diff --git a/src/tools/delegate-task/unstable-agent-cleanup.test.ts b/src/tools/delegate-task/unstable-agent-cleanup.test.ts
index 298bbdb32..3647351e0 100644
--- a/src/tools/delegate-task/unstable-agent-cleanup.test.ts
+++ b/src/tools/delegate-task/unstable-agent-cleanup.test.ts
@@ -115,7 +115,7 @@ describe("executeUnstableAgentTask cleanup", () => {
         manager: mockManager,
         client: {
           session: {
-            status: async () => ({ data: { ses_timeout_cleanup: { type: "running" } } }),
+            status: async () => ({ data: { ses_timeout_cleanup: { type: "busy" } } }),
             messages: async () => ({ data: [] }),
           },
         },
diff --git a/src/tools/delegate-task/unstable-agent-task.ts b/src/tools/delegate-task/unstable-agent-task.ts
index 335699fda..8aa2dce81 100644
--- a/src/tools/delegate-task/unstable-agent-task.ts
+++ b/src/tools/delegate-task/unstable-agent-task.ts
@@ -223,6 +223,9 @@ ${textContent || "(No text output)"}
 session_id: ${sessionID}
 </task_metadata>`
   } catch (error) {
+    if (!cleanupReason) {
+      cleanupReason = "exception"
+    }
     return formatDetailedError(error, {
       operation: "Launch monitored background task",
       args,