sdlc-angular-state-and-rx

State management for Angular 18-21: signals (signal/computed/effect), services-as-state, NgRx Store + Effects + Selectors, NgRx Component Store, NgRx Signals (newer signal-based store). RxJS essentials — operators, async pipe, takeUntilDestroyed, signal/observable interop. Use this skill to: - Pick the right state tool (signals / services / NgRx variant / vue-query equivalent). - Use signals correctly (signal/computed/effect — when each). - Build a Pinia-style service-as-state singleton. - Set up NgRx Store + Effects + Selectors. - Use RxJS without leaking subscriptions (async pipe, takeUntilDestroyed, Subject patterns). - Bridge signals ↔ observables via toSignal / toObservable. Do NOT use this skill for: - General Angular conventions (see angular-conventions). - Routing state (see angular-routing). - Form state (see angular-forms). - Testing state (see angular-testing).