[NiloCK]

A const prompt across all of Anthropic's subscribers could draw from a global cache rather than per-user?

Although saying that out loud makes me question it - each per-user chat and growing cache would need eventually to own its own ~contiguous memory block.

[mixermachine]

If there are no changes to the system message, yes this is possible and also likely done by Anthropic. When there are additional local MCPs, reusability will be lower.

I think that Anthropic will bill you in any case :D