fs/list returns HTTP 500 for the project worktree root when serve is started in a non-git directory

Description

When opencode serve is started in a directory that is not a git repository, the web UI directory picker is completely broken: it shows "No folders found" and every directory-related action fails. The server-side cause is that fs/list returns HTTP 500 for / — which is the project worktree itself in this scenario.

I know Project.resolve returning worktree / for non-git dirs is working as designed (see #38992), so this issue is about the fs API failing on its own worktree, not about the worktree resolution.

Plugins

None.

OpenCode version

1.18.11

Steps to reproduce

1. Start the server in a non-git directory (e.g. a fresh VM home dir):

   cd /root   # NOT inside a git repository
   opencode serve --port 34192 --hostname 0.0.0.0
   

2. The project worktree resolves to /:

   curl -u opencode:<password> http://127.0.0.1:34192/project/current
   # {"id":"global","worktree":"/", ...}
   

3. Listing the worktree itself returns HTTP 500, even though / contains 23 entries:

   curl -u opencode:<password> "http://127.0.0.1:34192/api/fs/list?path=/"
   # HTTP 500
   # {"name":"UnknownError","data":{"message":"Unexpected server error. Check server logs for details.","ref":"err_..."}}
   

4. Same 500 for any path outside the startup directory: /tmp, /etc, /var.

5. Starting inside a git repo works fine: worktree resolves to the repo path and fs/list returns 200.

Screenshot and/or share link

No share link available (headless server). Can attach screenshot of the web UI empty picker if needed.

Operating System

Ubuntu 24.04 (server) / Safari on iOS (web UI client)

Terminal

None — web UI only.