Doesn’t that blow your token cache hit rate and balloon your costs (essentially everything is billed at the input token rate, not the cached rate)?
Doesn’t that blow your token cache hit rate and balloon your costs (essentially everything is billed at the input token rate, not the cached rate)?
If it moved a block like
<system_prompt>
<tools_etc>
<project_prompts>
<user_call>
<llm_response>
=>
<system_prompt>
<tools_etc>
//Removed project_prompts
<user_call>
<llm_response>
<user_call>
<project_prompts> //reinserted
<llm_response>
Cache would break but if you did instead
<system_prompt>
<tools_etc>
<project_prompts>
<user_call>
<llm_response>
<user_call>
<project_prompts> //Duplicated with new user messsage
<llm_response>
It wouldn't bust cache, it would just make your input prompts slightly larger. Technically inefficient as you're duplicating the same rules over and over but I imagine for a smallish checklist/principles that it is tremendously more efficient than a cache break every message
By the time it does 10 turns of tool calls it forgets about the nagging again. It can and does ignore direct instruction from the user prompt too, sometimes repeatedly
so first, we treat context like a stack. Things are popped onto the stack; if we try to remove anything but the top of the stack, we'll break the cache.
So a good harness should be popping tool prompts, user hints after every return from the top so the context of tools and user hints never repeats and are allways prefixed to the current user prompt.
I've never inspected any harness, but opencode with the dynamic context compaction plugin appears to do this well.