feat(security): add oauth helpers

src/fastapi_toolsets/security/__init__.py

@@ -1,13 +1,24 @@
 """Authentication helpers for FastAPI using Security()."""
 
 from .abc import AuthSource
-from .sources import BearerTokenAuth, CookieAuth, MultiAuth, OAuth2Auth, OpenIDAuth
+from .oauth import (
+    build_authorization_redirect,
+    decode_oauth_state,
+    encode_oauth_state,
+    fetch_userinfo,
+    resolve_provider_urls,
+)
+from .sources import APIKeyHeaderAuth, BearerTokenAuth, CookieAuth, MultiAuth
 
 __all__ = [
+    "APIKeyHeaderAuth",
     "AuthSource",
     "BearerTokenAuth",
     "CookieAuth",
     "MultiAuth",
-    "OAuth2Auth",
-    "OpenIDAuth",
+    "build_authorization_redirect",
+    "decode_oauth_state",
+    "fetch_userinfo",
+    "encode_oauth_state",
+    "resolve_provider_urls",
 ]

src/fastapi_toolsets/security/oauth.py

@@ -0,0 +1,138 @@
+"""OAuth 2.0 / OIDC helper utilities."""
+
+import base64
+from typing import Any
+from urllib.parse import urlencode
+
+import httpx
+from fastapi.responses import RedirectResponse
+
+_discovery_cache: dict[str, dict] = {}
+
+
+async def resolve_provider_urls(discovery_url: str) -> tuple[str, str, str | None]:
+    """Fetch the OIDC discovery document and return endpoint URLs.
+
+    Args:
+        discovery_url: URL of the provider's ``/.well-known/openid-configuration``.
+
+    Returns:
+        A ``(authorization_url, token_url, userinfo_url)`` tuple.
+        *userinfo_url* is ``None`` when the provider does not advertise one.
+    """
+    if discovery_url not in _discovery_cache:
+        async with httpx.AsyncClient() as client:
+            resp = await client.get(discovery_url)
+            resp.raise_for_status()
+            _discovery_cache[discovery_url] = resp.json()
+    cfg = _discovery_cache[discovery_url]
+    return (
+        cfg["authorization_endpoint"],
+        cfg["token_endpoint"],
+        cfg.get("userinfo_endpoint"),
+    )
+
+
+async def fetch_userinfo(
+    *,
+    token_url: str,
+    userinfo_url: str,
+    code: str,
+    client_id: str,
+    client_secret: str,
+    redirect_uri: str,
+) -> dict[str, Any]:
+    """Exchange an authorization code for tokens and return the userinfo payload.
+
+    Performs the two-step OAuth 2.0 / OIDC token exchange:
+
+    1. POSTs the authorization *code* to *token_url* to obtain an access token.
+    2. GETs *userinfo_url* using that access token as a Bearer credential.
+
+    Args:
+        token_url: Provider's token endpoint.
+        userinfo_url: Provider's userinfo endpoint.
+        code: Authorization code received from the provider's callback.
+        client_id: OAuth application client ID.
+        client_secret: OAuth application client secret.
+        redirect_uri: Redirect URI that was used in the authorization request.
+
+    Returns:
+        The JSON payload returned by the userinfo endpoint as a plain ``dict``.
+    """
+    async with httpx.AsyncClient() as client:
+        token_resp = await client.post(
+            token_url,
+            data={
+                "grant_type": "authorization_code",
+                "code": code,
+                "client_id": client_id,
+                "client_secret": client_secret,
+                "redirect_uri": redirect_uri,
+            },
+            headers={"Accept": "application/json"},
+        )
+        token_resp.raise_for_status()
+        access_token = token_resp.json()["access_token"]
+
+        userinfo_resp = await client.get(
+            userinfo_url,
+            headers={"Authorization": f"Bearer {access_token}"},
+        )
+        userinfo_resp.raise_for_status()
+        return userinfo_resp.json()
+
+
+def build_authorization_redirect(
+    authorization_url: str,
+    *,
+    client_id: str,
+    scopes: str,
+    redirect_uri: str,
+    destination: str,
+) -> RedirectResponse:
+    """Return an OAuth 2.0 authorization ``RedirectResponse``.
+
+    Args:
+        authorization_url: Provider's authorization endpoint.
+        client_id: OAuth application client ID.
+        scopes: Space-separated list of requested scopes.
+        redirect_uri: URI the provider should redirect back to after authorization.
+        destination: URL the user should be sent to after the full OAuth flow
+            completes (encoded as ``state``).
+
+    Returns:
+        A :class:`~fastapi.responses.RedirectResponse` to the provider's
+        authorization page.
+    """
+    params = urlencode(
+        {
+            "client_id": client_id,
+            "response_type": "code",
+            "scope": scopes,
+            "redirect_uri": redirect_uri,
+            "state": encode_oauth_state(destination),
+        }
+    )
+    return RedirectResponse(f"{authorization_url}?{params}")
+
+
+def encode_oauth_state(url: str) -> str:
+    """Base64url-encode a URL to embed as an OAuth ``state`` parameter."""
+    return base64.urlsafe_b64encode(url.encode()).decode()
+
+
+def decode_oauth_state(state: str | None, *, fallback: str) -> str:
+    """Decode a base64url OAuth ``state`` parameter.
+
+    Handles missing padding (some providers strip ``=``).
+    Returns *fallback* if *state* is absent, the literal string ``"null"``,
+    or cannot be decoded.
+    """
+    if not state or state == "null":
+        return fallback
+    try:
+        padded = state + "=" * (4 - len(state) % 4)
+        return base64.urlsafe_b64decode(padded).decode()
+    except Exception:
+        return fallback

src/fastapi_toolsets/security/sources/__init__.py

@@ -1,9 +1,8 @@
 """Built-in authentication source implementations."""
 
+from .header import APIKeyHeaderAuth
 from .bearer import BearerTokenAuth
 from .cookie import CookieAuth
 from .multi import MultiAuth
-from .oauth2 import OAuth2Auth
-from .openid import OpenIDAuth
 
-__all__ = ["BearerTokenAuth", "CookieAuth", "MultiAuth", "OAuth2Auth", "OpenIDAuth"]
+__all__ = ["APIKeyHeaderAuth", "BearerTokenAuth", "CookieAuth", "MultiAuth"]

src/fastapi_toolsets/security/sources/header.py

@@ -0,0 +1,71 @@
+"""API key header authentication source."""
+
+import inspect
+from typing import Annotated, Any, Callable
+
+from fastapi import Depends, Request
+from fastapi.security import APIKeyHeader, SecurityScopes
+
+from fastapi_toolsets.exceptions import UnauthorizedError
+
+from ..abc import AuthSource, _call_validator
+
+
+class APIKeyHeaderAuth(AuthSource):
+    """API key header authentication source.
+
+    Wraps :class:`fastapi.security.APIKeyHeader` for OpenAPI documentation.
+    The validator is called as ``await validator(api_key, **kwargs)``
+    where ``kwargs`` are the extra keyword arguments provided at instantiation.
+
+    Args:
+        name: HTTP header name that carries the API key (e.g. ``"X-API-Key"``).
+        validator: Sync or async callable that receives the API key and any
+            extra keyword arguments, and returns the authenticated identity.
+            Should raise :class:`~fastapi_toolsets.exceptions.UnauthorizedError`
+            on failure.
+        **kwargs: Extra keyword arguments forwarded to the validator on every
+            call (e.g. ``role=Role.ADMIN``).
+    """
+
+    def __init__(
+        self,
+        name: str,
+        validator: Callable[..., Any],
+        **kwargs: Any,
+    ) -> None:
+        self._name = name
+        self._validator = validator
+        self._kwargs = kwargs
+        self._scheme = APIKeyHeader(name=name, auto_error=False)
+
+        _scheme = self._scheme
+        _validator = validator
+        _kwargs = kwargs
+
+        async def _call(
+            security_scopes: SecurityScopes,  # noqa: ARG001
+            api_key: Annotated[str | None, Depends(_scheme)] = None,
+        ) -> Any:
+            if api_key is None:
+                raise UnauthorizedError()
+            return await _call_validator(_validator, api_key, **_kwargs)
+
+        self._call_fn = _call
+        self.__signature__ = inspect.signature(_call)
+
+    async def extract(self, request: Request) -> str | None:
+        """Extract the API key from the configured header."""
+        return request.headers.get(self._name) or None
+
+    async def authenticate(self, credential: str) -> Any:
+        """Validate a credential and return the identity."""
+        return await _call_validator(self._validator, credential, **self._kwargs)
+
+    def require(self, **kwargs: Any) -> "APIKeyHeaderAuth":
+        """Return a new instance with additional (or overriding) validator kwargs."""
+        return APIKeyHeaderAuth(
+            self._name,
+            self._validator,
+            **{**self._kwargs, **kwargs},
+        )

src/fastapi_toolsets/security/sources/multi.py

@@ -60,6 +60,7 @@ class MultiAuth:
         async def _call(
             request: Request,
             security_scopes: SecurityScopes,  # noqa: ARG001
+            **kwargs: Any,  # noqa: ARG001  — absorbs scheme values injected by FastAPI
         ) -> Any:
             for source in _sources:
                 credential = await source.extract(request)
@@ -68,7 +69,29 @@ class MultiAuth:
             raise UnauthorizedError()
 
         self._call_fn = _call
-        self.__signature__ = inspect.signature(_call)
+
+        # Build a merged signature that includes the security-scheme Depends()
+        # parameters from every source so FastAPI registers them in OpenAPI docs.
+        seen: set[str] = {"request", "security_scopes"}
+        merged: list[inspect.Parameter] = [
+            inspect.Parameter(
+                "request",
+                inspect.Parameter.POSITIONAL_OR_KEYWORD,
+                annotation=Request,
+            ),
+            inspect.Parameter(
+                "security_scopes",
+                inspect.Parameter.POSITIONAL_OR_KEYWORD,
+                annotation=SecurityScopes,
+            ),
+        ]
+        for i, source in enumerate(sources):
+            for name, param in inspect.signature(source).parameters.items():
+                if name in seen:
+                    continue
+                merged.append(param.replace(name=f"_s{i}_{name}"))
+                seen.add(name)
+        self.__signature__ = inspect.Signature(merged, return_annotation=Any)
 
     async def __call__(self, **kwargs: Any) -> Any:
         return await self._call_fn(**kwargs)

src/fastapi_toolsets/security/sources/oauth2.py

@@ -1,72 +0,0 @@
-"""OAuth2 password-bearer authentication source."""
-
-import inspect
-from typing import Annotated, Any, Callable
-
-from fastapi import Depends, Request
-from fastapi.security import OAuth2PasswordBearer, SecurityScopes
-
-from fastapi_toolsets.exceptions import UnauthorizedError
-
-from ..abc import AuthSource, _call_validator
-
-
-class OAuth2Auth(AuthSource):
-    """OAuth2 password-bearer authentication source.
-
-    Wraps :class:`fastapi.security.OAuth2PasswordBearer` for OpenAPI
-    documentation.
-
-    Args:
-        token_url: URL of the token endpoint (used in OpenAPI docs).
-        validator: Sync or async callable that receives the token and any extra
-            keyword arguments, and returns the authenticated identity.
-        **kwargs: Extra keyword arguments forwarded to the validator on every
-            call.
-    """
-
-    def __init__(
-        self,
-        token_url: str,
-        validator: Callable[..., Any],
-        **kwargs: Any,
-    ) -> None:
-        self._token_url = token_url
-        self._validator = validator
-        self._kwargs = kwargs
-        self._scheme = OAuth2PasswordBearer(tokenUrl=token_url, auto_error=False)
-
-        _scheme = self._scheme
-        _validator = validator
-        _kwargs = kwargs
-
-        async def _call(
-            security_scopes: SecurityScopes,  # noqa: ARG001
-            token: Annotated[str | None, Depends(_scheme)] = None,
-        ) -> Any:
-            if token is None:
-                raise UnauthorizedError()
-            return await _call_validator(_validator, token, **_kwargs)
-
-        self._call_fn = _call
-        self.__signature__ = inspect.signature(_call)
-
-    async def extract(self, request: Request) -> str | None:
-        """Extract the bearer token from the Authorization header."""
-        auth = request.headers.get("Authorization", "")
-        if not auth.startswith("Bearer "):
-            return None
-        token = auth[7:]
-        return token or None
-
-    async def authenticate(self, credential: str) -> Any:
-        """Validate a credential and return the identity."""
-        return await _call_validator(self._validator, credential, **self._kwargs)
-
-    def require(self, **kwargs: Any) -> "OAuth2Auth":
-        """Return a new instance with additional (or overriding) validator kwargs."""
-        return OAuth2Auth(
-            self._token_url,
-            self._validator,
-            **{**self._kwargs, **kwargs},
-        )

src/fastapi_toolsets/security/sources/openid.py

@@ -1,84 +0,0 @@
-"""OpenID Connect authentication source."""
-
-import inspect
-from typing import Annotated, Any, Callable
-
-from fastapi import Depends, Request
-from fastapi.security import OpenIdConnect, SecurityScopes
-
-from fastapi_toolsets.exceptions import UnauthorizedError
-
-from ..abc import AuthSource, _call_validator
-
-
-class OpenIDAuth(AuthSource):
-    """OpenID Connect authentication source.
-
-    Wraps :class:`fastapi.security.OpenIdConnect` for OpenAPI documentation.
-    Token extraction reads the ``Authorization: Bearer <token>`` header;
-    validation is fully delegated to the user-supplied validator (use any
-    OIDC / JWT library such as ``authlib``, ``python-jose``, or ``PyJWT``).
-
-    Args:
-        openid_connect_url: URL of the OIDC discovery document
-            (``/.well-known/openid-configuration``). Used only for OpenAPI
-            documentation — no requests are made to this URL by this class.
-        validator: Sync or async callable that receives the raw bearer token
-            and any extra keyword arguments, and returns the authenticated
-            identity. Should raise
-            :class:`~fastapi_toolsets.exceptions.UnauthorizedError` on failure.
-        **kwargs: Extra keyword arguments forwarded to the validator on every
-            call (e.g. ``audience="my-app"``).
-    """
-
-    def __init__(
-        self,
-        openid_connect_url: str,
-        validator: Callable[..., Any],
-        **kwargs: Any,
-    ) -> None:
-        self._openid_connect_url = openid_connect_url
-        self._validator = validator
-        self._kwargs = kwargs
-        self._scheme = OpenIdConnect(
-            openIdConnectUrl=openid_connect_url, auto_error=False
-        )
-
-        _scheme = self._scheme
-        _validator = validator
-        _kwargs = kwargs
-
-        async def _call(
-            security_scopes: SecurityScopes,  # noqa: ARG001
-            authorization: Annotated[str | None, Depends(_scheme)] = None,
-        ) -> Any:
-            if authorization is None:
-                raise UnauthorizedError()
-            if not authorization.startswith("Bearer "):
-                raise UnauthorizedError()
-            token = authorization[7:]
-            if not token:
-                raise UnauthorizedError()
-            return await _call_validator(_validator, token, **_kwargs)
-
-        self._call_fn = _call
-        self.__signature__ = inspect.signature(_call)
-
-    async def extract(self, request: Request) -> str | None:
-        """Extract the bearer token from the Authorization header."""
-        auth = request.headers.get("Authorization", "")
-        if not auth.startswith("Bearer "):
-            return None
-        return auth[7:] or None
-
-    async def authenticate(self, credential: str) -> Any:
-        """Validate a credential and return the identity."""
-        return await _call_validator(self._validator, credential, **self._kwargs)
-
-    def require(self, **kwargs: Any) -> "OpenIDAuth":
-        """Return a new instance with additional (or overriding) validator kwargs."""
-        return OpenIDAuth(
-            self._openid_connect_url,
-            self._validator,
-            **{**self._kwargs, **kwargs},
-        )

tests/test_security.py

@@ -1,17 +1,24 @@
 """Tests for fastapi_toolsets.security."""
 
+from unittest.mock import AsyncMock, MagicMock, patch
+from urllib.parse import parse_qs, urlparse
+
 import pytest
 from fastapi import FastAPI, Security
 from fastapi.testclient import TestClient
 
 from fastapi_toolsets.exceptions import UnauthorizedError, init_exceptions_handlers
 from fastapi_toolsets.security import (
+    APIKeyHeaderAuth,
     AuthSource,
     BearerTokenAuth,
     CookieAuth,
     MultiAuth,
-    OAuth2Auth,
-    OpenIDAuth,
+    build_authorization_redirect,
+    decode_oauth_state,
+    encode_oauth_state,
+    fetch_userinfo,
+    resolve_provider_urls,
 )
 
 
@@ -316,73 +323,85 @@ class TestCookieAuth:
         assert await auth.extract(request) == "abc"
 
 
-class TestOAuth2Auth:
-    def test_valid_token_returns_identity(self):
-        oauth = OAuth2Auth(token_url="/token", validator=simple_validator)
+class TestAPIKeyHeaderAuth:
+    def test_valid_key_returns_identity(self):
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
 
         def setup(app: FastAPI):
             @app.get("/me")
-            async def me(user=Security(oauth)):
+            async def me(user=Security(auth)):
                 return user
 
         client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": f"Bearer {VALID_TOKEN}"})
+        response = client.get("/me", headers={"X-API-Key": VALID_TOKEN})
         assert response.status_code == 200
         assert response.json() == {"user": "alice"}
 
-    def test_missing_token_returns_401(self):
-        oauth = OAuth2Auth(token_url="/token", validator=simple_validator)
+    def test_missing_header_returns_401(self):
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
 
         def setup(app: FastAPI):
             @app.get("/me")
-            async def me(user=Security(oauth)):
+            async def me(user=Security(auth)):
                 return user
 
         client = TestClient(_app(setup))
         response = client.get("/me")
         assert response.status_code == 401
 
-    @pytest.mark.anyio
-    async def test_extract_no_header(self):
-        from starlette.requests import Request
+    def test_invalid_key_returns_401(self):
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
 
-        auth = OAuth2Auth("/token", simple_validator)
-        scope = {"type": "http", "method": "GET", "path": "/", "headers": []}
-        request = Request(scope)
-        assert await auth.extract(request) is None
+        def setup(app: FastAPI):
+            @app.get("/me")
+            async def me(user=Security(auth)):
+                return user
 
-    @pytest.mark.anyio
-    async def test_extract_empty_token(self):
-        from starlette.requests import Request
+        client = TestClient(_app(setup))
+        response = client.get("/me", headers={"X-API-Key": "wrong"})
+        assert response.status_code == 401
 
-        auth = OAuth2Auth("/token", simple_validator)
-        scope = {
-            "type": "http",
-            "method": "GET",
-            "path": "/",
-            "headers": [(b"authorization", b"Bearer ")],
-        }
-        request = Request(scope)
-        assert await auth.extract(request) is None
+    def test_kwargs_forwarded_to_validator(self):
+        auth = APIKeyHeaderAuth("X-API-Key", role_validator, role="admin")
 
-    @pytest.mark.anyio
-    async def test_extract_token(self):
-        from starlette.requests import Request
+        def setup(app: FastAPI):
+            @app.get("/me")
+            async def me(user=Security(auth)):
+                return user
 
-        auth = OAuth2Auth("/token", simple_validator)
-        scope = {
-            "type": "http",
-            "method": "GET",
-            "path": "/",
-            "headers": [(b"authorization", b"Bearer mytoken")],
-        }
-        request = Request(scope)
-        assert await auth.extract(request) == "mytoken"
+        client = TestClient(_app(setup))
+        response = client.get("/me", headers={"X-API-Key": VALID_TOKEN})
+        assert response.status_code == 200
+        assert response.json() == {"user": "alice", "role": "admin"}
+
+    def test_require_forwards_kwargs(self):
+        auth = APIKeyHeaderAuth("X-API-Key", role_validator)
+
+        def setup(app: FastAPI):
+            @app.get("/admin")
+            async def admin(user=Security(auth.require(role="admin"))):
+                return user
+
+        client = TestClient(_app(setup))
+        response = client.get("/admin", headers={"X-API-Key": VALID_TOKEN})
+        assert response.status_code == 200
+        assert response.json() == {"user": "alice", "role": "admin"}
+
+    def test_require_preserves_name(self):
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
+        derived = auth.require(role="admin")
+        assert derived._name == "X-API-Key"
+
+    def test_require_does_not_mutate_original(self):
+        auth = APIKeyHeaderAuth("X-API-Key", role_validator, role="user")
+        auth.require(role="admin")
+        assert auth._kwargs == {"role": "user"}
 
     def test_in_multi_auth(self):
-        """OAuth2Auth.authenticate() is exercised when used inside MultiAuth."""
-        oauth = OAuth2Auth(token_url="/token", validator=simple_validator)
-        multi = MultiAuth(oauth)
+        """APIKeyHeaderAuth.authenticate() is exercised inside MultiAuth."""
+        bearer = BearerTokenAuth(simple_validator)
+        api_key = APIKeyHeaderAuth("X-API-Key", simple_validator)
+        multi = MultiAuth(bearer, api_key)
 
         def setup(app: FastAPI):
             @app.get("/me")
@@ -390,10 +409,52 @@ class TestOAuth2Auth:
                 return user
 
         client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": f"Bearer {VALID_TOKEN}"})
+        # No bearer → falls through to API key header
+        response = client.get("/me", headers={"X-API-Key": VALID_TOKEN})
         assert response.status_code == 200
         assert response.json() == {"user": "alice"}
 
+    def test_is_auth_source(self):
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
+        assert isinstance(auth, AuthSource)
+
+    @pytest.mark.anyio
+    async def test_extract_no_header(self):
+        from starlette.requests import Request
+
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
+        scope = {"type": "http", "method": "GET", "path": "/", "headers": []}
+        request = Request(scope)
+        assert await auth.extract(request) is None
+
+    @pytest.mark.anyio
+    async def test_extract_empty_header(self):
+        from starlette.requests import Request
+
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
+        scope = {
+            "type": "http",
+            "method": "GET",
+            "path": "/",
+            "headers": [(b"x-api-key", b"")],
+        }
+        request = Request(scope)
+        assert await auth.extract(request) is None
+
+    @pytest.mark.anyio
+    async def test_extract_key_present(self):
+        from starlette.requests import Request
+
+        auth = APIKeyHeaderAuth("X-API-Key", simple_validator)
+        scope = {
+            "type": "http",
+            "method": "GET",
+            "path": "/",
+            "headers": [(b"x-api-key", b"mykey")],
+        }
+        request = Request(scope)
+        assert await auth.extract(request) == "mykey"
+
 
 class TestMultiAuth:
     def test_first_source_matches(self):
@@ -626,26 +687,6 @@ class TestRequire:
         derived = cookie.require(scope="admin")
         assert derived._name == "session"
 
-    def test_oauth2_require_forwards_kwargs(self):
-        oauth = OAuth2Auth("/token", role_validator)
-
-        def setup(app: FastAPI):
-            @app.get("/admin")
-            async def admin(user=Security(oauth.require(role="admin"))):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get(
-            "/admin", headers={"Authorization": f"Bearer {VALID_TOKEN}"}
-        )
-        assert response.status_code == 200
-        assert response.json() == {"user": "alice", "role": "admin"}
-
-    def test_oauth2_require_preserves_token_url(self):
-        oauth = OAuth2Auth("/token", simple_validator)
-        derived = oauth.require(role="admin")
-        assert derived._token_url == "/token"
-
     def test_bearer_require_in_multi_auth(self):
         """require() instances work seamlessly inside MultiAuth."""
         PREFIXED_TOKEN = f"user_{VALID_TOKEN}"
@@ -671,141 +712,6 @@ class TestRequire:
         assert response.json() == {"user": "alice", "role": "admin"}
 
 
-class TestOpenIDAuth:
-    DISCOVERY_URL = "https://accounts.example.com/.well-known/openid-configuration"
-
-    def test_valid_token_returns_identity(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-
-        def setup(app: FastAPI):
-            @app.get("/me")
-            async def me(user=Security(oidc)):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": f"Bearer {VALID_TOKEN}"})
-        assert response.status_code == 200
-        assert response.json() == {"user": "alice"}
-
-    def test_missing_token_returns_401(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-
-        def setup(app: FastAPI):
-            @app.get("/me")
-            async def me(user=Security(oidc)):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get("/me")
-        assert response.status_code == 401
-
-    def test_invalid_token_returns_401(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-
-        def setup(app: FastAPI):
-            @app.get("/me")
-            async def me(user=Security(oidc)):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": "Bearer wrong"})
-        assert response.status_code == 401
-
-    def test_kwargs_forwarded_to_validator(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, role_validator, role="admin")
-
-        def setup(app: FastAPI):
-            @app.get("/me")
-            async def me(user=Security(oidc)):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": f"Bearer {VALID_TOKEN}"})
-        assert response.status_code == 200
-        assert response.json() == {"user": "alice", "role": "admin"}
-
-    def test_require_forwards_kwargs(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, role_validator)
-
-        def setup(app: FastAPI):
-            @app.get("/admin")
-            async def admin(user=Security(oidc.require(role="admin"))):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get(
-            "/admin", headers={"Authorization": f"Bearer {VALID_TOKEN}"}
-        )
-        assert response.status_code == 200
-        assert response.json() == {"user": "alice", "role": "admin"}
-
-    def test_require_preserves_discovery_url(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-        derived = oidc.require(role="admin")
-        assert derived._openid_connect_url == self.DISCOVERY_URL
-
-    def test_require_does_not_mutate_original(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, role_validator, role="user")
-        oidc.require(role="admin")
-        assert oidc._kwargs == {"role": "user"}
-
-    def test_is_auth_source(self):
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-        assert isinstance(oidc, AuthSource)
-
-    def test_in_multi_auth(self):
-        """OpenIDAuth works seamlessly inside MultiAuth."""
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-        multi = MultiAuth(oidc)
-
-        def setup(app: FastAPI):
-            @app.get("/me")
-            async def me(user=Security(multi)):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": f"Bearer {VALID_TOKEN}"})
-        assert response.status_code == 200
-        assert response.json() == {"user": "alice"}
-
-    @pytest.mark.anyio
-    async def test_extract_no_header(self):
-        from starlette.requests import Request
-
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-        scope = {"type": "http", "method": "GET", "path": "/", "headers": []}
-        request = Request(scope)
-        assert await oidc.extract(request) is None
-
-    @pytest.mark.anyio
-    async def test_extract_empty_token(self):
-        from starlette.requests import Request
-
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-        scope = {
-            "type": "http",
-            "method": "GET",
-            "path": "/",
-            "headers": [(b"authorization", b"Bearer ")],
-        }
-        request = Request(scope)
-        assert await oidc.extract(request) is None
-
-    @pytest.mark.anyio
-    async def test_extract_token(self):
-        from starlette.requests import Request
-
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-        scope = {
-            "type": "http",
-            "method": "GET",
-            "path": "/",
-            "headers": [(b"authorization", b"Bearer mytoken")],
-        }
-        request = Request(scope)
-        assert await oidc.extract(request) == "mytoken"
-
-
 class TestSyncValidators:
     """Sync (non-async) validators — covers the sync path in _call_validator."""
 
@@ -849,36 +755,6 @@ class TestSyncValidators:
         assert response.json() == {"user": "alice"}
 
 
-class TestOpenIDAuthEdgeCases:
-    DISCOVERY_URL = "https://accounts.example.com/.well-known/openid-configuration"
-
-    def test_non_bearer_authorization_returns_401(self):
-        """Authorization header present but not Bearer scheme."""
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-
-        def setup(app: FastAPI):
-            @app.get("/me")
-            async def me(user=Security(oidc)):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": "Basic dXNlcjpwYXNz"})
-        assert response.status_code == 401
-
-    def test_empty_bearer_token_returns_401(self):
-        """Authorization: Bearer with no token after the scheme prefix."""
-        oidc = OpenIDAuth(self.DISCOVERY_URL, simple_validator)
-
-        def setup(app: FastAPI):
-            @app.get("/me")
-            async def me(user=Security(oidc)):
-                return user
-
-        client = TestClient(_app(setup))
-        response = client.get("/me", headers={"Authorization": "Bearer "})
-        assert response.status_code == 401
-
-
 class TestCookieAuthSigned:
     """CookieAuth with HMAC-SHA256 signed cookies (secret_key path)."""
 
@@ -1029,14 +905,10 @@ class TestAuthSource:
     def test_builtin_classes_are_auth_sources(self):
         bearer = BearerTokenAuth(simple_validator)
         cookie = CookieAuth("session", cookie_validator)
-        oauth = OAuth2Auth("/token", simple_validator)
-        oidc = OpenIDAuth(
-            "https://example.com/.well-known/openid-configuration", simple_validator
-        )
+        api_key = APIKeyHeaderAuth("X-API-Key", simple_validator)
         assert isinstance(bearer, AuthSource)
         assert isinstance(cookie, AuthSource)
-        assert isinstance(oauth, AuthSource)
-        assert isinstance(oidc, AuthSource)
+        assert isinstance(api_key, AuthSource)
 
     def test_custom_source_standalone_valid(self):
         """Default __call__ wires extract + authenticate via Request injection."""
@@ -1098,3 +970,214 @@ class TestAuthSource:
         response = client.get("/me", headers={"X-Token": "s3cr3t"})
         assert response.status_code == 200
         assert response.json() == {"token": "s3cr3t"}
+
+
+# ---------------------------------------------------------------------------
+# OAuth helpers
+# ---------------------------------------------------------------------------
+
+
+def _make_async_client_mock(get_return=None, post_return=None):
+    """Return a patched httpx.AsyncClient context-manager mock."""
+    mock_client = AsyncMock()
+    if get_return is not None:
+        mock_client.get.return_value = get_return
+    if post_return is not None:
+        mock_client.post.return_value = post_return
+    cm = MagicMock()
+    cm.__aenter__ = AsyncMock(return_value=mock_client)
+    cm.__aexit__ = AsyncMock(return_value=None)
+    return cm, mock_client
+
+
+class TestEncodeDecodeOAuthState:
+    def test_encode_returns_base64url_string(self):
+        result = encode_oauth_state("https://example.com/dashboard")
+        assert isinstance(result, str)
+        assert "+" not in result
+        assert "/" not in result
+
+    def test_round_trip(self):
+        url = "https://example.com/after-login?next=/home"
+        assert decode_oauth_state(encode_oauth_state(url), fallback="/") == url
+
+    def test_decode_none_returns_fallback(self):
+        assert decode_oauth_state(None, fallback="/home") == "/home"
+
+    def test_decode_null_string_returns_fallback(self):
+        assert decode_oauth_state("null", fallback="/home") == "/home"
+
+    def test_decode_invalid_base64_returns_fallback(self):
+        assert decode_oauth_state("!!!notbase64!!!", fallback="/home") == "/home"
+
+    def test_decode_handles_missing_padding(self):
+        url = "https://example.com/x"
+        encoded = encode_oauth_state(url).rstrip("=")
+        assert decode_oauth_state(encoded, fallback="/") == url
+
+
+class TestBuildAuthorizationRedirect:
+    def test_returns_redirect_response(self):
+        from fastapi.responses import RedirectResponse
+
+        response = build_authorization_redirect(
+            "https://auth.example.com/authorize",
+            client_id="my-client",
+            scopes="openid email",
+            redirect_uri="https://app.example.com/callback",
+            destination="https://app.example.com/dashboard",
+        )
+        assert isinstance(response, RedirectResponse)
+
+    def test_redirect_location_contains_all_params(self):
+        response = build_authorization_redirect(
+            "https://auth.example.com/authorize",
+            client_id="my-client",
+            scopes="openid email",
+            redirect_uri="https://app.example.com/callback",
+            destination="https://app.example.com/dashboard",
+        )
+        location = response.headers["location"]
+        parsed = urlparse(location)
+        assert (
+            parsed.scheme + "://" + parsed.netloc + parsed.path
+            == "https://auth.example.com/authorize"
+        )
+        params = parse_qs(parsed.query)
+        assert params["client_id"] == ["my-client"]
+        assert params["response_type"] == ["code"]
+        assert params["scope"] == ["openid email"]
+        assert params["redirect_uri"] == ["https://app.example.com/callback"]
+        assert (
+            decode_oauth_state(params["state"][0], fallback="")
+            == "https://app.example.com/dashboard"
+        )
+
+
+class TestResolveProviderUrls:
+    def _discovery(self, *, userinfo=True):
+        doc = {
+            "authorization_endpoint": "https://auth.example.com/authorize",
+            "token_endpoint": "https://auth.example.com/token",
+        }
+        if userinfo:
+            doc["userinfo_endpoint"] = "https://auth.example.com/userinfo"
+        return doc
+
+    @pytest.mark.anyio
+    async def test_returns_all_endpoints(self):
+        mock_resp = MagicMock()
+        mock_resp.raise_for_status = MagicMock()
+        mock_resp.json.return_value = self._discovery()
+        cm, mock_client = _make_async_client_mock(get_return=mock_resp)
+
+        with patch("fastapi_toolsets.security.oauth._discovery_cache", {}):
+            with patch("httpx.AsyncClient", return_value=cm):
+                auth_url, token_url, userinfo_url = await resolve_provider_urls(
+                    "https://auth.example.com/.well-known/openid-configuration"
+                )
+
+        assert auth_url == "https://auth.example.com/authorize"
+        assert token_url == "https://auth.example.com/token"
+        assert userinfo_url == "https://auth.example.com/userinfo"
+
+    @pytest.mark.anyio
+    async def test_userinfo_url_none_when_absent(self):
+        mock_resp = MagicMock()
+        mock_resp.raise_for_status = MagicMock()
+        mock_resp.json.return_value = self._discovery(userinfo=False)
+        cm, mock_client = _make_async_client_mock(get_return=mock_resp)
+
+        with patch("fastapi_toolsets.security.oauth._discovery_cache", {}):
+            with patch("httpx.AsyncClient", return_value=cm):
+                _, _, userinfo_url = await resolve_provider_urls(
+                    "https://auth.example.com/.well-known/openid-configuration"
+                )
+
+        assert userinfo_url is None
+
+    @pytest.mark.anyio
+    async def test_caches_discovery_document(self):
+        mock_resp = MagicMock()
+        mock_resp.raise_for_status = MagicMock()
+        mock_resp.json.return_value = self._discovery()
+        cm, mock_client = _make_async_client_mock(get_return=mock_resp)
+
+        url = "https://auth.example.com/.well-known/openid-configuration"
+        with patch("fastapi_toolsets.security.oauth._discovery_cache", {}):
+            with patch("httpx.AsyncClient", return_value=cm):
+                await resolve_provider_urls(url)
+                await resolve_provider_urls(url)
+
+        assert mock_client.get.call_count == 1
+
+
+class TestFetchUserinfo:
+    @pytest.mark.anyio
+    async def test_returns_userinfo_payload(self):
+        token_resp = MagicMock()
+        token_resp.raise_for_status = MagicMock()
+        token_resp.json.return_value = {"access_token": "tok123"}
+
+        userinfo_resp = MagicMock()
+        userinfo_resp.raise_for_status = MagicMock()
+        userinfo_resp.json.return_value = {
+            "sub": "user-1",
+            "email": "alice@example.com",
+        }
+
+        cm, mock_client = _make_async_client_mock(
+            post_return=token_resp, get_return=userinfo_resp
+        )
+
+        with patch("httpx.AsyncClient", return_value=cm):
+            result = await fetch_userinfo(
+                token_url="https://auth.example.com/token",
+                userinfo_url="https://auth.example.com/userinfo",
+                code="authcode123",
+                client_id="client-id",
+                client_secret="client-secret",
+                redirect_uri="https://app.example.com/callback",
+            )
+
+        assert result == {"sub": "user-1", "email": "alice@example.com"}
+
+    @pytest.mark.anyio
+    async def test_posts_correct_token_request_and_uses_bearer(self):
+        token_resp = MagicMock()
+        token_resp.raise_for_status = MagicMock()
+        token_resp.json.return_value = {"access_token": "tok123"}
+
+        userinfo_resp = MagicMock()
+        userinfo_resp.raise_for_status = MagicMock()
+        userinfo_resp.json.return_value = {}
+
+        cm, mock_client = _make_async_client_mock(
+            post_return=token_resp, get_return=userinfo_resp
+        )
+
+        with patch("httpx.AsyncClient", return_value=cm):
+            await fetch_userinfo(
+                token_url="https://auth.example.com/token",
+                userinfo_url="https://auth.example.com/userinfo",
+                code="authcode123",
+                client_id="my-client",
+                client_secret="my-secret",
+                redirect_uri="https://app.example.com/callback",
+            )
+
+        mock_client.post.assert_called_once_with(
+            "https://auth.example.com/token",
+            data={
+                "grant_type": "authorization_code",
+                "code": "authcode123",
+                "client_id": "my-client",
+                "client_secret": "my-secret",
+                "redirect_uri": "https://app.example.com/callback",
+            },
+            headers={"Accept": "application/json"},
+        )
+        mock_client.get.assert_called_once_with(
+            "https://auth.example.com/userinfo",
+            headers={"Authorization": "Bearer tok123"},
+        )