feat: add consent check to authorization flow

src/porchlight/app.py

@@ -19,6 +19,7 @@ from porchlight.oidc.endpoints import router as oidc_router
 from porchlight.oidc.provider import create_oidc_server
 from porchlight.store.sqlite.db import open_db
 from porchlight.store.sqlite.repositories import (
+    SQLiteConsentRepository,
     SQLiteCredentialRepository,
     SQLiteMagicLinkRepository,
     SQLiteUserRepository,
@@ -36,6 +37,7 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
             app.state.user_repo = SQLiteUserRepository(db)
             app.state.credential_repo = SQLiteCredentialRepository(db)
             app.state.magic_link_repo = SQLiteMagicLinkRepository(db)
+            app.state.consent_repo = SQLiteConsentRepository(db)
 
             # Auth services
             app.state.password_service = PasswordService()

src/porchlight/oidc/endpoints.py

@@ -14,6 +14,13 @@ from porchlight.oidc.claims import PorchlightUserInfo, user_to_claims
 
 router = APIRouter(tags=["oidc"])
 
+SCOPE_DESCRIPTIONS: dict[str, str] = {
+    "openid": "Sign you in (required)",
+    "profile": "Your name and profile information",
+    "email": "Your email address",
+    "phone": "Your phone number",
+}
+
 
 @router.get("/.well-known/openid-configuration")
 async def provider_configuration(request: Request) -> JSONResponse:
@@ -63,7 +70,7 @@ async def authorization(request: Request) -> Response:
     username = request.session.get("username")
 
     if userid and username:
-        return await _complete_authorization(request, oidc_server, endpoint, parsed, userid, username)
+        return await _check_consent_or_complete(request, oidc_server, endpoint, parsed, userid, username, query_params)
 
     # Not authenticated — store and redirect to login
     request.session["oidc_auth_request"] = query_params
@@ -94,7 +101,40 @@ async def authorization_complete(request: Request) -> Response:
         error_desc = parsed.get("error_description", parsed["error"])
         return HTMLResponse(f"<h1>Error</h1><p>{error_desc}</p>", status_code=400)
 
-    return await _complete_authorization(request, oidc_server, endpoint, parsed, userid, username)
+    return await _check_consent_or_complete(
+        request, oidc_server, endpoint, parsed, userid, username, auth_request_params
+    )
+
+
+async def _check_consent_or_complete(
+    request: Request,
+    oidc_server: object,
+    endpoint: object,
+    parsed: object,
+    userid: str,
+    username: str,
+    auth_params: dict,
+) -> Response:
+    """Check if consent is needed; if so redirect to /consent, otherwise complete."""
+    settings = request.app.state.settings
+    client_id = auth_params.get("client_id", "")
+
+    # Manage-app bypasses consent
+    if client_id == settings.manage_client_id:
+        return await _complete_authorization(request, oidc_server, endpoint, parsed, userid, username)
+
+    # Check stored consent
+    consent_repo = request.app.state.consent_repo
+    requested_scopes = auth_params.get("scope", "openid").split()
+    stored_consent = await consent_repo.get_consent(userid, client_id)
+
+    if stored_consent and set(requested_scopes) <= set(stored_consent.scopes):
+        # All requested scopes already approved
+        return await _complete_authorization(request, oidc_server, endpoint, parsed, userid, username)
+
+    # Consent needed — store auth state and redirect
+    request.session["consent_auth_request"] = auth_params
+    return RedirectResponse("/consent", status_code=303)
 
 
 async def _complete_authorization(
@@ -246,3 +286,75 @@ async def userinfo_endpoint(request: Request) -> JSONResponse:
         response_data = response_data.to_dict()
 
     return JSONResponse(response_data)
+
+
+@router.get("/consent")
+async def consent_page(request: Request) -> Response:
+    """Show the consent form."""
+    auth_params = request.session.get("consent_auth_request")
+    if auth_params is None:
+        return HTMLResponse("<h1>Error</h1><p>No pending consent request</p>", status_code=400)
+
+    userid = request.session.get("userid")
+    if not userid:
+        return RedirectResponse("/login", status_code=303)
+
+    client_id = auth_params.get("client_id", "")
+    requested_scopes = auth_params.get("scope", "openid").split()
+
+    scope_info = [
+        {"name": s, "description": SCOPE_DESCRIPTIONS.get(s, s), "required": s == "openid"} for s in requested_scopes
+    ]
+
+    templates = request.app.state.templates
+    return templates.TemplateResponse(
+        request,
+        "consent.html",
+        {"client_id": client_id, "scopes": scope_info},
+    )
+
+
+@router.post("/consent")
+async def consent_submit(request: Request) -> Response:
+    """Handle consent form submission."""
+    auth_params = request.session.pop("consent_auth_request", None)
+    if auth_params is None:
+        return HTMLResponse("<h1>Error</h1><p>No pending consent request</p>", status_code=400)
+
+    userid = request.session.get("userid")
+    username = request.session.get("username")
+    if not userid or not username:
+        return RedirectResponse("/login", status_code=303)
+
+    form = await request.form()
+    action = form.get("action")
+    client_id = auth_params.get("client_id", "")
+    redirect_uri = auth_params.get("redirect_uri", "")
+    state = auth_params.get("state", "")
+
+    if action == "deny":
+        params = urlencode({"error": "access_denied", "state": state})
+        return RedirectResponse(f"{redirect_uri}?{params}", status_code=303)
+
+    # Allow — collect approved scopes
+    approved_scopes = form.getlist("scope")
+    if "openid" not in approved_scopes:
+        approved_scopes = ["openid", *list(approved_scopes)]
+
+    # Save consent
+    consent_repo = request.app.state.consent_repo
+    await consent_repo.set_consent(userid, client_id, list(approved_scopes))
+
+    # Filter auth request scopes to only approved
+    auth_params["scope"] = " ".join(approved_scopes)
+
+    # Re-parse and complete
+    oidc_server = request.app.state.oidc_server
+    endpoint = oidc_server.get_endpoint("authorization")
+
+    try:
+        parsed = endpoint.parse_request(auth_params)
+    except Exception as exc:
+        return HTMLResponse(f"<h1>Error</h1><p>{exc}</p>", status_code=400)
+
+    return await _complete_authorization(request, oidc_server, endpoint, parsed, userid, username)