Topic
Storing and reusing HTTP responses in intermediaries and browsers according to cache keys, TTLs, revalidation directives and invalidation rules.
The IETF published RFC 10008 in June 2026 and IANA registered QUERY as safe and idempotent, so a structured read no longer has to travel as a POST. Whether the response stays cacheable depends on the caches on the path.
Reality
Password-reset queries made up 38% of one support RAG bot's vector lookups, says a dev.to write-up that moves retrieval behind an HTTP cache. Any saving depends on identical queries repeating within one tenant inside five minutes.
Reality
Support for the Vary header has landed in Cloudflare's Cache Rules on every plan. The judgement it moves to the edge is how much of a request header's variation deserves a cache entry of its own.
Reality
YouTube's public feed answers a view-count query with a stale number, a valid 200 and an unremarkable byte count, so a program that reads it once takes the wrong answer for the real one.
Reality
Web cache poisoning starts when the origin reads a request field the cache left out of its key, so a response generated for one request gets stored and replayed to everyone asking for that path.
Reality
Workers CPU wall time counts only handler execution, so at 0.1 requests per second ScribeToAny's cold isolates spent seconds compiling before the 5ms render, and the platform dashboard showed none of it.
Reality