photoanalyzer/delivery_backlog/stories/US04-03-rename-apply.md

US04-03 — Apply and Verify Guarded Renames

Epic: E04

As a user, I want confirmed plans applied without overwrites so reorganizing the library preserves identity and bytes.

Acceptance criteria

• Apply requires current plan/version confirmation and an exclusive mutation lease.
• Preconditions are rechecked immediately before each mutation; unexpected targets are never overwritten.
• Case-only and cross-filesystem operations use safe staged procedures.
• Postconditions verify bytes and paths, update occurrences, and reconcile stable IDs.

Automated tests

• Filesystem integration tests cover normal, case-only, collision, cross-filesystem, stale source, and repeated apply.
• Tests assert byte preservation and database/path consistency after restart.

Dependencies

• US04-02