# Example: OAuth Authentication Feature

**Context**: Implement OAuth authentication with Google and GitHub providers for Bitwarden

## Phase 1: Architecture & Design

**Task 1.1**: Design OAuth authentication flow

- **Description**: Create sequence diagrams for OAuth login, token refresh, and logout flows
- **Team/Role**: Backend architecture team
- **Estimated Duration**: 3-4 hours
- **Dependencies**: None
- **Deliverables**:
  - Authentication flow diagrams (Mermaid format)
  - State management design
  - Error handling strategy
- **Acceptance Criteria**:
  - Covers Google and GitHub OAuth flows
  - Includes token refresh and expiration handling
  - Addresses security principle P05 (Controlled Access to Vault Data)

**Task 1.2**: Design database schema for OAuth users and sessions

- **Description**: Define database schema for storing OAuth provider information, user mappings, and session tokens
- **Team/Role**: Backend architecture team
- **Estimated Duration**: 2-3 hours
- **Dependencies**: None
- **Deliverables**:
  - Schema definition (SQL)
  - Index specifications
  - Migration script outline
- **Acceptance Criteria**:
  - Normalized schema, no redundant data
  - Protected Data encrypted at rest (P02)
  - Supports multiple OAuth providers per user

**Task 1.3**: Security threat modeling for OAuth integration

- **Description**: Conduct threat modeling session to identify OAuth-specific security risks
- **Team/Role**: Security team (can use `Skill(threat-modeling)` if available)
- **Estimated Duration**: 3-4 hours
- **Dependencies**: Task 1.1 complete (need flow diagrams)
- **Deliverables**:
  - Security definition document
  - Threat catalog with STRIDE analysis
  - Mitigation requirements
- **Acceptance Criteria**:
  - Addresses token storage security
  - Covers CSRF, token replay, and session hijacking threats
  - Defines secure channel requirements (P01 Zero Knowledge maintained)

---

## Phase 2: Implementation

**Task 2.1**: Implement OAuth client library integration

- **Description**: Integrate OAuth client libraries for Google and GitHub, implement authorization code flow
- **Team/Role**: Backend implementation team
- **Estimated Duration**: 6-8 hours
- **Dependencies**: Task 1.1, Task 1.3 (need flow design and security requirements)
- **Deliverables**:
  - OAuth client wrapper classes
  - Configuration management for client IDs/secrets
  - Authorization request and callback handlers
- **Acceptance Criteria**:
  - Can initiate OAuth flow with Google and GitHub
  - Handles authorization callbacks correctly
  - Implements PKCE for additional security

**Task 2.2**: Implement user session management

- **Description**: Create session middleware to manage OAuth tokens, refresh logic, and user authentication state
- **Team/Role**: Backend implementation team
- **Estimated Duration**: 4-6 hours
- **Dependencies**: Task 1.2, Task 2.1 (need schema and OAuth client)
- **Deliverables**:
  - Session middleware
  - Token storage and retrieval logic
  - Automatic token refresh implementation
- **Acceptance Criteria**:
  - Sessions persist across requests
  - Tokens refresh automatically before expiration
  - Encrypted token storage (P02)

**Task 2.3**: Implement authentication middleware

- **Description**: Create middleware to protect routes requiring authentication, verify OAuth tokens
- **Team/Role**: Backend implementation team
- **Estimated Duration**: 3-4 hours
- **Dependencies**: Task 2.2 (need session management)
- **Deliverables**:
  - Authentication middleware
  - Route protection decorators
  - Unauthorized access handling
- **Acceptance Criteria**:
  - Protected routes require valid OAuth authentication
  - Returns 401 for unauthenticated requests
  - Returns 403 for unauthorized access attempts

**Task 2.4**: Create OAuth login UI components

- **Description**: Build UI components for OAuth provider selection and login flow
- **Team/Role**: Frontend implementation team
- **Estimated Duration**: 4-5 hours
- **Dependencies**: Task 2.1 (need backend OAuth endpoints)
- **Deliverables**:
  - Login page with provider buttons
  - OAuth callback handling UI
  - Error messaging UI
- **Acceptance Criteria**:
  - Displays Google and GitHub login options
  - Handles OAuth redirects properly
  - Shows clear error messages for failed authentication

**Task 2.5**: Implement user account linking

- **Description**: Allow existing users to link OAuth providers to their accounts
- **Team/Role**: Backend implementation team
- **Estimated Duration**: 5-6 hours
- **Dependencies**: Task 2.2, Task 2.3 (need session and auth middleware)
- **Deliverables**:
  - Account linking endpoints
  - Provider management UI backend
  - Unlinking functionality
- **Acceptance Criteria**:
  - Users can link multiple OAuth providers
  - Can unlink providers (if not sole login method)
  - Existing vault data remains accessible

---

## Phase 3: Testing

**Task 3.1**: Write OAuth integration unit tests

- **Description**: Create comprehensive unit tests for OAuth client, session management, and authentication middleware
- **Team/Role**: QA team / Backend team
- **Estimated Duration**: 5-6 hours
- **Dependencies**: Phase 2 implementation tasks complete
- **Deliverables**:
  - Unit test suite with >85% code coverage
  - Mock OAuth provider responses
  - Token lifecycle tests
- **Acceptance Criteria**:
  - All OAuth flows tested (login, refresh, logout)
  - Error scenarios covered (invalid tokens, expired tokens, provider errors)
  - Security checks validated (CSRF, token encryption)

**Task 3.2**: Create OAuth integration end-to-end tests

- **Description**: Build automated E2E tests using test OAuth providers
- **Team/Role**: QA team
- **Estimated Duration**: 6-8 hours
- **Dependencies**: Task 3.1, Phase 2 complete
- **Deliverables**:
  - E2E test suite for OAuth flows
  - Test OAuth provider configurations
  - Cross-browser test coverage
- **Acceptance Criteria**:
  - Complete login/logout flows tested
  - Account linking flows tested
  - Error handling verified
  - Tests run on Chrome, Firefox, Safari

**Task 3.3**: Manual cross-platform testing

- **Description**: Manually test OAuth on all Bitwarden clients (web, desktop, mobile)
- **Team/Role**: QA team
- **Estimated Duration**: 4-5 hours
- **Dependencies**: Phase 2 complete, Task 3.2 (automated tests pass)
- **Deliverables**:
  - Test execution report
  - Bug tracking for any issues found
  - Platform-specific behavior documentation
- **Acceptance Criteria**:
  - OAuth works on web vault, desktop apps (Windows, macOS, Linux), mobile (iOS, Android)
  - User experience consistent across platforms
  - No regressions in existing authentication

**Task 3.4**: Security testing and penetration testing

- **Description**: Conduct security-focused testing of OAuth implementation
- **Team/Role**: Security team
- **Estimated Duration**: 6-8 hours
- **Dependencies**: Task 3.1, Task 3.2 (functional testing complete)
- **Deliverables**:
  - Security test report
  - Penetration test findings
  - Mitigation verification
- **Acceptance Criteria**:
  - No high or critical security vulnerabilities found
  - All threat model mitigations verified
  - Token storage encryption validated
  - CSRF protections confirmed

---

## Phase 4: Documentation & Deployment

**Task 4.1**: Write OAuth setup documentation

- **Description**: Create user-facing documentation for setting up and using OAuth login
- **Team/Role**: Technical writing team
- **Estimated Duration**: 3-4 hours
- **Dependencies**: Phase 2 implementation complete
- **Deliverables**:
  - User guide for OAuth login
  - Provider configuration instructions
  - Troubleshooting guide
- **Acceptance Criteria**:
  - Covers Google and GitHub setup steps
  - Includes screenshots of login flow
  - Addresses common issues

**Task 4.2**: Create API documentation for OAuth endpoints

- **Description**: Document all OAuth-related API endpoints for developer reference
- **Team/Role**: Backend team / Technical writing
- **Estimated Duration**: 2-3 hours
- **Dependencies**: Phase 2 implementation complete
- **Deliverables**:
  - API endpoint documentation
  - Request/response examples
  - Error code reference
- **Acceptance Criteria**:
  - All endpoints documented with examples
  - Authentication requirements specified
  - Rate limits and constraints noted

**Task 4.3**: Prepare deployment and migration procedures

- **Description**: Create deployment scripts, database migrations, and rollout plan
- **Team/Role**: DevOps team
- **Estimated Duration**: 4-5 hours
- **Dependencies**: Phase 2 complete, Task 3.1-3.4 (all testing passed)
- **Deliverables**:
  - Database migration scripts
  - Deployment runbook
  - Rollback procedures
- **Acceptance Criteria**:
  - Migrations tested on staging environment
  - Zero-downtime deployment plan
  - Rollback tested and verified

---

**Why This Breakdown Works**:

- ✅ Each task is 2-8 hours (right-sized for tracking)
- ✅ Clear dependencies prevent blocking and enable parallel work
- ✅ Phases group related work logically
- ✅ Each task has specific team assignment and acceptance criteria
- ✅ Can be implemented and tested incrementally
- ✅ Security considerations integrated throughout
- ✅ Documentation and deployment explicitly planned