diff --git a/web/hwlab-cloud-web/scripts/workbench-server-state.test.ts b/web/hwlab-cloud-web/scripts/workbench-server-state.test.ts
index 1fdf5c1b..508e4d1f 100644
--- a/web/hwlab-cloud-web/scripts/workbench-server-state.test.ts
+++ b/web/hwlab-cloud-web/scripts/workbench-server-state.test.ts
@@ -73,8 +73,11 @@ test("Workbench session tab status is read from server projection", () => {
     ]
   };
 
-  const tab = sessionToSessionTab(session, "ses_tab_projection");
+  const rawTab = sessionToSessionTab(session, "ses_tab_projection");
+  const tab = sessionToSessionTab(session, "ses_tab_projection", { ses_tab_projection: { sessionId: "ses_tab_projection", status: "running", lastTraceId: "trc_tab_projection" } });
 
+  assert.equal(rawTab.status, "unknown");
+  assert.equal(rawTab.running, false);
   assert.equal(tab.status, "running");
   assert.equal(tab.running, true);
 });
diff --git a/web/hwlab-cloud-web/src/components/workbench/ConversationPanel.vue b/web/hwlab-cloud-web/src/components/workbench/ConversationPanel.vue
index cd6ad4cb..75c07f83 100644
--- a/web/hwlab-cloud-web/src/components/workbench/ConversationPanel.vue
+++ b/web/hwlab-cloud-web/src/components/workbench/ConversationPanel.vue
@@ -23,9 +23,10 @@ const clipboard = useClipboard();
 const panelRef = ref<HTMLElement | null>(null);
 const following = ref(true);
 const detailMessageId = ref<string | null>(null);
-const detailMessage = computed(() => workbench.messages.find((message) => message.id === detailMessageId.value) ?? null);
+const visibleMessages = computed(() => workbench.sessionDetailLoading ? [] : workbench.activeMessages);
+const detailMessage = computed(() => workbench.activeMessages.find((message) => message.id === detailMessageId.value) ?? null);
 const traceTimelinePolicy = computed(() => workbenchTraceTimelinePolicy());
-const scrollSignature = computed(() => workbench.messages.map((message) => [
+const scrollSignature = computed(() => workbench.activeMessages.map((message) => [
   message.id,
   message.status,
   message.text?.length ?? 0,
@@ -69,7 +70,12 @@ function isAwaitingAgentBody(message: ChatMessage): boolean {
 }
 
 function showMessageText(message: ChatMessage): boolean {
-  return message.role !== "agent" || Boolean(String(message.text ?? "").trim());
+  return !messageDiagnosticText(message) && (message.role !== "agent" || Boolean(String(message.text ?? "").trim()));
+}
+
+function messageDiagnosticText(message: ChatMessage): string | null {
+  if (message.role !== "user" || String(message.text ?? "").trim()) return null;
+  return "消息内容缺失：Workbench read model 未返回 user text。";
 }
 
 function onPanelScroll(): void {
@@ -85,7 +91,7 @@ function scrollToBottom(): void {
 }
 
 function acknowledgeVisibleMessages(): void {
-  acknowledgeWorkbenchVisibleAfterPaint({ messages: workbench.messages, activeSessionId: workbench.activeSessionId, detailLoading: workbench.sessionDetailLoading });
+  acknowledgeWorkbenchVisibleAfterPaint({ messages: workbench.activeMessages, activeSessionId: workbench.activeSessionId, detailLoading: workbench.sessionDetailLoading });
 }
 
 function traceStorageKey(message: ChatMessage): string {
@@ -100,7 +106,7 @@ function traceAutoExpanded(message: ChatMessage): boolean | null {
 <template>
   <section id="conversation-list" ref="panelRef" class="conversation-panel" :data-following="following ? 'true' : 'false'" @scroll="onPanelScroll">
     <LoadingState v-if="workbench.sessionDetailLoading" class="conversation-detail-loading" label="加载中" />
-    <article v-for="message in workbench.sessionDetailLoading ? [] : workbench.messages" :key="message.id" class="message-card" :data-role="message.role" :data-status="message.status">
+    <article v-for="message in visibleMessages" :key="message.id" class="message-card" :data-role="message.role" :data-status="message.status">
       <header v-if="message.role !== 'user'">
         <strong>{{ message.title }}</strong>
         <div class="message-header-actions">
@@ -111,10 +117,11 @@ function traceAutoExpanded(message: ChatMessage): boolean | null {
       </header>
       <TraceTimeline v-if="message.role === 'agent' && message.runnerTrace" :trace="message.runnerTrace" :auto-expanded="traceAutoExpanded(message)" :storage-key="traceStorageKey(message)" />
       <LoadingState v-if="isAwaitingAgentBody(message)" class="message-loading" label="思考中..." compact />
-      <MessageMarkdown v-if="showMessageText(message)" class="message-text" :source="message.text" />
+      <p v-if="messageDiagnosticText(message)" class="message-text projection-diagnostic">{{ messageDiagnosticText(message) }}</p>
+      <MessageMarkdown v-else-if="showMessageText(message)" class="message-text" :source="message.text" />
     </article>
-    <div v-if="!workbench.sessionDetailLoading && workbench.messages.length === 0 && workbench.error" class="conversation-empty-hint conversation-error-hint">加载失败：{{ workbench.error }}</div>
-    <div v-else-if="!workbench.sessionDetailLoading && workbench.messages.length === 0" class="conversation-empty-hint">发起对话，或从左侧选择 session。</div>
+    <div v-if="!workbench.sessionDetailLoading && workbench.activeMessages.length === 0 && workbench.error" class="conversation-empty-hint conversation-error-hint">加载失败：{{ workbench.error }}</div>
+    <div v-else-if="!workbench.sessionDetailLoading && workbench.activeMessages.length === 0" class="conversation-empty-hint">发起对话，或从左侧选择 session。</div>
     <div v-if="detailMessage" class="workbench-dialog-backdrop" role="presentation" @click.self="detailMessageId = null">
       <section id="message-detail-dialog" class="workbench-dialog wide" role="dialog" aria-modal="true" aria-labelledby="message-detail-title">
         <header>
diff --git a/web/hwlab-cloud-web/src/stores/workbench-server-state.ts b/web/hwlab-cloud-web/src/stores/workbench-server-state.ts
index 0420dd31..181e7cd0 100644
--- a/web/hwlab-cloud-web/src/stores/workbench-server-state.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench-server-state.ts
@@ -5,6 +5,7 @@ import type { ChatMessage, WorkbenchSessionRecord } from "@/types";
 import type { SessionStatusAuthority, TurnStatusAuthority } from "./workbench-session";
 
 export interface WorkbenchServerState {
+  sessionOrder: string[];
   sessionsById: Record<string, WorkbenchSessionRecord>;
   messagesBySessionId: Record<string, ChatMessage[]>;
   sessionStatusById: Record<string, SessionStatusAuthority>;
@@ -15,6 +16,7 @@ export interface WorkbenchServerState {
 export type WorkbenchServerAction =
   | { type: "session.list"; sessions: WorkbenchSessionRecord[] }
   | { type: "session.detail"; session: WorkbenchSessionRecord | null | undefined }
+  | { type: "session.messages"; sessionId: string | null | undefined; messages: ChatMessage[] }
   | { type: "session.status"; session: SessionStatusAuthority }
   | { type: "session.forget"; sessionId: string }
   | { type: "turn.status"; turn: TurnStatusAuthority }
@@ -23,6 +25,7 @@ export type WorkbenchServerAction =
 
 export function createWorkbenchServerState(): WorkbenchServerState {
   return {
+    sessionOrder: [],
     sessionsById: {},
     messagesBySessionId: {},
     sessionStatusById: {},
@@ -34,13 +37,21 @@ export function createWorkbenchServerState(): WorkbenchServerState {
 export function reduceWorkbenchServerState(state: WorkbenchServerState, action: WorkbenchServerAction): WorkbenchServerState {
   switch (action.type) {
     case "session.list":
-      return action.sessions.reduce((next, session) => reduceWorkbenchServerState(next, { type: "session.detail", session }), state);
+      return reduceSessionList(state, action.sessions);
     case "session.detail":
       return reduceSessionDetail(state, action.session);
+    case "session.messages":
+      return reduceSessionMessages(state, action.sessionId, action.messages);
     case "session.status":
       return { ...state, sessionStatusById: { ...state.sessionStatusById, [action.session.sessionId]: action.session } };
     case "session.forget":
-      return { ...state, sessionStatusById: withoutKey(state.sessionStatusById, action.sessionId) };
+      return {
+        ...state,
+        sessionOrder: state.sessionOrder.filter((id) => id !== action.sessionId),
+        sessionsById: withoutKey(state.sessionsById, action.sessionId),
+        messagesBySessionId: withoutKey(state.messagesBySessionId, action.sessionId),
+        sessionStatusById: withoutKey(state.sessionStatusById, action.sessionId)
+      };
     case "turn.status":
       return { ...state, turnStatusByTraceId: { ...state.turnStatusByTraceId, [action.turn.traceId]: action.turn } };
     case "turn.forget":
@@ -62,6 +73,10 @@ export function selectTraceAuthorityById(state: WorkbenchServerState): Readonly<
   return state.traceById;
 }
 
+export function selectSessionList(state: WorkbenchServerState): WorkbenchSessionRecord[] {
+  return state.sessionOrder.map((sessionId) => state.sessionsById[sessionId]).filter((session): session is WorkbenchSessionRecord => Boolean(session));
+}
+
 export function selectActiveSession(state: WorkbenchServerState, sessionId: string | null): WorkbenchSessionRecord | null {
   return sessionId ? state.sessionsById[sessionId] ?? null : null;
 }
@@ -73,20 +88,53 @@ export function selectActiveMessages(state: WorkbenchServerState, sessionId: str
 function reduceSessionDetail(state: WorkbenchServerState, session: WorkbenchSessionRecord | null | undefined): WorkbenchServerState {
   const sessionId = session?.sessionId;
   if (!sessionId || !session) return state;
+  const existing = state.sessionsById[sessionId];
+  const messages = Array.isArray(session.messages) ? session.messages : state.messagesBySessionId[sessionId] ?? existing?.messages ?? [];
+  const merged = mergeSessionRecord(existing, { ...session, messages });
   const sessionStatus = sessionStatusAuthorityFromDetail(session);
   return {
     ...state,
-    sessionsById: { ...state.sessionsById, [sessionId]: session },
+    sessionOrder: state.sessionOrder.includes(sessionId) ? state.sessionOrder : [sessionId, ...state.sessionOrder],
+    sessionsById: { ...state.sessionsById, [sessionId]: merged },
     sessionStatusById: sessionStatus
       ? { ...state.sessionStatusById, [sessionId]: sessionStatus }
       : state.sessionStatusById,
     messagesBySessionId: {
       ...state.messagesBySessionId,
-      [sessionId]: Array.isArray(session.messages) ? session.messages : state.messagesBySessionId[sessionId] ?? []
+      [sessionId]: messages
     }
   };
 }
 
+function reduceSessionList(state: WorkbenchServerState, sessions: WorkbenchSessionRecord[]): WorkbenchServerState {
+  const sessionIds = sessions.map((session) => session.sessionId).filter((sessionId): sessionId is string => Boolean(sessionId));
+  const next = sessions.reduce((current, session) => reduceSessionDetail(current, session), state);
+  return { ...next, sessionOrder: unique(sessionIds) };
+}
+
+function reduceSessionMessages(state: WorkbenchServerState, sessionId: string | null | undefined, messages: ChatMessage[]): WorkbenchServerState {
+  if (!sessionId) return state;
+  const existing = state.sessionsById[sessionId];
+  const session = existing ? { ...existing, messages, messageCount: messages.length } : null;
+  return {
+    ...state,
+    sessionsById: session ? { ...state.sessionsById, [sessionId]: session } : state.sessionsById,
+    messagesBySessionId: { ...state.messagesBySessionId, [sessionId]: messages }
+  };
+}
+
+function mergeSessionRecord(existing: WorkbenchSessionRecord | undefined, incoming: WorkbenchSessionRecord): WorkbenchSessionRecord {
+  if (!existing) return incoming;
+  const incomingMessages = Array.isArray(incoming.messages) ? incoming.messages : undefined;
+  const existingMessages = Array.isArray(existing.messages) ? existing.messages : [];
+  return {
+    ...existing,
+    ...incoming,
+    messages: incomingMessages ?? existing.messages,
+    messageCount: incoming.messageCount ?? existing.messageCount ?? incomingMessages?.length ?? existingMessages.length
+  };
+}
+
 function sessionStatusAuthorityFromDetail(session: WorkbenchSessionRecord): SessionStatusAuthority | null {
   const sessionId = session.sessionId;
   if (!sessionId || typeof session.status !== "string") return null;
@@ -105,3 +153,7 @@ function withoutKey<T>(source: Record<string, T>, key: string): Record<string, T
   delete next[key];
   return next;
 }
+
+function unique(values: string[]): string[] {
+  return [...new Set(values)];
+}
diff --git a/web/hwlab-cloud-web/src/stores/workbench-session.ts b/web/hwlab-cloud-web/src/stores/workbench-session.ts
index f2798e60..415b1303 100644
--- a/web/hwlab-cloud-web/src/stores/workbench-session.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench-session.ts
@@ -251,9 +251,9 @@ function latestAgentMessage(messages: ChatMessage[] | undefined): ChatMessage |
 }
 
 function resolveSessionTabStatus(session: WorkbenchSessionRecord, authority: SessionStatusAuthority | null | undefined): string {
+  void session;
   const authorityStatus = normalizeSessionStatus(authority?.status);
-  if (authorityStatus) return authorityStatus;
-  return normalizeSessionStatus(session.status) ?? "unknown";
+  return authorityStatus ?? "unknown";
 }
 
 function messageBelongsToCancelTarget(message: ChatMessage, input: { targetSessionId?: string | null; targetThreadId?: string | null }): boolean {
diff --git a/web/hwlab-cloud-web/src/stores/workbench.ts b/web/hwlab-cloud-web/src/stores/workbench.ts
index 7d534195..c3beb735 100644
--- a/web/hwlab-cloud-web/src/stores/workbench.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench.ts
@@ -1,7 +1,7 @@
 // SPEC: PJ2026-010403 API契约 draft-2026-06-18-r1; PJ2026-010401 Web工作台 draft-2026-06-18-r1; PJ2026-0104010803 唯一投影 draft-2026-06-18-p0-unique-projection; PJ2026-01060505 Workbench Performance draft-2026-06-17-p0.
 // Responsibility: Session-first Workbench state orchestration for selection, turn admission, and trace lifecycle rendering.
 
-import { computed, ref } from "vue";
+import { computed, nextTick, ref } from "vue";
 import { defineStore } from "pinia";
 import { api } from "@/api";
 import { connectWorkbenchEvents, type WorkbenchEventStream, type WorkbenchRealtimeEvent } from "@/api/workbench-events";
@@ -11,7 +11,7 @@ import { firstNonEmptyString, nextProtocolId, normalizeWorkbenchSessionId, norma
 import { failWorkbenchSessionSwitch, failWorkbenchSubmitJourney, finishWorkbenchSessionSwitchFullLoad, markWorkbenchSubmitApiAccepted, markWorkbenchTraceEventsReceived, markWorkbenchTraceProjected, startWorkbenchSessionSwitch, startWorkbenchSubmitJourney } from "@/utils/workbench-performance";
 import { RECENT_DRAFTS_STORAGE_KEY, defaultProviderProfileOptions, isArchivedSession, mergeSessionIntoList, normalizeChatMessageStatus, normalizeRecentDrafts, normalizeWorkbenchMessageTitle, providerProfileOptionsFromPayload, recordRecentDraft, resolveCancelableAgentMessage, resolveComposerState, shouldShowSessionListLoading, sortSessionTabs, stableSessionList, type DraftEntry, type ProviderProfileOption, type TurnStatusAuthority } from "./workbench-session";
 import { initialWorkbenchSessionIdFromLocation } from "./workbench-projection";
-import { createWorkbenchServerState, reduceWorkbenchServerState, selectSessionStatusAuthority, selectTraceAuthorityById, selectTurnStatusAuthority, type WorkbenchServerAction } from "./workbench-server-state";
+import { createWorkbenchServerState, reduceWorkbenchServerState, selectActiveMessages, selectActiveSession, selectSessionList, selectSessionStatusAuthority, selectTraceAuthorityById, selectTurnStatusAuthority, type WorkbenchServerAction } from "./workbench-server-state";
 
 const DEFAULT_CODE_AGENT_TIMEOUT_MS = 1_800_000;
 const DEFAULT_GATEWAY_TIMEOUT_MS = 120_000;
@@ -19,17 +19,14 @@ const TRACE_HYDRATION_PAGE_LIMIT = 100;
 const TRACE_HYDRATION_MAX_PAGES = 60;
 const TRACE_HYDRATION_MAX_ATTEMPTS = 3;
 const TRACE_HYDRATION_RETRY_DELAY_MS = 700;
-const PROJECTION_CATCHUP_DELAY_MS = 1_000;
-const PROJECTION_CATCHUP_MAX_ATTEMPTS = 120;
-
+const ACTIVE_TURN_GAP_DELAY_MS = 1_000;
+const ACTIVE_TURN_GAP_MAX_ATTEMPTS = 12;
 interface HydrateOptions {
   sessionId?: string | null;
   invalidRouteId?: string | null;
 }
 
 export const useWorkbenchStore = defineStore("workbench", () => {
-  const sessions = ref<WorkbenchSessionRecord[]>([]);
-  const messages = ref<ChatMessage[]>([]);
   const providerProfile = ref<ProviderProfile>(readString("hwlab.workbench.providerProfile.v1", "codex"));
   const providerOptions = ref<ProviderProfileOption[]>(defaultProviderProfileOptions(providerProfile.value));
   const recentDrafts = ref<DraftEntry[]>(readRecentDrafts());
@@ -47,20 +44,23 @@ export const useWorkbenchStore = defineStore("workbench", () => {
   const explicitSessionId = ref<string | null>(initialWorkbenchSessionIdFromLocation());
   const selectionEpoch = ref(0);
   const serverState = ref(createWorkbenchServerState());
+  const sessions = computed(() => selectSessionList(serverState.value));
   const sessionStatusAuthority = computed(() => selectSessionStatusAuthority(serverState.value));
   const turnStatusAuthority = computed(() => selectTurnStatusAuthority(serverState.value));
   const traceAuthorityById = computed(() => selectTraceAuthorityById(serverState.value));
   const traceHydrationInFlight = new Set<string>();
   const terminalRealtimeRefreshInFlight = new Set<string>();
-  const projectionCatchupAttempts = new Map<string, number>();
+  const activeTurnGapAttempts = new Map<string, number>();
   let realtimeStream: WorkbenchEventStream | null = null;
   let realtimeKey = "";
   let realtimeGapTimer: number | null = null;
-  let projectionCatchupTimer: number | null = null;
+  let activeTurnGapTimer: number | null = null;
 
-  const activeSession = computed(() => explicitSessionId.value ? sessions.value.find((item) => item.sessionId === explicitSessionId.value) ?? null : null);
+  const activeSession = computed(() => selectActiveSession(serverState.value, explicitSessionId.value));
   const selectedSessionId = computed(() => firstNonEmptyString(activeSession.value?.sessionId, explicitSessionId.value));
   const activeSessionId = computed(() => selectedSessionId.value);
+  const activeMessages = computed(() => selectActiveMessages(serverState.value, activeSessionId.value));
+  const messages = activeMessages;
   const selectedThreadId = computed(() => firstNonEmptyString(activeSession.value?.threadId));
   const sessionTabs = computed(() => sortSessionTabs(sessions.value, activeSessionId.value, sessionStatusAuthority.value));
   const sessionListLoading = computed(() => shouldShowSessionListLoading({ loading: loading.value, sessionsReady: sessionsReady.value }));
@@ -97,14 +97,13 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       setActiveSessionSelection(targetSessionId);
     }
     if (targetSessionId) sessionDetailLoadingId.value = targetSessionId;
-    const previousMessages = messages.value;
     const selected = targetSessionId ? await loadWorkbenchSession(targetSessionId, listedSessions.find((item) => item.sessionId === targetSessionId) ?? null) : null;
-    if (selected && !isArchivedSession(selected) && isCurrentSessionSelection(requestEpoch, selected.sessionId)) applySelectedSessionDetail(selected, previousMessages);
+    if (selected && !isArchivedSession(selected) && routeRequestId && !routeSessionId && requestEpoch === selectionEpoch.value) setActiveSessionSelection(selected.sessionId);
+    if (selected && !isArchivedSession(selected) && isCurrentSessionSelection(requestEpoch, selected.sessionId)) applySelectedSessionDetail(selected);
     if (selected && !isArchivedSession(selected) && routeRequestId && !isCurrentSessionSelection(requestEpoch, selected.sessionId)) rememberSessionDetail(selected);
-    if (selected && isArchivedSession(selected)) isolateSessionLoadFailure(selected.sessionId, null, [], "session archived", { restorePrevious: false });
-    if (options.invalidRouteId || (targetSessionId && !selected)) isolateSessionLoadFailure(targetSessionId ?? options.invalidRouteId ?? "invalid-session", null, [], "session URL not found", { restorePrevious: false });
+    if (selected && isArchivedSession(selected)) isolateSessionLoadFailure(selected.sessionId, "session archived");
+    if (options.invalidRouteId || (targetSessionId && !selected)) isolateSessionLoadFailure(targetSessionId ?? options.invalidRouteId ?? "invalid-session", "session URL not found");
     const nextSessions = stableSessionList(sessions.value, listedSessions, selected?.sessionId ?? routeSessionId ?? includeSessionId, selected);
-    sessions.value = nextSessions;
     rememberSessionList(nextSessions);
     sessionsReady.value = true;
     void refreshSessionStatusAuthority(nextSessions);
@@ -137,8 +136,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       error.value = response.error ?? "session create failed";
       return;
     }
-    sessions.value = mergeSessionIntoList(sessions.value, created);
-    rememberSessionDetail(created);
+    rememberSessionList(mergeSessionIntoList(sessions.value, created));
     sessionsReady.value = true;
     setActiveSessionSelection(created.sessionId);
     await selectSession(created);
@@ -155,8 +153,6 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       error.value = "invalid session URL";
       return false;
     }
-    const previousSessionId = activeSessionId.value;
-    const previousMessages = messages.value;
     const existing = seed ?? sessions.value.find((session) => session.sessionId === normalized) ?? null;
     const requestEpoch = beginSessionSelection();
     startWorkbenchSessionSwitch({ sessionId: normalized ?? requestId, source: existing ? "rail" : "deeplink", targetState: existing?.status ?? "unknown", cache: (existing?.messages?.length ?? 0) > 0 ? "warm" : "cold" });
@@ -165,26 +161,31 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     loading.value = true;
     if (normalized) setActiveSessionSelection(normalized);
     if (existing) {
-      sessions.value = mergeSessionIntoList(sessions.value, existing);
-      rememberSessionDetail(existing);
+      rememberSessionList(mergeSessionIntoList(sessions.value, existing));
       sessionsReady.value = true;
     }
     const selected = await loadWorkbenchSession(requestId, existing);
-    if (!isCurrentSessionRequest(requestEpoch, requestId, selected?.sessionId ?? normalized)) return true;
-    if (selected && !isArchivedSession(selected)) {
-      applySelectedSessionDetail(selected, previousMessages);
+    if (selected && !isArchivedSession(selected) && !normalized && requestEpoch === selectionEpoch.value) setActiveSessionSelection(selected.sessionId);
+    if (!isCurrentSessionRequest(requestEpoch, requestId, selected?.sessionId ?? normalized)) {
       clearSessionDetailLoading(requestId);
       clearSwitchingSession(requestId);
+      return true;
+    }
+    if (selected && !isArchivedSession(selected)) {
+      applySelectedSessionDetail(selected);
+      await nextTick();
       loading.value = false;
+      clearSessionDetailLoading(requestId);
+      clearSwitchingSession(requestId);
       error.value = null;
       await refreshSessions(selected.sessionId);
       finishWorkbenchSessionSwitchFullLoad(selected.sessionId, "ok");
       return activeSessionId.value === selected.sessionId;
     }
-    isolateSessionLoadFailure(requestId, previousSessionId, previousMessages, isArchivedSession(selected) ? "session archived" : "session URL not found", { restorePrevious: Boolean(seed && normalized) });
+    loading.value = false;
     clearSessionDetailLoading(requestId);
     clearSwitchingSession(requestId);
-    loading.value = false;
+    isolateSessionLoadFailure(requestId, isArchivedSession(selected) ? "session archived" : "session URL not found");
     failWorkbenchSessionSwitch(normalized ?? requestId);
     return false;
   }
@@ -198,7 +199,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       error.value = response.error ?? "session delete failed";
       return;
     }
-    sessions.value = sessions.value.filter((session) => session.sessionId !== sessionId);
+    forgetSession(sessionId);
     await refreshSessions(null);
     const next = sessions.value.find((session) => !isArchivedSession(session)) ?? null;
     replaceActiveSessionSelection(next?.sessionId ?? null);
@@ -207,7 +208,6 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       await selectSession(next);
       return;
     }
-    messages.value = [];
     restartRealtime("delete-current-session");
   }
 
@@ -215,7 +215,6 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     const response = await api.workbench.sessions({ includeSessionId });
     if (response.ok) {
       const next = stableSessionList(sessions.value, workbenchSessionsFromPayload(response.data), includeSessionId, activeSession.value);
-      sessions.value = next;
       rememberSessionList(next);
       sessionsReady.value = true;
       await refreshSessionStatusAuthority(next);
@@ -237,6 +236,26 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     reduceServerState({ type: "session.list", sessions: source });
   }
 
+  function forgetSession(sessionId: string): void {
+    reduceServerState({ type: "session.forget", sessionId });
+  }
+
+  function rememberSessionMessages(sessionId: string | null | undefined, source: ChatMessage[]): void {
+    reduceServerState({ type: "session.messages", sessionId, messages: source });
+  }
+
+  function replaceActiveMessages(source: ChatMessage[]): void {
+    rememberSessionMessages(activeSessionId.value, source);
+  }
+
+  function updateActiveMessages(project: (source: ChatMessage[]) => ChatMessage[]): void {
+    replaceActiveMessages(project(messages.value));
+  }
+
+  function appendActiveMessages(...items: ChatMessage[]): void {
+    replaceActiveMessages([...messages.value, ...items]);
+  }
+
   function setActiveSessionSelection(sessionId: string | null | undefined): void {
     explicitSessionId.value = normalizeWorkbenchSessionId(sessionId) ?? explicitSessionId.value;
   }
@@ -296,7 +315,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     const status = statusFromResult(result.status);
     const terminal = (result as AgentChatResultResponse).terminal === true || isTerminalMessageStatus(status);
     const authoritySessionId = traceResultSessionId(result);
-    messages.value = messages.value.map((message) => {
+    updateActiveMessages((source) => source.map((message) => {
       if (!shouldApplyTraceToMessage(message, traceId, authoritySessionId)) return message;
       const runnerTrace = mergeTerminalResultTrace(message.runnerTrace, result as AgentChatResultResponse);
       rememberTraceAuthority(runnerTrace);
@@ -309,7 +328,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
         ? firstNonEmptyString((result as AgentChatResultResponse).assistantText, finalResponseText((result as AgentChatResultResponse).finalResponse), replyText, errorText, (result as AgentChatResultResponse).text, (result as AgentChatResultResponse).summary, traceAssistantText, message.text, "Code Agent 已完成，但没有返回可展示的 final response。") ?? message.text
         : message.text;
       return { ...message, status, text, runnerTrace, error: error ?? message.error ?? null, agentRun: agentRun ?? undefined, updatedAt: new Date().toISOString() };
-    });
+    }));
   }
 
   async function submitMessage(text: string): Promise<void> {
@@ -317,7 +336,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     if (!value) return;
     beginSessionSelection();
     if (!composer.value.sessionId) {
-      messages.value.push(makeMessage("system", "session_required：请先显式新建或选择 Code Agent session。", "blocked", { title: "需要 Session" }));
+      error.value = "session_required：请先显式新建或选择 Code Agent session。";
       return;
     }
     const steerMode = composer.value.submitMode === "steer";
@@ -329,7 +348,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     const providerThreadId = providerThreadIdForRequest(threadId);
     const user = makeMessage("user", value, "sent", { traceId: steerTraceId ?? traceId, sessionId, threadId, title: steerMode ? "用户引导" : "用户" });
     const pending = makeMessage("agent", "", "running", { traceId, sessionId, threadId, title: "Code Agent", retryInput: value, traceAutoLifecycle: "running" });
-    messages.value.push(user, pending);
+    appendActiveMessages(user, pending);
     startWorkbenchSubmitJourney({ traceId, sessionId, entry: submitEntry, backend: providerProfile.value, transport: "sse" });
     chatPending.value = true;
     currentRequest.value = { traceId, sessionId, threadId, status: "running" };
@@ -440,18 +459,11 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     await Promise.all(source.filter(messageNeedsTraceHydration).slice(-12).map((message) => hydrateTraceEventsForMessage(message)));
   }
 
-  function restoreMessagesTraceAuthority(source: ChatMessage[], previous: ChatMessage[] = []): ChatMessage[] {
-    const previousTraceById = new Map<string, NonNullable<ChatMessage["runnerTrace"]>>();
-    for (const message of previous) {
-      const trace = message.runnerTrace;
-      const traceId = firstNonEmptyString(message.traceId, trace?.traceId);
-      if (!traceId || !trace || !traceHasEvents(trace)) continue;
-      previousTraceById.set(traceId, trace);
-    }
+  function messagesWithTraceAuthority(source: ChatMessage[]): ChatMessage[] {
     return source.map((message) => {
       if (message.role !== "agent") return message;
       const traceId = firstNonEmptyString(message.traceId, message.runnerTrace?.traceId);
-      const authority = traceId ? traceAuthorityById.value[traceId] ?? previousTraceById.get(traceId) ?? null : null;
+      const authority = traceId ? traceAuthorityById.value[traceId] ?? null : null;
       if (!authority) return message;
       return { ...message, runnerTrace: mergeRunnerTrace(message.runnerTrace, authority) };
     });
@@ -471,7 +483,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     if (!shouldApplyActiveTraceAuthority(traceId, authoritySessionId)) return;
     const events = Array.isArray(result.events) ? result.events : Array.isArray(result.traceEvents) ? result.traceEvents : [];
     markWorkbenchTraceEventsReceived({ traceId, events, transport: "rest_gap" });
-    messages.value = messages.value.map((message) => {
+    updateActiveMessages((source) => source.map((message) => {
       if (!shouldApplyTraceToMessage(message, traceId, authoritySessionId)) return message;
       const runnerTrace = mergeRunnerTrace(message.runnerTrace, {
         ...(result.runnerTrace ?? {}),
@@ -507,7 +519,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       const agentRun = agentRunFromResult(result, runnerTrace) ?? agentRunFromMessage(message);
       rememberTraceAuthority(runnerTrace);
       return { ...message, status, text, runnerTrace, error: error ?? message.error ?? null, agentRun: agentRun ?? undefined, updatedAt: new Date().toISOString() };
-    });
+    }));
     markWorkbenchTraceProjected(traceId);
   }
 
@@ -537,7 +549,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
 
   function clearSessionMessages(): void {
     const activeTraceId = activeTraceIdFromMessages(messages.value, turnStatusAuthority.value);
-    messages.value = [];
+    replaceActiveMessages([]);
     currentRequest.value = null;
     if (activeTraceId) void clearActiveTrace(activeTraceId, "clear-session-messages");
     restartRealtime("clear-session-messages");
@@ -545,7 +557,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
 
   function reattachTrace(traceId: string): void {
     const initial: AgentChatResponse = { status: "running", traceId, turnUrl: `/v1/workbench/turns/${encodeURIComponent(traceId)}` };
-    if (!messages.value.some((message) => message.traceId === traceId)) messages.value.push(makeMessage("agent", "", "running", { traceId, sessionId: selectedSessionId.value ?? undefined, threadId: selectedThreadId.value ?? undefined, title: "Code Agent", traceAutoLifecycle: "running" }));
+    if (!messages.value.some((message) => message.traceId === traceId)) appendActiveMessages(makeMessage("agent", "", "running", { traceId, sessionId: selectedSessionId.value ?? undefined, threadId: selectedThreadId.value ?? undefined, title: "Code Agent", traceAutoLifecycle: "running" }));
     currentRequest.value = { traceId, sessionId: selectedSessionId.value ?? null, threadId: selectedThreadId.value ?? null, status: initial.status };
     restartRealtime("reattach");
     scheduleRealtimeGapHydration("reattach");
@@ -721,27 +733,27 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       hydrateTraceEvents(messages.value)
     ]);
     restartRealtime(`gap:${reason}`);
-    scheduleProjectionCatchup(reason);
+    scheduleActiveTurnGapRefresh(reason);
   }
 
-  function scheduleProjectionCatchup(reason: string): void {
-    const traceId = activeProjectionCatchupTraceId();
+  function scheduleActiveTurnGapRefresh(reason: string): void {
+    const traceId = activeTurnGapTraceId();
     if (!traceId) {
-      clearProjectionCatchup();
+      clearActiveTurnGapRefresh();
       return;
     }
-    if (projectionCatchupTimer) return;
-    const attempts = projectionCatchupAttempts.get(traceId) ?? 0;
-    if (attempts >= PROJECTION_CATCHUP_MAX_ATTEMPTS) return;
-    projectionCatchupAttempts.set(traceId, attempts + 1);
+    if (activeTurnGapTimer) return;
+    const attempts = activeTurnGapAttempts.get(traceId) ?? 0;
+    if (attempts >= ACTIVE_TURN_GAP_MAX_ATTEMPTS) return;
+    activeTurnGapAttempts.set(traceId, attempts + 1);
     if (typeof window === "undefined") return;
-    projectionCatchupTimer = window.setTimeout(() => {
-      projectionCatchupTimer = null;
-      void hydrateRealtimeGap(`projection-catchup:${reason}`);
-    }, PROJECTION_CATCHUP_DELAY_MS);
+    activeTurnGapTimer = window.setTimeout(() => {
+      activeTurnGapTimer = null;
+      void hydrateRealtimeGap(`active-turn-gap:${reason}`);
+    }, ACTIVE_TURN_GAP_DELAY_MS);
   }
 
-  function activeProjectionCatchupTraceId(): string | null {
+  function activeTurnGapTraceId(): string | null {
     const traceId = realtimeTraceId();
     if (!traceId) return null;
     const turn = turnStatusAuthority.value[traceId];
@@ -754,11 +766,11 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     return active ? traceId : null;
   }
 
-  function clearProjectionCatchup(traceId?: string | null): void {
-    if (traceId) projectionCatchupAttempts.delete(traceId);
-    else projectionCatchupAttempts.clear();
-    if (typeof window !== "undefined" && projectionCatchupTimer) window.clearTimeout(projectionCatchupTimer);
-    projectionCatchupTimer = null;
+  function clearActiveTurnGapRefresh(traceId?: string | null): void {
+    if (traceId) activeTurnGapAttempts.delete(traceId);
+    else activeTurnGapAttempts.clear();
+    if (typeof window !== "undefined" && activeTurnGapTimer) window.clearTimeout(activeTurnGapTimer);
+    activeTurnGapTimer = null;
   }
 
   function installRealtimeVisibilityHandler(): void {
@@ -777,7 +789,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     rememberTurnStatus(traceId, snapshot);
     const status = statusFromResult(snapshot.status);
     const terminal = isTerminalMessageStatus(status);
-    messages.value = messages.value.map((message) => {
+    updateActiveMessages((source) => source.map((message) => {
       if (!shouldApplyTraceToMessage(message, traceId, authoritySessionId)) return message;
       const runnerTrace = mergeRunnerTrace(message.runnerTrace, trace);
       rememberTraceAuthority(runnerTrace);
@@ -790,7 +802,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
           ? firstNonEmptyString(traceAssistantText, finalResponseText(runnerTrace.finalResponse), errorText, message.text) ?? message.text
           : message.text;
       return { ...message, status, text: nextText, traceAutoLifecycle: terminal ? "terminal" : "running", runnerTrace, error: error ?? message.error ?? null, updatedAt: new Date().toISOString() };
-    });
+    }));
     markWorkbenchTraceProjected(traceId);
     void refreshSessions(trace.sessionId ?? selectedSessionId.value);
   }
@@ -798,21 +810,21 @@ export const useWorkbenchStore = defineStore("workbench", () => {
   function completeTrace(traceId: string, result: AgentChatResultResponse): void {
     const authoritySessionId = traceResultSessionId(result);
     if (!shouldApplyActiveTraceAuthority(traceId, authoritySessionId)) return;
-    clearProjectionCatchup(traceId);
     const resultTrace = recordValue(result.runnerTrace);
     const traceAssistantText = assistantTextFromTraceEvents(firstArray(result.events, result.traceEvents, resultTrace?.events));
     const text = firstNonEmptyString(result.assistantText, finalResponseText(result.finalResponse), typeof result.reply === "string" ? result.reply : result.reply?.content, agentErrorDisplayText(result.error), result.text, result.summary, traceAssistantText) ?? "Code Agent 已完成，但没有返回可展示的 final response。";
     const terminalStatus = result.status === "completed" ? "completed" : statusFromResult(result.status);
-    messages.value = messages.value.map((message) => {
+    updateActiveMessages((source) => source.map((message) => {
       if (!shouldApplyTraceToMessage(message, traceId, authoritySessionId)) return message;
       const runnerTrace = mergeTerminalResultTrace(message.runnerTrace, result);
       rememberTraceAuthority(runnerTrace);
       const error = normalizeAgentError(result.error ?? runnerTrace?.error ?? message.error);
       const agentRun = agentRunFromResult(result, runnerTrace) ?? agentRunFromMessage(message);
       return { ...message, status: terminalStatus, text, traceAutoLifecycle: "terminal", runnerTrace, error: error ?? message.error ?? null, agentRun: agentRun ?? undefined, updatedAt: new Date().toISOString() };
-    });
+    }));
     rememberTurnStatus(traceId, result);
     markWorkbenchTraceProjected(traceId);
+    clearActiveTurnGapRefresh(traceId);
     void hydrateTraceEvents(messages.value);
     chatPending.value = false;
     currentRequest.value = null;
@@ -836,7 +848,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
   function applyTerminalResultDiagnostics(traceId: string, result: AgentChatResultResponse): void {
     const authoritySessionId = traceResultSessionId(result);
     if (!shouldApplyActiveTraceAuthority(traceId, authoritySessionId)) return;
-    messages.value = messages.value.map((message) => {
+    updateActiveMessages((source) => source.map((message) => {
       if (!shouldApplyTraceToMessage(message, traceId, authoritySessionId)) return message;
       const runnerTrace = mergeTerminalResultTrace(message.runnerTrace, result);
       rememberTraceAuthority(runnerTrace);
@@ -844,7 +856,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       const agentRun = agentRunFromResult(result, runnerTrace) ?? agentRunFromMessage(message);
       const status = statusFromResult(result.status);
       return { ...message, status, title: normalizeWorkbenchMessageTitle(message.role, message.title), runnerTrace, error: error ?? message.error ?? null, agentRun: agentRun ?? undefined, updatedAt: new Date().toISOString() };
-    });
+    }));
     void hydrateTraceEvents(messages.value);
     void refreshSessions(result.sessionId ?? activeSessionId.value);
   }
@@ -862,7 +874,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     reduceServerState({ type: "turn.status", turn: { traceId: input.traceId, status: "running", running: true, terminal: false, sessionId: input.sessionId, threadId: input.threadId, updatedAt: now, loadedAt: now } });
     reduceServerState({ type: "session.status", session: { sessionId: input.sessionId, status: "running", updatedAt: now, lastTraceId: input.traceId, loadedAt: now } });
     const existing = sessions.value.find((session) => session.sessionId === input.sessionId) ?? null;
-    sessions.value = mergeSessionIntoList(sessions.value, {
+    rememberSessionList(mergeSessionIntoList(sessions.value, {
       ...(existing ?? {}),
       sessionId: input.sessionId,
       threadId: firstNonEmptyString(input.threadId, existing?.threadId),
@@ -872,12 +884,11 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       firstUserMessagePreview: firstNonEmptyString(existing?.firstUserMessagePreview, input.userText),
       messageCount: Math.max(existing?.messageCount ?? 0, messages.value.filter((message) => firstNonEmptyString(message.sessionId, message.runnerTrace?.sessionId) === input.sessionId).length),
       messages: messages.value.filter((message) => firstNonEmptyString(message.sessionId, message.runnerTrace?.sessionId) === input.sessionId)
-    } as WorkbenchSessionRecord);
-    rememberSessionList(sessions.value);
+    } as WorkbenchSessionRecord));
   }
 
   function markMessage(traceId: string, patch: Partial<ChatMessage>): void {
-    messages.value = messages.value.map((message) => message.traceId === traceId && message.role === "agent" ? { ...message, ...patch, updatedAt: new Date().toISOString() } : message);
+    updateActiveMessages((source) => source.map((message) => message.traceId === traceId && message.role === "agent" ? { ...message, ...patch, updatedAt: new Date().toISOString() } : message));
   }
 
   function alignOptimisticTurnMessages(traceId: string, lifecycle: AgentChatResponse): string {
@@ -886,21 +897,21 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     const userMessageId = firstNonEmptyString(lifecycle.userMessageId);
     const assistantMessageId = firstNonEmptyString(lifecycle.assistantMessageId);
     if (!turnId && !userMessageId && !assistantMessageId && canonicalTraceId === traceId) return canonicalTraceId;
-    messages.value = messages.value.map((message) => {
+    updateActiveMessages((source) => source.map((message) => {
       if (message.traceId !== traceId) return message;
       const runnerTrace = message.runnerTrace ? { ...message.runnerTrace, traceId: canonicalTraceId } : message.runnerTrace;
       const base = { ...message, traceId: canonicalTraceId, runnerTrace, updatedAt: new Date().toISOString() };
       if (message.role === "user" && userMessageId) return { ...base, id: userMessageId, messageId: userMessageId, turnId };
       if (message.role === "agent" && assistantMessageId) return { ...base, id: assistantMessageId, messageId: assistantMessageId, turnId };
       return turnId ? { ...base, turnId } : base;
-    });
+    }));
     return canonicalTraceId;
   }
 
   async function clearActiveTrace(traceId: string, reason: string): Promise<void> {
     void reason;
     if (currentRequest.value?.traceId === traceId) currentRequest.value = null;
-    if (!activeProjectionCatchupTraceId()) clearProjectionCatchup(traceId);
+    clearActiveTurnGapRefresh(traceId);
   }
 
   function beginSessionSelection(): number {
@@ -927,11 +938,10 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     if (!sessionId || sessionDetailLoadingId.value === sessionId) sessionDetailLoadingId.value = null;
   }
 
-  function applySelectedSessionDetail(session: WorkbenchSessionRecord, previousMessages: ChatMessage[]): void {
+  function applySelectedSessionDetail(session: WorkbenchSessionRecord): void {
     setActiveSessionSelection(session.sessionId);
-    rememberSessionDetail(session);
-    messages.value = restoreMessagesTraceAuthority(messagesFromSession(session), previousMessages);
-    sessions.value = mergeSessionIntoList(sessions.value, session);
+    const projectedMessages = messagesWithTraceAuthority(messagesFromSession(session));
+    rememberSessionDetail({ ...session, messages: projectedMessages, messageCount: session.messageCount ?? projectedMessages.length });
     sessionsReady.value = true;
     currentRequest.value = null;
     void hydrateTurnStatusAuthority(messages.value);
@@ -941,24 +951,9 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     restartRealtime("apply-selected-session");
   }
 
-  function isolateSessionLoadFailure(sessionId: string, previousSessionId: string | null, previousMessages: ChatMessage[], message: string, options: { restorePrevious?: boolean } = {}): void {
-    sessions.value = sessions.value.filter((item) => item.sessionId !== sessionId || (item.messages?.length ?? 0) > 0);
-    if (options.restorePrevious === true && previousSessionId && previousSessionId !== sessionId) {
-      const previous = sessions.value.find((item) => item.sessionId === previousSessionId) ?? null;
-      replaceActiveSessionSelection(previousSessionId);
-      if (previous) {
-        rememberSessionDetail(previous);
-        messages.value = restoreMessagesTraceAuthority(messagesFromSession(previous), previousMessages);
-        void hydrateTurnStatusAuthority(messages.value);
-        void hydrateTraceEvents(messages.value);
-        reattachRestoredActiveTrace();
-      } else {
-        messages.value = previousMessages;
-      }
-    } else {
-      replaceActiveSessionSelection(null);
-      messages.value = [];
-    }
+  function isolateSessionLoadFailure(sessionId: string, message: string): void {
+    forgetSession(sessionId);
+    replaceActiveSessionSelection(null);
     currentRequest.value = null;
     error.value = message;
     sessionsReady.value = sessions.value.length > 0;
@@ -973,7 +968,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
 
   installRealtimeVisibilityHandler();
 
-  return { sessions, messages, providerProfile, providerOptions, recentDrafts, codeAgentTimeoutMs, gatewayShellTimeoutMs, live, loading, sessionListLoading, sessionDetailLoading, chatPending, error, activeSessionId, selectedSessionId, selectedThreadId, sessionTabs, composer, hydrate, refreshLive, createSession, selectSession, selectSessionById, deleteCurrentSession, refreshSessions, submitMessage, cancelAgentMessage, cancelRunningTrace, retryAgentMessage, setProviderProfile, refreshProviderOptions, pickDraft, clearRecentDrafts, clearSessionMessages, recordActivity };
+  return { sessions, messages, activeMessages, providerProfile, providerOptions, recentDrafts, codeAgentTimeoutMs, gatewayShellTimeoutMs, live, loading, sessionListLoading, sessionDetailLoading, chatPending, error, activeSessionId, selectedSessionId, selectedThreadId, sessionTabs, composer, hydrate, refreshLive, createSession, selectSession, selectSessionById, deleteCurrentSession, refreshSessions, submitMessage, cancelAgentMessage, cancelRunningTrace, retryAgentMessage, setProviderProfile, refreshProviderOptions, pickDraft, clearRecentDrafts, clearSessionMessages, recordActivity };
 });
 
 function workbenchSessionsFromPayload(payload: unknown): WorkbenchSessionRecord[] {
@@ -1012,32 +1007,10 @@ async function loadWorkbenchSession(sessionId: string, seed: WorkbenchSessionRec
   const base = detailSession ?? seed;
   if (!base) return null;
   const page = messages.ok ? messages.data : null;
-  const pageMessages = Array.isArray(page?.messages) ? repairWorkbenchMessagePage(page.messages.map((message) => normalizeChatMessage(message as ChatMessage)), base) : base.messages;
+  const pageMessages = Array.isArray(page?.messages) ? page.messages.map((message) => normalizeChatMessage(message as ChatMessage)) : base.messages;
   return { ...base, sessionId: id, messages: pageMessages, messageCount: page?.total ?? pageMessages?.length ?? base.messageCount };
 }
 
-function repairWorkbenchMessagePage(messages: ChatMessage[], session: WorkbenchSessionRecord): ChatMessage[] {
-  const userFallback = firstNonEmptyString(session.firstUserMessagePreview, session.snapshot?.firstUserMessagePreview, session.userPreview, session.title, session.name);
-  return messages.map((message, index) => {
-    if (message.role !== "user" || firstNonEmptyString(message.text)) return message;
-    const matched = findMessageTextFallback(message, index, session.messages ?? []);
-    const text = firstNonEmptyString(matched, index === 0 ? userFallback : null);
-    return text ? { ...message, text } : message;
-  });
-}
-
-function findMessageTextFallback(message: ChatMessage, index: number, candidates: ChatMessage[]): string | null {
-  const messageId = firstNonEmptyString(message.messageId, message.id);
-  const traceId = firstNonEmptyString(message.traceId, message.runnerTrace?.traceId);
-  const turnId = firstNonEmptyString(message.turnId);
-  const matched = candidates.find((candidate) => candidate.role === message.role && Boolean(
-    (messageId && firstNonEmptyString(candidate.messageId, candidate.id) === messageId)
-    || (traceId && firstNonEmptyString(candidate.traceId, candidate.runnerTrace?.traceId) === traceId)
-    || (turnId && firstNonEmptyString(candidate.turnId) === turnId)
-  ));
-  return firstNonEmptyString(matched?.text, candidates.filter((candidate) => candidate.role === message.role)[index]?.text);
-}
-
 function providerThreadIdForRequest(threadId: string | null | undefined): string | null {
   const value = firstNonEmptyString(threadId) ?? null;
   if (!value) return null;
diff --git a/web/hwlab-cloud-web/tests/workbench-e2e/specs/submit-authority.spec.ts b/web/hwlab-cloud-web/tests/workbench-e2e/specs/submit-authority.spec.ts
index 3905a545..73df9c3c 100644
--- a/web/hwlab-cloud-web/tests/workbench-e2e/specs/submit-authority.spec.ts
+++ b/web/hwlab-cloud-web/tests/workbench-e2e/specs/submit-authority.spec.ts
@@ -22,10 +22,12 @@ test.describe("submit session authority", () => {
     expect(legacyGets).toEqual([]);
   });
 
-  test("replay preserves user prompt when messages page has empty user text but list preview has authority", async ({ page }) => {
+  test("message page empty user text is diagnostic, not repaired from list preview", async ({ page }) => {
     await gotoWorkbench(page, "/workbench/sessions/ses_submit_split");
     await expect(page.locator(sessionTab("ses_submit_split"))).toContainText("workbench submit race probe redacted");
-    await expect(page.locator(`${selectors.messageCard}[data-role="user"]`).first()).toContainText("workbench submit race probe redacted");
+    const userCard = page.locator(`${selectors.messageCard}[data-role="user"]`).first();
+    await expect(userCard).not.toContainText("workbench submit race probe redacted");
+    await expect(userCard).toContainText("Workbench read model 未返回 user text");
     await expect(page.locator(`${selectors.messageCard}[data-role="agent"][data-status="running"]`)).toBeVisible();
 
     const state = await fakeServerState(page);