angular-services

To prevent stale state in Angular services, choose the narrowest valid `providedIn` scope instead of defaulting to `providedIn: 'root'`. Route-scoped or component-scoped provisioning ensures services reset appropriately during navigation and do not act as accidental singletons.

Use `providedIn: 'root'` only when a service truly requires a singleton lifecycle across the entire application. For feature-specific logic, apply route-scoped or component-scoped `providedIn` to ensure the service resets correctly and avoids leaking state across navigation boundaries.

Using the `inject()` function instead of constructor injection promotes cleaner service design and safer dependency injection lifecycles. It aligns services with their owning features and helps manage stateful logic so it does not persist unexpectedly across app, component, or route boundaries.

The best way to scope an Angular service for lazy loading is to select the narrowest valid `providedIn` scope based on the service's real ownership. This prevents overly broad singleton provisioning and ensures state resets appropriately when the lazy route is exited.

If an Angular service is used by a single component, it does not need `providedIn: 'root'`. You can omit `providedIn` or scope it narrowly to the component, preventing accidental singletons and ensuring stateful logic does not persist unexpectedly outside the component's lifecycle.

Review an existing `.service.ts` file by evaluating its `providedIn` scope and dependency injection method. Ensure it uses `inject()` instead of constructor injection and applies the narrowest valid scope based on the service's real lifecycle and feature ownership to avoid DI leaks.