domain-analysis

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Summary

Maps business domains and suggests service boundaries in any codebase using DDD Strategic Design. Use when asking "what are the domains in this codebase?", "where should I draw service boundaries?", "identify bounded contexts", "classify subdomains", "DDD analysis", or analyzing domain cohesion. Do NOT use for grouping existing components into domains (use domain-identification-grouping) or dependency analysis (use coupling-analysis).

SKILL.md

Subdomain Identification & Bounded Context Analysis

This skill analyzes codebases to identify subdomains (Core, Supporting, Generic) and suggest bounded contexts following Domain-Driven Design Strategic Design principles.

When to Use

Apply this skill when:

Analyzing domain boundaries in any codebase
Identifying Core, Supporting, and Generic subdomains
Mapping bounded contexts from problem space to solution space
Assessing domain cohesion and detecting coupling issues
Planning domain-driven refactoring
Understanding business capabilities in code

Core Principles

Subdomain Classification

Core Domain: Competitive advantage, highest business value, requires best developers

Indicators: Complex business logic, frequent changes, domain experts needed

Supporting Subdomain: Essential but not differentiating, business-specific

Indicators: Supports Core Domain, moderate complexity, business-specific rules

Generic Subdomain: Common functionality, could be outsourced

Indicators: Well-understood problem, low differentiation, standard functionality

Bounded Context

An explicit linguistic boundary where domain terms have specific, unambiguous meanings.

Primary nature: Linguistic boundary, not technical
Key rule: Inside boundary, all Ubiquitous Language terms are unambiguous
Goal: Align 1 subdomain to 1 bounded context (ideal)

Analysis Process

Phase 1: Extract Concepts

Scan codebase for business concepts (not infrastructure):

Is it a competitive advantage?
  YES → Core Domain
  NO → Does it require business-specific knowledge?
        YES → Supporting Subdomain
        NO → Generic Subdomain

Score = (
  Linguistic Cohesion (0-3) +    // Shared vocabulary
  Usage Cohesion (0-3) +         // Used together
  Data Cohesion (0-2) +          // Entity relationships
  Change Cohesion (0-2)          // Change together
) / 10

8-10: High Cohesion ✅
5-7:  Medium Cohesion ⚠️
0-4:  Low Cohesion ❌

## Domain: {Name}

**Type**: Core Domain | Supporting Subdomain | Generic Subdomain

**Ubiquitous Language**: {key business terms}

**Business Capability**: {what business problem it solves}

**Key Concepts**:

- {Concept} (Entity|Service|UseCase) - {brief description}

**Subdomains** (if applicable):

1. {Subdomain} (Core|Supporting|Generic)
   - Concepts: {list}
   - Cohesion: {score}/10
   - Dependencies: → {other domains}

**Suggested Bounded Context**: {Name}Context

- Linguistic boundary: {where terms have specific meaning}
- Integration: {how it should integrate with other contexts}

**Dependencies**:

- → {OtherDomain} via {interface/API}
- ← {OtherDomain} via {interface/API}

**Cohesion Score**: {score}/10

## Cross-Domain Cohesion

| Domain A | Domain B | Cohesion | Issue              | Recommendation          |
| -------- | -------- | -------- | ------------------ | ----------------------- |
| Billing  | Identity | 2/10     | ❌ Direct coupling | Use interface           |
| Content  | Billing  | 6/10     | ⚠️ Usage tracking  | Event-based integration |

## Issues Detected

### Priority: High

**Issue**: {description}

- **Location**: {file/class/method}
- **Problem**: {what's wrong}
- **Concepts**: {involved concepts}
- **Cohesion**: {score}/10
- **Recommendation**: {suggested fix}

### Priority: Medium

{similar format}

## Suggested Bounded Contexts

### {ContextName}Context

**Contains Subdomains**:

- {Subdomain1} (Core)
- {Subdomain2} (Supporting)

**Ubiquitous Language**:

- Term: Definition in this context

**Integration Requirements**:

- Consumes from: {OtherContext} via {pattern}
- Publishes to: {OtherContext} via {pattern}

**Implementation Notes**:

- Separate persistence
- Independent deployment
- Explicit API boundaries

Analyze business capability
└─ Is it competitive advantage?
   ├─ YES → Core Domain
   └─ NO → Is it business-specific?
      ├─ YES → Supporting Subdomain
      └─ NO → Generic Subdomain

Same vocabulary? → High linguistic cohesion
Used together? → High usage cohesion
Direct relationships? → High data cohesion
Change together? → High change cohesion

All high → Strong subdomain candidate
Mix of high/low → Review boundaries
All low → Likely wrong grouping

Clear boundary signs:
✅ Distinct Ubiquitous Language
✅ Concepts have unambiguous meaning
✅ Different meanings across contexts
✅ Clear integration points

Unclear boundary signs:
❌ Same terms with same meanings everywhere
❌ Concepts used identically across system
❌ No clear linguistic differences
❌ Tight coupling everywhere

domain-analysis

Summary

SKILL.md

Subdomain Identification & Bounded Context Analysis

When to Use

Core Principles

Subdomain Classification

Bounded Context

Analysis Process

Phase 1: Extract Concepts

Phase 2: Group by Ubiquitous Language

Phase 3: Identify Subdomains

Phase 4: Assess Cohesion

Phase 5: Detect Low Cohesion Issues

Phase 6: Map Bounded Contexts

Output Format

Domain Map

Cohesion Matrix

Low Cohesion Report

Bounded Context Map

Best Practices

Do's ✅

Don'ts ❌

Analysis Checklist

Quick Reference

Subdomain Decision Tree

Cohesion Quick Check

Bounded Context Signals

Anti-Patterns to Avoid

Notes

Validation Criteria

Related skills