🤖 fix: bump parent recency on subagent report

When a subagent calls agent_report, we append the report message to the parent history and emit chat events. Also bump the parent workspace recency (using the same message timestamp) so sidebar ordering reflects background task completions.

Signed-off-by: Thomas Kosiewski <tk@coder.com>

---
_Generated with `mux` • Model: `openai:gpt-5.2` • Thinking: `xhigh`_

Change-Id: I605ccc04ef857ee2fadf0daa44a11090738c087c

Author: ThomasK33

src/node/services/taskService.ts

@@ -427,10 +427,12 @@ export class TaskService {
       ? `### Subagent report (${preset.agentType})\n\n`
       : "### Subagent report\n\n";
 
+    const messageTimestamp = Date.now();
     const reportMessage = createMuxMessage(
       this.config.generateStableId(),
       "assistant",
-      `${reportHeader}${report.reportMarkdown}`
+      `${reportHeader}${report.reportMarkdown}`,
+      { timestamp: messageTimestamp }
     );
 
     const appendResult = await this.historyService.appendToHistory(
@@ -448,6 +450,7 @@ export class TaskService {
         ...reportMessage,
         type: "message",
       } satisfies WorkspaceChatMessage);
+      await this.workspaceService.bumpRecencyTimestamp(parentWorkspaceId, messageTimestamp);
     }
 
     // Mark reported after best-effort delivery to the parent.

src/node/services/workspaceService.ts

@@ -210,6 +210,19 @@ export class WorkspaceService extends EventEmitter {
     this.emit("activity", { workspaceId, activity: snapshot });
   }
 
+  /**
+   * Bump recency/activity for a workspace.
+   *
+   * Useful when the backend appends messages outside of the normal send/stream lifecycle
+   * (e.g. subagent reports written into a parent workspace).
+   */
+  public async bumpRecencyTimestamp(workspaceId: string, timestamp?: number): Promise<void> {
+    assert(typeof workspaceId === "string", "workspaceId must be a string");
+    const trimmed = workspaceId.trim();
+    assert(trimmed.length > 0, "workspaceId must not be empty");
+
+    await this.updateRecencyTimestamp(trimmed, timestamp);
+  }
   private async updateRecencyTimestamp(workspaceId: string, timestamp?: number): Promise<void> {
     try {
       const snapshot = await this.extensionMetadata.updateRecency(