Anthropic Prompt Caching Deep Dive — Automatic Caching, 1-Hour TTL, and the Gotchas They Don't Tell You

Anthropic's prompt caching got major updates in 2026: Automatic Caching removes manual breakpoint headaches, 1-hour TTL keeps caches alive longer, and the invalidation hierarchy decides what blows up when you change things. Plus our real-world $13.86 billing disaster story.