bug: stale snapshot index.lock breaks Modified Files and undo for one workspace #22275

Description

In one specific workspace, OpenCode stopped showing Modified Files, and revert undo messages and file changes no longer worked correctly. Other workspaces on the same machine were fine.

I traced it to a stale lock file in OpenCode's local snapshot cache for that workspace. The OpenCode logs repeatedly showed snapshot failures like:

fatal: Unable to create .../snapshot/<project-id>/<hash>/index.lock: File exists.

After removing the stale index.lock and then backing up/removing the workspace's snapshot cache under ~/.local/share/opencode/snapshot/<project-id>, the problem immediately went away.

This makes the workspace get stuck in a bad state where snapshot tracking is broken persistently, which seems to break both Modified Files and undo/revert behavior.

Plugins

None that seem relevant.

OpenCode version

1.3.7

Steps to reproduce

1. Use OpenCode in a git workspace until its local snapshot repo ends up with a stale index.lock under ~/.local/share/opencode/snapshot/<project-id>/.../index.lock.
2. Open that workspace again.
3. Make a file change through OpenCode.
4. Observe that Modified Files may not show up for that workspace, and revert undo messages and file changes does not correctly revert file changes.
5. Check OpenCode logs and see repeated snapshot failures with index.lock: File exists.
6. Remove the stale lock / reset the workspace snapshot cache, then restart OpenCode.
7. Observe that the workspace starts working normally again.

Screenshot and/or share link

I did not capture a share link, but I confirmed the root cause locally from the OpenCode log and snapshot cache.

Operating System

macOS (Apple Silicon)

Terminal

VSCode integrated terminal