[Bug] Footer agent list shows finished background subagent as still running

Bug Description
Footer agent list shows a finished background subagent as if it were still running. In a long session, the footer list under the prompt kept a general-purpose row with a frozen timer (19m59s) and its last progress label (“Committing build.gradle plugin removal”). The row used the same hollow ○ as the live agent. That agent had finished more than 1.5 hours earlier: its final report is in its transcript, and the main session got its completion notice. Other views disagree with the footer: the “← 1 agent” counter and /tasks both correctly show 1 running agent (a review-agent). Repro attempts: a short session with one or two background agents, plus /compact while one agent was still running, did not reproduce it. The affected session had run for several hours with several compactions, and the stale agent had run for about 20 minutes before it finished. Expected: a finished agent leaves the footer list, or is clearly marked done. Version: Claude Code 2.1.289, macOS.

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.289
• Feedback ID: 9adc34c2-5789-478d-80b7-05ed2a9e42ba