improve-codebase-architecture

Improve this codebase's architecture using principles from *A Philosophy of Software Design* (APOSD) by John Ousterhout. The APOSD module-shape vocabulary this skill names problems with — shallow module, interface, depth, seam, adapter, leverage, locality — is defined in the `codebase-design` skill. Load it when you need the precise definitions or the deepening/design-it-twice procedures. ## Prerequisites 1. Check for `CONTEXT.md` or `UBIQUITOUS_LANGUAGE.md` — load if present. These define the canonical vocabulary for all naming decisions. 2. If neither exists: "Domain model not established. Naming recommendations may not align with ubiquitous language. Run `domain-model` first for best results." ## Scoping Phase Decide *where* to look before you look — deepening a module only pays off where change is frequent, so scope before scanning. 1. If the user named a module, subsystem, or pain point, take it and skip step 2. 2. Otherwise walk back the commit history (`git log --oneline -- <path>`, or repo-wide) and rank paths by change frequency. The hot spots are the candidates; let them pull your attention first. If changes are scattered with no clear hot spot, widen the net. ## Analysis Phase Find the worst offenders first, within the scope set above. Use `references/DEEPENING.md` as a checklist. 1. **Shallow modules** — interfaces that expose more complexity than they abstract. Red flag: method count approaches implementation line count. 2. **Information ...