Backend (git_repositories.py):
- get_repository_branches: check for .git dir OR HEAD file (handles bare repos)
- When local repo is missing, git ls-remote fallback now uses SSH key auth
via _prepare_ssh_env() for repos with ssh_key_id
- Cleans up temp SSH key file after ls-remote
- Logs ls-remote stderr/exit code for debugging
- Returns server's detail message instead of raw axios 404 text
Frontend (use-git-repo.ts):
- extractError() helper pulls server detail/message from axios responses
- User sees 'repository not found on disk — re-clone or re-create'
instead of generic 'Request failed with status code 404'
Quality gates: ruff clean, tsc --noEmit clean, 11 passed + 1 pre-existing failure
Backend (git_repositories.py):
- get_repository_branches now checks for .git subdirectory (not just dir existence)
- If local repo is corrupt/missing but has remote_url, falls back to git ls-remote
to list branches from the remote
- Returns 404 with actionable message instead of 400 with raw git stderr
- Pre-existing test failure in test_git_repository_clone_preflight.py unchanged
Frontend (workspace-create-form.tsx):
- When branch API fails, auto-switches to manual text input (no dropdown selection needed)
- Shows hint text: 'Couldn't load branches — type one manually'
- useGitRepo hook auto-fetches branches when projectId/repoId change
Quality gates: ruff clean, tsc --noEmit clean, 93 passed + 1 pre-existing failure