Angular State Management V2

Angular State Management

Overview

This public intake copy packages plugins/antigravity-awesome-skills/skills/angular-state-management from https://github.com/sickn33/antigravity-awesome-skills into the native Omni Skills editorial shape without hiding its origin.

Use it when the operator needs the upstream workflow, support files, and repository context to stay intact while the public validator and private enhancer continue their normal downstream flow.

This intake keeps the copied upstream files intact and uses the external_source block in metadata.json plus ORIGIN.md as the provenance anchor for review.

Angular State Management Comprehensive guide to modern Angular state management patterns, from Signal-based local state to global stores and server state synchronization.

Imported source sections that did not map cleanly to the public headings are still preserved below or in the support files. Notable imported sections: Core Concepts, Quick Start: Signal-Based State, NgRx Store (Global State), RxJS-Based Patterns, Server State with Signals, Migration Path.

When to Use This Skill

Use this section as the trigger filter. It should make the activation boundary explicit before the operator loads files, runs commands, or opens a pull request.

• Setting up global state management in Angular
• Choosing between Signals, NgRx, or Akita
• Managing component-level stores
• Implementing optimistic updates
• Debugging state-related issues
• Migrating from legacy state patterns

Operating Table

Workflow

This workflow is intentionally editorial and operational at the same time. It keeps the imported source useful to the operator while still satisfying the public intake standards that feed the downstream enhancer flow.

1. Confirm the user goal, the scope of the imported workflow, and whether this skill is still the right router for the task.
2. Read the overview and provenance files before loading any copied upstream support files.
3. Load only the references, examples, prompts, or scripts that materially change the outcome for the current request.
4. Execute the upstream workflow while keeping provenance and source boundaries explicit in the working notes.
5. Validate the result against the upstream expectations and the evidence you can point to in the copied files.
6. Escalate or hand off to a related skill when the work moves out of this imported workflow's center of gravity.
7. Before merge or closure, record what was used, what changed, and what the reviewer still needs to verify.

Imported Workflow Notes

Imported: Core Concepts

State Categories

Selection Criteria

Small app, simple state → Signal Services
Medium app, moderate state → Component Stores
Large app, complex state → NgRx Store
Heavy server interaction → NgRx Query + Signal Services
Real-time updates → RxAngular + Signals

Examples

Example 1: Ask for the upstream workflow directly

Use @angular-state-management-v2 to handle <task>. Start from the copied upstream workflow, load only the files that change the outcome, and keep provenance visible in the answer.

Explanation: This is the safest starting point when the operator needs the imported workflow, but not the entire repository.

Example 2: Ask for a provenance-grounded review

Review @angular-state-management-v2 against metadata.json and ORIGIN.md, then explain which copied upstream files you would load first and why.

Explanation: Use this before review or troubleshooting when you need a precise, auditable explanation of origin and file selection.

Example 3: Narrow the copied support files before execution

Use @angular-state-management-v2 for <task>. Load only the copied references, examples, or scripts that change the outcome, and name the files explicitly before proceeding.

Explanation: This keeps the skill aligned with progressive disclosure instead of loading the whole copied package by default.

Example 4: Build a reviewer packet

Review @angular-state-management-v2 using the copied upstream files plus provenance, then summarize any gaps before merge.

Explanation: This is useful when the PR is waiting for human review and you want a repeatable audit packet.

Best Practices

Treat the generated public skill as a reviewable packaging layer around the upstream repository. The goal is to keep provenance explicit and load only the copied source material that materially improves execution.

• Practice - Why
• Use Signals for local state - Simple, reactive, no subscriptions
• Use computed() for derived data - Auto-updates, memoized
• Colocate state with feature - Easier to maintain
• Use NgRx for complex flows - Actions, effects, devtools
• Prefer inject() over constructor - Cleaner, works in factories
• Anti-Pattern - Instead

Imported Operating Notes

Imported: Best Practices

Do's

Don'ts

Troubleshooting

Problem: The operator skipped the imported context and answered too generically

Symptoms: The result ignores the upstream workflow in plugins/antigravity-awesome-skills/skills/angular-state-management, fails to mention provenance, or does not use any copied source files at all. Solution: Re-open metadata.json, ORIGIN.md, and the most relevant copied upstream files. Check the external_source block first, then restate the provenance before continuing.

Problem: The imported workflow feels incomplete during review

Symptoms: Reviewers can see the generated SKILL.md, but they cannot quickly tell which references, examples, or scripts matter for the current task. Solution: Point at the exact copied references, examples, scripts, or assets that justify the path you took. If the gap is still real, record it in the PR instead of hiding it.

Problem: The task drifted into a different specialization

Symptoms: The imported skill starts in the right place, but the work turns into debugging, architecture, design, security, or release orchestration that a native skill handles better. Solution: Use the related skills section to hand off deliberately. Keep the imported provenance visible so the next skill inherits the right context instead of starting blind.

Related Skills

• @00-andruia-consultant - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @00-andruia-consultant-v2 - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @10-andruia-skill-smith - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @10-andruia-skill-smith-v2 - Use when the work is better handled by that native specialization after this imported skill establishes context.

Additional Resources

Use this support matrix and the linked files below as the operator packet for this imported skill. They should reflect real copied source material, not generic scaffolding.

• README.md

Imported Reference Notes

Imported: Resources

• Angular Signals Guide
• NgRx Documentation
• NgRx SignalStore
• RxAngular

Imported: Quick Start: Signal-Based State

Pattern 1: Simple Signal Service

// services/counter.service.ts
import { Injectable, signal, computed } from "@angular/core";

@Injectable({ providedIn: "root" })
export class CounterService {
  // Private writable signals
  private _count = signal(0);

  // Public read-only
  readonly count = this._count.asReadonly();
  readonly doubled = computed(() => this._count() * 2);
  readonly isPositive = computed(() => this._count() > 0);

  increment() {
    this._count.update((v) => v + 1);
  }

  decrement() {
    this._count.update((v) => v - 1);
  }

  reset() {
    this._count.set(0);
  }
}

// Usage in component
@Component({
  template: `
    <p>Count: {{ counter.count() }}</p>
    <p>Doubled: {{ counter.doubled() }}</p>
    <button (click)="counter.increment()">+</button>
  `,
})
export class CounterComponent {
  counter = inject(CounterService);
}

Pattern 2: Feature Signal Store

// stores/user.store.ts
import { Injectable, signal, computed, inject } from "@angular/core";
import { HttpClient } from "@angular/common/http";
import { toSignal } from "@angular/core/rxjs-interop";

interface User {
  id: string;
  name: string;
  email: string;
}

interface UserState {
  user: User | null;
  loading: boolean;
  error: string | null;
}

@Injectable({ providedIn: "root" })
export class UserStore {
  private http = inject(HttpClient);

  // State signals
  private _user = signal<User | null>(null);
  private _loading = signal(false);
  private _error = signal<string | null>(null);

  // Selectors (read-only computed)
  readonly user = computed(() => this._user());
  readonly loading = computed(() => this._loading());
  readonly error = computed(() => this._error());
  readonly isAuthenticated = computed(() => this._user() !== null);
  readonly displayName = computed(() => this._user()?.name ?? "Guest");

  // Actions
  async loadUser(id: string) {
    this._loading.set(true);
    this._error.set(null);

    try {
      const user = await fetch(`/api/users/${id}`).then((r) => r.json());
      this._user.set(user);
    } catch (e) {
      this._error.set("Failed to load user");
    } finally {
      this._loading.set(false);
    }
  }

  updateUser(updates: Partial<User>) {
    this._user.update((user) => (user ? { ...user, ...updates } : null));
  }

  logout() {
    this._user.set(null);
    this._error.set(null);
  }
}

Pattern 3: SignalStore (NgRx Signals)

// stores/products.store.ts
import {
  signalStore,
  withState,
  withMethods,
  withComputed,
  patchState,
} from "@ngrx/signals";
import { inject } from "@angular/core";
import { ProductService } from "./product.service";

interface ProductState {
  products: Product[];
  loading: boolean;
  filter: string;
}

const initialState: ProductState = {
  products: [],
  loading: false,
  filter: "",
};

export const ProductStore = signalStore(
  { providedIn: "root" },

  withState(initialState),

  withComputed((store) => ({
    filteredProducts: computed(() => {
      const filter = store.filter().toLowerCase();
      return store
        .products()
        .filter((p) => p.name.toLowerCase().includes(filter));
    }),
    totalCount: computed(() => store.products().length),
  })),

  withMethods((store, productService = inject(ProductService)) => ({
    async loadProducts() {
      patchState(store, { loading: true });

      try {
        const products = await productService.getAll();
        patchState(store, { products, loading: false });
      } catch {
        patchState(store, { loading: false });
      }
    },

    setFilter(filter: string) {
      patchState(store, { filter });
    },

    addProduct(product: Product) {
      patchState(store, ({ products }) => ({
        products: [...products, product],
      }));
    },
  })),
);

// Usage
@Component({
  template: `
    <input (input)="store.setFilter($event.target.value)" />
    @if (store.loading()) {
      <app-spinner />
    } @else {
      @for (product of store.filteredProducts(); track product.id) {
        <app-product-card [product]="product" />
      }
    }
  `,
})
export class ProductListComponent {
  store = inject(ProductStore);

  ngOnInit() {
    this.store.loadProducts();
  }
}

Imported: NgRx Store (Global State)

Setup

// store/app.state.ts
import { ActionReducerMap } from "@ngrx/store";

export interface AppState {
  user: UserState;
  cart: CartState;
}

export const reducers: ActionReducerMap<AppState> = {
  user: userReducer,
  cart: cartReducer,
};

// main.ts
bootstrapApplication(AppComponent, {
  providers: [
    provideStore(reducers),
    provideEffects([UserEffects, CartEffects]),
    provideStoreDevtools({ maxAge: 25 }),
  ],
});

Feature Slice Pattern

// store/user/user.actions.ts
import { createActionGroup, props, emptyProps } from "@ngrx/store";

export const UserActions = createActionGroup({
  source: "User",
  events: {
    "Load User": props<{ userId: string }>(),
    "Load User Success": props<{ user: User }>(),
    "Load User Failure": props<{ error: string }>(),
    "Update User": props<{ updates: Partial<User> }>(),
    Logout: emptyProps(),
  },
});

// store/user/user.reducer.ts
import { createReducer, on } from "@ngrx/store";
import { UserActions } from "./user.actions";

export interface UserState {
  user: User | null;
  loading: boolean;
  error: string | null;
}

const initialState: UserState = {
  user: null,
  loading: false,
  error: null,
};

export const userReducer = createReducer(
  initialState,

  on(UserActions.loadUser, (state) => ({
    ...state,
    loading: true,
    error: null,
  })),

  on(UserActions.loadUserSuccess, (state, { user }) => ({
    ...state,
    user,
    loading: false,
  })),

  on(UserActions.loadUserFailure, (state, { error }) => ({
    ...state,
    loading: false,
    error,
  })),

  on(UserActions.logout, () => initialState),
);

// store/user/user.selectors.ts
import { createFeatureSelector, createSelector } from "@ngrx/store";
import { UserState } from "./user.reducer";

export const selectUserState = createFeatureSelector<UserState>("user");

export const selectUser = createSelector(
  selectUserState,
  (state) => state.user,
);

export const selectUserLoading = createSelector(
  selectUserState,
  (state) => state.loading,
);

export const selectIsAuthenticated = createSelector(
  selectUser,
  (user) => user !== null,
);

// store/user/user.effects.ts
import { Injectable, inject } from "@angular/core";
import { Actions, createEffect, ofType } from "@ngrx/effects";
import { switchMap, map, catchError, of } from "rxjs";

@Injectable()
export class UserEffects {
  private actions$ = inject(Actions);
  private userService = inject(UserService);

  loadUser$ = createEffect(() =>
    this.actions$.pipe(
      ofType(UserActions.loadUser),
      switchMap(({ userId }) =>
        this.userService.getUser(userId).pipe(
          map((user) => UserActions.loadUserSuccess({ user })),
          catchError((error) =>
            of(UserActions.loadUserFailure({ error: error.message })),
          ),
        ),
      ),
    ),
  );
}

Component Usage

@Component({
  template: `
    @if (loading()) {
      <app-spinner />
    } @else if (user(); as user) {
      <h1>Welcome, {{ user.name }}</h1>
      <button (click)="logout()">Logout</button>
    }
  `,
})
export class HeaderComponent {
  private store = inject(Store);

  user = this.store.selectSignal(selectUser);
  loading = this.store.selectSignal(selectUserLoading);

  logout() {
    this.store.dispatch(UserActions.logout());
  }
}

Imported: RxJS-Based Patterns

Component Store (Local Feature State)

// stores/todo.store.ts
import { Injectable } from "@angular/core";
import { ComponentStore } from "@ngrx/component-store";
import { switchMap, tap, catchError, EMPTY } from "rxjs";

interface TodoState {
  todos: Todo[];
  loading: boolean;
}

@Injectable()
export class TodoStore extends ComponentStore<TodoState> {
  constructor(private todoService: TodoService) {
    super({ todos: [], loading: false });
  }

  // Selectors
  readonly todos$ = this.select((state) => state.todos);
  readonly loading$ = this.select((state) => state.loading);
  readonly completedCount$ = this.select(
    this.todos$,
    (todos) => todos.filter((t) => t.completed).length,
  );

  // Updaters
  readonly addTodo = this.updater((state, todo: Todo) => ({
    ...state,
    todos: [...state.todos, todo],
  }));

  readonly toggleTodo = this.updater((state, id: string) => ({
    ...state,
    todos: state.todos.map((t) =>
      t.id === id ? { ...t, completed: !t.completed } : t,
    ),
  }));

  // Effects
  readonly loadTodos = this.effect<void>((trigger$) =>
    trigger$.pipe(
      tap(() => this.patchState({ loading: true })),
      switchMap(() =>
        this.todoService.getAll().pipe(
          tap({
            next: (todos) => this.patchState({ todos, loading: false }),
            error: () => this.patchState({ loading: false }),
          }),
          catchError(() => EMPTY),
        ),
      ),
    ),
  );
}

Imported: Server State with Signals

HTTP + Signals Pattern

// services/api.service.ts
import { Injectable, signal, inject } from "@angular/core";
import { HttpClient } from "@angular/common/http";
import { toSignal } from "@angular/core/rxjs-interop";

interface ApiState<T> {
  data: T | null;
  loading: boolean;
  error: string | null;
}

@Injectable({ providedIn: "root" })
export class ProductApiService {
  private http = inject(HttpClient);

  private _state = signal<ApiState<Product[]>>({
    data: null,
    loading: false,
    error: null,
  });

  readonly products = computed(() => this._state().data ?? []);
  readonly loading = computed(() => this._state().loading);
  readonly error = computed(() => this._state().error);

  async fetchProducts(): Promise<void> {
    this._state.update((s) => ({ ...s, loading: true, error: null }));

    try {
      const data = await firstValueFrom(
        this.http.get<Product[]>("/api/products"),
      );
      this._state.update((s) => ({ ...s, data, loading: false }));
    } catch (e) {
      this._state.update((s) => ({
        ...s,
        loading: false,
        error: "Failed to fetch products",
      }));
    }
  }

  // Optimistic update
  async deleteProduct(id: string): Promise<void> {
    const previousData = this._state().data;

    // Optimistically remove
    this._state.update((s) => ({
      ...s,
      data: s.data?.filter((p) => p.id !== id) ?? null,
    }));

    try {
      await firstValueFrom(this.http.delete(`/api/products/${id}`));
    } catch {
      // Rollback on error
      this._state.update((s) => ({ ...s, data: previousData }));
    }
  }
}

Imported: Migration Path

From BehaviorSubject to Signals

// Before: RxJS-based
@Injectable({ providedIn: "root" })
export class OldUserService {
  private userSubject = new BehaviorSubject<User | null>(null);
  user$ = this.userSubject.asObservable();

  setUser(user: User) {
    this.userSubject.next(user);
  }
}

// After: Signal-based
@Injectable({ providedIn: "root" })
export class UserService {
  private _user = signal<User | null>(null);
  readonly user = this._user.asReadonly();

  setUser(user: User) {
    this._user.set(user);
  }
}

Bridging Signals and RxJS

import { toSignal, toObservable } from '@angular/core/rxjs-interop';

// Observable → Signal
@Component({...})
export class ExampleComponent {
  private route = inject(ActivatedRoute);

  // Convert Observable to Signal
  userId = toSignal(
    this.route.params.pipe(map(p => p['id'])),
    { initialValue: '' }
  );
}

// Signal → Observable
export class DataService {
  private filter = signal('');

  // Convert Signal to Observable
  filter$ = toObservable(this.filter);

  filteredData$ = this.filter$.pipe(
    debounceTime(300),
    switchMap(filter => this.http.get(`/api/data?q=${filter}`))
  );
}

Imported: Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.