# 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 - 2025-10-01 03:58:19



# Architecture Document Update
Generated: 2025-10-01T04:40:40.000Z

## System Overview - To Do App Feature
The "To Do App" will be integrated as a new, self-contained feature within the existing Angular Clarity Boilerplate. It will provide core task management functionalities including adding new tasks, viewing active and completed tasks, marking tasks as complete, and deleting tasks. This feature will leverage the boilerplate's modular architecture, Angular's reactive capabilities, and the Clarity Design System for its user interface, primarily utilizing client-side local storage for data persistence.

## Architecture Pattern - To Do App Feature
The To Do App will adhere to the existing boilerplate's modular architecture, implementing the functionality within a dedicated **Lazy-Loaded Feature Module**. This module will follow a clear **Component-Service Pattern**, where UI components are responsible for presentation and user interaction, and a dedicated service handles data logic and persistence.

## Component Design - To Do App Feature

### TodoModule (Feature Module)
-   **Purpose:** Encapsulates all components, services, and routing for the To Do App feature.
-   **Loading:** Lazy-loaded via the `AppRoutingModule`.

### Components
-   **`TodoPageComponent`**
    -   **Role:** The main container component for the To Do feature. Orchestrates the `TodoInputComponent` and `TodoListComponent`.
    -   **Responsibilities:** Connects `TodoInputComponent` with the `TodoService` for adding tasks and passes task data from `TodoService` to `TodoListComponent`.
-   **`TodoInputComponent`**
    -   **Role:** Handles user input for adding new tasks.
    -   **Responsibilities:**
        -   Provides an input field for task descriptions.
        -   Includes an "Add Task" button.
        -   Handles 'Enter' key press for adding tasks (US-001).
        -   Validates input to prevent empty tasks (US-001).
        -   Emits an event with the new task description to `TodoPageComponent`.
-   **`TodoListComponent`**
    -   **Role:** Displays the collection of tasks.
    -   **Responsibilities:**
        -   Receives a list of `Task` objects as input.
        -   Iterates through the tasks and renders an `TodoItemComponent` for each.
        -   Visually distinguishes between active and completed tasks (US-002).
        -   Displays tasks in a logical order (e.g., by creation date, US-002).
-   **`TodoItemComponent`**
    -   **Role:** Renders a single task item.
    -   **Responsibilities:**
        -   Displays the task description.
        -   Includes a control (e.g., checkbox) to mark a task as complete/incomplete (US-003).
        -   Includes a "Delete" button/icon for task removal (US-004).
        -   Emits events for task completion status changes and task deletion requests to `TodoListComponent` or directly to `TodoService`.

## Data Architecture - To Do App Feature

### Data Model
-   **`Task` Interface (TypeScript):**
    ```typescript
    interface Task {
        id: string; // Unique identifier for the task
        description: string; // The text content of the task
        completed: boolean; // Status: true if completed, false otherwise
        createdAt: Date; // Timestamp of task creation for ordering
    }
    ```

### Data Service (`TodoService`)
-   **Role:** Manages all CRUD operations for tasks.
-   **Responsibilities:**
    -   Provides methods for `addTask(description: string)`, `toggleTaskComplete(id: string)`, `deleteTask(id: string)`.
    -   Manages an internal collection of `Task` objects.
    -   Exposes the current list of tasks as an RxJS `BehaviorSubject` or `Observable` for reactive UI updates.
    -   Handles persistence of tasks to `localStorage`.
    -   Generates unique `id` for new tasks.

### Persistence
-   **Mechanism:** Client-side `localStorage` (Web Storage API).
-   **Storage Format:** Tasks will be serialized to JSON strings before being stored in `localStorage` under a specific key (e.g., `'todo_tasks'`).
-   **Loading:** On application initialization (or `TodoService` instantiation), tasks will be loaded from `localStorage`.
-   **Saving:** Any modification (add, update, delete) to the task list will trigger an update to `localStorage`.

### Data Flow
1.  **Add Task:** `TodoInputComponent` emits description -> `TodoPageComponent` receives -> calls `TodoService.addTask()` -> `TodoService` updates internal state and `localStorage` -> `TodoService`'s observable emits new task list.
2.  **View Tasks:** `TodoPageComponent` subscribes to `TodoService`'s task observable -> `TodoListComponent` receives tasks as input -> renders `TodoItemComponent`s.
3.  **Mark Complete:** `TodoItemComponent` emits toggle event -> `TodoPageComponent` (or direct call) calls `TodoService.toggleTaskComplete()` -> `TodoService` updates internal state and `localStorage` -> `TodoService`'s observable emits updated task list.
4.  **Delete Task:** `TodoItemComponent` emits delete event -> `TodoPageComponent` (or direct call) calls `TodoService.deleteTask()` -> `TodoService` updates internal state and `localStorage` -> `TodoService`'s observable emits updated task list.

## API Design - To Do App Feature
For the initial implementation, the To Do App will not interact with a backend API. All data operations are handled client-side by the `TodoService` using `localStorage`. This adheres to the boilerplate's backend-agnostic nature while meeting immediate user requirements.

Should a backend API become a requirement in the future, the `TodoService` can be refactored to use Angular's `HttpClient` to communicate with RESTful endpoints, without requiring significant changes to the UI components.

## Security Architecture - To Do App Feature
Given the client-side persistence approach with `localStorage`, security considerations are primarily focused on standard frontend best practices:
-   **XSS Protection:** Angular's built-in sanitization will protect against Cross-Site Scripting (XSS) attacks in displayed task descriptions.
-   **Data Sensitivity:** Since data is stored in `localStorage`, it is accessible to the client-side browser and browser extensions. This is acceptable for a personal To Do app but would require a backend and proper authentication/authorization for sensitive data or multi-user scenarios.
-   No new backend security measures are introduced as there is no server-side component for this feature.

## Scalability Considerations - To Do App Feature
-   **Modular Design:** The To Do App as a lazy-loaded feature module ensures it can be developed, tested, and maintained independently, enhancing overall application scalability and extensibility (NFR-003, NFR-004).
-   **Client-Side Persistence:** Using `localStorage` is suitable for individual users with a limited number of tasks. For enterprise-scale applications or multi-user support, the `TodoService` is designed to be easily swappable with an API-driven implementation for backend persistence.
-   **Performance:** The use of RxJS and efficient component rendering will ensure a responsive user experience for typical task list sizes. The lazy-loading of the `TodoModule` will also contribute to faster initial load times for the main application.
