Issue with 5-Hour Usage Limit and Subagent Bug

The main agent was started while the 5-hour usage quota was still available. However, when the quota was close to being exhausted, the main agent launched a subagent, which then encountered an error.

<img width="756" height="648" alt="Image" src="https://github.com/user-attachments/assets/97d95077-5156-4fa0-aee9-edde99bedfcb" />

The subagent displayed a usage quota exhausted message and was forced to interrupt its task. However, the UI continued to show “subagent is working,” which made it look as if the subagent was still running.

<img width="500" height="181" alt="Image" src="https://github.com/user-attachments/assets/cc48ecbe-dfc2-4a54-aabb-54a87c47e8e6" />

The main agent did not properly terminate or close the subagent. Instead, it directly marked the current task as completed/finalized.

I think subagents should be allowed to complete their current work even after the 5-hour usage quota is exhausted, similar to the main agent. Once the subagent finishes, the main agent should properly terminate the subagent and then finalize the task.