• Client Tier (Frontend): A Single Page Application (SPA) built with React, consuming data via RESTful APIs.
• Application Tier (Backend): A Node.js server exposing RESTful APIs, handling business logic, authentication, and data persistence.
• Data Tier: A PostgreSQL relational database for structured data, potentially supplemented by object storage for files.

3. Frontend Architecture

Technology Stack:

• Framework: React v18+
• Language: TypeScript
• State Management: React Query (for server state) and Zustand/Redux Toolkit (for global client state)
• Routing: React Router DOM v6+
• Styling: Tailwind CSS (for utility-first styling) with SCSS modules (for complex components)
• Form Management: React Hook Form with Zod (for validation)
• HTTP Client: Axios
• Build Tool: Vite
• Testing: Jest, React Testing Library, Cypress (E2E)

Component Structure:

• Atomic Design Principles:

* src/components/atoms: Basic HTML elements (Button, Input, Icon).

* src/components/molecules: Groups of atoms (LoginForm, TaskCard).

* src/components/organisms: Groups of molecules (ProjectList, TaskDetailModal).

* src/components/templates: Page layouts (AuthLayout, DashboardLayout).

* src/components/pages: Specific page implementations using templates (LoginPage, ProjectPage).

• Feature-based Organization: Components, hooks, and utilities related to a specific feature (e.g., src/features/projects, src/features/tasks) will be co-located.

State Management Strategy:

• Server State (Data Fetching, Caching, Syncing): React Query will be used to manage asynchronous data fetching, caching, and synchronization with the backend, reducing the need for complex global state for server-derived data.
• Client State (UI-specific, non-persistent): Zustand or Redux Toolkit will manage truly global client-side state (e.g., user preferences, theme, notification queue).

Routing:

• Defined using React Router DOM for client-side navigation.
• Protected routes will enforce authentication and authorization checks.

Accessibility (A11y):

• Adherence to WCAG guidelines.
• Semantic HTML, ARIA attributes, keyboard navigation support.

4. Backend Architecture

Technology Stack:

• Runtime: Node.js v18+
• Framework: NestJS (for its opinionated, modular, and scalable architecture)
• Language: TypeScript
• Database ORM: TypeORM / Prisma
• HTTP Server: Express.js (underlying NestJS)
• Authentication: Passport.js with JWT strategy
• Validation: Class-validator
• Logging: Winston / Pino
• Task Scheduling: Node-cron / BullMQ (for background jobs)
• Testing: Jest, Supertest

API Design (RESTful):

• Standard Conventions: Use standard HTTP methods (GET, POST, PUT, DELETE), status codes, and clear resource naming (e.g., /api/v1/projects, /api/v1/projects/:id/tasks).
• Version Control: API versioning (e.g., /api/v1/) to allow for future changes without breaking existing clients.
• Error Handling: Consistent and informative error responses (e.g., {"message": "Resource not found", "statusCode": 404}).
• Pagination, Filtering, Sorting: Implement query parameters for efficient data retrieval.

Service Structure (NestJS Modules):

• Modular Architecture: Each major feature (Users, Projects, Tasks, Teams, Auth) will be a separate NestJS module.
• Layered Design:

* Controllers: Handle incoming requests, route to services, and return responses.

* Services: Encapsulate business logic, orchestrate data operations.

* Repositories: Interact directly with the database via ORM.

* DTOs (Data Transfer Objects): Define data shapes for requests and responses, used with class-validator for input validation.

Middleware:

• Authentication middleware (JWT validation).
• Authorization middleware (RBAC checks).
• Logging middleware.
• Error handling middleware.
• CORS configuration.

5. Database Design

Database Type: PostgreSQL (Relational Database)

• Rationale: ACID compliance, strong data integrity, complex querying capabilities, mature ecosystem, and excellent support for structured data and relationships.

Schema Considerations (Conceptual Entities):

• Users: id, username, email, passwordHash, firstName, lastName, createdAt, updatedAt, lastLogin.
• Teams: id, name, description, ownerId (FK to Users), createdAt, updatedAt.
• UserTeams (Join Table): userId (FK), teamId (FK), role (e.g., 'admin', 'member').
• Projects: id, name, description, teamId (FK to Teams), status, startDate, endDate, createdAt, updatedAt.
• Tasks: id, title, description, projectId (FK to Projects), assignedToId (FK to Users), status, priority, dueDate, createdAt, updatedAt.
• Comments: id, content, taskId (FK to Tasks), userId (FK to Users), createdAt.
• Attachments: id, filename, fileUrl, fileType, size, uploadedBy (FK to Users), taskId (FK to Tasks, nullable), projectId (FK to Projects, nullable), createdAt.

ORM/ODM:

• TypeORM or Prisma will be used to interact with PostgreSQL, providing an object-relational mapping layer for easier data manipulation and type safety.

Database Migrations:

• Automated database migrations (e.g., using TypeORM's migration system or Prisma Migrate) will be implemented to manage schema changes and ensure database version control.

6. Authentication & Authorization

Authentication Strategy:

• JWT (JSON Web Tokens): Users will authenticate by sending credentials (username/password) to the backend. Upon successful validation, the server will issue a JWT.
• Token Storage: The JWT will be stored securely (e.g., in an HTTP-only cookie or browser memory for short-lived tokens) on the client side.
• Token Refresh: Implement a refresh token mechanism to securely obtain new access tokens without requiring re-authentication for extended sessions.

Authorization Strategy (Role-Based Access Control - RBAC):

• Roles: Define roles such as Admin, Project Manager, Team Member, Viewer.
• Permissions: Each role will have a set of defined permissions (e.g., create_project, edit_task, delete_user).
• Enforcement:

* Backend: Authorization guards (NestJS) will check the user's role/permissions against the required permissions for specific API endpoints.

* Frontend: UI elements (buttons, forms) will be conditionally rendered or disabled based on the user's roles/permissions fetched from the backend.

7. Deployment Strategy

Frontend Deployment:

• Static Hosting: The built React application will be deployed as static assets to a Content Delivery Network (CDN) via services like Vercel, Netlify, or AWS S3 + CloudFront.
• Continuous Deployment: Automated deployments triggered by pushes to the main branch (e.g., using Vercel/Netlify integrations or GitHub Actions).

Backend Deployment:

• Containerization: Docker will be used to containerize the Node.js application, ensuring consistent environments across development, testing, and production.
• Orchestration: Kubernetes (EKS/GKE/AKS) or AWS ECS/Fargate for managing containerized applications, enabling scalability, load balancing, and self-healing.
• Cloud Provider: AWS (EC2, RDS for PostgreSQL, S3 for file storage, ECR for Docker images) or a similar cloud platform (GCP, Azure).
• Load Balancing: An application load balancer (e.g., AWS ALB) will distribute traffic across multiple backend instances.
• Database Hosting: Managed database service (e.g., AWS RDS for PostgreSQL) for high availability, backups, and scaling.

CI/CD Pipeline (GitHub Actions / GitLab CI):

• Build: Lint, test, build frontend assets, build Docker images for backend.
• Test: Run unit, integration, and E2E tests.
• Deploy: Push Docker images to a registry, deploy frontend to static hosting, deploy backend to container orchestration.
• Environments: Separate pipelines/configurations for development, staging, and production environments.

8. Testing Strategy

Frontend Testing:

• Unit Tests (Jest + React Testing Library): For individual components, hooks, and utility functions, ensuring they render correctly and behave as expected.
• Component Tests (Jest + React Testing Library): For isolated UI components, simulating user interactions and verifying state changes.
• End-to-End (E2E) Tests (Cypress / Playwright): Simulate full user journeys through the application, interacting with the deployed frontend and backend, ensuring critical flows work end-to-end.

Backend Testing:

• **Unit Tests (Jest /

Full Stack Application Blueprint: Detailed Code Generation

This document provides a comprehensive, detailed, and production-ready blueprint for a full-stack application, encompassing frontend components, backend API, database design, authentication, deployment configuration, and test suites. Each section includes well-commented code examples and explanations, designed to be directly actionable for development teams.

1. Technology Stack Overview

To provide a concrete and modern blueprint, we've selected a popular and robust technology stack:

• Frontend: React with TypeScript
• Backend: Node.js (Express.js) with TypeScript
• Database: PostgreSQL
• Authentication: JSON Web Tokens (JWT)
• Deployment: Docker & Docker Compose

2. Frontend Blueprint (React with TypeScript)

This section outlines the structure and provides example code for a React frontend, focusing on component design, API interaction, and authentication integration.

2.1. Frontend Project Structure

frontend/
├── public/
│   └── index.html
├── src/
│   ├── assets/               # Static assets (images, fonts)
│   ├── components/           # Reusable UI components
│   │   ├── Button/
│   │   │   └── Button.tsx
│   │   └── common/
│   │       └── Loader.tsx
│   ├── contexts/             # React Contexts (e.g., AuthContext)
│   │   └── AuthContext.tsx
│   ├── hooks/                # Custom React Hooks
│   │   └── useAuth.ts
│   ├── pages/                # Page-level components (views)
│   │   ├── HomePage.tsx
│   │   ├── LoginPage.tsx
│   │   └── DashboardPage.tsx
│   ├── services/             # API interaction services
│   │   └── api.ts
│   │   └── authService.ts
│   ├── types/                # TypeScript type definitions
│   │   └── index.d.ts
│   ├── utils/                # Utility functions
│   │   └── helpers.ts
│   ├── App.tsx               # Main application component
│   ├── index.tsx             # Entry point
│   └── react-app-env.d.ts
├── tests/                    # Frontend tests
│   └── components/
│       └── Button.test.tsx
├── .env                      # Environment variables
├── package.json              # Project dependencies and scripts
├── tsconfig.json             # TypeScript configuration
└── webpack.config.js         # (Optional) Webpack configuration if not using CRA

2.2. Example: AuthContext.tsx (Authentication Context)

This context manages the user's authentication state across the application.

// frontend/src/contexts/AuthContext.tsx
import React, {
  createContext,
  useState,
  useEffect,
  useCallback,
  ReactNode,
} from "react";
import * as authService from "../services/authService";
import { User } from "../types"; // Assuming a User type defined in types/index.d.ts

interface AuthContextType {
  user: User | null;
  isAuthenticated: boolean;
  login: (token: string, userData: User) => void;
  logout: () => void;
  loading: boolean;
}

export const AuthContext = createContext<AuthContextType | undefined>(
  undefined
);

interface AuthProviderProps {
  children: ReactNode;
}

export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => {
  const [user, setUser] = useState<User | null>(null);
  const [isAuthenticated, setIsAuthenticated] = useState<boolean>(false);
  const [loading, setLoading] = useState<boolean>(true);

  // Function to handle user login
  const login = useCallback((token: string, userData: User) => {
    localStorage.setItem("jwtToken", token);
    setUser(userData);
    setIsAuthenticated(true);
  }, []);

  // Function to handle user logout
  const logout = useCallback(() => {
    localStorage.removeItem("jwtToken");
    setUser(null);
    setIsAuthenticated(false);
  }, []);

  // Effect to check for an existing token on app load
  useEffect(() => {
    const token = localStorage.getItem("jwtToken");
    if (token) {
      // In a real app, you'd verify the token with your backend
      // and fetch user data, or decode it if safe (e.g., for non-sensitive public claims).
      // For this blueprint, we'll simulate a successful verification.
      const decodedUser: User = {
        id: "user-123",
        username: "demoUser",
        email: "demo@example.com",
      }; // Placeholder for decoded user data
      setUser(decodedUser);
      setIsAuthenticated(true);
    }
    setLoading(false);
  }, []);

  const value = { user, isAuthenticated, login, logout, loading };

  return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;
};

2.3. Example: api.ts (API Service Integration)

This service sets up Axios for making HTTP requests, including an interceptor for JWT.

// frontend/src/services/api.ts
import axios from "axios";

const API_BASE_URL = process.env.REACT_APP_API_BASE_URL || "http://localhost:3001/api";

const api = axios.create({
  baseURL: API_BASE_URL,
  headers: {
    "Content-Type": "application/json",
  },
});

// Request interceptor to add JWT token to headers
api.interceptors.request.use(
  (config) => {
    const token = localStorage.getItem("jwtToken");
    if (token) {
      config.headers.Authorization = `Bearer ${token}`;
    }
    return config;
  },
  (error) => {
    return Promise.reject(error);
  }
);

// Response interceptor to handle token expiration or unauthorized responses
api.interceptors.response.use(
  (response) => {
    return response;
  },
  (error) => {
    if (error.response && error.response.status === 401) {
      // Handle unauthorized errors (e.g., redirect to login)
      console.error("Unauthorized request. Redirecting to login...");
      localStorage.removeItem("jwtToken");
      // You might want to dispatch a global event or use a router to redirect
      window.location.href = "/login"; // Example redirect
    }
    return Promise.reject(error);
  }
);

export default api;

2.4. Example: DashboardPage.tsx (Page Component)

A page component demonstrating data fetching and authentication.

// frontend/src/pages/DashboardPage.tsx
import React, { useEffect, useState } from "react";
import api from "../services/api";
import { useAuth } from "../hooks/useAuth"; // Custom hook for AuthContext
import { User } from "../types"; // Assuming a User type

interface DashboardData {
  message: string;
  users: User[];
}

const DashboardPage: React.FC = () => {
  const { user, isAuthenticated, logout } = useAuth();
  const [data, setData] = useState<DashboardData | null>(null);
  const [loading, setLoading] = useState<boolean>(true);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!isAuthenticated) {
      // Redirect to login if not authenticated (handled by router in real app)
      // For this example, we just log it.
      console.log("Not authenticated, please log in.");
      setLoading(false);
      return;
    }

    const fetchDashboardData = async () => {
      try {
        const response = await api.get<DashboardData>("/users"); // Example API endpoint
        setData(response.data);
      } catch (err) {
        setError("Failed to fetch dashboard data.");
        console.error("Error fetching dashboard data:", err);
      } finally {
        setLoading(false);
      }
    };

    fetchDashboardData();
  }, [isAuthenticated]);

  if (loading) {
    return <p>Loading dashboard...</p>;
  }

  if (error) {
    return <p style={{ color: "red" }}>Error: {error}</p>;
  }

  if (!isAuthenticated) {
    return (
      <div>
        <p>You are not logged in. Please navigate to the login page.</p>
      </div>
    );
  }

  return (
    <div style={{ padding: "20px", fontFamily: "Arial, sans-serif" }}>
      <h1>Welcome to your Dashboard, {user?.username}!</h1>
      <p>{data?.message}</p>

      <h2>Users List (Protected Data)</h2>
      {data?.users && data.users.length > 0 ? (
        <ul>
          {data.users.map((u) => (
            <li key={u.id}>
              {u.username} ({u.email})
            </li>
          ))}
        </ul>
      ) : (
        <p>No users found or data not loaded.</p>
      )}

      <button
        onClick={logout}
        style={{
          marginTop: "20px",
          padding: "10px 20px",
          backgroundColor: "#dc3545",
          color: "white",
          border: "none",
          borderRadius: "5px",
          cursor: "pointer",
        }}
      >
        Logout
      </button>
    </div>
  );
};

export default DashboardPage;

2.5. Example: DashboardPage.test.tsx (Frontend Test)

Using React Testing Library and Jest for component testing.

// frontend/tests/pages/DashboardPage.test.tsx
import React from "react";
import { render, screen, waitFor } from "@testing-library/react";
import "@testing-library/jest-dom";
import DashboardPage from "../../src/pages/DashboardPage";
import { AuthContext } from "../../src/contexts/AuthContext";
import api from "../../src/services/api";

// Mock the API module
jest.mock("../../src/services/api");
const mockedApi = api as jest.Mocked<typeof api>;

describe("DashboardPage", () => {
  const mockUser = { id: "1", username: "testuser", email: "test@example.com" };
  const mockAuthContextValue = {
    user: mockUser,
    isAuthenticated: true,
    login: jest.fn(),
    logout: jest.fn(),
    loading: false,
  };

  beforeEach(() => {
    // Reset mocks before each test
    mockedApi.get.mockClear();
    mockAuthContextValue.logout.mockClear();
  });

  test("renders loading state initially", () => {
    render(
      <AuthContext.Provider value={{ ...mockAuthContextValue, loading: true }}>
        <DashboardPage />
      </AuthContext.Provider>
    );
    expect(screen.getByText(/loading dashboard/i)).toBeInTheDocument();
  });

  test("renders dashboard data after successful fetch", async () => {
    const mockDashboardData = {
      message: "Welcome to your dashboard!",
      users: [{ id: "2", username: "admin", email: "admin@example.com" }],
    };
    mockedApi.get.mockResolvedValueOnce({ data: mockDashboardData });

    render(
      <AuthContext.Provider value={mockAuthContextValue}>
        <DashboardPage />
      </AuthContext.Provider>
    );

    await waitFor(() => {
      expect(screen.getByText(/welcome to your dashboard, testuser!/i)).toBeInTheDocument();
      expect(screen.getByText(/welcome to your dashboard!/i)).toBeInTheDocument();
      expect(screen.getByText(/admin \(admin@example.com\)/i)).toBeInTheDocument();
    });
    expect(mockedApi.get).toHaveBeenCalledWith("/users");
  });

  test("handles API fetch error gracefully", async () => {
    mockedApi.get.mockRejectedValueOnce(new Error("Network error"));

    render(
      <AuthContext.Provider value={mockAuthContextValue}>
        <DashboardPage />
      </AuthContext.Provider>
    );

    await waitFor(() => {
      expect(screen.getByText(/failed to fetch dashboard data/i)).toBeInTheDocument();
    });
    expect(mockedApi.get).toHaveBeenCalledWith("/users");
  });

  test("calls logout on button click", async () => {
    const mockDashboardData = { message: "Test", users: [] };
    mockedApi.get.mockResolvedValueOnce({ data: mockDashboardData });

    render(
      <AuthContext.Provider value={mockAuthContextValue}>
        <DashboardPage />
      </AuthContext.Provider>
    );

Full Stack Application Blueprint: Task Management System

1. Executive Summary

This document provides a comprehensive, detailed blueprint for a modern, scalable, and secure Full Stack Task Management System. It outlines the architecture, technology stack, design principles, and implementation strategies for the frontend, backend API, database, authentication, deployment, and testing. This blueprint serves as a foundational guide, enabling your development team to proceed with confidence and clarity, ensuring a robust and maintainable application.

The proposed system will empower users to efficiently manage tasks, collaborate on projects, track progress, and organize their work effectively.

2. Application Overview: Collaborative Task Management System

Application Name: PantheraTasks

Core Functionality:

PantheraTasks is designed to be an intuitive and powerful platform for individuals and teams to organize, track, and complete tasks and projects.

• User Management: Register, login, manage profiles.
• Project Management: Create, view, update, delete projects; assign members to projects.
• Task Management: Create, view, update, delete tasks; assign tasks to users; set due dates, priorities, and statuses.
• Collaboration: Comment on tasks, share project updates.
• Dashboard: Personalized overview of assigned tasks, project progress, and upcoming deadlines.
• Search & Filtering: Efficiently find tasks and projects based on various criteria.

Target Audience: Small to medium-sized teams, project managers, and individual professionals seeking an organized approach to task and project management.

3. Core Technologies Stack

To ensure a performant, scalable, and maintainable application, the following technology stack is recommended:

• Frontend:

* Framework: React (with Next.js for server-side rendering, routing, and API routes)

* Styling: Tailwind CSS (for utility-first styling)

* State Management: React Context API / Zustand (for simpler global state)

• Backend (API):

* Language/Runtime: Node.js

* Framework: Express.js

* ORM: Prisma (for type-safe database access)

* Authentication: JSON Web Tokens (JWT)

• Database:

* Type: PostgreSQL (Relational Database)

* Hosting: AWS RDS

• Deployment & Infrastructure:

* Cloud Provider: Amazon Web Services (AWS)

* Frontend Hosting: AWS S3 + CloudFront (for CDN)

* Backend Hosting: AWS EC2 / AWS Fargate (via ECS for containerized deployment)

* CI/CD: GitHub Actions

* Containerization: Docker

• Testing:

* Frontend: Jest, React Testing Library, Cypress (for E2E)

* Backend: Jest, Supertest

4. Frontend Blueprint: React with Next.js

The frontend will be built as a Single Page Application (SPA) leveraging Next.js for its robust features, including server-side rendering (SSR), static site generation (SSG), and API routes, enhancing performance and SEO.

• Architecture:

* Framework: React 18+

* Meta-framework: Next.js 14+ (App Router for modern features)

* Rendering: Primarily Client-Side Rendering (CSR) for interactive dashboards, with SSR/SSG for static content or initial page loads where SEO/performance is critical (e.g., marketing pages, public project views).

• Key Components & Pages:

* Layout Components: Header, Sidebar, Footer, AuthLayout, DashboardLayout.

* Authentication Pages:

* /login: User login form.

* /register: New user registration form.

* /forgot-password, /reset-password.

* Dashboard Page: /dashboard

* Overview of assigned tasks, project summaries, upcoming deadlines.

* Widgets for quick task creation, project status.

* Project Management:

* /projects: List all projects.

* /projects/[id]: Project detail page (tasks within project, members, comments).

* /projects/create: Form to create a new project.

* Task Management:

* /tasks: List all tasks (can be filtered by project, user, status).

* /tasks/[id]: Task detail page (description, assignee, due date, priority, comments).

* /tasks/create: Form to create a new task.

* User Profile: /profile

* View and edit user details.

* Manage notifications.

* Utility Components: Button, Input, Modal, Dropdown, ToastNotification, LoadingSpinner.

• State Management:

* Local Component State: useState, useReducer hooks.

* Global State: React Context API for application-wide concerns (e.g., authentication status, theme). Zustand can be considered for more complex global state management due to its simplicity and performance.

* Data Fetching & Caching: React Query or SWR for efficient data fetching, caching, and revalidation, greatly improving UX and reducing boilerplate.

• Styling:

* Framework: Tailwind CSS for rapid UI development with utility classes.

* Component Library (Optional): Headless UI (for unstyled, accessible components) combined with Tailwind.

• Routing:

* Leverage Next.js App Router for file-system-based routing, nested layouts, and easy page creation.

• Error Handling:

* UI Errors: React Error Boundaries for gracefully handling component rendering errors.

* API Errors: Centralized error handling for API responses, displaying user-friendly messages via toast notifications.

• Performance Considerations:

* Code Splitting: Automatic by Next.js.

* Image Optimization: Next.js Image component.

* Lazy Loading: For components not immediately visible.

* Data Caching: Via React Query/SWR.

* Bundle Analysis: Webpack Bundle Analyzer to identify and optimize large bundles.

5. Backend API Blueprint: Node.js with Express.js

The backend will expose a RESTful API to serve data to the frontend, manage business logic, and interact with the database.

• Architecture:

* Framework: Express.js for building robust API endpoints.

* ORM: Prisma for database interactions, providing type safety and a powerful query builder.

* Structure: Modular, organized by resource (e.g., users, projects, tasks), with dedicated layers for routes, controllers, services, and models.

• Key Endpoints & Resources:

* User Management (/api/users):

* POST /register: Register a new user.

* POST /login: Authenticate user, return JWT.

* GET /profile: Retrieve authenticated user's profile.

* PUT /profile: Update authenticated user's profile.

* GET /users/:id: Retrieve user by ID (admin/project member only).

* Project Management (/api/projects):

* POST /projects: Create a new project.

* GET /projects: Retrieve all projects (or projects user is a member of).

* GET /projects/:id: Retrieve a specific project.

* PUT /projects/:id: Update a project.

* DELETE /projects/:id: Delete a project.

* POST /projects/:id/members: Add member to project.

* DELETE /projects/:id/members/:userId: Remove member from project.

* Task Management (/api/tasks):

* POST /tasks: Create a new task (within a project).

* GET /tasks: Retrieve all tasks (with filters: by user, project, status).

* GET /tasks/:id: Retrieve a specific task.

* PUT /tasks/:id: Update a task.

* DELETE /tasks/:id: Delete a task.

* Comments (/api/tasks/:taskId/comments):

* POST /tasks/:taskId/comments: Add a comment to a task.

* GET /tasks/:taskId/comments: Retrieve comments for a task.

* DELETE /comments/:commentId: Delete a comment.

• Data Models (via Prisma Schema):

* User: id, email, passwordHash, firstName, lastName, role (ADMIN, MEMBER), createdAt, updatedAt.

* Project: id, name, description, status, ownerId (FK to User), createdAt, updatedAt.

* ProjectMembership: id, projectId (FK to Project), userId (FK to User), role (MANAGER, DEVELOPER), createdAt.

* Task: id, title, description, status (TODO, IN_PROGRESS, DONE), priority (LOW, MEDIUM, HIGH), dueDate, projectId (FK to Project), assigneeId (FK to User), createdAt, updatedAt.

* Comment: id, content, taskId (FK to Task), authorId (FK to User), createdAt.

• Request/Response Formats:

* All API communication will use JSON.

* Standardized response structures for success (e.g., {"data": {...}}) and error (e.g., {"error": "message", "statusCode": 400}).

• Error Handling & Validation:

* Validation: Joi or Zod for schema validation of incoming request bodies and query parameters.

* Global Error Middleware: Centralized error handling to catch unhandled exceptions and send consistent error responses.

* Custom Error Classes: For specific application errors (e.g., NotFoundError, UnauthorizedError).

• API Versioning:

* Initial version will be v1. Future versions will use URL prefixing (e.g., /api/v1/users).

• Rate Limiting:

* Implement rate limiting (e.g., express-rate-limit) to prevent abuse and brute-force attacks on sensitive endpoints (e.g., login, registration).

6. Database Design Blueprint: PostgreSQL

A robust PostgreSQL database will serve as the persistent data store, chosen for its reliability, ACID compliance, and extensive feature set.

• Database Type: PostgreSQL
• Hosting: AWS RDS (Relational Database Service) for managed database service, ensuring high availability, backups, and scaling.
• Schema Design (Conceptual):

* Users Table:

* id (UUID, PK)

* email (VARCHAR(255), UNIQUE, NOT NULL)

* password_hash (VARCHAR(255), NOT NULL)

* first_name (VARCHAR(100), NOT NULL)

* last_name (VARCHAR(100), NOT NULL)

* role (ENUM('ADMIN', 'MEMBER'), DEFAULT 'MEMBER', NOT NULL)

* created_at (TIMESTAMP WITH TIME ZONE, DEFAULT CURRENT_TIMESTAMP)

* updated_at (TIMESTAMP WITH TIME ZONE, DEFAULT CURRENT_TIMESTAMP)

* Projects Table:

* id (UUID, PK)

* name (VARCHAR(255), NOT NULL)

* description (TEXT)

* status (ENUM('ACTIVE', 'ARCHIVED', 'COMPLETED'), DEFAULT 'ACTIVE', NOT NULL)

* owner_id (UUID, FK to Users.id, NOT NULL)

* created_at (TIMESTAMP WITH TIME ZONE, DEFAULT CURRENT_TIMESTAMP)

* updated_at (TIMESTAMP WITH TIME ZONE, DEFAULT CURRENT_TIMESTAMP)

* ProjectMemberships Table (Junction Table for Many-to-Many):

* id (UUID, PK)

* project_id (UUID, FK to Projects.id, NOT NULL)

* user_id (UUID, FK to Users.id, NOT NULL)

* role (ENUM('MANAGER', 'DEVELOPER'), DEFAULT 'DEVELOPER', NOT NULL)

* created_at (TIMESTAMP WITH TIME ZONE, DEFAULT CURRENT_TIMESTAMP)

* Composite UNIQUE constraint: (project_id, user_id)

* Tasks Table:

* id (UUID, PK)

* title (VARCHAR(255), NOT NULL)

* description (TEXT)

* status (ENUM('TODO', 'IN_PROGRESS', 'DONE'), DEFAULT 'TODO', NOT NULL)

* priority (ENUM('LOW', 'MEDIUM', 'HIGH'), DEFAULT 'MEDIUM', NOT NULL)

* due_date (DATE)

* project_id (UUID, FK to Projects.id, NOT NULL)

* assignee_id (UUID, FK to Users