fix(workbench): 用 agent session 上下文补齐 durable 投影 sessionId (#2013)

* fix(workbench): pass projection context to message writer

* fix(workbench): resolve session id from agent session context

internal/cloud/code-agent-trace-store.test.ts

@@ -64,7 +64,7 @@ test("durable code agent trace store projects appended events without counting a
   });
   const traceId = "trc_trace-store-durable-projection";
 
-  traceStore.append(traceId, { type: "request", status: "accepted", label: "request:accepted", sessionId: "ses_trace_store_durable" });
+  traceStore.append(traceId, { type: "request", status: "accepted", label: "request:accepted" }, { agentSessionId: "ses_trace_store_durable" });
   traceStore.appendAssistantDelta(traceId, { itemId: "assistant", chunk: "hello" });
   await Promise.resolve();
   await Promise.resolve();

internal/cloud/code-agent-trace-store.ts

@@ -253,10 +253,12 @@ function persistTraceEvent(traceEventStore, event, meta = {}, workbenchEventWrit
 
 async function persistTraceEventAsync(traceEventStore, event, meta = {}, workbenchEventWriter = null) {
   try {
+    const resolvedAgentSessionId = event.agentSessionId ?? event.sessionId ?? meta.agentSessionId ?? meta.sessionId;
+    const resolvedSessionId = event.sessionId ?? meta.sessionId ?? resolvedAgentSessionId;
     const projectionContext = {
       traceId: event.traceId,
-      agentSessionId: event.agentSessionId ?? event.sessionId ?? meta.agentSessionId ?? meta.sessionId,
-      sessionId: event.sessionId ?? meta.sessionId
+      agentSessionId: resolvedAgentSessionId,
+      sessionId: resolvedSessionId
     };
     try {
       await traceEventStore.writeAgentTraceEvent({ event }, projectionContext);