fix(v02): preserve trace for terminal chat responses (#868)

Co-authored-by: Codex Agent <codex@hwlab.local>

web/hwlab-cloud-web/src/state/runner-trace.test.ts

@@ -195,6 +195,47 @@ test("subscribeToTrace preserves trace when terminal result with text arrives be
   }
 });
 
+test("subscribeToTrace preserves trace when initial response is already terminal", async () => {
+  const originalFetch = globalThis.fetch;
+  const events: TraceEvent[] = [
+    { seq: 1, label: "agentrun:request:accepted", status: "accepted" },
+    { seq: 2, label: "agentrun:result:failed", type: "result", status: "failed", message: "provider failed" }
+  ];
+  const fetches: string[] = [];
+  globalThis.fetch = (async (input: RequestInfo | URL) => {
+    const url = String(input);
+    fetches.push(url);
+    if (url.includes("/trace/")) {
+      return jsonResponse({ status: "failed", traceId: "trc_initial_terminal", events, eventCount: events.length });
+    }
+    return jsonResponse({});
+  }) as typeof fetch;
+
+  try {
+    const snapshots: TraceSnapshot[] = [];
+    const completed = await new Promise<AgentChatResultResponse>((resolve, reject) => {
+      void subscribeToTrace({
+        traceId: "trc_initial_terminal",
+        initial: { status: "failed", traceId: "trc_initial_terminal", assistantText: "provider failed" },
+        onActivity: () => undefined,
+        onSnapshot: (snapshot) => snapshots.push(snapshot),
+        onComplete: resolve,
+        onInfrastructureError: (error) => reject(new Error(error)),
+        signal: new AbortController().signal,
+        inactivityTimeoutMs: 1000
+      }).catch(reject);
+    });
+    assert.equal(completed.assistantText, "provider failed");
+    assert.equal(completed.runnerTrace?.events?.length, 2);
+    assert.equal(completed.runnerTrace?.eventCount, 2);
+    assert.equal(completed.traceEvents?.length, 2);
+    assert.equal(snapshots.length, 1);
+    assert.deepEqual(fetches, ["/v1/agent/chat/trace/trc_initial_terminal?projectId=prj_device_pod_workbench"]);
+  } finally {
+    globalThis.fetch = originalFetch;
+  }
+});
+
 test("subscribeToTrace merges terminal result without text with trace assistant content", async () => {
   const originalFetch = globalThis.fetch;
   const originalSetTimeout = globalThis.window?.setTimeout;

web/hwlab-cloud-web/src/state/runner-trace.ts

@@ -184,9 +184,14 @@ export interface TraceSubscriptionConfig {
 export async function subscribeToTrace(config: TraceSubscriptionConfig): Promise<void> {
   const { traceId, initial, onActivity, onSnapshot, onComplete, onInfrastructureError, signal, inactivityTimeoutMs } = config;
 
-  // If the initial response is already terminal, fire onComplete and return.
+  // If the initial response is already terminal, still fetch the trace once.
+  // Provider fast-fail responses can include final text immediately while the
+  // trace endpoint already has the event list needed for refresh persistence.
   if (isTerminalStatus(initial.status)) {
-    onComplete(initial as AgentChatResultResponse);
+    const traceSnapshot = await fetchTerminalTraceSnapshot(traceId, traceId, inactivityTimeoutMs, signal);
+    if (signal.aborted) return;
+    if (traceSnapshot) onSnapshot(traceSnapshot);
+    onComplete(mergeTraceResults(initial as AgentChatResultResponse, traceSnapshot));
     return;
   }
   if (!initial.resultUrl) {
@@ -308,6 +313,22 @@ export async function subscribeToTrace(config: TraceSubscriptionConfig): Promise
   }
 }
 
+async function fetchTerminalTraceSnapshot(traceId: string, traceUrlOrId: string, inactivityTimeoutMs: number, signal: AbortSignal): Promise<TraceSnapshot | null> {
+  if (signal.aborted) return null;
+  const url = traceUrlOrId.startsWith("/") ? traceUrlOrId : `/v1/agent/chat/trace/${encodeURIComponent(traceUrlOrId)}?projectId=prj_device_pod_workbench`;
+  const tracePolled = await api.getAgentChatResult(url, inactivityTimeoutMs, null);
+  if (signal.aborted || !tracePolled.ok || !tracePolled.data) return null;
+  const events = Array.isArray(tracePolled.data.events) ? tracePolled.data.events : [];
+  const last = events.at(-1);
+  return snapshotToTraceSnapshot({
+    ...tracePolled.data,
+    traceId,
+    events,
+    eventCount: Number(tracePolled.data.eventCount ?? events.length) || 0,
+    lastEventLabel: String(last?.label ?? last?.type ?? tracePolled.data.lastEventLabel ?? "")
+  } as AgentChatResultResponse);
+}
+
 function snapshotToTraceSnapshot(result: AgentChatResultResponse): TraceSnapshot {
   const events = Array.isArray((result as { events?: TraceEvent[] }).events) ? ((result as { events?: TraceEvent[] }).events ?? []) : [];
   return {