Git worktree index and commit repair

Repository: kairos-mcp. Skill index: .agents/skills/README.md. Hook authority: .husky/pre-commit (always re-read before automating).

When to use

• error: invalid object …
• error: Error building trees
• Failure after a long pre-commit (for example npm run lint)
• git write-tree fails while staging looks plausible

Root cause

The index references a blob OID not present in this repo’s object database. Worktrees share one .git/objects store with the main repo; corruption or GC there affects every worktree.

Common phantom-entry sources: