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#prompt-caching
1 articles
01
2026-08-27
·
Inference & Serving
·
★ MEMBER
·
10 min read
Prompt Caching and Context Design — One Prefix Rule That Moves Your Bill by an Order of Magnitude
Are you paying to have the same system prompt re-read on every single request? Prompt caching only works on exact prefixes — and that one rule decides what goes where in your context. Why a single timestamp at the top wipes out everything below it, and how misreading the TTL can make caching 25% more expensive than not caching at all.