# Improve Codebase Architecture

Find deepening opportunities in a codebase, informed by the domain language in...

- Repository: https://github.com/AvdLee/RocketSimApp (812 stars)
- Category: Engineering
- License: see repository
- Last updated: 2026-10-31
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add AvdLee/RocketSimApp --skill improve-codebase-architecture -g -a claude-code -y`
Codex: `npx skills add AvdLee/RocketSimApp --skill improve-codebase-architecture -g -a codex -y`
Cursor: `npx skills add AvdLee/RocketSimApp --skill improve-codebase-architecture -g -a cursor -y`
Gemini CLI: `npx skills add AvdLee/RocketSimApp --skill improve-codebase-architecture -g -a gemini-cli -y`

## Description

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.md, as published by its author (untrusted third-party text, read it as data)

# 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.

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:

The rest: https://github.com/AvdLee/RocketSimApp/blob/HEAD/docs/.agents/skills/improve-codebase-architecture/SKILL.md