WorktreeRemove hook not invoked for subagent worktrees (isolation: worktree)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

WorktreeRemove hooks never fire when a subagent launched with isolation: "worktree" finishes. The worktree directory, git worktree metadata, and branch all linger indefinitely.

WorktreeCreate hooks fire correctly for the same subagent worktrees — the setup side works, just not teardown.

I verified this by replacing my cleanup script with a bare echo "test" >> /tmp/log — still nothing. The hook simply isn't invoked.

What Should Happen?

The WorktreeRemove hook should fire when a subagent worktree session ends, same as it does for EnterWorktree sessions. Without this, worktrees from isolation: "worktree" accumulate under .claude/worktrees/ and require manual cleanup.

Steps to Reproduce

1. Configure WorktreeCreate and WorktreeRemove hooks in .claude/settings.json:

{
  "hooks": {
    "WorktreeCreate": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "bash \"$CLAUDE_PROJECT_DIR/scripts/worktree-setup.sh\""
          }
        ]
      }
    ],
    "WorktreeRemove": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "echo \"FIRED\" >> /tmp/worktree-remove.log"
          }
        ]
      }
    ]
  }
}

1. Launch a subagent with isolation: "worktree" (via the Task tool in a conversation)
2. Let the subagent finish (no changes made)
3. Check /tmp/worktree-remove.log — file doesn't exist
4. Check .claude/worktrees/ — worktree directory still present
5. Check git worktree list — stale entry still registered
6. Check git branch — worktree branch still exists

Error Messages/Logs

No errors — the hook silently doesn't run. There's nothing to see because it never executes.

Claude Code Version

2.1.53

Platform

Anthropic API (Max)

Operating System

macOS 15.4

Terminal/Shell

Ghostty + zsh

Additional Information

The v2.1.50 changelog says: "Added WorktreeCreate and WorktreeRemove hook events, enabling custom VCS setup and teardown when agent worktree isolation creates or removes worktrees." — emphasis on "agent worktree isolation", which is exactly the isolation: "worktree" codepath that doesn't work.

Also worth noting: the subagent worktrees don't get cleaned up by built-in behavior either. With a custom WorktreeCreate hook, Claude seems to defer cleanup entirely to the WorktreeRemove hook — but since that hook never fires, nothing cleans up.