fatal: not a git repository

The "not a git repository" error has a non-obvious trigger in git worktrees — a feature since Git 2.5 that allows multiple working directories from the same repository. When you use git worktree add ../feature-branch, Git creates a directory with a special .git file (not a directory) that points back to the main repo's .git. Some tools that check for git initialization by looking for a .git directory (rather than running git rev-parse --git-dir) incorrectly report "not a git repository" in a worktree. A second edge case: the .git directory can exist but be in an inconsistent state after a failed git clone interrupted midway. The directory structure exists but is incomplete — HEAD or config files may be missing — causing git commands to fail even though the .git folder is visible. Running ls -la .git typically reveals the missing files. Git 2.35.2+ introduced security hardening (CVE-2022-24765) that refuses to operate on directories owned by a different user. CI setups that run git operations as root on files checked out as another user, or symlink structures where the repo directory is owned by a different user than the running process, trigger this error. The fix: git config --global --add safe.directory /path/to/repo, or in GitHub Actions the actions/checkout action handles this automatically since version 3.1.0.