Working notes on edge caching, format negotiation and the long tail of things that break when you serve pictures at scale.
Device, DPR and format in one key — and when that quietly costs you your hit ratio.
Why purge-by-URL is never enough once transforms are in front of the origin.
Cheap kernels, expensive correctness: keeping output stable across library versions.
Ordering, matching precedence, and the two-minute rule for anything stateful.