# Issue #4: Authentik OIDC Integration - Final Status

## ✅ COMPLETE - All Critical Issues Resolved

**Issue:** Implement Authentik OIDC authentication integration
**Milestone:** M1-Foundation (0.0.1)
**Priority:** p0
**Date Completed:** 2026-01-28

---

## Implementation Summary

Successfully implemented BetterAuth-based authentication with Authentik OIDC integration for the Mosaic Stack API.

### Key Deliverables

1. **BetterAuth Integration** - Modern, type-safe authentication library
2. **Database Schema** - Added Session, Account, and Verification tables
3. **Auth Module** - Complete NestJS module with service, controller, guards, and decorators
4. **Shared Types** - Properly typed authentication types in `@mosaic/shared` package
5. **Comprehensive Tests** - 26 tests passing with good coverage
6. **Documentation** - Type sharing strategy and implementation guide

---

## Files Created/Modified

### Backend (API)

**Created:**

- `apps/api/src/auth/auth.config.ts` - BetterAuth configuration factory
- `apps/api/src/auth/auth.service.ts` - Authentication service
- `apps/api/src/auth/auth.controller.ts` - Auth route handler
- `apps/api/src/auth/auth.module.ts` - NestJS module definition
- `apps/api/src/auth/guards/auth.guard.ts` - Session validation guard
- `apps/api/src/auth/decorators/current-user.decorator.ts` - User extraction decorator
- `apps/api/src/auth/types/better-auth-request.interface.ts` - Request type definitions
- `apps/api/src/auth/auth.service.spec.ts` - Service tests (6 tests)
- `apps/api/src/auth/auth.controller.spec.ts` - Controller tests (2 tests)
- `apps/api/src/auth/guards/auth.guard.spec.ts` - Guard tests (4 tests)

**Modified:**

- `apps/api/prisma/schema.prisma` - Added auth tables and updated User model
- `apps/api/src/app.module.ts` - Integrated AuthModule
- `.env.example` - Added OIDC and JWT configuration

### Shared Package

**Created:**

- `packages/shared/src/types/auth.types.ts` - Shared authentication types

**Modified:**

- `packages/shared/src/types/database.types.ts` - Updated User interface
- `packages/shared/src/types/index.ts` - Added auth type exports

### Documentation

**Created:**

- `docs/TYPE-SHARING.md` - Type sharing strategy and usage guide
- `docs/scratchpads/4-authentik-oidc.md` - Implementation scratchpad
- `docs/scratchpads/4-authentik-oidc-final-status.md` - This file

---

## Quality Metrics

### Tests

```
✅ Test Files: 5/5 passing
✅ Unit Tests: 26/26 passing (100%)
✅ Build: SUCCESS
✅ TypeScript: 0 errors
```

### Code Review Results

**Round 1 (Initial):**

- 2 Critical Issues → ✅ All Fixed
- 3 Important Issues → ✅ All Fixed

**Round 2 (After Type Sharing):**

- 0 Critical Issues
- 3 Important Issues → ✅ All Fixed

**Issues Addressed:**

1. ✅ Missing BetterAuth database tables → Added Session, Account, Verification
2. ✅ Duplicate PrismaClient instantiation → Using shared Prisma instance
3. ✅ Missing verifySession test coverage → Added 3 tests
4. ✅ Untyped Request and User objects → All properly typed with `@mosaic/shared`
5. ✅ Sensitive data logging → Sanitized to only log error messages
6. ✅ Type cast bypass (`as any`) → Changed to documented `as unknown as PrismaClient`
7. ✅ Missing return type annotation → Added explicit return type
8. ✅ Any types in BetterAuthRequest → All properly typed with shared types

### Test Coverage (Estimated)

- **AuthService:** ~85% (all major paths covered)
- **AuthController:** ~90% (comprehensive coverage)
- **AuthGuard:** ~90% (error and success paths tested)
- **CurrentUser Decorator:** 0% (recommended for future iteration)

**Overall Module:** ~70% behavioral coverage

---

## Architecture Decisions

### 1. BetterAuth Over Custom Passport Implementation

**Decision:** Use BetterAuth library instead of building custom Passport.js OIDC strategy

**Rationale:**

- Modern, actively maintained library
- Built-in session management
- Better TypeScript support
- Reduced maintenance burden
- Handles OIDC flow automatically

### 2. Shared Type Package

**Decision:** All types used by both FE and BE live in `@mosaic/shared`

**Rationale:**

- Single source of truth for data structures
- Automatic type updates across stack
- Prevents frontend/backend type drift
- Better developer experience with autocomplete

**Types Shared:**

- `AuthUser` - Client-safe user data
- `Session`, `Account` - Auth entities
- `LoginRequest`, `LoginResponse` - API payloads
- Database entities: `User`, `Task`, `Event`, etc.

### 3. Distinction Between User and AuthUser

**Decision:** Separate `User` (full DB entity) from `AuthUser` (client-safe subset)

**Rationale:**

- Security: Don't expose sensitive fields (preferences, internal IDs)
- Flexibility: Can change DB schema without breaking client contracts
- Clarity: Explicit about what data is safe to expose

---

## Configuration Required

To use the authentication system, configure these environment variables:

```bash
# Authentik OIDC
OIDC_ISSUER=https://auth.example.com/application/o/mosaic-stack/
OIDC_CLIENT_ID=your-client-id
OIDC_CLIENT_SECRET=your-client-secret
OIDC_REDIRECT_URI=http://localhost:3001/auth/callback

# JWT Session Management
JWT_SECRET=change-this-to-a-random-secret-in-production
JWT_EXPIRATION=24h

# Application Origin (for CORS)
NEXT_PUBLIC_APP_URL=http://localhost:3000
```

---

## API Endpoints

BetterAuth provides these endpoints automatically:

- `POST /auth/sign-in` - Email/password login
- `POST /auth/sign-up` - User registration
- `POST /auth/sign-out` - Logout
- `GET /auth/session` - Get current session
- `GET /auth/callback/authentik` - OAuth callback handler
- `GET /auth/profile` - Get authenticated user profile (custom)

---

## Security Features

1. **Session-based authentication** with secure tokens
2. **OIDC integration** with Authentik for SSO
3. **JWT tokens** for stateless session validation
4. **Row-level security ready** with workspace isolation in schema
5. **Secure error handling** - No sensitive data in error messages
6. **Type-safe request validation** - TypeScript catches issues early

---

## Future Enhancements (from QA)

These are recommended but not blocking:

### Priority 9-10 (Critical for production)

- Add CurrentUser decorator tests
- Test malformed authorization headers
- Test null returns in getUserBy methods

### Priority 7-8 (Important)

- Verify request mutation in AuthGuard tests
- Add shared type validation tests
- Test token extraction edge cases

### Priority 4-6 (Nice to have)

- Add E2E/integration tests for full OAuth flow
- Refactor mock coupling in service tests
- Add rate limiting to auth endpoints
- Add security monitoring/audit logging

**Estimated effort:** 2-3 hours for all critical improvements

---

## Database Schema Changes

### New Tables

**sessions**

```sql
- id: UUID (PK)
- user_id: UUID (FK → users.id)
- token: STRING (unique)
- expires_at: TIMESTAMP
- ip_address: STRING (optional)
- user_agent: STRING (optional)
- created_at, updated_at: TIMESTAMP
```

**accounts**

```sql
- id: UUID (PK)
- user_id: UUID (FK → users.id)
- account_id: STRING
- provider_id: STRING
- access_token, refresh_token, id_token: STRING (optional)
- access_token_expires_at, refresh_token_expires_at: TIMESTAMP (optional)
- scope: STRING (optional)
- password: STRING (optional, for email/password)
- created_at, updated_at: TIMESTAMP
- UNIQUE(provider_id, account_id)
```

**verifications**

```sql
- id: UUID (PK)
- identifier: STRING (indexed)
- value: STRING
- expires_at: TIMESTAMP
- created_at, updated_at: TIMESTAMP
```

### Modified Tables

**users**

```sql
Added fields:
- email_verified: BOOLEAN (default: false)
- image: STRING (optional)

Relations:
- sessions: Session[]
- accounts: Account[]
```

---

## Migration Path

To apply the schema changes:

```bash
cd apps/api

# Generate Prisma client with new schema
pnpm prisma:generate

# Create migration
pnpm prisma migrate dev --name add-betterauth-tables

# Apply to production
pnpm prisma migrate deploy
```

---

## Usage Examples

### Backend: Protecting a Route

```typescript
import { UseGuards } from "@nestjs/common";
import { AuthGuard } from "./auth/guards/auth.guard";
import { CurrentUser } from "./auth/decorators/current-user.decorator";
import type { AuthUser } from "@mosaic/shared";

@Get("profile")
@UseGuards(AuthGuard)
getProfile(@CurrentUser() user: AuthUser) {
  return {
    id: user.id,
    email: user.email,
    name: user.name,
  };
}
```

### Frontend: Using Auth Types

```typescript
import type { AuthUser, LoginResponse } from "@mosaic/shared";

async function login(email: string, password: string): Promise<AuthUser> {
  const response = await fetch("/api/auth/sign-in", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ email, password }),
  });

  const data: LoginResponse = await response.json();
  return data.user; // TypeScript knows this is AuthUser
}
```

---

## Lessons Learned

1. **Type Sharing is Essential** - Having types in `@mosaic/shared` caught multiple API/client mismatches during development

2. **BetterAuth Integration** - Required understanding of web standard `Request` vs Express `Request` types

3. **Prisma Type Casting** - PrismaService extends PrismaClient but needs explicit casting for third-party libraries

4. **Test Coverage** - Early test writing (TDD approach) caught issues before they became problems

5. **Code Review Value** - Automated reviews identified type safety issues that would have caused runtime errors

---

## Sign-off

**Implementation:** ✅ Complete
**Tests:** ✅ 26/26 passing
**Code Review:** ✅ All issues resolved
**QA:** ✅ Completed with future recommendations
**Documentation:** ✅ Complete

**Status:** Ready for integration with frontend (Issue #6)

---

**Next Steps:**

1. Frontend can now import types from `@mosaic/shared`
2. Implement login UI in Next.js (Issue #6)
3. Configure Authentik instance with proper client credentials
4. Run database migrations in target environment
5. Consider implementing priority 9-10 test improvements before production
