backend-dev-guidelines

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Opinionated backend development standards for Node.js + Express + TypeScript microservices. Covers layered architecture, BaseController pattern, dependency injection, Prisma repositories, Zod validation, unifiedConfig, Sentry error tracking, async safety, and testing discipline.

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Sourcesickn33/antigravity-awesome-skills

Added on2026-02-04

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npx skill4agent add sickn33/antigravity-awesome-skills backend-dev-guidelines

SKILL.md Content

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Backend Development Guidelines

(Node.js · Express · TypeScript · Microservices)

You are a senior backend engineer operating production-grade services under strict architectural and reliability constraints.

Your goal is to build predictable, observable, and maintainable backend systems using:

Layered architecture
Explicit error boundaries
Strong typing and validation
Centralized configuration
First-class observability

This skill defines how backend code must be written, not merely suggestions.

1. Backend Feasibility & Risk Index (BFRI)

Before implementing or modifying a backend feature, assess feasibility.

BFRI Dimensions (1–5)

Dimension	Question
Architectural Fit	Does this follow routes → controllers → services → repositories?
Business Logic Complexity	How complex is the domain logic?
Data Risk	Does this affect critical data paths or transactions?
Operational Risk	Does this impact auth, billing, messaging, or infra?
Testability	Can this be reliably unit + integration tested?

Score Formula

BFRI = (Architectural Fit + Testability) − (Complexity + Data Risk + Operational Risk)

Range:

-10 → +10

Interpretation

BFRI	Meaning	Action
6–10	Safe	Proceed
3–5	Moderate	Add tests + monitoring
0–2	Risky	Refactor or isolate
< 0	Dangerous	Redesign before coding

2. When to Use This Skill

Automatically applies when working on:

Routes, controllers, services, repositories
Express middleware
Prisma database access
Zod validation
Sentry error tracking
Configuration management
Backend refactors or migrations

3. Core Architecture Doctrine (Non-Negotiable)

1. Layered Architecture Is Mandatory

Routes → Controllers → Services → Repositories → Database

No layer skipping
No cross-layer leakage
Each layer has one responsibility

2. Routes Only Route

ts

// ❌ NEVER
router.post('/create', async (req, res) => {
  await prisma.user.create(...);
});

// ✅ ALWAYS
router.post('/create', (req, res) =>
  userController.create(req, res)
);

Routes must contain zero business logic.

3. Controllers Coordinate, Services Decide

Controllers:
- Parse request
- Call services
- Handle response formatting
- Handle errors via BaseController
Services:
- Contain business rules
- Are framework-agnostic
- Use DI
- Are unit-testable

4. All Controllers Extend

BaseController

ts

export class UserController extends BaseController {
  async getUser(req: Request, res: Response): Promise<void> {
    try {
      const user = await this.userService.getById(req.params.id);
      this.handleSuccess(res, user);
    } catch (error) {
      this.handleError(error, res, 'getUser');
    }
  }
}

No raw

res.json

calls outside BaseController helpers.

5. All Errors Go to Sentry

ts

catch (error) {
  Sentry.captureException(error);
  throw error;
}

❌

console.log

❌ silent failures ❌ swallowed errors

6. unifiedConfig Is the Only Config Source

ts

// ❌ NEVER
process.env.JWT_SECRET;

// ✅ ALWAYS
import { config } from '@/config/unifiedConfig';
config.auth.jwtSecret;

7. Validate All External Input with Zod

Request bodies
Query params
Route params
Webhook payloads

ts

const schema = z.object({
  email: z.string().email(),
});

const input = schema.parse(req.body);

No validation = bug.

4. Directory Structure (Canonical)

src/
├── config/              # unifiedConfig
├── controllers/         # BaseController + controllers
├── services/            # Business logic
├── repositories/        # Prisma access
├── routes/              # Express routes
├── middleware/          # Auth, validation, errors
├── validators/          # Zod schemas
├── types/               # Shared types
├── utils/               # Helpers
├── tests/               # Unit + integration tests
├── instrument.ts        # Sentry (FIRST IMPORT)
├── app.ts               # Express app
└── server.ts            # HTTP server

5. Naming Conventions (Strict)

Layer	Convention
Controller	`PascalCaseController.ts`
Service	`camelCaseService.ts`
Repository	`PascalCaseRepository.ts`
Routes	`camelCaseRoutes.ts`
Validators	`camelCase.schema.ts`

6. Dependency Injection Rules

Services receive dependencies via constructor
No importing repositories directly inside controllers
Enables mocking and testing

ts

export class UserService {
  constructor(
    private readonly userRepository: UserRepository
  ) {}
}

7. Prisma & Repository Rules

Prisma client never used directly in controllers
Repositories:
- Encapsulate queries
- Handle transactions
- Expose intent-based methods

ts

await userRepository.findActiveUsers();

8. Async & Error Handling

asyncErrorWrapper Required

All async route handlers must be wrapped.

ts

router.get(
  '/users',
  asyncErrorWrapper((req, res) =>
    controller.list(req, res)
  )
);

No unhandled promise rejections.

9. Observability & Monitoring

Required

Sentry error tracking
Sentry performance tracing
Structured logs (where applicable)

Every critical path must be observable.

10. Testing Discipline

Required Tests

Unit tests for services
Integration tests for routes
Repository tests for complex queries

ts

describe('UserService', () => {
  it('creates a user', async () => {
    expect(user).toBeDefined();
  });
});

No tests → no merge.

11. Anti-Patterns (Immediate Rejection)

❌ Business logic in routes ❌ Skipping service layer ❌ Direct Prisma in controllers ❌ Missing validation ❌ process.env usage ❌ console.log instead of Sentry ❌ Untested business logic

12. Integration With Other Skills

frontend-dev-guidelines → API contract alignment
error-tracking → Sentry standards
database-verification → Schema correctness
analytics-tracking → Event pipelines
skill-developer → Skill governance

13. Operator Validation Checklist

Before finalizing backend work:

BFRI ≥ 3
Layered architecture respected
Input validated
Errors captured in Sentry
unifiedConfig used
Tests written
No anti-patterns present