- Move clearNotificationsForTask() to finally block to ensure cleanup even on success
- Add TASK_TTL_MS (30 min) constant for stale task detection
- Implement pruneStaleTasksAndNotifications() to remove expired tasks and notifications
- Add comprehensive tests for pruning functionality (fresh tasks, stale tasks, notifications)
- Prevents indefinite Map growth when tasks complete without errors
🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)
Previously, background_cancel(all=true) only cancelled direct child tasks, leaving grandchildren and deeper nested tasks uncancelled. This caused background agents to continue running even when their parent session was cancelled.
Changes:
- Added getAllDescendantTasks() method to BackgroundTaskManager for recursive task collection
- Updated background_cancel to use getAllDescendantTasks instead of getTasksByParentSession
- Added comprehensive test coverage for nested task cancellation scenarios
🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)
