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Context & Reliability~14 min
Prompt Caching: Make the Stable Prefix Cheap
Master cache_control breakpoints, TTL, prefix ordering, and the economics that make caching pay off across agent turns.
What you will be able to do
- ✓Add a cache_control ephemeral breakpoint to the correct content block in the Messages API
- ✓Order static content before dynamic content so the cached prefix matches exactly across requests
- ✓Reason about cache economics: write cost vs roughly 10% read cost, the 5-minute refreshing TTL, the 1-hour option, and minimum prefix length
- ✓Diagnose why an edit before a breakpoint wipes out all cache hits
3 concepts·6 hands-on exercises·3-question check