T10.2: Okta login-redirect and callback routes

Adds GET /api/auth/okta/login (redirect to Okta's authorize endpoint) and
GET /api/auth/okta/callback (exchange code, validate ID token, pull the
identity claim) to server/app.py, using the oauth.okta client from
okta_auth.py (T10.1).

Access gating is Okta's job, not this route's: only accounts assigned to
the app integration in Okta ever reach the callback, so there is no
app-side group/claim check layered on top (D15, wave-10.md T10.2).

Stops at NotImplementedError once the identity claim is in hand. Matching
that claim to a local account and issuing the session cookie is T10.3, kept
separate per the one-task-per-PR rule.

wave-10.md T10.2 / D15

server/app.py

@@ -9,6 +9,7 @@ Run (prod):    gunicorn -k uvicorn.workers.UvicornWorker -b 127.0.0.1:8000 serve
 Interactive docs: http://<host>/api/docs
 """
 import base64
+import logging
 import os
 import re
 import uuid
@@ -17,6 +18,7 @@ from time import monotonic
 from typing import Any, Optional
 from urllib.parse import urlparse
 
+from authlib.integrations.base_client import OAuthError
 from fastapi import FastAPI, Depends, HTTPException, Query, Request, Response, BackgroundTasks
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
@@ -26,7 +28,9 @@ from sqlalchemy import select, delete, func
 from sqlalchemy.orm import Session
 
 from .db import Base, engine, get_db
-from . import models, auth, notify, assets_db
+from . import models, auth, notify, assets_db, okta_auth
+
+log = logging.getLogger("wpsuite.app")
 
 # Schema management:
 #   • Local dev (SQLite) auto-creates tables for a zero-config run.
@@ -721,6 +725,41 @@ def logout(response: Response):
     return {"ok": True}
 
 
+# ── Okta OIDC sign-in (T10.2, wave 10 / D15) ────────────────────────────────────
+# Access gating is Okta's job: only accounts assigned to this app integration in Okta
+# can complete authorize_redirect at all. No app-side group/claim check is layered on
+# top here — see okta_auth.py's docstring and wave-10.md T10.2 for why.
+
+@app.get("/api/auth/okta/login")
+async def okta_login(request: Request):
+    """Send the browser to Okta's authorize endpoint."""
+    if not okta_auth.oauth:
+        raise HTTPException(status_code=503, detail="Sign-in is temporarily unavailable. Contact IT.")
+    return await okta_auth.oauth.okta.authorize_redirect(request, okta_auth.REDIRECT_URI)
+
+
+@app.get("/api/auth/okta/callback")
+async def okta_callback(request: Request, response: Response, db: Session = Depends(get_db)):
+    """Exchange the authorization code for tokens and validate the ID token. Identity
+    matching and session issuance are T10.3 — this route stops once the claim is in
+    hand, same one-task-per-PR split the wave file records."""
+    if not okta_auth.oauth:
+        raise HTTPException(status_code=503, detail="Sign-in is temporarily unavailable. Contact IT.")
+    try:
+        token = await okta_auth.oauth.okta.authorize_access_token(request)
+    except OAuthError as exc:
+        log.warning("Okta callback rejected: %s", exc)
+        raise HTTPException(status_code=401, detail="Sign-in was not completed.")
+    claims = token.get("userinfo") or {}
+    identity = (claims.get(okta_auth.IDENTITY_CLAIM) or "").strip()
+    if not identity:
+        log.error("Okta ID token had no %r claim — check OKTA_IDENTITY_CLAIM", okta_auth.IDENTITY_CLAIM)
+        raise HTTPException(status_code=503, detail="Sign-in is temporarily unavailable. Contact IT.")
+    # T10.3 picks up here: match `identity` to a local account (or JIT-provision one),
+    # then auth.create_token / auth.set_session_cookie the same way login() does today.
+    raise NotImplementedError("T10.3: identity matching and JIT provisioning")
+
+
 # ── Self-service password reset (needs email switched on) ──────────────────────
 RESET_COOLDOWN_SECONDS = int(os.getenv("AUTH_RESET_COOLDOWN_SECONDS", "120"))
 # In-process throttle: one reset mail per (account, client) per cooldown. Enough to