temper — Harden Dependency Injection Across Your Project

Dependency Injection is the foundation of testable, loosely-coupled backend code. When classes resolve their own dependencies — by calling container.resolve() mid-logic, or by instantiating collaborators with new — they become impossible to unit-test without spinning up the full runtime, and the hidden coupling they create is invisible to static analysis and architectural audits. forge temper automates the remediation: it walks your project, identifies classes that violate DI discipline, and applies the correct injection pattern for your active technology profile — whether that is tsyringe decorators, NestJS’s built-in DI system, or manual constructor injection.

Usage

# Via agent natural language: "templar", "endurecer", "mejorar"
# Direct invocation:
forge temper

What temper Does

temper adapts its behaviour to the DI strategy associated with your active technology profile (detected by forge profile):

tsyringe profiles
Manual DI profiles
NestJS profiles

Applies to: express-mongodb, express-prisma, express-drizzle, and fastify-prisma profiles that use tsyringe.

Adds @injectable() to every class that has injected dependencies
Adds @inject(TOKEN) to each constructor parameter, using class tokens — never plain strings
Removes container.resolve() calls from use cases, domain objects, and adapters (resolving is only allowed in bootstrap files such as app.ts or routes)

// Before
import { container } from "tsyringe";

export class CreateUserUseCase {
  execute(dto: CreateUserDto) {
    const repo = container.resolve(UserRepository); // ← service locator
    return repo.save(dto);
  }
}

// After
import { injectable, inject } from "tsyringe";
import { IUserRepository } from "../../domain/repositories/IUser.repository.js";
import { TOKENS } from "../../../platform/di/Tokens.js";

@injectable()
export class CreateUserUseCase {
  constructor(
    @inject(TOKENS.UserRepository)
    private readonly userRepository: IUserRepository,
  ) {}

  execute(dto: CreateUserDto) {
    return this.userRepository.save(dto);
  }
}

Applies to: express-postgres, fastify-mongodb, fastify-postgres and other profiles without a DI container.

Converts service-locator patterns to constructor injection
Removes container.resolve() calls and replaces them with constructor parameters
Dependencies are wired explicitly in the bootstrap layer

// Before
export class CreateOrderUseCase {
  execute(dto: CreateOrderDto) {
    const repo = getService("OrderRepository"); // ← service locator
    return repo.save(dto);
  }
}

// After
export class CreateOrderUseCase {
  constructor(
    private readonly orderRepository: IOrderRepository,
  ) {}

  execute(dto: CreateOrderDto) {
    return this.orderRepository.save(dto);
  }
}

Applies to: nestjs-mongodb, nestjs-postgres, nestjs-prisma.NestJS ships its own DI system. temper uses @Injectable() and @Inject() from @nestjs/common rather than tsyringe — it does not mix the two.

Adds @Injectable() to services, use cases, and repositories
Adds @Inject() with the correct token for non-class providers
Configures module providers and exports arrays

// Before
export class UserService {
  constructor() {
    this.userRepo = moduleRef.get(UserRepository); // ← anti-pattern
  }
}

// After
import { Injectable } from "@nestjs/common";
import { UserRepository } from "../repositories/User.repository.js";

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

DI Rules Enforced

Regardless of profile, temper enforces these universal rules:

Rule	Severity
Always use constructor injection	ERROR
No service locators (`container.resolve()` outside bootstrap)	ERROR
No global singletons shared across features	WARNING
No `new Dependency()` inside injected classes	WARNING

What is prohibited

❌ container.resolve() inside use cases, entities, or adapters
❌ new UseCase(dep1, dep2) in features that use a DI container
❌ Importing tsyringe in domain files
❌ Mixing manual DI and container DI within the same feature

Run forge quench after temper to verify that the Decorators category improves in the audit report (Decorators contributes 20 points to the total 180-point score). A clean temper pass should move this category toward full marks.

temper detects your active technology profile automatically via forge profile. If the detected profile does not match your intended DI strategy, run forge profile first to confirm it and adjust if necessary.

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Architecture Model

Commands

Agent Integration

Concepts

temper — Harden Dependency Injection Across Your Project

Usage

What temper Does

DI Rules Enforced

What is prohibited

Build docs developers (and LLMs) love

Get Started

Architecture Model

Commands

Agent Integration

Concepts

Documentation Index

​Usage

​What temper Does

​DI Rules Enforced

​What is prohibited

Build docs developers (and LLMs) love

Usage

What temper Does

DI Rules Enforced

What is prohibited