Clears stale .git/index.lock files before git write commands. Claude Code's internal git status polling leaves orphan locks (anthropics/claude-code#11005) that block add/commit/merge/push. The hook checks lsof/fuser before removing — only stale locks are cleared, never locks held by live processes. Read-only git commands are skipped entirely. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>