An Image Requested Once Before Its Upload Stayed a 404 at the Edge. I Split the Retention Rules by Status Code and Made Upload and Purge a Single Step
A new wallpaper stayed missing in some regions because the CDN kept a 404, fetched once before the upload, as long as it kept the image itself. Per-status retention, a two-request diagnosis, and pairing upload with purge, tested in Node.
I Moved the Thumbnails Assuming the Shipped Build Would Keep Asking for the Old Path
Reorganizing image directories on the server does not reach the builds already installed on people's phones. Here is the two-way fallback that returns 200 for both the old and new paths, the ordering rule for images versus catalog, and the four checks I run through a CDN before calling a release live.
Half the Bytes, the Same Wait: What AVIF Actually Cost My Wallpaper Apps
Switching to AVIF cut my transfer bill in half and did nothing for perceived speed. Here is the transfer-versus-decode breakdown, the Accept-negotiation trade-off, per-device fallback tiers, and the staged migration order that finally worked across six apps.