feat: Implement Desktop OAuth Support

[vreshch]

Summary

This PR implements Desktop OAuth Support for the Agentage platform, allowing desktop applications to authenticate users via web-based OAuth with localhost callback.

Changes

Backend

OAuth Routes ()

• Added support for desktop mode query parameters:
  • desktop=true - enables desktop authentication flow
  • callback - localhost callback URL for redirect
  • include_provider_token=true - includes provider access token in response
• Parameters are stored in OAuth state for CSRF protection
• All three providers supported: GitHub, Google, Microsoft

OAuth Callbacks ()

• Updated callback handlers to detect desktop mode from state
• Validate callback URL is localhost only (security requirement)
• Redirect to desktop callback with JWT token
• Include provider access token when requested (as github_token, google_token, or microsoft_token)

OAuth Service ()

• Modified OAuth strategies to capture provider access tokens
• Store tokens in req.user.providerToken for callback use
• Added proper TypeScript types for all OAuth profiles

Type Definitions ()

• Added providerToken?: string to Express.User interface

Frontend

Desktop Login Page ()

• New page at /desktop-login route
• Accepts callback query parameter (defaults to http://localhost:3739/callback)
• Displays authentication provider buttons (Google, GitHub, Microsoft)
• Modern UI with security information for users
• Each button redirects to OAuth with desktop parameters

How It Works

1. Desktop app opens browser to: https://agentage.io/desktop-login?callback=http://localhost:3739/callback
2. User selects authentication provider (e.g., GitHub)
3. Browser navigates to: /api/auth/github?desktop=true&callback=http://localhost:3739/callback&include_provider_token=true
4. User completes OAuth flow with the provider
5. Backend validates callback URL is localhost and redirects to: http://localhost:3739/callback?token=JWT&github_token=PROVIDER_TOKEN
6. Desktop app receives tokens and completes authentication

Security

• Localhost-only validation: Callback URLs must be localhost or 127.0.0.1
• CSRF protection: Desktop parameters stored in OAuth state parameter
• Port validation: Accepts ports 3000-65535

Testing

All verification commands passed:

• ✅ npm run type-check - TypeScript compilation successful
• ✅ npm run lint - No new linting errors
• ✅ npm run test - All tests passing
• ✅ npm run build - Production build successful

Related

• Implements requirements from specs/desktop-oauth.md
• Updates specs/auth.md status to ✅ Implemented

Files Changed

• packages/backend/src/routes/auth/index.ts (+206, -17)
• packages/backend/src/services/oauth/oauth.service.ts (+30, -4)
• packages/backend/src/types/express.d.ts (+3)
• packages/frontend/src/app/desktop-login/page.tsx (+116, new file)

Total: 4 files changed, 334 insertions(+), 21 deletions(-)

[github-actions]

✅ Pull Request Validation Successful

Step Results:

• ✅ 📦 Install dependencies: true
• ✅ 🔍 Run linting: true
• ✅ 🧪 Run tests: true
• ✅ 🏗️ Build packages: true

🎉 All quality checks passed! Ready to merge.

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🐳 Docker Images Built Successfully!

🏷️ Tag: pr-15

• Backend: ✅ Built
• Frontend: ✅ Built

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⏰ Generated at: 2025-12-12T01:24:33.776Z