Might be a dumb question but do you have to read the files in the same order in new sessions to ensure the correct prefix for the cache?

Yes, you have to use the same session, I guess you could load up a bunch of context, then fork the session into a few different tasks, although I haven't tried it.

Also curious. With tool calls reading/searching different files, possible compacting reading a large codebase / long threads, I can't imagine how you hit 99% cache rate.

Sorry, I was wrong here. I meant a single long session. And there’s no compression, the 1M context is only half used.