Phase 2 - Duplicate hash handling / idempotency #54
Description
Cause: Duplicate hashes are not handled; behavior undefined.
Analysis: Redundant work and potential data integrity issues.
Acceptance Criteria:
- Duplicate uploads are detected and short-circuited.
- Existing video metadata is returned reliably.
Solution Approach: - Add unique constraint on file hash.
- Treat hash as idempotency key and prevent duplicate task creation.