Angular Standards

Always analyze the project's Angular version before providing guidance, as best practices and available features can vary significantly between versions. If creating a new project with Angular CLI, do not specify a version unless prompted by the user.
When generating code, follow Angular's style guide and best practices for maintainability and performance. Use the Angular CLI for scaffolding components, services, directives, pipes, and routes to ensure consistency.
Once you finish generating code, run the project's configured build script to ensure there are no build errors. If there are errors, analyze the error messages and fix them before proceeding.

LIFT Principle

Before creating any new component, service, directive, guard, helper, generator, or test, apply the LIFT principle:

Locate: Find existing code, contracts, generators, patterns, and references in the project and domain.
Identify: Determine what already solves part of the problem and where there is potential duplication.
Find: Find the smallest coherent point of reuse, extension, or composition before introducing new code.
Try to be DRY: Eliminate real duplication without creating premature abstractions or unnecessary generic structures.

Creating New Projects

If no guidelines are provided by the user, here are some default rules to follow when creating a new Angular project:

Use the latest stable version of Angular unless the user specifies otherwise.
Use Signals Forms for form management in new projects (available in Angular v21 and newer) Find out more.

Execution Rules for ng new: When asked to create a new Angular project, you must determine the correct execution command by following these strict steps:

Step 1: Check for an explicit user version.

IF the user requests a specific version (e.g., Angular 15), bypass local installations and strictly use npx.
Command: npx @angular/cli@<requested_version> new <project-name>

Step 2: Check for an existing Angular installation.

IF no specific version is requested, run ng version in the terminal to check if the Angular CLI is already installed on the system.
IF the command succeeds and returns an installed version, use the local/global installation directly.
Command: ng new <project-name>

Step 3: Fallback to Latest.

IF no specific version is requested AND the ng version command fails (indicating no Angular installation exists), you must use npx to fetch the latest version.
Command: npx @angular/cli@latest new <project-name>

Main Rules

Standalone by default. Do not set standalone: true explicitly.
Apply LIFT before introducing new components, services, directives, guards, helpers, generators, or tests.
Always create the corresponding .spec.ts file when the resource requires unit testing.
When creating or updating unit tests, follow testing-conventions.md.
When creating or updating unit tests, reuse only the test tool, scripts, and utilities already configured in the project.
Every new interface must have a corresponding generator using faker.js, with a single random seed per execution, respecting the project's folder hierarchy.
Use Generator only for mock/test data; otherwise, prefer Factory or Builder.
When creating or modifying component styles, follow component-styles.md and keep the template aligned with HTML classes.
Use Signals for all component state.
Avoid getters and setters; prefer computed.
Use Signal-based APIs: input, output, model, viewChild.
Use inject() instead of constructor injection.
Always use ChangeDetectionStrategy.OnPush.
Use NgOptimizedImage for static images.
Use native control flow (@if, @for, @switch).
Prefer class and style bindings over ngClass and ngStyle.
Property ordering: enums, injects, queries, inputs, models, signals, outputs, computed, public properties, private properties.
Method ordering: constructor, angular hooks, public methods, private methods.
Avoid complex effects; use RxJS for complex logic and API calls.
In RxJS, do not place logic inside subscribe; use pipe with operators (e.g., tap).
Prefer semantic operators.
Avoid unnecessary subscriptions; always use takeUntilDestroyed for automatic unsubscribe.
Methods must be testable and readable; avoid unnecessary coupling.
Keep implementations separate; create new components/services when there is complexity or reuse.
Keep components simple (KISS, YAGNI).
Maintain 100% AXE and WCAG AA compliance.
Do not expose accessibility as configurable API (e.g., aria-label, aria-describedby, helper-text for a11y only).
Prefer self-contained internal semantics and accessible behavior.

Integration with Local References

When modifying general typing, shared contracts, interfaces, enums, or TypeScript modeling, follow typescript-standards.
When modifying *.component.scss, *.directive.scss, or template classes, follow component-styles.md.
When creating or modifying *.spec.ts files, follow testing-conventions.md.
When suggesting or running project scripts, respect the stack and scripts already configured in the project.
When preparing commits, follow git-commit.
In case of conflict, this order prevails: component-styles.md for component styles, testing-conventions.md for unit tests, typescript-standards for general TypeScript rules, git-commit for commits, and angular-standards for Angular architecture, code organization, reactivity, and accessibility.

Components

When working with Angular components, consult the following references based on the task:

Fundamentals: Anatomy, metadata, core concepts, and template control flow (@if, @for, @switch). Read components.md
Inputs: Signal-based inputs, transforms, and model inputs. Read inputs.md
Outputs: Signal-based outputs and custom event best practices. Read outputs.md
Host Elements: Host bindings and attribute injection. Read host-elements.md

If you require deeper documentation not found in the references above, read the documentation at https://angular.dev/guide/components.

Reactivity and Data Management

When managing state and data reactivity, use Angular Signals and consult the following references:

Signals Overview: Core signal concepts (signal, computed), reactive contexts, and untracked. Read signals-overview.md
Dependent State (linkedSignal): Creating writable state linked to source signals. Read linked-signal.md
Async Reactivity (resource): Fetching asynchronous data directly into signal state. Read resource.md
Side Effects (effect): Logging, third-party DOM manipulation (afterRenderEffect), and when NOT to use effects. Read effects.md

Forms

In most cases for new apps, prefer signal forms. When making a forms decision, analyze the project and consider the following guidelines:

If the application is using v21 or newer and this is a new form, prefer signal forms.
For older applications or when working with existing forms, use the appropriate form type that matches the application's current form strategy.
Signal Forms: Use signals for form state management. Read signal-forms.md
Template-driven forms: Use for simple forms. Read template-driven-forms.md
Reactive forms: Use for complex forms. Read reactive-forms.md

Dependency Injection

When implementing dependency injection in Angular, follow these guidelines:

Fundamentals: Overview of Dependency Injection, services, and the inject() function. Read di-fundamentals.md
Creating and Using Services: Creating services, the providedIn: 'root' option, and injecting into components or other services. Read creating-services.md
Defining Dependency Providers: Automatic vs manual provision, InjectionToken, useClass, useValue, useFactory, and scopes. Read defining-providers.md
Injection Context: Where inject() is allowed, runInInjectionContext, and assertInInjectionContext. Read injection-context.md
Hierarchical Injectors: The EnvironmentInjector vs ElementInjector, resolution rules, modifiers (optional, skipSelf), and providers vs viewProviders. Read hierarchical-injectors.md

Angular Aria

When building accessible custom components for any of the following patterns: Accordion, Listbox, Combobox, Menu, Tabs, Toolbar, Tree, Grid, consult the following reference:

Angular Aria Components: Building headless, accessible components (Accordion, Listbox, Combobox, Menu, Tabs, Toolbar, Tree, Grid) and styling ARIA attributes. Read angular-aria.md

Routing

When implementing navigation in Angular, consult the following references:

Define Routes: URL paths, static vs dynamic segments, wildcards, and redirects. Read define-routes.md
Route Loading Strategies: Eager vs lazy loading, and context-aware loading. Read loading-strategies.md
Show Routes with Outlets: Using <router-outlet>, nested outlets, and named outlets. Read show-routes-with-outlets.md
Navigate to Routes: Declarative navigation with RouterLink and programmatic navigation with Router. Read navigate-to-routes.md
Control Route Access with Guards: Implementing CanActivate, CanMatch, and other guards for security. Read route-guards.md
Data Resolvers: Pre-fetching data before route activation with ResolveFn. Read data-resolvers.md
Router Lifecycle and Events: Chronological order of navigation events and debugging. Read router-lifecycle.md
Rendering Strategies: CSR, SSG (Prerendering), and SSR with hydration. Read rendering-strategies.md
Route Transition Animations: Enabling and customizing the View Transitions API. Read route-animations.md

If you require deeper documentation or more context, visit the official Angular Routing guide.

Styling and Animations

When implementing styling and animations in Angular, consult the following references:

Using Tailwind CSS with Angular: Integrating Tailwind CSS into Angular projects. Read tailwind-css.md
Angular Animations: Using native CSS (recommended) or the legacy DSL for dynamic effects. Read angular-animations.md
Component Styling: Best practices for component styles and encapsulation. Read component-styling.md
Component Styles (Project): BEM, SCSS toolbox, ITCSS, and project-specific styling conventions. Read component-styles.md

Testing

When writing or updating tests, consult the following references based on the task:

Testing Conventions (Project): Project-specific rules for logic-only unit tests, faker.js, spies, coverage, and test structure. Read testing-conventions.md
Fundamentals: Best practices for unit testing (Vitest), async patterns, and TestBed. Read testing-fundamentals.md
Component Harnesses: Standard patterns for robust component interaction. Read component-harnesses.md
Router Testing: Using RouterTestingHarness for reliable navigation tests. Read router-testing.md
End-to-End (E2E) Testing: Best practices for E2E tests with Cypress. Read e2e-testing.md

Tooling

When working with Angular tooling, consult the following references:

Angular CLI: Creating applications, generating code (components, routes, services), serving, and building. Read cli.md
Angular MCP Server: Available tools, configuration, and experimental features. Read mcp.md

Procedure

Apply LIFT to locate, identify, and reuse what already exists before creating new structures.
Model state with Signals and computed.
Configure OnPush and use inject().
Structure the template with native control flow and clear class and style bindings.
If there is general typing or shared contracts, also align with typescript-standards.
If there are component styles or template class changes, apply component-styles.md.
Write RxJS with pipe and semantic operators.
Use takeUntilDestroyed when there are subscriptions.
If there are unit tests, follow testing-conventions.md.
Ensure WCAG AA accessibility without exposing a11y as configurable API.

Quality Checklist

.spec.ts file created when applicable.
LIFT applied before introducing new structures or duplicating implementations.
If general typing was changed, typescript-standards was followed.
If *.spec.ts was changed, testing-conventions.md was followed.
If component SCSS or template classes were changed, component-styles.md was followed.
New interfaces with corresponding generator using faker.js, unique seed, and correct hierarchy.
Generator names only for mocks/tests.
Signals used for all component state.
No getters/setters; computed used when necessary.
OnPush active and inject() used.
Native control flow used.
RxJS without logic inside subscribe.
Subscriptions with automatic unsubscribe via takeUntilDestroyed.
Methods readable, testable, and with low complexity.
Properties and methods in the defined order.
Component simple, without excess code.
AXE and WCAG AA met.
No configurable accessibility API; internal semantics used.

Notes

Do not run ng build automatically; follow the project's package.json scripts.
This skill defines architectural standards; do not duplicate SCSS and unit test operational rules here.
For component styles, use component-styles.md.
For logic unit tests, use testing-conventions.md and preserve the project's configured test stack.
For project scripts, respect the stack and scripts already configured in the project.
For commits, use git-commit.
Harnesses and router testing are complementary references for specific UI and navigation cases.
effect only for simple cases; complex logic belongs in RxJS.
resource is experimental; use with caution.

angular-standards