Deep module
Also called Shallow module
A module that does a lot behind a small interface. A shallow one has an interface nearly as complicated as what it does, so using it spares you very little. The words are John Ousterhout's.
A deep module means less to hold in context per task, and one obvious place to make a change. Asking an agent for small pieces without asking for depth can get you the opposite: every helper correct, and the caller left doing the real work.
Say it to your agent
“Merge these six exported cache helpers into one function: cached(key, ttlMs, compute). Expiry and the key format become private. Callers must not know either exists.”