Codebase Improver

Take a codebase from "I think there are problems" to "the problems are mapped, prioritized, and fixed" — end to end, human in control at every gate.

The improvement engine is built on deep modules (John Ousterhout, A Philosophy of Software Design): a deep module has a small interface hiding a large implementation. Deep modules are more testable, more AI-navigable, and let you test at the boundary instead of inside. The goal of the Deepen stage is to turn shallow, tightly-coupled clusters into deep modules.

This skill is self-contained (Python/TS); worker roles run inline by default and may use explicitly authorized delegation.

Map ──► Audit ──► Deepen (recursive) ──► (next round)
 │        │          │
scan    parallel   explore → candidates → design N interfaces
        subagents  → RFC → optionally implement → recurse

Host portability