diff --git a/internal/cloud/server-workbench-http.test.ts b/internal/cloud/server-workbench-http.test.ts
index af350403..22ad3308 100644
--- a/internal/cloud/server-workbench-http.test.ts
+++ b/internal/cloud/server-workbench-http.test.ts
@@ -186,6 +186,85 @@ test("workbench read model recovers trace events from durable projection without
   }
 });
 
+test("workbench read model projects terminal result atomically across session, messages, and turn", async () => {
+  const traceStore = createCodeAgentTraceStore();
+  const results = createCodeAgentChatResultStore();
+  const traceId = "trc_workbench_terminal_atomic";
+  const finalText = "terminal projection final response";
+  const session = {
+    id: "ses_workbench_terminal_atomic",
+    projectId: "prj_hwpod_workbench",
+    agentId: "hwlab-code-agent",
+    status: "running",
+    ownerUserId: ACTOR.id,
+    conversationId: "cnv_workbench_terminal_atomic",
+    threadId: "thread-workbench-terminal-atomic",
+    lastTraceId: traceId,
+    updatedAt: "2026-06-17T02:10:00.000Z",
+    session: {
+      sessionStatus: "running",
+      lastTraceId: traceId,
+      messages: [
+        { role: "user", text: "terminal atomic ping", traceId, status: "sent", createdAt: "2026-06-17T02:09:58.000Z" },
+        { role: "agent", text: "", traceId, status: "running", createdAt: "2026-06-17T02:09:59.000Z" }
+      ],
+      valuesRedacted: true,
+      secretMaterialStored: false
+    }
+  };
+  traceStore.append(traceId, { seq: 1, type: "request", status: "accepted", label: "request:accepted" });
+  traceStore.append(traceId, { seq: 2, type: "result", status: "completed", label: "result:completed", terminal: true });
+  results.set(traceId, {
+    status: "completed",
+    traceId,
+    ownerUserId: ACTOR.id,
+    conversationId: session.conversationId,
+    sessionId: session.id,
+    threadId: session.threadId,
+    finalResponse: { text: finalText, status: "completed", traceId },
+    agentRun: { runId: "run_workbench_terminal_atomic", commandId: "cmd_workbench_terminal_atomic", status: "completed", terminalStatus: "completed" }
+  });
+  const accessController = {
+    store: {
+      async listAgentSessionsForUser() { return [session]; },
+      async getAgentSession(sessionId) { return sessionId === session.id ? session : null; },
+      async getAgentSessionByTraceId(requestTraceId) { return requestTraceId === traceId ? session : null; }
+    },
+    async ensureBootstrap() {},
+    async authenticate() { return { ok: true, actor: ACTOR, session: { id: "uss_workbench_reader" } }; }
+  };
+  const server = createCloudApiServer({ accessController, traceStore, codeAgentChatResults: results });
+  await new Promise((resolve) => server.listen(0, "127.0.0.1", resolve));
+
+  try {
+    const { port } = server.address();
+    const sessions = await getJson(port, `/v1/workbench/sessions?includeSessionId=${encodeURIComponent(session.id)}`);
+    assert.equal(sessions.status, 200);
+    assert.equal(sessions.body.sessions[0].status, "completed");
+    assert.equal(sessions.body.sessions[0].running, false);
+    assert.equal(sessions.body.sessions[0].terminal, true);
+
+    const messages = await getJson(port, `/v1/workbench/sessions/${encodeURIComponent(session.id)}/messages?limit=10`);
+    assert.equal(messages.status, 200);
+    assert.equal(messages.body.total, 2);
+    const assistant = messages.body.messages[1];
+    assert.equal(assistant.role, "agent");
+    assert.equal(assistant.status, "completed");
+    assert.equal(assistant.text, finalText);
+    assert.equal(assistant.parts[0].status, "completed");
+    assert.equal(assistant.parts[0].text, finalText);
+
+    const turn = await getJson(port, `/v1/workbench/turns/${encodeURIComponent(traceId)}`);
+    assert.equal(turn.status, 200);
+    assert.equal(turn.body.turn.status, "completed");
+    assert.equal(turn.body.turn.terminal, true);
+    assert.equal(turn.body.turn.assistantText, finalText);
+    assert.equal(turn.body.turn.finalResponse.text, finalText);
+  } finally {
+    await new Promise((resolve, reject) => server.close((error) => error ? reject(error) : resolve()));
+  }
+});
+
 test("workbench read model does not expose trace-only memory without visible session or result owner", async () => {
   const traceStore = createCodeAgentTraceStore();
   const traceId = "trc_workbench_trace_only";
diff --git a/internal/cloud/server-workbench-http.ts b/internal/cloud/server-workbench-http.ts
index 11c7fb3d..f7c8d9d3 100644
--- a/internal/cloud/server-workbench-http.ts
+++ b/internal/cloud/server-workbench-http.ts
@@ -1,5 +1,5 @@
 /*
- * SPEC: PJ2026-010403 API契约 draft-2026-06-18-r1; PJ2026-010401 Web工作台 draft-2026-06-18-r1; PJ2026-01060505 Workbench Performance draft-2026-06-17-p0
+ * 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
  * 职责: Workbench REST read model。只读投影 session/message/turn/trace facts，不执行 AgentRun sync、billing finalize 或 workspace repair。
  */
 import { createHash } from "node:crypto";
@@ -244,7 +244,7 @@ async function handleWorkbenchSessionDetail(response, options, actor, sessionId)
 async function handleWorkbenchMessagePage(response, url, options, actor, sessionId) {
   const session = await visibleSessionByRouteId(options.accessController?.store, sessionId, actor);
   if (!session) return sendJson(response, 404, workbenchError("workbench_session_not_found", "Workbench session is not visible to the current actor.", { sessionId }));
-  const messages = sessionMessages(session);
+  const messages = sessionMessages(session, options);
   const limit = boundedLimit(url.searchParams.get("limit"));
   const offset = cursorOffset(url.searchParams.get("cursor") ?? url.searchParams.get("after"));
   const page = messages.slice(offset, offset + limit);
@@ -347,7 +347,7 @@ function sessionSummary(session, options) {
   const snapshot = objectValue(session.session);
   const traceId = safeTraceId(session.lastTraceId ?? snapshot.lastTraceId ?? snapshot.currentTraceId) ?? null;
   const trace = traceId ? traceSnapshotSync(options, traceId) : null;
-  const messages = sessionMessages(session);
+  const messages = sessionMessages(session, options);
   const status = canonicalWorkbenchStatus(snapshot.sessionStatus ?? session.status, trace?.status);
   return {
     sessionId: session.id,
@@ -388,23 +388,81 @@ function sessionDetail(session, options) {
   };
 }
 
-function sessionMessages(session) {
+function sessionMessages(session, options = {}) {
   const snapshot = objectValue(session.session);
   const raw = Array.isArray(snapshot.messages) ? snapshot.messages : Array.isArray(snapshot.chatMessages) ? snapshot.chatMessages : [];
-  const messages = raw.map((message, index) => messageFact(message, index, session, snapshot)).filter(Boolean);
   const finalTraceId = safeTraceId(session.lastTraceId ?? snapshot.lastTraceId ?? snapshot.currentTraceId) ?? null;
+  const terminalProjection = terminalMessageProjection(session, snapshot, options, finalTraceId);
+  const messages = raw
+    .map((message, index) => messageFact(message, index, session, snapshot))
+    .filter(Boolean)
+    .map((message) => applyTerminalMessageProjection(message, terminalProjection));
   const hasAssistantLikeFinal = messages.some((message) => isAssistantLikeRole(message.role) && (!finalTraceId || message.traceId === finalTraceId));
-  if (!hasAssistantLikeFinal && textValue(snapshot.finalResponse)) {
-    messages.push(messageFact({ role: "assistant", text: snapshot.finalResponse, traceId: session.lastTraceId ?? snapshot.lastTraceId, source: "finalResponse" }, messages.length, session, snapshot));
+  const finalText = terminalProjection?.text ?? projectionText(snapshot.finalResponse);
+  if (!hasAssistantLikeFinal && finalText) {
+    messages.push(messageFact({ role: "assistant", text: finalText, status: terminalProjection?.status ?? session.status, traceId: finalTraceId, source: terminalProjection?.source ?? "finalResponse" }, messages.length, session, snapshot));
   }
   return messages;
 }
 
+function terminalMessageProjection(session, snapshot, options, traceId) {
+  if (!traceId) return null;
+  const result = options.result ?? options.codeAgentChatResults?.get?.(traceId) ?? null;
+  const trace = options.trace ?? traceSnapshotSync(options, traceId);
+  const status = canonicalWorkbenchStatus(
+    result?.status ?? result?.agentRun?.terminalStatus ?? result?.agentRun?.commandState ?? result?.agentRun?.status ?? session?.status ?? snapshot.sessionStatus,
+    trace?.status
+  );
+  if (!TERMINAL_STATUSES.has(status) || RUNNING_STATUSES.has(status)) return null;
+  const text = projectionText(result?.finalResponse, result?.assistantText, result?.reply, result?.text, result?.summary, trace?.finalResponse, trace?.terminalEvidence?.finalResponse, snapshot.finalResponse);
+  return { traceId, status, text, source: result ? "turn-result" : trace?.status && trace.status !== "missing" ? "trace-projection" : "session-snapshot" };
+}
+
+function applyTerminalMessageProjection(message, projection) {
+  if (!projection || !isAssistantLikeRole(message.role)) return message;
+  if (projection.traceId && message.traceId && message.traceId !== projection.traceId) return message;
+  const text = projection.text || message.text || "";
+  const parts = projectTerminalMessageParts(message.parts, message.messageId, projection.traceId ?? message.traceId, projection, text);
+  return {
+    ...message,
+    traceId: projection.traceId ?? message.traceId,
+    turnId: message.turnId ?? projection.traceId ?? null,
+    status: projection.status,
+    parts,
+    text,
+    textPreview: text ? text.slice(0, 240) : message.textPreview ?? null,
+    updatedAt: message.updatedAt ?? null
+  };
+}
+
+function projectTerminalMessageParts(parts, messageId, traceId, projection, text) {
+  const sourceParts = Array.isArray(parts) ? parts : [];
+  const textIndex = sourceParts.findIndex((part) => part?.type === "text" || part?.text);
+  if (textIndex >= 0) {
+    return sourceParts.map((part, index) => index === textIndex ? { ...part, traceId, text: text || part.text || null, status: projection.status } : part);
+  }
+  if (!text) return sourceParts;
+  return [partFact({ type: "text", text, status: projection.status }, 0, messageId, traceId), ...sourceParts];
+}
+
+function projectionText(...values) {
+  for (const value of values) {
+    if (value && typeof value === "object") {
+      const nested = textValue(value.text ?? value.content ?? value.message ?? value.summary ?? value.preview ?? value.title);
+      if (nested) return nested;
+      continue;
+    }
+    const text = textValue(value);
+    if (text) return text;
+  }
+  return null;
+}
+
 function messageFact(message, index, session, snapshot) {
   const role = textValue(message?.role) || (index % 2 === 0 ? "user" : "assistant");
   const traceId = safeTraceId(message?.traceId ?? message?.turnTraceId ?? session.lastTraceId ?? snapshot.lastTraceId) ?? null;
   const messageId = safeMessageId(message?.messageId ?? message?.id) || `msg_${hash(`${session.id}:${index}:${role}:${traceId ?? "none"}`).slice(0, 24)}`;
-  const text = textValue(message?.text ?? message?.content ?? message?.message ?? message?.finalResponse);
+  const text = projectionText(message?.text, message?.content, message?.message, message?.finalResponse);
   const rawParts = Array.isArray(message?.parts) ? message.parts : [];
   const parts = rawParts.length > 0
     ? rawParts.map((part, partIndex) => partFact(part, partIndex, messageId, traceId)).filter(Boolean)
@@ -442,9 +500,10 @@ function partFact(part, index, messageId, traceId) {
 }
 
 function turnSnapshot({ turnId, traceId, status, result, session, trace }) {
-  const messages = session ? sessionMessages(session) : [];
+  const messages = session ? sessionMessages(session, { result, trace }) : [];
   const userMessage = messages.find((message) => message.role === "user") ?? null;
   const assistantMessage = [...messages].reverse().find((message) => isAssistantLikeRole(message.role)) ?? null;
+  const finalText = projectionText(result?.finalResponse, result?.assistantText, result?.reply, result?.text, trace?.finalResponse, trace?.terminalEvidence?.finalResponse, assistantMessage?.text);
   return {
     turnId,
     traceId,
@@ -455,6 +514,8 @@ function turnSnapshot({ turnId, traceId, status, result, session, trace }) {
     threadId: safeOpaqueId(result?.threadId ?? result?.session?.threadId ?? session?.threadId) ?? (textValue(session?.threadId) || null),
     userMessageId: userMessage?.messageId ?? null,
     assistantMessageId: assistantMessage?.messageId ?? null,
+    assistantText: finalText ?? null,
+    finalResponse: finalText ? { text: finalText, status, traceId, valuesPrinted: false } : null,
     agentRun: result?.agentRun ?? null,
     trace: {
       traceId,
diff --git a/web/hwlab-cloud-web/scripts/workbench-e2e-server.ts b/web/hwlab-cloud-web/scripts/workbench-e2e-server.ts
index 8c97b8eb..a5b48243 100644
--- a/web/hwlab-cloud-web/scripts/workbench-e2e-server.ts
+++ b/web/hwlab-cloud-web/scripts/workbench-e2e-server.ts
@@ -1,4 +1,4 @@
-// SPEC: PJ2026-010401 Web工作台 draft-2026-06-18-r1; PJ2026-010403 API契约 draft-2026-06-18-r1.
+// SPEC: PJ2026-010401 Web工作台 draft-2026-06-18-r1; PJ2026-0104010803 唯一投影 draft-2026-06-18-p0-unique-projection; PJ2026-010403 API契约 draft-2026-06-18-r1.
 // Responsibility: Same-origin fake Workbench API and static server for Playwright browser regression tests.
 
 import { createReadStream, existsSync, statSync } from "node:fs";
@@ -423,6 +423,7 @@ function acceptChatTurn(body: JsonRecord): JsonRecord {
     state.liveBackfillTraceId = traceId;
     state.liveBackfillReadyAtMs = Date.now() + 2_000;
     state.traces[traceId] = liveBackfillEarlyTrace(sessionId, threadId, traceId);
+    scheduleLiveBackfillProjection(sessionId, threadId, traceId, state.liveBackfillReadyAtMs);
   } else {
     state.traces[traceId] = { traceId, status: "running", sessionId, threadId, events: [], eventCount: 0, fullTraceLoaded: false, hasMore: false };
   }
@@ -460,9 +461,40 @@ function liveBackfillCompletedTrace(sessionId: string, threadId: string | null,
   return { traceId, status: "completed", sessionId, threadId, events, eventCount: events.length, fullTraceLoaded: true, hasMore: false, finalResponse: { text: finalText, status: "completed" } };
 }
 
+function scheduleLiveBackfillProjection(sessionId: string, threadId: string | null, traceId: string, readyAtMs: number): void {
+  const scenarioId = state.scenarioId;
+  setTimeout(() => {
+    if (state.scenarioId !== scenarioId || state.liveBackfillTraceId !== traceId) return;
+    commitLiveBackfillProjection(sessionId, threadId, traceId);
+  }, Math.max(0, readyAtMs - Date.now()));
+}
+
+function commitLiveBackfillProjection(sessionId: string, threadId: string | null, traceId: string): void {
+  const completed = liveBackfillCompletedTrace(sessionId, threadId, traceId);
+  const finalText = typeof (completed.finalResponse as JsonRecord | undefined)?.text === "string" ? String((completed.finalResponse as JsonRecord).text) : "";
+  state.traces[traceId] = completed;
+  const session = sessionById(sessionId);
+  if (!session) return;
+  session.status = "completed";
+  session.updatedAt = new Date().toISOString();
+  session.messages = (session.messages ?? []).map((message) => {
+    if (message.role !== "agent" || message.traceId !== traceId) return message;
+    return { ...message, text: finalText, status: "completed", runnerTrace: completed };
+  });
+}
+
 function sessionSummary(session: SessionRecord): SessionRecord {
   const { messages: _messages, hidden: _hidden, ...rest } = session;
-  return rest as SessionRecord;
+  const status = typeof rest.status === "string" ? rest.status : "unknown";
+  return { ...rest, status, running: isRunningStatus(status), terminal: isTerminalStatus(status) } as SessionRecord;
+}
+
+function isRunningStatus(status: string): boolean {
+  return ["active", "accepted", "pending", "running"].includes(status);
+}
+
+function isTerminalStatus(status: string): boolean {
+  return ["blocked", "canceled", "cancelled", "completed", "failed", "timeout"].includes(status);
 }
 
 function workbenchSessionListPayload(url: URL): JsonRecord {
@@ -511,8 +543,7 @@ function turnPayload(traceId: string): JsonRecord {
     const session = state.sessions.find((item) => item.lastTraceId === traceId) ?? state.sessions[0];
     const sessionId = session?.sessionId ?? state.selectedSessionId;
     const threadId = typeof session?.threadId === "string" ? session.threadId : null;
-    if (state.liveBackfillReadyAtMs && Date.now() >= state.liveBackfillReadyAtMs) return liveBackfillCompletedTrace(sessionId, threadId, traceId);
-    return liveBackfillEarlyTrace(sessionId, threadId, traceId);
+    return state.traces[traceId] ?? liveBackfillEarlyTrace(sessionId, threadId, traceId);
   }
   const trace = state.traces[traceId] ?? { traceId, status: "unknown", events: [] };
   if (state.scenarioId === "terminal-turn-stale-session-active" && traceId === "trc_completed") return { ...trace, traceId, status: "active", running: true, terminal: false, trace: { status: "completed", eventCount: trace.eventCount ?? 0 } };
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 bcef3a6b..c0fcef27 100644
--- a/web/hwlab-cloud-web/scripts/workbench-server-state.test.ts
+++ b/web/hwlab-cloud-web/scripts/workbench-server-state.test.ts
@@ -4,6 +4,7 @@ import test from "node:test";
 import type { WorkbenchSessionRecord } from "../src/types/index.ts";
 import { initialWorkbenchSessionIdFromLocation } from "../src/stores/workbench-projection.ts";
 import { createWorkbenchServerState, reduceWorkbenchServerState, selectActiveMessages, selectActiveSession, selectTraceAuthorityById } from "../src/stores/workbench-server-state.ts";
+import { stableSessionList } from "../src/stores/workbench-session.ts";
 
 test("Workbench route parsing accepts only session routes", () => {
   assert.equal(initialWorkbenchSessionIdFromLocation({ pathname: "/workbench/sessions/ses_route" }), "ses_route");
@@ -26,3 +27,32 @@ test("Workbench server-state is keyed only by session and trace", () => {
   assert.deepEqual(selectActiveMessages(state, "ses_route").map((message) => message.id), ["msg_route"]);
   assert.equal(selectTraceAuthorityById(state).trc_route?.traceId, "trc_route");
 });
+
+test("Workbench session list keeps selected detail but lets server summary override stale running status", () => {
+  const selected: WorkbenchSessionRecord = {
+    sessionId: "ses_live",
+    threadId: "thr_live",
+    status: "running",
+    lastTraceId: "trc_live",
+    messageCount: 2,
+    messages: [
+      { id: "msg_live_user", messageId: "msg_live_user", role: "user", title: "用户", text: "ping", status: "sent", createdAt: "2026-06-18T00:00:00.000Z", sessionId: "ses_live", traceId: "trc_live" },
+      { id: "msg_live_agent", messageId: "msg_live_agent", role: "agent", title: "Code Agent", text: "", status: "running", createdAt: "2026-06-18T00:00:01.000Z", sessionId: "ses_live", traceId: "trc_live" }
+    ]
+  };
+  const serverSummary: WorkbenchSessionRecord = {
+    sessionId: "ses_live",
+    threadId: "thr_live",
+    status: "completed",
+    lastTraceId: "trc_live",
+    messageCount: 2,
+    updatedAt: "2026-06-18T00:00:03.000Z"
+  };
+
+  const next = stableSessionList([selected], [serverSummary], "ses_live", selected);
+
+  assert.equal(next[0]?.sessionId, "ses_live");
+  assert.equal(next[0]?.status, "completed");
+  assert.equal(next[0]?.updatedAt, "2026-06-18T00:00:03.000Z");
+  assert.equal(next[0]?.messages?.length, 2);
+});
diff --git a/web/hwlab-cloud-web/src/stores/workbench-session.ts b/web/hwlab-cloud-web/src/stores/workbench-session.ts
index 73873171..7b81eeaa 100644
--- a/web/hwlab-cloud-web/src/stores/workbench-session.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench-session.ts
@@ -1,4 +1,4 @@
-// SPEC: PJ2026-010403 API契约 draft-2026-06-18-r1; PJ2026-010401 Web工作台 draft-2026-06-18-r1.
+// 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.
 // Responsibility: Session-first Workbench UI helpers for composer state, tab projection, and local list stability.
 
 import type { ChatMessage, ProviderProfile, WorkbenchSessionRecord } from "@/types";
@@ -170,7 +170,7 @@ export function stableSessionList(current: WorkbenchSessionRecord[], candidate:
     : current.length > 0
       ? current
       : candidateList;
-  return selected ? mergeSessionIntoList(stable, selected) : stable.filter((session) => !isArchivedSession(session));
+  return selected ? mergeSelectedSessionDetail(stable, selected) : stable.filter((session) => !isArchivedSession(session));
 }
 
 export function mergeSessionIntoList(current: WorkbenchSessionRecord[], session: WorkbenchSessionRecord | null | undefined): WorkbenchSessionRecord[] {
@@ -238,6 +238,14 @@ function mergeSessionRecord(existing: WorkbenchSessionRecord, incoming: Workbenc
   };
 }
 
+function mergeSelectedSessionDetail(stable: WorkbenchSessionRecord[], selected: WorkbenchSessionRecord): WorkbenchSessionRecord[] {
+  const selectedId = firstNonEmptyString(selected.sessionId);
+  if (!selectedId) return stable.filter((session) => !isArchivedSession(session));
+  const existingIndex = stable.findIndex((session) => session.sessionId === selectedId);
+  if (existingIndex < 0) return mergeSessionIntoList(stable, selected);
+  return stable.map((session, index) => index === existingIndex ? mergeSessionRecord(selected, session) : session).filter((session) => !isArchivedSession(session));
+}
+
 function latestAgentMessage(messages: ChatMessage[] | undefined): ChatMessage | null {
   return [...(messages ?? [])].reverse().find((message) => message.role === "agent") ?? null;
 }
diff --git a/web/hwlab-cloud-web/src/stores/workbench.ts b/web/hwlab-cloud-web/src/stores/workbench.ts
index da29bc12..55fcbc77 100644
--- a/web/hwlab-cloud-web/src/stores/workbench.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench.ts
@@ -1,4 +1,4 @@
-// SPEC: PJ2026-010403 API契约 draft-2026-06-18-r1; PJ2026-010401 Web工作台 draft-2026-06-18-r1; PJ2026-01060505 Workbench Performance draft-2026-06-17-p0.
+// 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";
@@ -19,6 +19,8 @@ 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;
 
 interface HydrateOptions {
   sessionId?: string | null;
@@ -50,9 +52,11 @@ export const useWorkbenchStore = defineStore("workbench", () => {
   const traceAuthorityById = computed(() => selectTraceAuthorityById(serverState.value));
   const traceHydrationInFlight = new Set<string>();
   const terminalRealtimeRefreshInFlight = new Set<string>();
+  const projectionCatchupAttempts = new Map<string, number>();
   let realtimeStream: WorkbenchEventStream | null = null;
   let realtimeKey = "";
   let realtimeGapTimer: number | null = null;
+  let projectionCatchupTimer: number | null = null;
 
   const activeSession = computed(() => explicitSessionId.value ? sessions.value.find((item) => item.sessionId === explicitSessionId.value) ?? null : null);
   const selectedSessionId = computed(() => firstNonEmptyString(activeSession.value?.sessionId, explicitSessionId.value));
@@ -246,6 +250,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     const response = await api.agent.getAgentTurn(id, 8000, () => activityRef.value);
     if (response.ok && response.data) {
       applyTurnStatusSnapshot(id, response.data);
+      if (response.data.terminal === true || isTerminalMessageStatus(response.data.status)) completeTrace(id, response.data);
       return;
     }
     reduceServerState({ type: "turn.forget", traceId: id });
@@ -332,11 +337,23 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       return;
     }
     markWorkbenchSubmitApiAccepted(traceId);
-    alignOptimisticTurnMessages(traceId, response.data);
-    applyTurnStatusSnapshot(traceId, response.data);
+    const canonicalTraceId = alignOptimisticTurnMessages(traceId, response.data);
+    if (canonicalTraceId !== traceId) {
+      reduceServerState({ type: "turn.forget", traceId });
+      if (currentRequest.value?.traceId === traceId) {
+        currentRequest.value = {
+          ...currentRequest.value,
+          traceId: canonicalTraceId,
+          sessionId: firstNonEmptyString(response.data.sessionId, currentRequest.value.sessionId),
+          threadId: firstNonEmptyString(response.data.threadId, currentRequest.value.threadId),
+          status: response.data.status ?? currentRequest.value.status
+        };
+      }
+    }
+    applyTurnStatusSnapshot(canonicalTraceId, response.data);
     void refreshSessions(sessionId);
     if ((response.data as AgentChatResultResponse).terminal === true || isTerminalMessageStatus(response.data.status)) {
-      completeTrace(traceId, response.data as AgentChatResultResponse);
+      completeTrace(canonicalTraceId, response.data as AgentChatResultResponse);
       return;
     }
     restartRealtime("submit");
@@ -641,6 +658,44 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       hydrateTraceEvents(messages.value)
     ]);
     restartRealtime(`gap:${reason}`);
+    scheduleProjectionCatchup(reason);
+  }
+
+  function scheduleProjectionCatchup(reason: string): void {
+    const traceId = activeProjectionCatchupTraceId();
+    if (!traceId) {
+      clearProjectionCatchup();
+      return;
+    }
+    if (projectionCatchupTimer) return;
+    const attempts = projectionCatchupAttempts.get(traceId) ?? 0;
+    if (attempts >= PROJECTION_CATCHUP_MAX_ATTEMPTS) return;
+    projectionCatchupAttempts.set(traceId, attempts + 1);
+    if (typeof window === "undefined") return;
+    projectionCatchupTimer = window.setTimeout(() => {
+      projectionCatchupTimer = null;
+      void hydrateRealtimeGap(`projection-catchup:${reason}`);
+    }, PROJECTION_CATCHUP_DELAY_MS);
+  }
+
+  function activeProjectionCatchupTraceId(): string | null {
+    const traceId = realtimeTraceId();
+    if (!traceId) return null;
+    const turn = turnStatusAuthority.value[traceId];
+    const message = [...messages.value].reverse().find((item) => item.role === "agent" && firstNonEmptyString(item.traceId, item.runnerTrace?.traceId) === traceId) ?? null;
+    const active = currentRequest.value?.traceId === traceId
+      || turn?.running === true
+      || isTraceActiveStatus(turn?.status)
+      || isTraceActiveStatus(message?.status)
+      || isTraceActiveStatus(message?.runnerTrace?.status);
+    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 installRealtimeVisibilityHandler(): void {
@@ -676,6 +731,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
   }
 
   function completeTrace(traceId: string, result: AgentChatResultResponse): void {
+    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。";
@@ -755,22 +811,27 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     messages.value = messages.value.map((message) => message.traceId === traceId && message.role === "agent" ? { ...message, ...patch, updatedAt: new Date().toISOString() } : message);
   }
 
-  function alignOptimisticTurnMessages(traceId: string, lifecycle: AgentChatResponse): void {
-    const turnId = firstNonEmptyString(lifecycle.turnId, traceId);
+  function alignOptimisticTurnMessages(traceId: string, lifecycle: AgentChatResponse): string {
+    const canonicalTraceId = firstNonEmptyString(lifecycle.traceId, traceId) ?? traceId;
+    const turnId = firstNonEmptyString(lifecycle.turnId, canonicalTraceId);
     const userMessageId = firstNonEmptyString(lifecycle.userMessageId);
     const assistantMessageId = firstNonEmptyString(lifecycle.assistantMessageId);
-    if (!turnId && !userMessageId && !assistantMessageId) return;
+    if (!turnId && !userMessageId && !assistantMessageId && canonicalTraceId === traceId) return canonicalTraceId;
     messages.value = messages.value.map((message) => {
       if (message.traceId !== traceId) return message;
-      if (message.role === "user" && userMessageId) return { ...message, id: userMessageId, messageId: userMessageId, turnId, updatedAt: new Date().toISOString() };
-      if (message.role === "agent" && assistantMessageId) return { ...message, id: assistantMessageId, messageId: assistantMessageId, turnId, updatedAt: new Date().toISOString() };
-      return turnId ? { ...message, turnId, updatedAt: new Date().toISOString() } : 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);
   }
 
   function beginSessionSelection(): number {
diff --git a/web/hwlab-cloud-web/tests/workbench-e2e/specs/live-backfill-race.spec.ts b/web/hwlab-cloud-web/tests/workbench-e2e/specs/live-backfill-race.spec.ts
index 4f8477dd..796f7f04 100644
--- a/web/hwlab-cloud-web/tests/workbench-e2e/specs/live-backfill-race.spec.ts
+++ b/web/hwlab-cloud-web/tests/workbench-e2e/specs/live-backfill-race.spec.ts
@@ -20,8 +20,22 @@ test.describe("live REST backfill without terminal SSE", () => {
       return response.ok() ? ((await response.json()).turn?.status as string | undefined) : undefined;
     }).toBe("completed");
 
+    const listResponse = await page.request.get("/v1/workbench/sessions?includeSessionId=ses_completed");
+    const messagesResponse = await page.request.get("/v1/workbench/sessions/ses_completed/messages?limit=100");
+    expect(listResponse.ok()).toBe(true);
+    expect(messagesResponse.ok()).toBe(true);
+    const listPayload = await listResponse.json() as { sessions?: Array<{ sessionId?: string; status?: string; running?: boolean }> };
+    const messagesPayload = await messagesResponse.json() as { messages?: Array<{ role?: string; traceId?: string; status?: string; text?: string }> };
+    const sessionSummary = listPayload.sessions?.find((session) => session.sessionId === "ses_completed");
+    const assistantMessage = messagesPayload.messages?.find((message) => message.role === "agent" && message.traceId === "trc_live_backfill");
+    expect(sessionSummary?.status).toBe("completed");
+    expect(sessionSummary?.running).toBe(false);
+    expect(assistantMessage?.status).toBe("completed");
+    expect(assistantMessage?.text).toContain("fake AgentRun completed after REST backfill");
+
     await saveScreenshot(page, testInfo, "live-backfill-canonical-completed");
     await expect(page.locator(sessionTab("ses_completed"))).toHaveAttribute("data-active", "true");
+    await expect(page.locator(sessionTab("ses_completed"))).toHaveAttribute("data-status", "completed");
     const backfilledFinal = page.locator(`${selectors.messageCard}[data-role="agent"]`).filter({ hasText: "fake AgentRun completed after REST backfill" });
     await expect(backfilledFinal).toHaveAttribute("data-status", "completed");
     await expect(page.locator(`${selectors.traceTimeline}[data-status="completed"]`).last()).toBeVisible();