worktree: Stop filtering low-frequency .git file events

[Ariestar]

Problem

The git panel goes stale after git operations performed outside Zed (a terminal, an
agent tool, or a second Zed window). A common report: after git fetch / git pull
/ git commit in the terminal, the panel still shows old ahead/behind counts and
modified-file markers -- even clicking the panel's Fetch action does not update it.
No error is surfaced. See #61273, #60102, #60882.

Root cause

The worktree filters filesystem events inside .git directories, ignoring "noisy"
paths to avoid triggering unnecessary git rescans. That filtering included a
file-name denylist:

let skipped_file_names_in_dot_git =
    [COMMIT_MESSAGE, FETCH_HEAD, ORIG_HEAD, BISECT_LOG, GC_PID];

Every external git operation writes one of these files exactly once: FETCH_HEAD
(fetch/pull), ORIG_HEAD (reset/merge), COMMIT_EDITMSG (commit), BISECT_LOG
(bisect), gc.pid (gc). Because those events are dropped, the worktree never bumps
the repository's git_dir_scan_id, no UpdatedGitRepositories event is emitted, and
the git store never re-runs git status — so the panel stays stale indefinitely.
When a fetch brings no new refs, FETCH_HEAD is the only signal, so
refs-directory watches (#60660) do not cover this case.

Solution

Drop the file-name denylist entirely. Instead of maintaining a list of "which
low-frequency files are worth a rescan", treat every .git file event outside the
known high-frequency directories as worth one git-state check:

• Removed the file-name denylist (COMMIT_EDITMSG, FETCH_HEAD, ORIG_HEAD,
  BISECT_LOG, gc.pid now all trigger a rescan).
• Kept the directory-level filtering (objects/, logs/, fsmonitor-daemon/,
  lfs/, rebase-*, sequencer/) and the transient-file filtering (*.lock,
  single-level *.new / *.tmp). These are either written continuously during
  long-running git operations (fetch/gc), redundant with ref/index events, or
  necessary to avoid a rescan self-triggering loop (index.lock, see the existing
  comment in process_events).

This is safe against rescan storms by construction: the denylisted files are each
written once per git operation, and the existing snapshot diff
(git_dir_scan_id comparison) already suppresses UpdatedGitRepositories when git
state is unchanged.

Testing

• test_noisy_dot_git_events_do_not_emit_git_repo_update — FETCH_HEAD,
  ORIG_HEAD, COMMIT_EDITMSG, BISECT_LOG, gc.pid now assert that events emit
  UpdatedGitRepositories; object writes, reflogs, lock files, rebase-* and
  sequencer/ events still do not.
• All 21 git-related worktree tests pass, including the 100-seed random test
  test_random_git_updates_with_watcher_overflows.

Related issues

• Fixes Git panel Push status out of sync with repository even after triggering Fetch from Zed #61273
• Related: Git status markers don't update immediately when performing git actions from within a terminal #60102, Git panel / project panel stale when files are modified by an agent running in a different Zed window/project #60882, Git Panel History stays stale after converting a shallow clone to a full clone #62523

Release Notes:

• Fixed git panel not refreshing after git fetch / git pull / git commit
  performed outside Zed.

[cla-bot]

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[zed-industries-bot]

	Warnings
⚠️	worktree: stop filtering low-frequency .git file events ^ Write PR titles using sentence case.

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