Codebase improve

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.

Follow the codebase-design skill for design vocabulary and principles. Follow the domain-model skill when maintaining CONTEXT.md or ADRs.

Process

1. Explore

Scope the scan before exploring. Deepening pays off when future changes land in that area, so avoid speculative whole-repo review:

• If the user names a module, subsystem, or pain point, focus there.
• Otherwise inspect a useful stretch of git log --oneline for recurring files and areas. Start with those hot spots; widen only when history is scattered.

These commands run automatically when the skill loads — output replaces each line below:

• CONTEXT.md: !cat CONTEXT.md 2>/dev/null || true
• ADR list: !ls docs/adr/ 2>/dev/null || true

If CONTEXT.md content is present above, use that vocabulary throughout. If ADR list showed files, read the relevant ones before exploring.

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?

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 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 Mermaid via CDN for diagrams where a graph, flow, or sequence reliably communicates the structure. Mix Mermaid with hand-crafted CSS/SVG visuals: use Mermaid when relationships are graph-shaped, and hand-built divs/SVG for mass diagrams, cross-sections, and collapse diagrams. Each candidate gets a before/after visualization.

See ~/.claude/skills/almanac/codebase-improve/HTML-REPORT.md for the full HTML scaffold, diagram patterns, and styling guidance.

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 also in 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

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

Use CONTEXT.md vocabulary for the domain, and codebase-design vocabulary for architecture.

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 (e.g. "contradicts ADR-0007 — but worth reopening because…").

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, drop into a grilling conversation. Walk the decision 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:

• 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 so future reviews don't re-suggest it. Only offer when the reason would actually be needed by a future explorer.
• Want to explore alternative interfaces for the deepened module? Follow ~/.claude/skills/almanac/codebase-design/references/design-it-twice.md.