MyAiConfiguration/shared/rules/angular/references/services-and-http.md

Dependency Injection

• Prefer Angular dependency injection for application services.
• Keep injected dependencies minimal.
• Avoid service locator patterns.
• Prefer inject() where it improves readability and is consistent with the project.
• Do not inject services that are not used.
• Scope services intentionally.
• Prefer application-wide singletons only for truly shared stateless or coordinated state.
• Avoid storing request-specific or component-specific mutable state in root services.
• Use injection tokens for configuration or abstractions where appropriate.
• Do not create interfaces only to satisfy dependency injection when no abstraction is needed.

Services

• Keep services focused on a clear responsibility.
• Avoid large catch-all services.
• Separate API access, domain logic and UI state where practical.
• Avoid leaking transport models throughout the application.
• Do not expose mutable internal state directly.
• Prefer readonly APIs for state consumers.
• Avoid hidden side effects.
• Keep service methods predictable.
• Do not use services merely to move poorly structured component code elsewhere.

HTTP and APIs

• Keep API access centralized and strongly typed.
• Prefer dedicated API clients or data-access services.
• Do not use any for API responses.
• Treat all server responses as untrusted at runtime.
• Validate external data when the contract is security- or correctness-critical.
• Keep DTOs separate from domain models when their responsibilities differ.
• Avoid duplicate API calls.
• Cache only when the invalidation strategy is clear.
• Avoid manual URL string construction when typed helpers or centralized endpoints are available.
• Use interceptors only for cross-cutting concerns.
• Do not put unrelated business logic into HTTP interceptors.
• Handle cancellation where appropriate.
• Handle expected error states explicitly.