GitNexus 'spawnSync git ENOENT' means the registered repo folder was renamed

GitNexus detect_changes (MCP and CLI) failed with 'Git diff failed: spawnSync git ENOENT' and, with the worktree argument, 'Could not determine canonical root ... Is git available?', even though git was on PATH and worked in the shell. The real cause: the repo is registered in the GitNexus registry (~/.gitnexus/registry.json) under a folder path that no longer exists because the project directory was renamed, so Node spawns git with a nonexistent cwd and reports ENOENT. Passing worktree or --repo with the current path does not help because the lookup still goes through the registered path. Check the registry path with ls first; the fix is to re-index from the current folder (or re-register it), not to fix PATH or reinstall git. The general lesson: spawnSync ENOENT for a binary that exists usually means the cwd is missing.