# Improve Codebase Architecture > Find deepening opportunities in a codebase, informed by the domain language in CONTEXT.md and the decisions in docs/adr/. Use when the user wants to improve architecture, find refactoring opportunities, consolidate tightly-coupled modules, or make a codebase more testable and AI-navigable. - Skill: `adesolaodubiyi/improve-codebase-architecture` (Agent Skill, multi-file: 3 files) - Install (CLI): `npx skillmds@latest add adesolaodubiyi/improve-codebase-architecture` - Raw SKILL.md: https://api.skillmd.com/api/skills/adesolaodubiyi/improve-codebase-architecture/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: AdesolaOdubiyi (https://skillmd.com/u/adesolaodubiyi) - Updated: 2026-09-21 - Page: https://skillmd.com/skills/adesolaodubiyi/improve-codebase-architecture --- # Improve Codebase Architecture Surface architectural friction and propose **deepening opportunities** — refactors that turn shallow modules into deep ones. The aim is testability and AI-navigability. ## Glossary Use these terms exactly in every suggestion. Consistent language is the point — don't drift into "component," "service," "API," or "boundary." Full definitions in [LANGUAGE.md](LANGUAGE.md). - **Module** — anything with an interface and an implementation (function, class, package, slice). - **Interface** — everything a caller must know to use the module: types, invariants, error modes, ordering, config. Not just the type signature. - **Implementation** — the code inside. - **Depth** — leverage at the interface: a lot of behaviour behind a small interface. **Deep** = high leverage. **Shallow** = interface nearly as complex as the implementation. - **Seam** — where an interface lives; a place behaviour can be altered without editing in place. (Use this, not "boundary.") - **Adapter** — a concrete thing satisfying an interface at a seam. - **Leverage** — what callers get from depth. - **Locality** — what maintainers get from depth: change, bugs, knowledge concentrated in one place. Key principles (see [LANGUAGE.md](LANGUAGE.md) for the full list): - **Deletion test**: imagine deleting the module. If complexity vanishes, it was a pass-through. If complexity reappears across N callers, it was earning its keep. - **The interface is the test surface.** - **One adapter = hypothetical seam. Two adapters = real seam.** This skill is _informed_ by the project's domain model. The domain language gives names to good seams; ADRs record decisions the skill should not re-litigate. ## Process ### 1. Explore Read the project's domain glossary and any ADRs in the area you're touching first. **YAGNI-first scoping:** Before scanning broadly, run `git log --oneline -50` to find hot spots — files that change most frequently are where friction lives. Start your exploration there. Then walk the codebase organically and note where you experience friction: - Where does understanding one concept require bouncing between many small modules? - Where are modules **shallow** — interface nearly as complex as the implementation? - Where have pure functions been extracted just for testability, but the real bugs hide in how they're called (no **locality**)? - Where do tightly-coupled modules leak across their seams? - Which parts of the codebase are untested, or hard to test through their current interface? Apply the **deletion test** to anything you suspect is shallow: would deleting it concentrate complexity, or just move it? A "yes, concentrates" is the signal you want. ### 2. Present candidates Present a numbered list of deepening opportunities. For each candidate: - **Files** — which files/modules are involved - **Problem** — why the current architecture is causing friction - **Solution** — plain English description of what would change - **Benefits** — explained in terms of locality and leverage, and also in how tests would improve **Use CONTEXT.md vocabulary for the domain, and [LANGUAGE.md](LANGUAGE.md) vocabulary for the architecture.** If `CONTEXT.md` defines "Order," talk about "the Order intake module" — not "the FooBarHandler," and not "the Order service." **ADR conflicts**: if a candidate contradicts an existing ADR in `docs/adr/` or `docs/decisions/`, surface it with a `⚠️ ADR conflict` callout — include which ADR and why it conflicts. Do not silently skip the candidate; let the user decide whether it warrants reopening the ADR. Do NOT propose interfaces yet. Ask the user: "Which of these would you like to explore?" **After presenting candidates, generate an HTML report** at `$TMPDIR/architecture-review.html`: ```html ``` Open it: `open $TMPDIR/architecture-review.html` (macOS) or `xdg-open $TMPDIR/architecture-review.html` (Linux). Tell the user the file path. ### 3. Decision loop Once the user picks a candidate, use the `grilling` skill to walk the design tree — constraints, dependencies, the shape of the deepened module, what sits behind the seam, what tests survive. Side effects happen inline as decisions crystallize: - **Naming a deepened module after a concept not in `CONTEXT.md`?** Add the term to `CONTEXT.md` — same discipline as `grill-with-docs` (see [CONTEXT-FORMAT.md](../grill-with-docs/CONTEXT-FORMAT.md)). Create the file lazily if it doesn't exist. - **Sharpening a fuzzy term during the conversation?** Update `CONTEXT.md` right there. - **User rejects the candidate with a load-bearing reason?** Offer an ADR, framed as: _"Want me to record this as an ADR so future architecture reviews don't re-suggest it?"_ Only offer when the reason would actually be needed by a future explorer to avoid re-suggesting the same thing — skip ephemeral reasons ("not worth it right now") and self-evident ones. See [ADR-FORMAT.md](../grill-with-docs/ADR-FORMAT.md).