# Frontend Capability - Delta Specification

## ADDED Requirements

### Requirement: Next.js App Router Architecture
The frontend application SHALL be built using Next.js 15 with the App Router pattern, supporting both React Server Components and Client Components.

#### Scenario: Server-side rendering for public pages
- **WHEN** a user navigates to the landing page
- **THEN** the page SHALL be server-side rendered with Launch UI components
- **AND** the initial HTML SHALL contain fully rendered content for SEO

#### Scenario: Client-side interactivity for forms
- **WHEN** a user interacts with login or registration forms
- **THEN** the form components SHALL be client components with React state management
- **AND** form validation SHALL occur in real-time on the client

#### Scenario: Static generation for unchanged content
- **WHEN** building the application for production
- **THEN** static pages SHALL be pre-generated where possible
- **AND** metadata SHALL be statically optimized for search engines

### Requirement: Launch UI Component Integration
The frontend application SHALL integrate Launch UI components for all public-facing pages, including Navbar, Hero, Items, Logos, FAQ, Stats, CTA, and Footer.

#### Scenario: Landing page composition
- **WHEN** the landing page is rendered
- **THEN** it SHALL include Hero, Items, Logos, FAQ, Stats, and CTA components from Launch UI
- **AND** components SHALL be styled consistently with Tailwind CSS 4.0

#### Scenario: Global navigation and footer
- **WHEN** any page is rendered
- **THEN** it SHALL include the Navbar component at the top
- **AND** the Footer component at the bottom
- **AND** navigation links SHALL route correctly using Next.js Link components

#### Scenario: Component customization
- **WHEN** Launch UI components require customization
- **THEN** the components SHALL be copied to the local `/components/launch-ui/` directory
- **AND** customizations SHALL preserve the core shadcn/ui patterns

### Requirement: TypeScript 5.0 Type Safety
The application SHALL use TypeScript 5.0 with strict mode enabled for comprehensive type checking across all components and utilities.

#### Scenario: Type-safe API responses
- **WHEN** making API requests
- **THEN** all response types SHALL be explicitly defined with TypeScript interfaces
- **AND** the compiler SHALL enforce type safety at compile time

#### Scenario: Component prop validation
- **WHEN** passing props to React components
- **THEN** prop types SHALL be validated by TypeScript
- **AND** invalid prop combinations SHALL produce compile-time errors

## MODIFIED Requirements

### Requirement: Responsive Layout and Styling
The application SHALL provide a fully responsive user interface using Tailwind CSS 4.0 utility classes, optimized for mobile, tablet, and desktop viewports.

*(Modified from Angular implementation to Next.js + Launch UI implementation)*

#### Scenario: Mobile-first responsive design
- **WHEN** the application is viewed on a mobile device
- **THEN** all Launch UI components SHALL render in mobile-optimized layouts
- **AND** navigation SHALL collapse to a mobile menu
- **AND** forms SHALL stack vertically for narrow viewports

#### Scenario: Desktop layout expansion
- **WHEN** the application is viewed on desktop screens
- **THEN** content SHALL expand to utilize available width
- **AND** grid layouts SHALL display multiple columns
- **AND** the Navbar SHALL display full navigation links

#### Scenario: Tailwind CSS 4.0 utilities
- **WHEN** styling components
- **THEN** Tailwind CSS 4.0 utility classes SHALL be used exclusively
- **AND** custom CSS SHALL be minimized in favor of utility classes
- **AND** the Tailwind configuration SHALL extend Launch UI defaults

### Requirement: Client-Side Routing
The application SHALL provide client-side navigation between pages using Next.js App Router with optimized prefetching and smooth transitions.

*(Modified from Angular Router to Next.js App Router)*

#### Scenario: Navigation between public pages
- **WHEN** a user clicks a navigation link
- **THEN** the Next.js Link component SHALL perform client-side navigation
- **AND** the page SHALL transition without full-page reload
- **AND** the browser history SHALL be updated correctly

#### Scenario: Protected route access
- **WHEN** an unauthenticated user attempts to access the dashboard
- **THEN** the middleware SHALL intercept the request
- **AND** the user SHALL be redirected to the login page
- **AND** the original destination SHALL be preserved for post-login redirect

#### Scenario: Programmatic navigation
- **WHEN** a component needs to navigate programmatically (e.g., after login)
- **THEN** the `useRouter` hook SHALL be used for navigation
- **AND** navigation SHALL support query parameters and hash fragments

## REMOVED Requirements

### Requirement: Angular-Specific Dependency Injection
**Reason**: Next.js does not use Angular's dependency injection system; React Context API and hooks replace this pattern.

**Migration**: Convert all Angular services to React hooks or API client utility functions. Replace `providedIn: 'root'` services with Context Providers or singleton modules.

### Requirement: RxJS Observable State Management
**Reason**: React's built-in state management (useState, useContext) is more idiomatic and sufficient for the application's state complexity.

**Migration**: Replace RxJS BehaviorSubjects with React Context API. Convert Observable subscriptions to useEffect hooks with state updates.

### Requirement: Angular Reactive Forms Module
**Reason**: Next.js applications use React-based form libraries. Launch UI patterns align with React Hook Form.

**Migration**: Replace Angular ReactiveFormsModule with React Hook Form. Convert FormControl/FormGroup to React Hook Form's useForm hook and register pattern.

