v2.1.204: failed self-update deletes live background agents' worktrees; completed agents can't be removed (Ctrl+X no-op) and reappear after restart

Summary

On v2.1.204 (native install, macOS arm64), a failed background self-update deleted the git worktrees of live background agents, crashing those sessions, and left the claude agents view in a state where completed agents cannot be removed with Ctrl+X and reappear after a full restart.

Environment

• Claude Code 2.1.204 (native install, ~/.local/share/claude/versions/2.1.204)
• macOS 15 (Darwin), arm64
• Uses background agents + git worktrees (.claude/worktrees/)

What happened

1. Overnight the auto-updater ran and failed. ~/.claude/.last-update-result.json:

``json
{"timestamp":"<TS>","path":"native","outcome":"failed","status":"install_failed","version_from":"2.1.204","version_to":null}
`
(claude update` confirms 2.1.204 is already the latest — so this is a spurious/failed self-update on the current version, not a pending upgrade.)

1. Shortly after, two live background agents crashed because their worktree working-directories had been removed. ~/.claude/daemon.log (paths redacted):

``
<t1> [bg] bg settled <idA> (crashed): working directory no longer exists ... /.claude/worktrees/<worktreeA>
<t2> [bg] bg settled <idB> (crashed): working directory no longer exists ... /.claude/worktrees/<worktreeB>
`
The daemon only *detected* the dirs missing — it did not log removing them — so the worktree deletion came from the update/restart path, not the daemon. Committed work was safe on the remote (only the local worktrees were lost); recreating them via git worktree add` restored the sessions.

1. The claude agents view now lists all past conversations under "Completed", Ctrl+X (single and double) does not remove them, and previously-removed entries reappear after a full quit + relaunch.

Expected

• A failed/no-op self-update must never delete worktrees belonging to live background agents.
• Ctrl+X on a completed agent should remove it and it should stay removed across restarts.

Actual

• Live agents' worktrees deleted → crash loop.
• Completed agents un-removable and resurrect on restart, growing an unbounded list.

Impact

Background-agent users on worktrees lose live sessions and get a permanently cluttered, un-clearable agent view.