# Architecture Document
Generated: Tuesday, September 16, 2025

## System Overview
The Angular Clarity Boilerplate is a frontend-only, single-page application (SPA) template. It is designed to serve as a foundational starting point for developing enterprise-grade web applications. The system provides a pre-configured, modular, and scalable architecture using the Angular framework and is visually styled with the VMware Clarity Design System. Its primary purpose is to accelerate development by providing a structured and feature-rich starting point.

## Architecture Pattern
The boilerplate is built upon a **Component-Based Architecture**, which is fundamental to the Angular framework. The UI is composed of a tree of reusable and encapsulated components.

The overall architectural pattern follows best practices for scalable Angular applications, emphasizing a **Modular Design**. The application is segregated into a `CoreModule`, a `SharedModule`, and is designed for the addition of multiple `FeatureModules`. This structure promotes separation of concerns, reusability, and maintainability.

## Component Design (Frontend)

- **AppModule:** The root module of the application, responsible for bootstrapping the `AppComponent` and importing essential modules like the `CoreModule` and `AppRoutingModule`.

- **AppComponent:** The main application shell component. It contains the primary layout, including the Clarity header, sidebar navigation, and the main content area where routed components are displayed via `<router-outlet>`.

- **CoreModule:** This module is designed to be imported only once by the `AppModule`. It contains singleton services, route guards, and other one-time setup logic (e.g., HTTP interceptors). This pattern prevents services from being provided multiple times across the application.

- **SharedModule:** This module contains commonly used components, directives, and pipes that can be reused across different feature modules. It is imported by feature modules whenever they need access to these shared elements. It primarily exports common Angular modules (like `CommonModule`, `FormsModule`) and Clarity UI modules.

- **Feature Modules (Conceptual):** The architecture is designed for developers to create new feature modules (e.g., `DashboardModule`, `AdminModule`). These modules encapsulate all the components, services, and routing related to a specific business domain. They are typically **lazy-loaded** to improve initial application load performance.

## Data Architecture

### Primary Database
- Not applicable. As a frontend-only boilerplate, this project does not include a database. It is designed to connect to any backend with a data persistence layer.

### Data Model (Client-Side)
- Data models will be defined using **TypeScript interfaces or classes** within feature modules. These models will represent the structure of data objects retrieved from or sent to the backend API.
- **Example `User` model:**
  ```typescript
  export interface User {
    id: number;
    name: string;
    email: string;
    role: 'admin' | 'user';
  }

  Of course. Here is the architecture_document.md for the Angular Clarity boilerplate project, presented in a single code block for easy copying.

Markdown

# Architecture Document
Generated: Tuesday, September 16, 2025

## System Overview
The Angular Clarity Boilerplate is a frontend-only, single-page application (SPA) template. It is designed to serve as a foundational starting point for developing enterprise-grade web applications. The system provides a pre-configured, modular, and scalable architecture using the Angular framework and is visually styled with the VMware Clarity Design System. Its primary purpose is to accelerate development by providing a structured and feature-rich starting point.

## Architecture Pattern
The boilerplate is built upon a **Component-Based Architecture**, which is fundamental to the Angular framework. The UI is composed of a tree of reusable and encapsulated components.

The overall architectural pattern follows best practices for scalable Angular applications, emphasizing a **Modular Design**. The application is segregated into a `CoreModule`, a `SharedModule`, and is designed for the addition of multiple `FeatureModules`. This structure promotes separation of concerns, reusability, and maintainability.

## Component Design (Frontend)

- **AppModule:** The root module of the application, responsible for bootstrapping the `AppComponent` and importing essential modules like the `CoreModule` and `AppRoutingModule`.

- **AppComponent:** The main application shell component. It contains the primary layout, including the Clarity header, sidebar navigation, and the main content area where routed components are displayed via `<router-outlet>`.

- **CoreModule:** This module is designed to be imported only once by the `AppModule`. It contains singleton services, route guards, and other one-time setup logic (e.g., HTTP interceptors). This pattern prevents services from being provided multiple times across the application.

- **SharedModule:** This module contains commonly used components, directives, and pipes that can be reused across different feature modules. It is imported by feature modules whenever they need access to these shared elements. It primarily exports common Angular modules (like `CommonModule`, `FormsModule`) and Clarity UI modules.

- **Feature Modules (Conceptual):** The architecture is designed for developers to create new feature modules (e.g., `DashboardModule`, `AdminModule`). These modules encapsulate all the components, services, and routing related to a specific business domain. They are typically **lazy-loaded** to improve initial application load performance.

## Data Architecture

### Primary Database
- Not applicable. As a frontend-only boilerplate, this project does not include a database. It is designed to connect to any backend with a data persistence layer.

### Data Model (Client-Side)
- Data models will be defined using **TypeScript interfaces or classes** within feature modules. These models will represent the structure of data objects retrieved from or sent to the backend API.
- **Example `User` model:**
  ```typescript
  export interface User {
    id: number;
    name: string;
    email: string;
    role: 'admin' | 'user';
  }
Data Flow
API Call: A component's method calls a function in its corresponding service (e.g., userService.getUsers()).

Service Layer: The service uses Angular's HttpClient to make an HTTP request to the backend API.

Data Retrieval: The service receives the HTTP response and typically returns an Observable of the data, typed with the appropriate TypeScript interface.

Component Update: The component subscribes to the Observable. Once the data is received, it updates its local state, triggering Angular's change detection to re-render the template and display the new data.

API Design (Backend Communication)
This boilerplate is backend-agnostic. It is designed to communicate with any backend that exposes a RESTful or GraphQL API.

Communication Protocol
HTTP/HTTPS: Communication is handled via standard HTTP requests using Angular's HttpClient service.

Example Service Implementation
An example of a service making API calls:
// in user.service.ts
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
import { User } from '../models/user.model';
import { environment } from '../../environments/environment';

@Injectable({
  providedIn: 'root'
})
export class UserService {
  private apiUrl = `${environment.apiBaseUrl}/users`;

  constructor(private http: HttpClient) { }

  getUsers(): Observable<User[]> {
    return this.http.get<User[]>(this.apiUrl);
  }

  getUserById(id: number): Observable<User> {
    return this.http.get<User>(`${this.apiUrl}/${id}`);
  }
}

Error Handling
HTTP interceptors can be provided in the CoreModule to handle API errors globally (e.g., logging errors, redirecting on 401 Unauthorized responses).

Security Architecture
Authentication: Authentication logic (e.g., handling JWTs, interacting with OAuth providers) should be encapsulated within an AuthService provided in the CoreModule.

Authorization (Route Guards): The architecture uses Angular's Route Guards to protect routes. An AuthGuard can be implemented to prevent unauthorized users from accessing certain parts of the application.

Client-Side Security: The boilerplate does not inherently protect against all client-side vulnerabilities. Developers should follow best practices for preventing XSS and CSRF attacks.

Scalability Considerations
Lazy Loading: The architecture strongly encourages the use of lazy-loaded feature modules. This ensures that the initial application bundle size remains small, leading to faster load times. As new features are added, they do not impact the initial load performance.

Modular Design: The strict separation of concerns into Core, Shared, and Feature modules makes the codebase easier to manage, test, and scale as the application grows in complexity.

State Management: For applications with complex state, a state management library like NgRx or Akita can be easily integrated into this architecture without requiring significant refactoring.

---

## ARCHITECTURE UPDATE - 2025-10-04 11:50:36

### Calculator Feature Module Architecture
Generated: 2025-10-04T11:32:58.476921

Based on the user prompt for a "yellow calculator app" and the existing Angular Clarity Boilerplate (as outlined in `analysis_document.md` and `requirements_document.md`), the calculator will be integrated as a new, self-contained, lazy-loaded feature module. This approach aligns perfectly with the boilerplate's `FR-002: Modular Architecture` and `User Story 2: Add a New Feature`, ensuring scalability and maintainability.

#### System Overview (Calculator)
The "yellow calculator app" will function as a client-side web calculator, allowing users to perform basic arithmetic operations. It will be a distinct feature accessible via its own route within the main application shell provided by the boilerplate, leveraging the existing responsive layout and Clarity Design System for its UI.

#### Architecture Pattern
The calculator will implement a **Lazy-Loaded Feature Module** pattern. This means:
- A dedicated `CalculatorModule` will encapsulate all calculator-specific components, routing, and potential services.
- This module will be loaded asynchronously when its route is activated, optimizing initial application load times (NFR-001).
- It will be self-contained, importing `SharedModule` for common UI elements if needed, but avoiding direct dependencies on `CoreModule` services unless absolutely necessary (adhering to `Business Rules` from `analysis_document.md`).

#### Component Design (Calculator)
- **`CalculatorModule`**: The root module for the calculator feature, configured for lazy loading. It will declare and export its components and define its feature-specific routes.
- **`CalculatorComponent`**: The main container component for the calculator. It will manage the overall state and logic of the calculator (e.g., current input, result, operations queue). It will host the display and keypad components.
- **`CalculatorDisplayComponent`**: A presentational component responsible for displaying the current input, results, and potentially operation history. It will receive data from the `CalculatorComponent`.
- **`CalculatorKeypadComponent`**: A container component that arranges all the calculator buttons (numbers, operators, clear, equals). It will emit events when buttons are pressed, which the `CalculatorComponent` will listen to.
- **`CalculatorButtonComponent`**: A reusable presentational component for individual calculator buttons. It will display the button's value/symbol and emit click events.

#### Data Architecture (Calculator)
- **Client-Side State Management**: The calculator's state (e.g., current value, previous value, selected operator, display output) will be managed entirely on the client side within the `CalculatorComponent` or a dedicated service provided within the `CalculatorModule`. This state will be transient and not persisted.
- **No Database Interaction**: As a purely client-side calculator, no database integration is required.

#### API Design (Calculator)
- **No API Interaction**: The "yellow calculator app" will not require any backend API interaction. All computational logic will reside within the frontend application.

#### Security Architecture (Calculator)
- The calculator feature will inherit the security posture of the base Angular Clarity Boilerplate. As it's a client-side application with no data persistence or API calls, no specific additional security measures are required beyond standard web application best practices (e.g., input validation if complex parsing were involved, which is not the case for a basic calculator).

#### Scalability Considerations (Calculator)
- **Modular Isolation**: Encapsulating the calculator logic within its own feature module ensures that it can be developed, tested, and maintained independently without affecting other parts of the application. This contributes to the overall scalability and maintainability of the boilerplate as per `NFR-003` and `NFR-004`.
- **Component Reusability**: Designing distinct `CalculatorButtonComponent` and `CalculatorDisplayComponent` promotes reusability and simplifies future modifications.
- **Performance**: Lazy loading the `CalculatorModule` (FR-002, NFR-001) ensures that its code is only loaded when needed, maintaining optimal application performance.
