Deep modules and fast feedback

Hide meaningful complexity behind a contract that lets callers do useful work. The objective is lower cognitive/change cost with preserved behaviour, not more folders, a prescribed export count, or an abstraction around every function. Agent productivity is a hypothesis to measure, not a benefit proved by the tree shape.

Inspect a real change path

Start from the task and trace the relevant entry point through domain policy, state/data ownership, side effects, callers, and tests. Read actual dependencies, not only README architecture. Identify which information callers must know and which coordinated edits recur. A large file can be cohesive; a tiny wrapper can leak a complicated protocol. Do not equate lines of code with module depth.