diff --git a/src/features/background-agent/session-idle-event-handler.test.ts b/src/features/background-agent/session-idle-event-handler.test.ts
index 1e2efafbc..ecdfbcfdd 100644
--- a/src/features/background-agent/session-idle-event-handler.test.ts
+++ b/src/features/background-agent/session-idle-event-handler.test.ts
@@ -247,6 +247,27 @@ describe("handleSessionIdleBackgroundEvent", () => {
       expect(tryCompleteTask).toHaveBeenCalledWith(task, "session.idle event")
     })
 
+    it("#when task belongs to a team run #then should not auto-complete on idle", async () => {
+      //#given
+      const task = createRunningTask({ teamRunId: "team-run-1" })
+      const tryCompleteTask = mock(() => Promise.resolve(true))
+
+      //#when
+      handleSessionIdleBackgroundEvent({
+        properties: { sessionID: task.sessionID! },
+        findBySession: () => task,
+        idleDeferralTimers: new Map(),
+        validateSessionHasOutput: () => Promise.resolve(true),
+        checkSessionTodos: () => Promise.resolve(false),
+        tryCompleteTask,
+        emitIdleEvent: () => {},
+      })
+
+      //#then
+      await new Promise((resolve) => setTimeout(resolve, 10))
+      expect(tryCompleteTask).not.toHaveBeenCalled()
+    })
+
     it("#when session has no valid output #then should not complete task", async () => {
       //#given
       const task = createRunningTask()
diff --git a/src/features/background-agent/session-idle-event-handler.ts b/src/features/background-agent/session-idle-event-handler.ts
index 17fb70abd..c3396f75d 100644
--- a/src/features/background-agent/session-idle-event-handler.ts
+++ b/src/features/background-agent/session-idle-event-handler.ts
@@ -85,6 +85,14 @@ export function handleSessionIdleBackgroundEvent(args: {
         return
       }
 
+      if (task.teamRunId) {
+        log("[background-agent] Team member session went idle; skipping background auto-complete:", {
+          taskId: task.id,
+          teamRunId: task.teamRunId,
+        })
+        return
+      }
+
       await tryCompleteTask(task, "session.idle event")
     })
     .catch((err) => {