.git/index.lock stuck with "Resource busy" (EBUSY) — opencode holds `.git` dir open on encrypted APFS volume

Description

What happened

While working in a repository on an encrypted APFS volume, opencode performed git
operations (status/diff/log, then later a commit attempt). A .git/index.lock file
appeared and became permanently stuck:

• rm, mv, and python os.unlink() on .git/index.lock all fail with
  Resource busy (errno 16 / EBUSY).
• lsof .git/index.lock (and a search by inode) reports no holder.
• The lock file is 0 bytes.

Evidence / diagnosis

• The opencode process holds the repository root and the .git directory open as
  directory file descriptors (e.g. 49r, 54r, 55r → .git and repo cwd),
  even when it is not actively running a git command.
• The 0-byte lock suggests a git process created it via O_CREAT|O_EXCL and was
  interrupted before writing its content.
• On this encrypted APFS volume, unlinking a file inside a directory that another
  process keeps open (combined with fseventsd/mds activity) returns EBUSY, so the
  lock cannot be cleared without terminating the holder.

Workaround

Bypassed the lock by pointing git at a temporary index file:

export GIT_INDEX_FILE=/tmp/idx-myproject
git read-tree HEAD
git add <file>
git write-tree
git commit-tree <tree> -p HEAD
git update-ref HEAD <commit>

This works, but every subsequent normal git invocation inside the repo still hits
the stuck lock.

Questions / requested behavior

1. Does opencode keep the .git directory open as a directory watcher? If so, is it
   expected that this prevents .git/index.lock from being unlinked on macOS?
2. Should opencode clean up stray .git/index.lock files (or detect a dead lock)
   before running git operations?
3. Any known interaction with encrypted APFS volumes causing EBUSY on unlink?

Plugins

No response

OpenCode version

1.18.18 (installed via Homebrew, /opt/homebrew/bin/opencode)

Steps to reproduce

1. On macOS, clone a repository onto an encrypted APFS volume (Cryptomator WebDav)
   (/Volumes/CRYPT/...).
2. Open the repo with opencode (opencode, v1.18.18) and let it run its normal
   startup git inspection (git status, git diff, git log).
3. Attempt a commit from within the opencode session (e.g. git add + git commit)
   while opencode is still running.
4. Interrupt / let the session move on — a .git/index.lock file is left behind
   (0 bytes).
5. Observe:
   • ls -la .git/index.lock → file present, 0 bytes.
   • rm .git/index.lock → rm: .git/index.lock: Resource busy.
   • python3 -c "import os; os.unlink('.git/index.lock')" → OSError: [Errno 16] Resource busy.
   • lsof .git/index.lock → no output (no visible holder).
6. Confirm opencode still holds the .git directory open:
   lsof -p <opencode-pid> | grep '\.git' → DIR fds on .git and repo cwd.
7. Any subsequent git add/git commit inside the repo now fails with
   fatal: Unable to create '.../.git/index.lock': File exists..
   av(

Screenshot and/or share link

No response

Operating System

macOS 15.7.9, Apple Silicon

Terminal

No response