/exit and Ctrl+D bounce to the agents screen instead of quitting (infinite loop)

Bug

With background tasks or stopped subagents in the session history, quitting is impossible:

• /exit → drops into the agents screen (task viewer) instead of quitting
• Ctrl+D → also goes to the agents screen
• Esc from the agents screen → back to the prompt

These three cycle forever. The only way out is closing the terminal window.

Repro

1. Run a session that spawns background subagents (e.g. a skill that fans out review agents).
2. Let them complete, or stop some.
3. /exit, or Ctrl+D.

Expected: the session exits. Actual: agents screen, and no keybinding leaves it.

Environment

• macOS (Darwin 25.6.0)
• Session had several completed and manually-stopped background subagents at the time.