fix(session): remove duplicated turn-end step

packages/client/connection/src/client/fixture.ts

@@ -1516,7 +1516,7 @@ export function createFixtureApi(options: FixtureOptions = {}): ApiProxy {
         },
       })
       append(sessionId, { type: 'step/end', data: { turn: scenario.turn, step: 1 } })
-      append(sessionId, { type: 'turn/end', data: { turn: scenario.turn, step: 1, reason: { kind: 'aborted', reason: { kind: 'user' } },
+      append(sessionId, { type: 'turn/end', data: { turn: scenario.turn, reason: { kind: 'aborted', reason: { kind: 'user' } },
       } })
       retryScenarios.delete(sessionId)
       setRunning(sessionId, false)
@@ -1542,7 +1542,7 @@ export function createFixtureApi(options: FixtureOptions = {}): ApiProxy {
         },
       })
       append(sessionId, { type: 'step/end', data: { turn: scenario.turn, step: 1 } })
-      append(sessionId, { type: 'turn/end', data: { turn: scenario.turn, step: 1, reason: { kind: 'completed' } } })
+      append(sessionId, { type: 'turn/end', data: { turn: scenario.turn, reason: { kind: 'completed' } } })
       setRunning(sessionId, false)
     },
     /** Log append WITHOUT the mux emit: a frame lost in transit — history still serves it, the client must repull. */

packages/client/runtime/src/client/sessions/request-inspection.ts

@@ -240,6 +240,7 @@ function promptChange(
 function deriveRequests(events: readonly SessionEvent[]): readonly RequestView[] {
   const requests: RequestView[] = []
   const ordinaryByStep = new Map<string, number>()
+  const lastStepByTurn = new Map<number, string>()
   let activeStep: string | undefined
   let activePrompt: ConversationPromptSnapshot | undefined
   let activeCompaction: number | undefined
@@ -266,6 +267,7 @@ function deriveRequests(events: readonly SessionEvent[]): readonly RequestView[]
       const { turn, step } = sourceEvent.data
       const key = requestKey(turn, step)
       ordinaryByStep.set(key, requests.length)
+      lastStepByTurn.set(turn, key)
       requests.push({
         purpose: 'assistant',
         startSeq: sourceEvent.seq,
@@ -358,12 +360,15 @@ function deriveRequests(events: readonly SessionEvent[]): readonly RequestView[]
       })
       continue
     }
-    if (sourceEvent.type === 'turn/end' && sourceEvent.data.reason.kind === 'error') {
-      const reason = sourceEvent.data.reason
-      updateAssistant(ordinaryByStep.get(requestKey(sourceEvent.data.turn, sourceEvent.data.step)), {
-        status: 'error',
-        error: displayFailureMessage(reason.error),
-      })
+    if (sourceEvent.type === 'turn/end') {
+      const lastStep = lastStepByTurn.get(sourceEvent.data.turn)
+      if (sourceEvent.data.reason.kind === 'error') {
+        updateAssistant(lastStep === undefined ? undefined : ordinaryByStep.get(lastStep), {
+          status: 'error',
+          error: displayFailureMessage(sourceEvent.data.reason.error),
+        })
+      }
+      lastStepByTurn.delete(sourceEvent.data.turn)
       continue
     }
 

packages/client/runtime/src/client/sessions/session.ts

@@ -98,6 +98,8 @@ export class Session implements SessionFace {
   private readonly transcript = new TranscriptAdapter()
   private partial: PartialAccumulator | null = null
   private openCalls = new Map<string, RunningToolCall>()
+  /** Last entered step per turn, folded from step/start for terminal error placement. */
+  private lastStepByTurn = new Map<number, number>()
   /** Operational notices and interrupted-turn terminal nodes merged into the flow by seq.
    *  Derived from window events and rebuilt with partial/openCalls; the transcript is
    *  seq-monotonic, so a plain seq merge preserves event order. */
@@ -796,6 +798,10 @@ export class Session implements SessionFace {
     }
     switch (event.type) {
       case 'turn/start':
+        this.lastStepByTurn.set(event.data.turn, 0)
+        return
+      case 'step/start':
+        this.lastStepByTurn.set(event.data.turn, event.data.step)
         return
       case 'assistant/chunk': {
         const { turn, step, chunk } = event.data
@@ -826,6 +832,7 @@ export class Session implements SessionFace {
         return
       }
       case 'turn/end': {
+        const lastStep = this.lastStepByTurn.get(event.data.turn) ?? 0
         this.turnEnds.set(event.data.turn, event.seq)
         this.turnEndsRev++
         if (event.data.reason.kind === 'aborted') {
@@ -841,7 +848,7 @@ export class Session implements SessionFace {
             seq: event.seq,
             time: event.time,
             turn: event.data.turn,
-            step: event.data.step,
+            step: lastStep,
             message: displayFailureMessage(failure),
             code: failure.code,
           })
@@ -882,6 +889,7 @@ export class Session implements SessionFace {
           })
           this.derivedRev++
         }
+        this.lastStepByTurn.delete(event.data.turn)
         return
       }
       default:
@@ -916,6 +924,7 @@ export class Session implements SessionFace {
   private rebuildDerivedFromWindow(): void {
     this.partial = null
     this.openCalls.clear()
+    this.lastStepByTurn.clear()
     this.callsRev++
     this.derivedNodes = []
     this.derivedRev++