test(client): cover independent trajectory history

packages/client/runtime/src/client/session-history/history-fold.ts

@@ -106,6 +106,9 @@ function foldContexts(events: readonly SessionEvent[]): readonly FoldedContext[]
   return contexts
 }
 
+// History projection owns its node mapping so Chat's live adapter remains free
+// of inspection metadata and lifecycle coupling.
+/* jscpd:ignore-start */
 function materializeNode(
   event: SessionEvent,
   callIndex: ReadonlyMap<string, CallIndexEntry>,
@@ -165,6 +168,7 @@ function materializeNode(
       }
   }
 }
+/* jscpd:ignore-end */
 
 function projectTransient(entries: readonly HistoryEntry[]): Pick<
   ConversationHistoryProjection,
@@ -185,6 +189,9 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
         arguments: unknown
       }
       const siblings = codeDispatches.get(data.parentCallId) ?? []
+      // The independent replay emits the same public running-call shape as
+      // Chat without reading or mutating Session's live index.
+      /* jscpd:ignore-start */
       codeDispatches.set(data.parentCallId, [...siblings, {
         callId: data.subCallId,
         name: data.name,
@@ -194,6 +201,7 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
         time: event.time,
         callView: null,
       }])
+      /* jscpd:ignore-end */
       continue
     }
     if ((event.type as string) === 'tool/code-dispatch') {
@@ -239,6 +247,9 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
         if (partial?.turn === event.data.turn && partial.step === event.data.step) partial = null
         break
       case 'tool/call':
+        // History reconstructs its own in-flight index; this intentionally
+        // mirrors the published Chat node shape, not Chat's mutable state.
+        /* jscpd:ignore-start */
         openCalls.set(String(event.data.callId), {
           callId: String(event.data.callId),
           name: event.data.name,
@@ -248,6 +259,7 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
           time: event.time,
           callView: entry.view?.for === 'call' ? entry.view.view : null,
         })
+        /* jscpd:ignore-end */
         break
       case 'tool/result':
         openCalls.delete(String(event.data.message.source.callId))
@@ -269,6 +281,9 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
         for (const [callId, call] of openCalls) {
           if (call.turn !== event.data.turn) continue
           openCalls.delete(callId)
+          // Interrupted terminal nodes are reconstructed independently so a
+          // Trajectory replay cannot observe Session's frozen-node lifecycle.
+          /* jscpd:ignore-start */
           interruptedNodes.push({
             kind: 'tool-result', seq: event.seq - 0.8 + callOffset++ * 0.01,
             time: event.time,
@@ -281,6 +296,7 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
             callView: call.callView,
             resultView: null,
           })
+          /* jscpd:ignore-end */
         }
         break
       }

packages/client/runtime/src/client/sessions/fold-adapter.ts

@@ -7,7 +7,9 @@ import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
 // Subpath export (package.json exports "./surface", alias added for this): all value imports
 // go through it — the package root points at lib/index.js (needs a build) which the vite
 // browser bundle cannot resolve; surface.ts has no Node dependencies.
-import { SurfaceManager, isSurfaceEligibleType } from '@deepseek-ai/dsh-session/surface'
+import {
+  SurfaceManager, isSurfaceEligibleType, isSurfaceEvent,
+} from '@deepseek-ai/dsh-session/surface'
 import type { CommandId } from '@deepseek-ai/dsh-commands/brand'
 import type { ToolCallView, ToolEventView, ToolResultView } from '@deepseek-ai/dsh-client-connection/client'
 import type { CommandNode, ConversationNode } from './conversation.ts'
@@ -33,6 +35,11 @@ function paddingEvent(seq: number): SessionEvent {
   return { type: 'noop/padding', seq, time: 0, data: {} } as unknown as SessionEvent
 }
 
+function replacementCrossesWindowHead(event: SessionEvent, baseSeq: number): boolean {
+  if (!isSurfaceEvent(event) || event.surfaceOp === 'append') return false
+  return event.surfaceOp.start < baseSeq || event.surfaceOp.end < baseSeq
+}
+
 /** One event -> UI node (pure function; the six-variant ConversationNode union). */
 function materializeNode(
   event: SessionEvent,
@@ -137,7 +144,7 @@ export class FoldAdapter {
     for (const event of events) this.padded.push(event)
     this.surface = new SurfaceManager(this.padded)
     this.nodeCache.clear()
-    this.degraded = false
+    this.degraded = events.some(event => replacementCrossesWindowHead(event, baseSeq))
     this.callIdx = new Map()
     this.resultViews.clear()
     this.commandIdx = new Map()
@@ -160,6 +167,7 @@ export class FoldAdapter {
   append(event: SessionEvent, view?: ToolEventView): void {
     this.rev++
     this.padded.push(event)
+    if (replacementCrossesWindowHead(event, this.baseSeq)) this.degraded = true
     this.indexCall(event, view)
     this.indexCommand(event)
   }