Mern Add Feature

Purpose

Add a complete feature slice to an existing MERN project with all layers wired up and tests included.

Arguments

• feature-name — Feature name in kebab-case (e.g., user-profile, invoice)
• --no-ui — Skip UI components (API-only feature)
• --no-api — Skip API route (frontend-only feature)
• --no-model — Skip Mongoose model (use existing model)

What gets created

Default (all layers)

packages/shared/schemas/<feature>.ts           # Zod schemas + inferred types
apps/web/src/app/api/<feature>/route.ts        # API route handler
apps/web/src/server/db/models/<feature>.ts     # Mongoose model
apps/web/src/components/<feature>/         # UI components
  <Feature>List.tsx
  <Feature>Form.tsx
  <Feature>Card.tsx
apps/web/src/components/<feature>/__tests__/
  <Feature>Form.test.tsx

With flags

• --no-ui: Only schema + API + model
• --no-api: Only schema + UI (for client-side-only features)
• --no-model: Only schema + API route + UI (uses existing model)

Conventions

Naming

• Feature name: kebab-case (input)
• Schema/types: PascalCase (e.g., UserProfile, CreateUserProfileInput)
• Files: kebab-case.ts for utilities, PascalCase.tsx for React
• API routes: /api/<feature> for collection, /api/<feature>/[id] for item

Schema location

All Zod schemas go in packages/shared/schemas/<feature>.ts:

• Create<Feature>Schema — creation input
• Update<Feature>Schema — partial update input
• <Feature>Schema — full entity shape
• Inferred types exported alongside schemas

API route structure

• GET /api/<feature> — list (paginated)
• POST /api/<feature> — create
• GET /api/<feature>/[id] — get one
• PATCH /api/<feature>/[id] — update
• DELETE /api/<feature>/[id] — delete

Model conventions

• Timestamps enabled
• Indexes documented with reason
• toJSON transform to hide internal fields

Workflow

1. Create Zod schemas in packages/shared
2. Create Mongoose model (if not --no-model)
3. Create API routes (if not --no-api)
4. Create UI components (if not --no-ui)
5. Create tests for each layer
6. Run pnpm lint and pnpm test to verify

Output

Summarize: files created, API endpoints available, components ready to use.

Reference

For templates and patterns, see reference/mern-add-feature-reference.md