diff --git a/web/hwlab-cloud-web/scripts/workbench-r2-session-parity.test.ts b/web/hwlab-cloud-web/scripts/workbench-r2-session-parity.test.ts
index f8d705b0..6d7889a9 100644
--- a/web/hwlab-cloud-web/scripts/workbench-r2-session-parity.test.ts
+++ b/web/hwlab-cloud-web/scripts/workbench-r2-session-parity.test.ts
@@ -46,6 +46,22 @@ test("R2 session tabs expose label, model metadata source, count and active stat
   assert.match(tabs[0]?.subtitle ?? "", /trace trc_done/u);
 });
 
+test("R2 session tabs use latest message activity time instead of stale conversation time", () => {
+  const tabs = sortSessionTabs([
+    {
+      conversationId: "cnv_old_created_recent_message",
+      sessionId: "ses_old_created_recent_message",
+      firstUserMessagePreview: "三天前创建但刚刚更新",
+      updatedAt: "2026-01-01T00:00:00.000Z",
+      startedAt: "2026-01-01T00:00:00.000Z",
+      messages: [agentMessage({ traceId: "trc_recent", conversationId: "cnv_old_created_recent_message", updatedAt: "2026-01-04T00:01:00.000Z" })]
+    },
+    { conversationId: "cnv_newer_created", sessionId: "ses_newer_created", firstUserMessagePreview: "创建时间较新但未更新", updatedAt: "2026-01-03T00:00:00.000Z" }
+  ], null);
+  assert.equal(tabs[0]?.conversationId, "cnv_old_created_recent_message");
+  assert.equal(tabs[0]?.updatedAt, "2026-01-04T00:01:00.000Z");
+});
+
 test("R2 session tab labels normalize object previews and reject object placeholders", () => {
   const tabs = sortSessionTabs([
     { conversationId: "cnv_object", sessionId: "ses_object", firstUserMessagePreview: { text: "对象预览标题" } as unknown as string, updatedAt: "2026-01-03T00:00:00.000Z" },
diff --git a/web/hwlab-cloud-web/src/stores/workbench-session.ts b/web/hwlab-cloud-web/src/stores/workbench-session.ts
index 3620e025..fa2d451c 100644
--- a/web/hwlab-cloud-web/src/stores/workbench-session.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench-session.ts
@@ -90,7 +90,7 @@ export function workspaceWithClearedActiveTrace(workspace: WorkspaceRecord | nul
 export function conversationToSessionTab(conversation: ConversationRecord, activeConversationId: string | null): SessionTab {
   const sessionId = firstNonEmptyString(conversation.sessionId, conversation.session?.sessionId);
   const conversationId = conversation.conversationId;
-  const updatedAt = firstNonEmptyString(conversation.updatedAt, conversation.snapshot?.updatedAt, conversation.startedAt);
+  const updatedAt = conversationActivityUpdatedAt(conversation);
   const status = firstNonEmptyString(conversation.snapshot?.sessionStatus, conversation.status, conversation.messages?.at(-1)?.status) ?? "source";
   const trace = firstNonEmptyString(conversation.lastTraceId, conversation.messages?.at(-1)?.traceId);
   const userMessage = conversation.messages?.find((message) => message.role === "user");
@@ -223,6 +223,32 @@ function firstReadableSentence(...values: unknown[]): string | null {
   return null;
 }
 
+function conversationActivityUpdatedAt(conversation: ConversationRecord): string | null {
+  const messageTimes = (conversation.messages ?? []).flatMap((message) => [
+    message.updatedAt,
+    message.runnerTrace?.updatedAt,
+    message.createdAt
+  ]);
+  return latestTimestamp(
+    conversation.updatedAt,
+    conversation.snapshot?.updatedAt,
+    ...messageTimes,
+    conversation.startedAt
+  );
+}
+
+function latestTimestamp(...values: unknown[]): string | null {
+  let latest: { value: string; ms: number } | null = null;
+  for (const value of values) {
+    const text = firstNonEmptyString(value);
+    if (!text) continue;
+    const ms = timestampMs(text);
+    if (!ms) continue;
+    if (!latest || ms > latest.ms) latest = { value: text, ms };
+  }
+  return latest?.value ?? firstNonEmptyString(...values) ?? null;
+}
+
 function readableSentence(value: unknown): string | null {
   if (typeof value === "string") return firstSentenceFromText(value);
   if (typeof value === "number" || typeof value === "boolean") return String(value);
diff --git a/web/hwlab-cloud-web/src/stores/workbench.ts b/web/hwlab-cloud-web/src/stores/workbench.ts
index d8865bf1..34b4245b 100644
--- a/web/hwlab-cloud-web/src/stores/workbench.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench.ts
@@ -130,6 +130,43 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     if (response.ok) conversations.value = response.data?.conversations ?? [];
   }
 
+  function bumpConversationActivity(input: { conversationId?: string | null; sessionId?: string | null; threadId?: string | null; traceId?: string | null; status?: string | null; updatedAt?: string | null }): void {
+    const traceMessage = input.traceId ? messages.value.find((message) => message.traceId === input.traceId) : null;
+    const conversationId = firstNonEmptyString(input.conversationId, traceMessage?.conversationId, activeConversationId.value);
+    if (!conversationId) return;
+    const existing = conversations.value.find((conversation) => conversation.conversationId === conversationId) ?? null;
+    const activityMessages = activeConversationId.value === conversationId ? messages.value : messages.value.filter((message) => message.conversationId === conversationId);
+    const latestAgent = [...activityMessages].reverse().find((message) => message.role === "agent");
+    const latestTrace = [...activityMessages].reverse().find((message) => message.traceId);
+    const userMessage = activityMessages.find((message) => message.role === "user");
+    const updatedAt = firstNonEmptyString(input.updatedAt, traceMessage?.updatedAt, latestAgent?.updatedAt, latestAgent?.runnerTrace?.updatedAt, latestTrace?.updatedAt, new Date().toISOString()) ?? new Date().toISOString();
+    const status = firstNonEmptyString(input.status, latestAgent?.status, existing?.status) ?? existing?.status ?? null;
+    const sessionId = firstNonEmptyString(input.sessionId, traceMessage?.sessionId, latestAgent?.sessionId, existing?.sessionId, existing?.session?.sessionId, selectedSessionId.value) ?? null;
+    const threadId = firstNonEmptyString(input.threadId, traceMessage?.threadId, latestAgent?.threadId, existing?.threadId, existing?.session?.threadId, selectedThreadId.value) ?? null;
+    const lastTraceId = firstNonEmptyString(input.traceId, latestTrace?.traceId, existing?.lastTraceId) ?? null;
+    const nextMessages = activityMessages.length > 0 ? activityMessages : existing?.messages ?? [];
+    const firstUserMessagePreview = firstNonEmptyString(existing?.firstUserMessagePreview, existing?.snapshot?.firstUserMessagePreview, userMessage?.text) ?? null;
+    const next: ConversationRecord = {
+      ...(existing ?? { conversationId }),
+      conversationId,
+      projectId: existing?.projectId ?? activeProjectId.value,
+      sessionId,
+      threadId,
+      status,
+      lastTraceId,
+      updatedAt,
+      messages: nextMessages,
+      messageCount: nextMessages.length || existing?.messageCount,
+      firstUserMessagePreview,
+      snapshot: {
+        ...(existing?.snapshot ?? {}),
+        ...(status ? { sessionStatus: status } : {}),
+        updatedAt
+      }
+    };
+    conversations.value = [next, ...conversations.value.filter((conversation) => conversation.conversationId !== conversationId)];
+  }
+
   async function submitMessage(text: string): Promise<void> {
     const value = text.trim();
     if (!value) return;
@@ -146,6 +183,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
     const user = makeMessage("user", value, "sent", { traceId: steerTraceId ?? traceId, conversationId, sessionId, threadId, title: steerMode ? "用户引导" : "用户" });
     const pending = makeMessage("agent", "", "running", { traceId, conversationId, sessionId, threadId, title: "Code Agent", retryInput: value });
     messages.value.push(user, pending);
+    bumpConversationActivity({ conversationId, sessionId, threadId, traceId, status: "running" });
     chatPending.value = true;
     currentRequest.value = { traceId, conversationId, sessionId, threadId, status: "running" };
     rememberRecentDraft(value);
@@ -284,6 +322,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
   function applyTraceSnapshot(traceId: string, snapshot: TraceSnapshot): void {
     const trace = snapshotToRunnerTrace(snapshot);
     messages.value = messages.value.map((message) => message.traceId === traceId ? { ...message, runnerTrace: mergeRunnerTrace(message.runnerTrace, trace), updatedAt: new Date().toISOString() } : message);
+    bumpConversationActivity({ traceId, sessionId: trace.sessionId, threadId: trace.threadId, status: firstNonEmptyString(trace.status), updatedAt: firstNonEmptyString(trace.updatedAt) });
   }
 
   function completeTrace(traceId: string, result: AgentChatResultResponse): void {
@@ -295,6 +334,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       const agentRun = agentRunFromResult(result, runnerTrace) ?? agentRunFromMessage(message);
       return { ...message, status: result.status === "completed" ? "completed" : statusFromResult(result.status), text, runnerTrace, error: error ?? message.error ?? null, agentRun: agentRun ?? undefined, updatedAt: new Date().toISOString() };
     });
+    bumpConversationActivity({ conversationId: firstNonEmptyString((result as Record<string, unknown>).conversationId), sessionId: result.sessionId, threadId: result.threadId, traceId, status: statusFromResult(result.status), updatedAt: resultActivityUpdatedAt(result) });
     chatPending.value = false;
     currentRequest.value = null;
     void clearActiveTrace(traceId, "trace-terminal");
@@ -319,6 +359,7 @@ export const useWorkbenchStore = defineStore("workbench", () => {
       const agentRun = agentRunFromResult(result, runnerTrace) ?? agentRunFromMessage(message);
       return { ...message, runnerTrace, error: error ?? message.error ?? null, agentRun: agentRun ?? undefined, updatedAt: new Date().toISOString() };
     });
+    bumpConversationActivity({ conversationId: firstNonEmptyString((result as Record<string, unknown>).conversationId), sessionId: result.sessionId, threadId: result.threadId, traceId, status: statusFromResult(result.status), updatedAt: resultActivityUpdatedAt(result) });
   }
 
   function failTrace(traceId: string, message: string): void {
@@ -330,6 +371,8 @@ export const useWorkbenchStore = defineStore("workbench", () => {
 
   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);
+    const updated = messages.value.find((message) => message.traceId === traceId && message.role === "agent");
+    bumpConversationActivity({ conversationId: updated?.conversationId, sessionId: updated?.sessionId, threadId: updated?.threadId, traceId, status: patch.status ?? updated?.status, updatedAt: updated?.updatedAt });
   }
 
   async function ensureWorkspace(): Promise<WorkspaceRecord | null> {
@@ -483,6 +526,12 @@ function recordValue(value: unknown): Record<string, unknown> | null {
   return value && typeof value === "object" ? value as Record<string, unknown> : null;
 }
 
+function resultActivityUpdatedAt(result: AgentChatResultResponse): string | null {
+  const finalResponse = recordValue(result.finalResponse);
+  const reply = recordValue(result.reply);
+  return firstNonEmptyString(result.updatedAt, finalResponse?.updatedAt, reply?.updatedAt, finalResponse?.createdAt, reply?.createdAt);
+}
+
 function firstArray(...values: unknown[]): TraceEvent[] {
   for (const value of values) {
     if (Array.isArray(value)) return value as TraceEvent[];