> They need to have direct instruction that is in the context, that is appropriate for the project and codebase at hand

> I recognize that crafting a 'perfect' prompt is impossible, but neither is writing the perfect code, or even the 'perfect' code style guide

This is not about "perfect code" or style guides. For code styles we have linters, that does not require any instructions. I'm talking about software architecture for large complex web applications that dozens of people (that also change frequently) contribute to and that is spread across many different repos/services and an environment with constantly changing business requirements.

The terms that are relevant here are: coupling, cohesion, vertical slices, module boundaries and so on. This is software architecture and coding agents are terrible at this and there is no prompt and no instruction fixes this that could reasonably fit into a context window. I don't even think that coding agents fail because the lack the instructions and therefore adding instructions won't fix these failure modes.