/resume can't reopen sessions with live background tasks — forced detour through `claude agents`

Environment

• Claude Code version: 2.1.201
• Platform: Linux (Ubuntu, kernel 6.8), bash, CLI

Describe the bug

When a session that has running background tasks (background Bash tasks and/or a Monitor) is killed/closed, /resume in a new session refuses to reopen it:

That session is still running as a background agent. Open claude agents to attach to it, or stop it there first to resume here.

The session doesn't behave like every other session in the resume list — you have to know about claude agents, go find it there, and either attach or stop it before /resume works.

Steps to reproduce

1. In a session, start a long-running background Bash task (and/or a Monitor).
2. Kill the session (close the terminal / accidental exit) while the task is running.
3. Start a new claude session in the same project and run /resume.
4. The session is not resumable; only the error message above.

Expected behavior

Ideally /resume (or the resume picker) offers to attach to the still-running session directly — same one keystroke as resuming any other session — instead of requiring a manual detour. At minimum, the resume picker could show it with its running state and an attach action.

Additional context

The background tasks themselves surviving the session is great (my experiment kept running — that's the right behavior). The pain is purely the resume/attach discoverability seam between /resume and claude agents.