Applies modern Angular fundamentals — dependency injection, the typed-configuration (provide) pattern, environment/runtime configuration, and modern TypeScript/Angular idioms. Use when registering providers in any Angular app or library, defining InjectionToken-based configuration, choosing a provider scope, setting up environments and runtime config, or applying standalone APIs, signals, inject(), strict null checks, and DestroyRef-based teardown.
Applies modern Angular fundamentals — dependency injection, the typed-configuration (provide) pattern, environment/runtime configuration, and modern TypeScript/Angular idioms. Use when registering providers in any Angular app or library, defining InjectionToken-based configuration, choosing a provider scope, setting up environments and runtime config, or applying standalone APIs, signals, inject(), strict null checks, and DestroyRef-based teardown.
Modern Angular Fundamentals
When to Use
Working with Angular/TypeScript code
Registering providers (providedIn, providers: [...], provideXxx()) in any app, route, or component injector
Choosing a provider scope (root singleton, route/lazy scope, component instance)
Defining InjectionToken-based configuration and provideXxx(config) library APIs
Setting up environment.ts files, build-time file replacement, or runtime config loaded at bootstrap
Adopting standalone components, inject(), signals, strict null checks, or DestroyRef/takeUntilDestroyed teardown in new code
Core Principles
This skill is agnostic across Angular surfaces — standalone apps, libraries, and lazy-loaded routes all sit on these fundamentals. angular-components and angular-state build on top of them.
Token-first registration — depend on an abstraction (an abstract class or InjectionToken<T>), not a concrete class, when the implementation should be substitutable for testing or decoration. TypeScript interfaces don't exist at runtime, so they cannot be DI tokens — use an abstract class or InjectionToken.
No service locator — never inject Injector to resolve dependencies manually in business logic. Use inject() (or constructor injection) for the dependencies you actually need.
Typed config over scattered lookups — model configuration as a typed object provided via an InjectionToken and a provideXxx(config) function; do not read loose string keys all over the app.
Fail fast — validate required configuration at bootstrap (via provideAppInitializer / APP_INITIALIZER) so misconfiguration surfaces at startup, not at first use.
Immutable configuration — config objects use readonly members and are not mutated after provisioning.
Teardown flows everywhere — long-lived subscriptions and async work are torn down with takeUntilDestroyed() / DestroyRef (Angular's analogue to threading a CancellationToken), and HTTP cancellation happens by unsubscribing.
Signal-first APIs — author component surfaces with input()/output()/model() and signal queries (viewChild()/contentChild()), not decorators. Mark Angular-initialized members (input, model, output, queries) readonly so the framework-assigned value cannot be overwritten.
typed-configuration.md — typed configuration objects, provideXxx(config) library APIs, validation at bootstrap, environment- vs runtime-loaded config
configuration.md — environment.ts files, build-time fileReplacements, runtime config from assets/config.json, and why front-end apps have no real secrets
