Claude Prompt Caching Hit Rate Was 0%. One Timestamp Did It

I turned on Claude prompt caching, shipped it, and moved on. Nine days later I looked at the usage logs and saw cache_read_input_tokens: 0 on every one of 3,412 calls. Not a low hit rate. Zero. And it was worse than zero, because every one of those calls paid the cache write premium. Turning on caching had made my bill go up. The cause was one... Weiterlesen