CHEATSHEETOptimization
Prompt cache floors: 512 on Opus 5, 4,096 on Haiku 4.5
Anthropic's minimum cacheable prefix is model-dependent and runs backwards - newer, pricier models have the lower floor, so the same prefix can cache on Opus 5 and silently never cache on Haiku 4.5.
prompt-cachingcosttokensclaudecheatsheetcache-control