feat(auth): Add interactive device auth flow via browser

fordN · fordN · commit 37609621b5f1 · 2025-11-17T00:42:01.000-03:00
diff --git a/src/amp/auth/__init__.py b/src/amp/auth/__init__.py
@@ -4,7 +4,8 @@
 Reads and manages auth tokens from ~/.amp-cli-config.
 """
 
+from .device_flow import interactive_device_login
 from .models import AuthStorage, RefreshTokenResponse
 from .service import AuthService
 
-__all__ = ['AuthService', 'AuthStorage', 'RefreshTokenResponse']
+__all__ = ['AuthService', 'AuthStorage', 'RefreshTokenResponse', 'interactive_device_login']
diff --git a/src/amp/auth/device_flow.py b/src/amp/auth/device_flow.py
@@ -0,0 +1,289 @@
+"""OAuth2 Device Authorization Flow for Privy authentication.
+
+Implements the device authorization grant flow with PKCE for secure authentication.
+Matches the TypeScript CLI implementation.
+"""
+
+import base64
+import hashlib
+import secrets
+import time
+import webbrowser
+from typing import Optional, Tuple
+
+import httpx
+from pydantic import BaseModel, Field
+
+from .models import AuthStorage
+from .service import AUTH_PLATFORM_URL
+
+
+class DeviceAuthorizationResponse(BaseModel):
+    """Response from device authorization endpoint."""
+
+    device_code: str = Field(..., description='Device verification code for polling')
+    user_code: str = Field(..., description='Code for user to enter in browser')
+    verification_uri: str = Field(..., description='URL where user enters the code')
+    expires_in: int = Field(..., description='Seconds until device code expires')
+    interval: int = Field(..., description='Minimum polling interval in seconds')
+
+
+class DeviceTokenResponse(BaseModel):
+    """Response from device token endpoint (success case)."""
+
+    access_token: str = Field(..., description='Access token for authenticated requests')
+    refresh_token: str = Field(..., description='Refresh token for renewing access')
+    user_id: str = Field(..., description='Authenticated user ID')
+    user_accounts: list[str] = Field(..., description='List of user accounts/wallets')
+    expires_in: int = Field(..., description='Seconds until token expires')
+
+
+class DeviceTokenPendingResponse(BaseModel):
+    """Response when authorization is still pending."""
+
+    error: str = Field('authorization_pending', description='Error code')
+
+
+class DeviceTokenExpiredResponse(BaseModel):
+    """Response when device code has expired."""
+
+    error: str = Field('expired_token', description='Error code')
+
+
+def generate_pkce_pair() -> Tuple[str, str]:
+    """Generate PKCE code_verifier and code_challenge.
+
+    Returns:
+        Tuple of (code_verifier, code_challenge)
+    """
+    # Generate cryptographically random code_verifier
+    # Must be 43-128 characters using unreserved chars [A-Za-z0-9-._~]
+    code_verifier_bytes = secrets.token_bytes(32)
+    code_verifier = base64.urlsafe_b64encode(code_verifier_bytes).decode('utf-8').rstrip('=')
+
+    # Generate code_challenge = BASE64URL(SHA256(code_verifier))
+    challenge_bytes = hashlib.sha256(code_verifier.encode('utf-8')).digest()
+    code_challenge = base64.urlsafe_b64encode(challenge_bytes).decode('utf-8').rstrip('=')
+
+    return code_verifier, code_challenge
+
+
+def request_device_authorization(http_client: httpx.Client) -> Tuple[DeviceAuthorizationResponse, str]:
+    """Request device authorization from auth platform.
+
+    Args:
+        http_client: HTTP client to use for request
+
+    Returns:
+        Tuple of (DeviceAuthorizationResponse, code_verifier)
+
+    Raises:
+        httpx.HTTPStatusError: If request fails
+        ValueError: If response is invalid
+    """
+    # Generate PKCE parameters
+    code_verifier, code_challenge = generate_pkce_pair()
+
+    # Request device authorization
+    url = f'{AUTH_PLATFORM_URL}api/v1/device/authorize'
+    response = http_client.post(
+        url, json={'code_challenge': code_challenge, 'code_challenge_method': 'S256'}, timeout=30.0
+    )
+
+    if response.status_code != 200:
+        raise ValueError(f'Device authorization failed: {response.status_code} - {response.text}')
+
+    device_auth = DeviceAuthorizationResponse.model_validate(response.json())
+    return device_auth, code_verifier
+
+
+def poll_for_token(
+    http_client: httpx.Client, device_code: str, code_verifier: str
+) -> Optional[DeviceTokenResponse]:
+    """Poll device token endpoint once.
+
+    Args:
+        http_client: HTTP client to use for request
+        device_code: Device code from authorization response
+        code_verifier: PKCE code verifier
+
+    Returns:
+        DeviceTokenResponse if auth complete, None if still pending
+
+    Raises:
+        ValueError: If device code expired or other error
+    """
+    url = f'{AUTH_PLATFORM_URL}api/v1/device/token'
+    response = http_client.get(
+        url, params={'device_code': device_code, 'code_verifier': code_verifier}, timeout=10.0
+    )
+
+    data = response.json()
+
+    # Check for error responses
+    if 'error' in data:
+        error = data['error']
+        if error == 'authorization_pending':
+            return None  # Still pending
+        elif error == 'expired_token':
+            raise ValueError('Device code expired. Please try again.')
+        else:
+            raise ValueError(f'Token polling error: {error}')
+
+    # Success - parse token response
+    return DeviceTokenResponse.model_validate(data)
+
+
+def poll_until_authenticated(
+    http_client: httpx.Client,
+    device_code: str,
+    code_verifier: str,
+    interval: int,
+    expires_in: int,
+    on_poll: Optional[callable] = None,
+    verbose: bool = False,
+) -> DeviceTokenResponse:
+    """Poll for token until authenticated or timeout.
+
+    Args:
+        http_client: HTTP client to use for requests
+        device_code: Device code from authorization
+        code_verifier: PKCE code verifier
+        interval: Minimum polling interval in seconds
+        expires_in: Seconds until device code expires
+        on_poll: Optional callback called on each poll attempt
+
+    Returns:
+        DeviceTokenResponse when authentication completes
+
+    Raises:
+        ValueError: If authentication times out or fails
+    """
+    start_time = time.time()
+    poll_count = 0
+    max_polls = int(expires_in / interval) + 5  # Add some buffer
+
+    while poll_count < max_polls:
+        elapsed = time.time() - start_time
+        if elapsed > expires_in:
+            raise ValueError('Authentication timed out. Please try again.')
+
+        if on_poll:
+            on_poll(poll_count, elapsed)
+
+        # Poll for token
+        try:
+            token_response = poll_for_token(http_client, device_code, code_verifier)
+            if token_response:
+                return token_response
+        except ValueError as e:
+            if 'expired' in str(e).lower():
+                raise
+            # Other errors, log and continue polling
+            if verbose:
+                print(f'\n⚠ Polling error (will retry): {e}')
+            pass
+        except Exception as e:
+            # Log unexpected errors
+            if verbose:
+                print(f'\n⚠ Unexpected error (will retry): {type(e).__name__}: {e}')
+            pass
+
+        # Wait before next poll
+        time.sleep(interval)
+        poll_count += 1
+
+    raise ValueError('Authentication timed out. Please try again.')
+
+
+def open_browser(url: str) -> bool:
+    """Open URL in browser.
+
+    Args:
+        url: URL to open
+
+    Returns:
+        True if browser opened successfully
+    """
+    try:
+        webbrowser.open(url)
+        return True
+    except Exception:
+        return False
+
+
+def interactive_device_login(
+    verbose: bool = True, auto_open_browser: bool = True
+) -> AuthStorage:
+    """Perform interactive device authorization flow.
+
+    Args:
+        verbose: Print progress messages
+        auto_open_browser: Automatically open browser for user
+
+    Returns:
+        AuthStorage with tokens
+
+    Raises:
+        ValueError: If authentication fails
+    """
+    http_client = httpx.Client()
+
+    try:
+        # Step 1: Request device authorization
+        if verbose:
+            print('🔐 Starting authentication...\n')
+
+        device_auth, code_verifier = request_device_authorization(http_client)
+
+        # Step 2: Display user code and open browser
+        if verbose:
+            print(f'📱 Verification Code: {device_auth.user_code}')
+            print(f'🌐 Verification URL: {device_auth.verification_uri}\n')
+
+        if auto_open_browser:
+            if verbose:
+                print('Opening browser...')
+            if open_browser(device_auth.verification_uri):
+                if verbose:
+                    print('✓ Browser opened')
+            else:
+                if verbose:
+                    print('✗ Could not open browser automatically')
+                    print(f'  Please open: {device_auth.verification_uri}')
+
+        if verbose:
+            print(f'\n⏳ Waiting for authentication (expires in {device_auth.expires_in}s)...')
+            print('   Complete the authentication in your browser.\n')
+
+        # Step 3: Poll for token
+        spinner_frames = ['⠋', '⠙', '⠹', '⠸', '⠼', '⠴', '⠦', '⠧', '⠇', '⠏']
+
+        def poll_callback(count: int, elapsed: float):
+            if verbose:
+                spinner = spinner_frames[count % len(spinner_frames)]
+                print(f'\r{spinner} Polling... ({int(elapsed)}s elapsed)', end='', flush=True)
+
+        token_response = poll_until_authenticated(
+            http_client, device_auth.device_code, code_verifier, device_auth.interval, device_auth.expires_in, poll_callback, verbose=verbose
+        )
+
+        if verbose:
+            print('\r✓ Authentication successful!     \n')
+
+        # Step 4: Create auth storage
+        now_ms = int(time.time() * 1000)
+        expiry_ms = now_ms + (token_response.expires_in * 1000)
+
+        auth_storage = AuthStorage(
+            accessToken=token_response.access_token,
+            refreshToken=token_response.refresh_token,
+            userId=token_response.user_id,
+            accounts=token_response.user_accounts,
+            expiry=expiry_ms,
+        )
+
+        return auth_storage
+
+    finally:
+        http_client.close()
diff --git a/src/amp/auth/service.py b/src/amp/auth/service.py
@@ -225,3 +225,32 @@ def __enter__(self):
     def __exit__(self, exc_type, exc_val, exc_tb):
         """Context manager exit."""
         self._http.close()
+
+    def login(self, verbose: bool = True, auto_open_browser: bool = True) -> None:
+        """Perform interactive browser-based login.
+
+        Opens browser for OAuth2 device authorization flow with PKCE.
+        Saves authentication tokens to ~/.amp-cli-config/amp_cli_auth.
+
+        Args:
+            verbose: Print progress messages
+            auto_open_browser: Automatically open browser
+
+        Raises:
+            ValueError: If authentication fails
+
+        Example:
+            >>> auth = AuthService()
+            >>> auth.login()  # Opens browser for authentication
+            >>> # Auth tokens saved to ~/.amp-cli-config/amp_cli_auth
+        """
+        from .device_flow import interactive_device_login
+
+        # Perform device authorization flow
+        auth_storage = interactive_device_login(verbose=verbose, auto_open_browser=auto_open_browser)
+
+        # Save to config file
+        self.save_auth(auth_storage)
+
+        if verbose:
+            print(f'✓ Authentication saved to {self.config_path}')
