Using nestjs hexagonal

Using NestJS Hexagonal

This is a routing skill. When working in a NestJS project that follows hexagonal architecture, check this skill FIRST to find the right tool for the job.

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Detection — When Does This Plugin Apply?

This plugin applies when ANY of these are true:

• Project has @nestjs/core and @nestjs/cqrs in dependencies
• Project structure has domain/, application/, infrastructure/ layers
• Files contain AggregateRoot, @EventsHandler, @CommandHandler, @QueryHandler
• User mentions: entity, value object, bounded context, CQRS, hexagonal, DDD, aggregate
• CLAUDE.md references nestjs-hexagonal skills

If detected, route ALL architectural tasks through this plugin's skills and agents.

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Routing Table — What Are You Doing?

Creating or Modifying Code

Task	Route to	Type
Create new bounded context / module	nestjs-hexagonal:create-subdomain	Skill (orchestrator)
Create entity (AggregateRoot)	nestjs-hexagonal:domain-agent	Agent (Opus 5)
Create value object	nestjs-hexagonal:domain	Skill
Create domain event	nestjs-hexagonal:domain	Skill
Create repository interface	nestjs-hexagonal:domain	Skill
Create data builder (testing)	nestjs-hexagonal:domain	Skill
Create use case	nestjs-hexagonal:application	Skill
Create CQRS command/query handler	nestjs-hexagonal:application	Skill
Create DTO	nestjs-hexagonal:application	Skill
Create port (cross-module interface)	nestjs-hexagonal:application	Skill
Create Prisma repository	nestjs-hexagonal:infrastructure	Skill
Wire NestJS module	nestjs-hexagonal:infrastructure	Skill
Create adapter (port implementation)	nestjs-hexagonal:infrastructure	Skill
Create controller	nestjs-hexagonal:presentation	Skill
Create request DTO (class-validator)	nestjs-hexagonal:presentation	Skill
Create event listener (same-BC)	nestjs-hexagonal:event-listeners	Skill
Create event listener (cross-BC)	nestjs-hexagonal:event-listeners	Skill
Create WebSocket broadcast	nestjs-hexagonal:websocket-broadcasting	Skill
Create WS gateway	nestjs-hexagonal:websocket-broadcasting	Skill
Create frontend event consumer	nestjs-hexagonal:broadcasting-agent	Agent (Sonnet 5)

Reviewing or Debugging

Task	Route to	Type
Review bounded context	nestjs-hexagonal:architecture-reviewer	Agent (Opus 5)
Check for over-engineering	nestjs-hexagonal:architecture-reviewer	Agent (Opus 5)
Debug event not reaching frontend	nestjs-hexagonal:event-debug-agent	Agent (Opus 5)
Debug event not being consumed	nestjs-hexagonal:event-debug-agent	Agent (Opus 5)

Setting Up

Task	Route to	Type
Configure GSD to use this plugin	nestjs-hexagonal:gsd-installer	Skill
Review all available patterns	Read CLAUDE.md at plugin root	Reference

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Agent Selection by Model

Decision Type	Agent	Model	Why
Domain modeling (what entities, VOs, events)	domain-agent	Opus 5	Critical architectural decisions
Architecture review	architecture-reviewer	Opus 5	Deep judgment for smells + over-engineering
Event chain debugging	event-debug-agent	Opus 5	6-layer systematic tracing
Application layer (use cases, handlers)	application-agent	Sonnet 5	Follows established patterns
Infrastructure (repos, modules)	infrastructure-agent	Sonnet 5	Mechanical pattern application
Presentation (controllers, DTOs)	presentation-agent	Sonnet 5	Mechanical pattern application
WebSocket + frontend	broadcasting-agent	Sonnet 5	Follows WS skill patterns
Event listeners	listener-agent	Sonnet 5	Follows listener skill patterns

Rule: Use Opus 5 for DECISIONS (what to build), Sonnet 5 for EXECUTION (how to build it).

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Architecture Rules (always enforce)

These rules apply to ALL tasks routed through this plugin:

1. Entity extends AggregateRoot — uses this.apply(event) to queue events
2. Repository is PURE persistence — no event dispatch, no domain logic
3. EventPublisher in Handler ONLY — UseCase returns entity, Handler commits events
4. Module exports ONLY Port tokens — never use cases, never repositories
5. class-validator ONLY in presentation — never in domain or application
6. Write returns void or ID — CQRS strict, no full objects on command side
7. No over-engineering — no use case for trivial findById, no abstractions for single use
8. Listeners in CONSUMING BC — cross-BC listeners live where they're consumed, not emitted
9. try/catch in all listeners — listener failure never breaks the event chain

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Workflow Order (when building a full BC)

1. Domain (Opus 5)   → entities, VOs, events, repo interface, data builders
2. Application       → use cases / handlers, DTOs, ports
3. Infrastructure    → Prisma repo, module wiring, adapters, listeners
4. Presentation      → controllers, request DTOs, Swagger
5. Broadcasting      → WS gateway + frontend hooks (if real-time needed)
6. Verification      → lint, types, tests, build
7. Review (Opus 5)   → architecture compliance + over-engineering audit

Use nestjs-hexagonal:create-subdomain to orchestrate this automatically.

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Pattern Quick Reference

Application Layer — Which Pattern?

Scenario	Pattern
Simple CRUD, no events needed	A — Plain UseCase + TOKEN
Module uses CQRS, events on write	B — Command/Query handlers
Complex orchestration, multiple ports	C — Handler as Orchestrator
Trivial findById, no RBAC	No pattern — repo directly in controller

Event Listeners — Which Type?

Scenario	Type
Update Redis projection after event	Same-BC listener
Another BC reacts to this event	Cross-BC listener
Frontend needs real-time update	Bridge listener (WS)
External service needs notification	Bridge listener (broker/email/webhook)
3+ consumers sharing pre-processing	Strategy + Gateway pattern
Simple side effect, single consumer	Put it in the command handler directly

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Red Flags — Stop and Route

If you catch yourself doing any of these, STOP and invoke the correct skill:

What you're about to do	Problem	Route to
Adding @Injectable to a domain class	Framework leak into domain	nestjs-hexagonal:domain
Putting EventPublisher in a UseCase	UseCase must be framework-agnostic	nestjs-hexagonal:application
Exporting a repository from a module	Only Port tokens should be exported	nestjs-hexagonal:infrastructure
Adding class-validator to a VO	Validation layers are separate	nestjs-hexagonal:domain
Making repository dispatch events	Repository is pure persistence	nestjs-hexagonal:infrastructure
Creating use case for simple findById	Over-engineering	Check architecture-reviewer criteria
Importing a service from another BC	Use ports instead	nestjs-hexagonal:application (ports)
Creating generic event relay	Over-engineering	nestjs-hexagonal:event-listeners