What Belongs in Each Layer

The practical test for which layer something belongs in is simple: will this rule apply to basically every future request, or is it specific to what you need right now? Tone, formatting defaults, and standing rules belong in the persistent layer. The specific topic, the actual content to work with, and one-time details belong in the user message.

Say you want a coding assistant to always explain its reasoning before giving code, always use a specific programming language unless told otherwise, and never apologize excessively. Those are standing rules — they belong in the persistent instruction. But 'write a function that sorts this list' is a one-time task — it belongs in the user message, every time, because it's different every time.

Mixing the two up creates two different problems. Stuff a persistent instruction full of details for last Tuesday's specific task, and it keeps applying that irrelevant detail to everything else you ask forever. Leave a standing rule out of the persistent layer and put it only in one user message, and you'll have to remember to retype it every single time — or forget, and get inconsistent results.

Which of these is a standing rule that belongs in a persistent instruction rather than a one-off user message?

A rule that should apply to basically every future request, like a default tone or format, belongs in the ____ layer.

Putting a one-time, task-specific detail into a persistent instruction is a good way to keep it handy for future requests.