Matt Pocock deep module design

Workflow

Matt Pocock’s codebase-design reference defines modules, interfaces, test seams and adapters, then uses depth, leverage and locality to evaluate architecture and testability.

Run this command in your project after reviewing the instructions and access terms. Install complete upstream directories to keep referenced rules and scripts.

npx skills add https://github.com/mattpocock/skills/tree/5beb35b040e3de97e54fa9e386d7e42d15c295c2/skills/engineering/codebase-design --skill codebase-design --agent claude-code

Project file: .claude/skills/codebase-design/SKILL.md

This brief helps you choose the skill. Read the complete upstream SKILL.md and companion files for its actual instructions.

# Matt Pocock deep module design (matt-pocock-codebase-design)
Matt Pocock’s codebase-design reference defines modules, interfaces, test seams and adapters, then uses depth, leverage and locality to evaluate architecture and testability.

## Use when
- Design a module interface or assess a refactor’s effect on testability.

## Required inputs
- Current module and its consumers
- Behavior, dependency variation and test constraints

## Prerequisites
- Project source and representative consumers.
- Keep DEEPENING.md and DESIGN-IT-TWICE.md; the optional alternative-design exercise needs subagent support.

## Expected outputs
- Proposed interfaces and test seams
- Architecture tradeoffs grounded in callers

Source: https://github.com/mattpocock/skills/blob/5beb35b040e3de97e54fa9e386d7e42d15c295c2/skills/engineering/codebase-design/SKILL.md
Full SKILL.md: https://agenttaste.dev/skills/matt-pocock-codebase-design/SKILL.md

## Popularity evidence
- 297,596 GitHub repo stars — mattpocock/skills; checked 2026-10-20. Source: https://github.com/mattpocock/skills/stargazers
- 825,720 skill installs (all time) — mattpocock/skills / codebase-design · skills.sh · all time; checked 2026-10-20. Source: https://skills.sh/mattpocock/skills/codebase-design
Adoption counts are not user ratings or guarantees of quality.