Dependency Injection

DI is centralized in backend/src/Containers/inversify.config.ts.

Design goals

• Keep controllers/use cases independent from concrete repository/service implementations.
• Allow adapter replacement (e.g., OCR provider, token service) without route rewrites.
• Keep one composition root for easier code review and onboarding.

Binding groups

• Repositories: user, wallet, category, transaction, budget, budget allocation.
• Use cases: auth, wallet, category, transaction, budget, dashboard.
• Ports/services: token hashing, ID generation, OCR, voice, logger.
• Presentation: controllers and auth middleware factory.

Symbol registry

• All injectable symbols are declared in backend/src/Containers/Types.ts.

Internal snippet

container
  .bind<TransactionCreatorPort>(TYPES.TransactionCreatorPort)
  .toService(TYPES.AddTransactionImpl);

This alias lets AI flows reuse the same transaction creation use case.