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Express + Prisma + Vitest rules for AI coding agents

Full stack: Node.js + Express + Prisma + Zod validation + Vitest + Docker

Ready-to-commit rules for Node.js + Express + Prisma + Zod validation + Vitest + Docker in every major format: AGENTS.md (Codex, Cursor, Copilot), CLAUDE.md (Claude Code), Cursor .mdc project rules, legacy .cursorrules, Copilot instructions, Windsurf rules and GEMINI.md. A TypeScript REST API with Express 5, Prisma and Zod.

Last reviewed 2026-10-21 · Customise in the generator · Raw: AGENTS.md, CLAUDE.md

The mistake agents make most on this stack

Agents skip input validation and return 500s for what should be 400s.

Generated files

AGENTS.md
# AGENTS.md - this project

Instructions for AI coding agents working in this repository.

## Project

A Node.js + Express + Prisma + Zod validation + Vitest + Docker project.

Stack: Node.js + Express, Prisma, Zod validation, Vitest, Docker.

## Commands

- Dev server: `npm run dev`
- Build: `npm run build`
- Type-check: `npx tsc --noEmit`
- Create and apply migration (dev): `npx prisma migrate dev --name <change>`
- Regenerate client: `npx prisma generate`
- Apply migrations (prod): `npx prisma migrate deploy`
- Unit tests: `npx vitest run`
- Local services: `docker compose up -d`

## Project structure

- `src/routes/` for routers, `src/services/` for business logic, `src/middleware/` for middleware.
- Keep route handlers thin: parse input, call a service, return a response.

## How to work in this repo

- Read the relevant files before editing. Follow the patterns already in the codebase over these generic rules.
- Make the smallest change that solves the task. Do not refactor or reformat unrelated code.
- Before saying a task is done, run the type-check, lint and tests listed under Commands and fix what you broke.
- If requirements are ambiguous, ask one clear question instead of guessing.
- Never commit secrets, API keys or `.env` files. Use env vars and keep `.env.example` up to date.
- Do not add a new dependency when the standard library or an existing dependency already covers it.
- Ask before adding, removing or upgrading any dependency.
- Ask before changing database schemas, auth, payments or CI configuration.
- Never delete files, drop data or run destructive commands (`rm -rf`, `git push --force`, `DROP TABLE`) without explicit approval.
- Keep each change under ~200 changed lines where possible; split larger work into steps.

## Node.js + Express

- Express 5 forwards rejected promises from async handlers to the error middleware; do not wrap every handler in try/catch.
- Have one central error-handling middleware that logs the error and returns a consistent JSON error shape.
- Validate every request body, query and param before using it.
- Use `helmet`, a strict CORS allow-list and rate limiting on public endpoints.
- Read config from env vars once at startup in a typed config module; fail fast if a required var is missing.
- Return correct HTTP status codes (400 validation, 401 unauthenticated, 403 forbidden, 404 not found, 409 conflict).

## Prisma

- Change the database only through `schema.prisma` + `prisma migrate dev`. Never edit an applied migration.
- Reuse a single PrismaClient instance (cache it on `globalThis` in dev to survive hot reload).
- Use `select` / `include` to fetch only the fields you need.
- Wrap multi-step writes in `prisma.$transaction`.
- Run `npx prisma generate` after schema changes before type-checking.

## Zod validation

- Validate all untrusted input (request bodies, form data, env vars, third-party API responses) with a Zod schema at the boundary.
- Derive TypeScript types from schemas with `z.infer<typeof schema>`; do not hand-write duplicate types.
- Use `safeParse` where you need to return validation errors to the user.

## Vitest

- Co-locate tests next to the code as `*.test.ts(x)`.
- Test behaviour through public APIs; for components use Testing Library queries by role/label.
- Mock network calls at the boundary (e.g. MSW) rather than mocking internal modules.
- Every bug fix adds a test that fails without the fix.

## Docker

- Use multi-stage builds and slim, pinned base images.
- Run the app as a non-root user in the final image.
- Keep a `.dockerignore` that excludes `.git`, `node_modules`, `.env` and build output.
- Never bake secrets into images; pass them at runtime.

## Reference docs

- [Express docs](https://expressjs.com)
- [Prisma docs](https://www.prisma.io/docs)
- [Zod docs](https://zod.dev)
- [Vitest docs](https://vitest.dev)
- [Dockerfile best practices](https://docs.docker.com/build/building/best-practices/)

Commands your agent should run

TaskCommand
Dev servernpm run dev
Buildnpm run build
Type-checknpx tsc --noEmit
Create and apply migration (dev)npx prisma migrate dev --name <change>
Regenerate clientnpx prisma generate
Apply migrations (prod)npx prisma migrate deploy
Unit testsnpx vitest run
Local servicesdocker compose up -d

What the rules cover

Node.js + Express

Express 5 REST API in TypeScript on Node.js. Scoped to src/**/*.ts in Cursor, Copilot and Windsurf.

  • Express 5 forwards rejected promises from async handlers to the error middleware; do not wrap every handler in try/catch.
  • Have one central error-handling middleware that logs the error and returns a consistent JSON error shape.
  • Validate every request body, query and param before using it.
  • Use helmet, a strict CORS allow-list and rate limiting on public endpoints.
  • Read config from env vars once at startup in a typed config module; fail fast if a required var is missing.
  • Return correct HTTP status codes (400 validation, 401 unauthenticated, 403 forbidden, 404 not found, 409 conflict).

Source docs: Express docs

Prisma

Type-safe ORM with Prisma schema and migrations. Scoped to prisma/**, **/*.prisma in Cursor, Copilot and Windsurf.

  • Change the database only through schema.prisma + prisma migrate dev. Never edit an applied migration.
  • Reuse a single PrismaClient instance (cache it on globalThis in dev to survive hot reload).
  • Use select / include to fetch only the fields you need.
  • Wrap multi-step writes in prisma.$transaction.
  • Run npx prisma generate after schema changes before type-checking.

Source docs: Prisma docs

Zod validation

Runtime schema validation with Zod. Scoped to **/*.ts, **/*.tsx in Cursor, Copilot and Windsurf.

  • Validate all untrusted input (request bodies, form data, env vars, third-party API responses) with a Zod schema at the boundary.
  • Derive TypeScript types from schemas with z.infer<typeof schema>; do not hand-write duplicate types.
  • Use safeParse where you need to return validation errors to the user.

Source docs: Zod docs

Vitest

Unit and component tests with Vitest. Scoped to **/*.test.ts, **/*.test.tsx, **/*.spec.ts in Cursor, Copilot and Windsurf.

  • Co-locate tests next to the code as *.test.ts(x).
  • Test behaviour through public APIs; for components use Testing Library queries by role/label.
  • Mock network calls at the boundary (e.g. MSW) rather than mocking internal modules.
  • Every bug fix adds a test that fails without the fix.

Source docs: Vitest docs

Docker

Containerised builds and local services with Docker. Scoped to Dockerfile, **/Dockerfile, compose.yaml, docker-compose.yml, .dockerignore in Cursor, Copilot and Windsurf.

  • Use multi-stage builds and slim, pinned base images.
  • Run the app as a non-root user in the final image.
  • Keep a .dockerignore that excludes .git, node_modules, .env and build output.
  • Never bake secrets into images; pass them at runtime.

Source docs: Dockerfile best practices

How to install

  1. Copy AGENTS.md to your repo root. That covers Codex, Cursor, GitHub Copilot and most other agents.
  2. Using Claude Code? Add a CLAUDE.md with the single line @AGENTS.md, or use the standalone CLAUDE.md tab above.
  3. Want rules that only load for certain files in Cursor? Add the .cursor/rules/*.mdc files.
  4. Commit the files so your whole team (and every agent) shares them.

FAQ

Where do I put the AGENTS.md for Node.js + Express + Prisma + Zod validation + Vitest + Docker?

Save it as AGENTS.md in the root of your repository, next to your main config file. Codex, Cursor and GitHub Copilot pick it up automatically. For Claude Code, add a CLAUDE.md containing @AGENTS.md (or use the standalone CLAUDE.md on this page).

What is the most common mistake AI agents make with Node.js + Express?

Agents skip input validation and return 500s for what should be 400s.

Which commands should the agent run to check its work?

For this stack: npm run dev, npm run build, npx tsc --noEmit, npx prisma migrate dev --name <change>. They are listed in the generated files so the agent runs them before finishing a task.

Do these Node.js + Express + Prisma + Zod validation + Vitest + Docker rules work with Cursor and Claude Code?

Yes. This page includes the same rules as AGENTS.md, CLAUDE.md, Cursor .mdc project rules, a legacy .cursorrules file, GitHub Copilot instructions, Windsurf rules and GEMINI.md.

Can I customise these rules?

Yes. Open this stack in the generator to add or remove libraries, set your project name and package manager, switch beginner explanations on, and download everything as a zip.

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