improve-codebase-architecture

Files (2)

• HTML-REPORT.md
• SKILL.md

SKILL.md (first lines)

# Improve Codebase Architecture

Surface architectural friction and propose two kinds of candidate, both decided by the **deletion test**: **deepening opportunities** — refactors that turn shallow modules into deep ones — and **simplify / delete opportunities** — shallow or speculative structure to cut. The aim is testability and AI-navigability. A codebase improves as much by deleting shallow cruft as by deepening.

This command is _informed_ by the project's domain model and built on a shared design vocabulary:

- Run the `dmi-superpowers:codebase-design` skill for the architecture vocabulary (**module**, **interface**, **depth**, **seam**, **adapter**, **leverage**, **locality**) and its principles (the deletion test, "the interface is the test surface", "one adapter = hypothetical seam, two = real"). Use these terms exactly in every suggestion — don't drift into "component," "service," "API," or "boundary."
- The domain language in `CONTEXT.md` gives names to good seams; ADRs in `docs/adr/` record decisions this command should not re-litigate.

## Process

### 1. Explore

Read the project's domain glossary (`CONTEXT.md`) and any ADRs in the area you're touching first.

Then use the Agent tool with `subagent_type=Explore` to walk the codebase. Don't follow rigid heuristics — explore 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?
- Where is there **over-engineering to cut** — a reinvented standard-library
  function, a dependency doing what the platform already does, an interface
  with one implementation, config nobody sets, dead flexibility? These are
  **Simplify / delete** candidates.

Apply the **deletion test** to every candidate: delete the thing and ask what happens to the complexity. If it *concentrates* because the thing was hiding real work, it is a **deep module** — a Deepen candidate, keep and extend it. If it vanishes or merely moves, the thing was **shallow** or speculative — a Simplify / delete candidate, cut it.

### 2. Present candidates as an HTML report

Write a self-contained HTML file to the OS temp directory so nothing lands in the repo. Resolve the temp dir from `$TMPDIR`, falling back to `/tmp` (or `%TEMP%` on Windows), and write to `<tmpdir>/architecture-review-<timestamp>.html` so each run gets a fresh file. Open it for the user — `xdg-open <path>` on Linux, `open <path>` on macOS, `start <path>` on Windows — and tell them the absolute path.

The report uses **Tailwind via CDN** for layout and styling, and **Mermaid via CDN** for diagrams where a graph/flow/sequence reliably communicates the structure. Mix Mermaid with hand-crafted CSS/SVG visuals — use Mermaid when relationships are graph-shaped (call graphs, dependencies, sequences), and hand-built divs/SVG when you want something more editorial (mass diagrams, cross-sections, collapse animations). Each candidate gets a **before/after visualisation**. Be visual.

For each candidate, render a card with:

- **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 how tests would improve
- **Before / After diagram** — side-by-side, custom-drawn, illustrating the shallowness and the deepening
- **Recommendation strength** — one of `Strong`, `Worth exploring`, `Speculative`, rendered as a badge

**Candidate type:** tag each card as **Deepen** or **Simplify / delete**. For
Simplify / delete cards, label the specific move with the tag taxonomy —
`delete:` / `stdlib:` / `native:` / `yagni:` / `shrink:` — and state the line
count the deletion saves. That count must come from performing or dry-running the
deletion — read every file you propose to collapse. A number estimated from file
sizes routinely overstates the saving several-fold, because most of what looks
duplicated turns out to be genuinely per-case; a report whose purpose is
prioritisation is the wrong place for that error. If you have not done the read,
label the figure an estimate and say how you arrived at it. The before/after
diagram shows the structure shrinking rather than deepening.

End the report with a **Top recommendation** section: which candidate you'd tackle first and why.

**Use CONTEXT.md vocabulary for the domain, and the `dmi-superpowers:codebase-design` 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, only surface it when the friction is real enough to warrant revisiting the ADR. Mark it clearly in the card (e.g. a warning callout: _"contradicts ADR-0007 — but worth reopening because…"_). Don't list every theoretical refactor an ADR forbids.

See [HTML-REPORT.md](HTML-REPORT.md) for the full HTML scaffold, diagram patterns, and styling guidance.

Do NOT propose interfaces yet. After the file is written, ask the user: "Which of these would you like to explore?"

### 3. Grilling loop

Once the user picks a candidate, run the `dmi-superpowers:grilling` skill to walk the design tree with them — constraints, dependencies, the shape of the deepened module, what sits behind the seam, what tests survive.

Side effects happen inline as decisions crystallize — run the `dmi-superpowers:domain-modeling` skill to keep the domain model current as you go:

- **Naming a deepened module after a concept not in `CONTEXT.md`?** Add the term to `CONTEXT.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.
- **Want to explore alternative interfaces for the deepened module?** Run the `dmi-superpowers:codebase-design` skill and use its design-it-twice parallel sub-agent pattern.

From HundredBillion/dmi_superpowers, MIT.

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