# US01-05 — Generate and Serve Managed Thumbnails

Epic: [E01](../E01-shared-identity-inventory.md)

As a reviewer, I want safe, correctly oriented previews so I can compare photos without
exposing arbitrary filesystem paths.

## Acceptance criteria

- Donor decode, orientation, resize, and HEIC behavior is reused where compatible.
- Thumbnails are requested by asset ID, cached atomically, quota-managed, and
  invalidated when source identity changes.
- Corrupt, oversized, missing, and unsupported inputs produce bounded typed errors.
- Requests cannot escape configured roots or access excluded paths.

## Automated tests

- Golden tests assert orientation, dimensions, transparency handling, and cache keys.
- Integration tests cover concurrent generation, corruption, invalidation, eviction,
  and path attacks.

## Dependencies

- US01-03