualified as Context
 import Baikai.Error (BaikaiError, decodeError, processError, providerError)
 import Baikai.Evidence qualified as Ev
 import Baikai.Evidence.Build qualified as Build
@@ -70,6 +71,7 @@
 import Baikai.ThinkingLevel (ThinkingLevel (ThinkingMinimal), renderThinkingLevel)
 import Baikai.Usage (Usage, zeroUsage)
 import Control.Exception (SomeException, displayException, fromException)
+import Control.Exception qualified
 import Control.Lens ((&), (.~), (^.))
 import Data.Aeson qualified as Aeson
 import Data.ByteString qualified as BS
@@ -220,6 +222,7 @@
 
 runClaudeCli :: ClaudeCliConfig -> Model -> Context -> Options -> IO Resp.Response
 runClaudeCli cfg m ctx opts = do
+  either Control.Exception.throwIO pure (Context.refuseAssistantDataHistory ctx)
   let (exe, args) = claudeCliCommand cfg m ctx opts
   start <- getCurrentTime
   executed <-
diff --git a/src/Baikai/Provider/Claude/Internal/Request.hs b/src/Baikai/Provider/Claude/Internal/Request.hs
--- a/src/Baikai/Provider/Claude/Internal/Request.hs
+++ b/src/Baikai/Provider/Claude/Internal/Request.hs
@@ -23,6 +23,8 @@
 import Baikai.Compat (AnthropicMessagesCompat (..), AnthropicThinkingStyle (..))
 import Baikai.Content qualified as Content
 import Baikai.Context (Context (..))
+import Baikai.Context qualified as Context
+import Baikai.Error qualified as Error
 import Baikai.Evidence
   ( ThinkingAdjustment (..),
     ThinkingMode (..),
@@ -79,6 +81,7 @@
 mapRequest ::
   Model -> Context -> Options -> Either Text (Messages.CreateMessage, ThinkingTranslation)
 mapRequest m ctx opts = do
+  either (Left . Error.message) pure (Context.refuseAssistantDataHistory ctx)
   case opts ^. #toolChoice of
     Just Tool.ToolChoiceRequired | not (anthropicMessagesCompatFor m).supportsForcedToolChoice -> unsupportedForcedChoice
     Just (Tool.ToolChoiceSpecific _) | not (anthropicMessagesCompatFor m).supportsForcedToolChoice -> unsupportedForcedChoice
@@ -616,6 +619,7 @@
     | Text.null t -> Nothing
     | otherwise ->
         Just Messages.Content_Text {Messages.text = t, Messages.cache_control = Nothing}
+  Content.UserData v -> userContentToBlock (Content.UserText (Content.TextContent (Content.canonicalDataText v)))
   Content.UserImage img ->
     Just
       Messages.Content_Image
@@ -649,6 +653,7 @@
                 Messages.signature = sig
               }
         Nothing -> Nothing
+  Content.AssistantData _ -> Nothing
   Content.AssistantToolCall tc ->
     Just
       Messages.Content_Tool_Use
diff --git a/src/Baikai/Provider/Claude/Internal/Stream.hs b/src/Baikai/Provider/Claude/Internal/Stream.hs
--- a/src/Baikai/Provider/Claude/Internal/Stream.hs
+++ b/src/Baikai/Provider/Claude/Internal/Stream.hs
@@ -32,6 +32,7 @@
 import Baikai.CacheRetention (CacheRetention (..))
 import Baikai.Content qualified as Content
 import Baikai.Context (Context (..))
+import Baikai.Context qualified as Context
 import Baikai.Cost (CostEstimateReason (CacheDurationNotReported, SpeedNotReported), estimateCost)
 import Baikai.Cost.Pricing qualified as Pricing
 import Baikai.Error (BaikaiError, contentFiltered, invalidRequest, providerError)
@@ -208,37 +209,39 @@
 
 prepareCall ::
   Model -> Context -> Options -> IO (Either BaikaiError ClaudeCall)
-prepareCall m ctx opts = do
-  case mapRequest m ctx opts of
-    Left e -> pure (Left (invalidRequest e))
-    Right (req, translation) -> do
-      let url = resolvedBaseUrl m
-          compat = anthropicMessagesCompatFor m
-          version = Just "2023-06-01"
-      -- Checked before the key is resolved, so a base URL baikai will
-      -- not send to never causes a credential to be read out of the
-      -- environment. The message names the problem and what to write
-      -- instead; it renders the URL without its userinfo or query, so an
-      -- error reaching a log cannot carry a key someone put in either.
-      case Url.baseUrlProblem url of
-        Just problem ->
-          pure (Left (invalidRequest ("Model.baseUrl is not usable: " <> problem)))
-        Nothing -> do
-          key <- Transport.resolveKey url opts
-          env <- Transport.getClientEnvCached url
-          let body = streamRequestBody compat ctx opts req
-              headers = Transport.requestHeaders key version compat ctx m opts
-          pure
-            ( Right
-                ClaudeCall
-                  { clientEnv = env,
-                    requestHeaders = headers,
-                    timeoutMs = opts ^. #timeoutMs,
-                    requestBody = body,
-                    baseUrl = url,
-                    thinking = translation
-                  }
-            )
+prepareCall m ctx opts
+  | Left e <- Context.refuseAssistantDataHistory ctx = pure (Left e)
+  | otherwise = do
+      case mapRequest m ctx opts of
+        Left e -> pure (Left (invalidRequest e))
+        Right (req, translation) -> do
+          let url = resolvedBaseUrl m
+              compat = anthropicMessagesCompatFor m
+              version = Just "2023-06-01"
+          -- Checked before the key is resolved, so a base URL baikai will
+          -- not send to never causes a credential to be read out of the
+          -- environment. The message names the problem and what to write
+          -- instead; it renders the URL without its userinfo or query, so an
+          -- error reaching a log cannot carry a key someone put in either.
+          case Url.baseUrlProblem url of
+            Just problem ->
+              pure (Left (invalidRequest ("Model.baseUrl is not usable: " <> problem)))
+            Nothing -> do
+              key <- Transport.resolveKey url opts
+              env <- Transport.getClientEnvCached url
+              let body = streamRequestBody compat ctx opts req
+                  headers = Transport.requestHeaders key version compat ctx m opts
+              pure
+                ( Right
+                    ClaudeCall
+                      { clientEnv = env,
+                        requestHeaders = headers,
+                        timeoutMs = opts ^. #timeoutMs,
+                        requestBody = body,
+                        baseUrl = url,
+                        thinking = translation
+                      }
+                )
 
 -- | Worker body: drive the SDK's typed callback, forwarding events onto
 -- the frame queue. Any synchronous exception is converted into a
diff --git a/src/Baikai/Provider/Claude/Transport.hs b/src/Baikai/Provider/Claude/Transport.hs
--- a/src/Baikai/Provider/Claude/Transport.hs
+++ b/src/Baikai/Provider/Claude/Transport.hs
@@ -149,7 +149,8 @@
       httpStatus = Nothing,
       retryAfterSeconds = Nothing,
       exitCode = Nothing,
-      refusalCategory = Nothing
+      refusalCategory = Nothing,
+      requestProblem = Nothing
     }
 
 -- | Apply caller overrides over the provider's own headers.
diff --git a/test/DataInputSpec.hs b/test/DataInputSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/DataInputSpec.hs
@@ -0,0 +1,54 @@
+module DataInputSpec (tests) where
+
+import Baikai
+import Baikai.Prelude
+import Baikai.Provider.Claude.Cli qualified as Cli
+import Baikai.Provider.Claude.Internal.Request qualified as R
+import Baikai.Provider.Claude.Internal.Stream qualified as S
+import Control.Exception (try)
+import Data.Aeson qualified as A
+import Data.ByteString.Lazy.Char8 qualified as BL
+import Data.IORef
+import Data.Text qualified as T
+import Data.Vector qualified as V
+import Streamly.Data.Stream qualified as Stream
+import Test.Tasty
+import Test.Tasty.HUnit
+
+modelFixture :: Model
+modelFixture = emptyModel & #modelId .~ "fixture" & #api .~ AnthropicMessages
+
+dataFixture :: A.Value
+dataFixture = A.object ["z" A..= [1 :: Int, 2], "a" A..= ("日本語" :: T.Text)]
+
+history :: Context
+history = contextOf [AssistantMessage ((emptyResponse ^. #message) & #content .~ V.singleton (AssistantData (DataContent A.Null Nothing Nothing Nothing)))]
+
+tests :: TestTree
+tests =
+  testGroup
+    "structured input and history"
+    [ testCase "actual wire request contains canonical JSON in block position" $ do
+        let ctx = contextOf [UserMessage (UserPayload (V.fromList [UserText (TextContent "before"), UserData dataFixture, UserText (TextContent "after")]) Nothing)]
+        req <- either (assertFailure . T.unpack) pure (R.mapRequest modelFixture ctx emptyOptions)
+        let wire = A.toJSON (fst req)
+            bytes = BL.unpack (A.encode wire)
+            jsonText = BL.unpack (A.encode (canonicalDataText dataFixture))
+        assertBool ("structured text missing: " <> bytes) (T.pack jsonText `T.isInfixOf` T.pack bytes),
+      testCase "AnthropicMessages refuses assistant data with zero driver calls" $ do
+        calls <- newIORef (0 :: Int)
+        let driver _ _ _ = modifyIORef' calls (+ 1)
+        es <- Stream.toList (S.claudeMessagesStreamWith driver modelFixture history emptyOptions)
+        readIORef calls >>= (@?= 0)
+        case [e | EventError p <- es, Just e <- [p ^. #errorInfo]] of
+          [e] -> e ^. #requestProblem @?= Just (UnsupportedFeature "messages[0].content[0]")
+          _ -> assertFailure (show es),
+      testCase "CLI request carries JSON and refuses data history before spawning" $ do
+        let cfg = Cli.defaultClaudeCliConfig & #executable .~ "/nonexistent-baikai-data-test"
+            (_, args) = Cli.claudeCliCommand cfg modelFixture (contextOf [userData dataFixture]) emptyOptions
+        assertBool "canonical JSON reaches argument vector" (any (T.isInfixOf (canonicalDataText dataFixture) . T.pack) args)
+        result <- try ((Cli.claudeCliProvider cfg ^. #complete) modelFixture history emptyOptions) :: IO (Either BaikaiError Response)
+        case result of
+          Left e -> e ^. #requestProblem @?= Just (UnsupportedFeature "messages[0].content[0]")
+          Right r -> assertFailure (show r)
+    ]
diff --git a/test/LifecycleSpec.hs b/test/LifecycleSpec.hs
--- a/test/LifecycleSpec.hs
+++ b/test/LifecycleSpec.hs
@@ -100,11 +100,14 @@
                 (claudeMessagesStreamWith (countingDriver reads' closedRef (Just gate)) testModel emptyContext testOptions)
             )
         putMVar outcome (r :: Either SomeException [AssistantMessageEvent])
-    threadDelay 100000
+    -- Wait for the driver to enter its bracket and reach the blocked read.
+    -- A startup delay can cancel before a response exists under build load.
+    ready <- pollFor 200 10000 ((>= 4) <$> readIORef reads')
     throwTo tid ThreadKilled
+    r <- takeMVar outcome
+    assertBool "consumer reached the blocked response read before cancellation" ready
     released <- pollFor 100 10000 (readIORef closedRef)
     assertBool "cancellation releases the connection without a GC" released
-    r <- takeMVar outcome
     case r of
       Left e | Just ThreadKilled <- fromException e -> pure ()
       other -> assertFailure ("expected the drained thread to die by ThreadKilled, got: " <> show (fmap length other))
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -29,6 +29,7 @@
 import Data.Generics.Labels ()
 import Data.Text qualified as Text
 import Data.Vector qualified as Vector
+import DataInputSpec qualified
 import ErrorClassSpec qualified
 import EvidenceSpec qualified
 import FableContractsSpec qualified
@@ -53,7 +54,8 @@
   defaultMain $
     testGroup
       "Baikai.Provider.Claude"
-      [ commandRenderingTest,
+      [ DataInputSpec.tests,
+        commandRenderingTest,
         effortRenderingTests,
         safetyRefusalTest,
         safetyStillRendersTest,
