Asked about Prompt caching

What breaks prompt caching?

An answer that works

Any change in the prefix, since matching runs from the start and stops at the first difference. Timestamps, request ids, a user name near the top, or JSON serialised with unstable key order all invalidate it silently.

Reading an answer is not being able to give one. The section that teaches this is Prompt caching, 5 hours of Prompt caching.

Learn this properly

Also asked about Prompt caching

What is prompt caching and when does it help?How do you verify caching is working?When does prompt caching not save money?What are the risks of semantic caching?Your cached prefix has a five-minute lifetime. How often do requests have to arrive before caching pays?