# Modular Decomposition

Runs a sequenced monolith-to-modular pipeline that sizes and inventories components...

- Repository: https://github.com/tech-leads-club/agent-skills (7121 stars)
- Category: DevOps
- License: see repository
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add tech-leads-club/agent-skills --skill modular-decomposition -g -a claude-code -y`
Codex: `npx skills add tech-leads-club/agent-skills --skill modular-decomposition -g -a codex -y`
Cursor: `npx skills add tech-leads-club/agent-skills --skill modular-decomposition -g -a cursor -y`
Gemini CLI: `npx skills add tech-leads-club/agent-skills --skill modular-decomposition -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add tech-leads-club/agent-skills`

## Description

Runs a sequenced monolith-to-modular pipeline that sizes and inventories components, finds shared domain duplication, addresses flattening and hierarchy issues, analyzes coupling, then groups components into candidate domain-aligned units, with optional embedded DDD strategic analysis for bounded contexts. Use when asking how to split a monolith, size components before extraction, find duplicated domain logic, clean up module hierarchy, measure coupling between modules, or group components into services. Do NOT use for phased extraction roadmaps or prioritization without the prior analysis steps (use decomposition-planning-roadmap after this pipeline), end-to-end legacy migration strategy writeups (use legacy-migration-planner), pure infrastructure capacity sizing, or when you only need DDD without the structural pipeline (install domain-analysis standalone).

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

# Modular Decomposition

This skill runs the **Patterns 1, 5** analysis pipeline before service extraction. Each pattern is plain markdown under `references/`; load the file for that step and execute it against the user’s codebase.

## How to Use

### Quick start (what users can say)

- **Full pipeline:** “Run modular decomposition Patterns 1 through 5 on this repo,” “Analyze this monolith for splitting, inventory, coupling, and domain grouping.”
- **Single early step:** “Identify and size components here,” “Find duplicated domain logic across modules,” “Analyze coupling between our packages.”
- **With DDD lens:** “Group components into domains and check bounded contexts,” “Use DDD strategic design on this codebase before we group services.”

If the user only wants **extraction order, phases, or migration roadmap** after analysis exists, use **decomposition-planning-roadmap** instead. If they need a **full legacy migration plan** (strangler fig, research, multi-stack), use **legacy-migration-planner** as well or instead of this skill when that is the primary ask.

### How the agent should run it

The rest: https://github.com/tech-leads-club/agent-skills/blob/HEAD/packages/skills-catalog/skills/(architecture)/modular-decomposition/SKILL.md