Bedrock
3 articles
AI
◆Prompt Caching, End to End · Part 4
Prompt Caching (Part 4): AWS Documents 4,096 — I Measured 1,024
AWS gives Claude Sonnet 4.5 a 4,096-token minimum cacheable prefix. Bisecting on Bedrock put the real threshold at 1,024. Three control models matched their docs; only this row was off.
AI
◆Prompt Caching, End to End · Part 2
Prompt Caching (Part 2): Five Vendors, Three Clouds, One Bill
AWS documents a 4,096-token minimum for Sonnet 4.5 on Bedrock; I measured 1,024. Multipliers, TTL tiers and cross-region behaviour for five vendors — measured kept apart from documented.
DEEP
The Mysterious 400 in Claude Multi-Turn Chats: Debugging a Thinking Signature Corruption
A customer's Claude extended-thinking conversations kept failing with 400 Invalid signature — but only on some gateway channels. A full postmortem: what the signature mechanism is, how a proxy's JSON re-serialization silently corrupts base64, five controlled experiments that pinned it down, and a fix checklist for every LLM gateway developer.