fix: block /auth/token for OAuth-only users without password_hash

Users without a password_hash (Google OAuth / magic-link accounts) could
obtain a JWT by simply posting their email to /auth/token. Add an else
clause that rejects such requests with 401, directing them to their
configured auth provider. Update and extend tests accordingly.

app/auth/router.py

@@ -38,7 +38,7 @@ async def create_token(
     request: TokenRequest,
     conn: duckdb.DuckDBPyConnection = Depends(_get_db),
 ):
-    """Issue a JWT token. For dev/demo: any registered user gets a token."""
+    """Issue a JWT token. Requires password authentication."""
     repo = UserRepository(conn)
     user = repo.get_by_email(request.email)
     if not user:
@@ -54,6 +54,12 @@ async def create_token(
             ph.verify(user["password_hash"], request.password)
         except Exception:
             raise HTTPException(status_code=401, detail="Invalid password")
+    else:
+        # No password set — must use their auth provider (Google OAuth, magic link)
+        raise HTTPException(
+            status_code=401,
+            detail="This account uses external authentication. Please log in via your configured provider.",
+        )
 
     token = create_access_token(
         user_id=user["id"],

tests/test_auth_providers.py

@@ -64,10 +64,15 @@ class TestTokenEndpoint:
         assert data["email"] == "pw@test.com"
 
     def test_token_no_password_hash_user_gets_token(self, client):
-        """User without password_hash (e.g. OAuth-only user) still gets a token without a password."""
+        """User without password_hash (OAuth-only) must be rejected at /auth/token."""
         resp = client.post("/auth/token", json={"email": "ml@test.com"})
-        assert resp.status_code == 200
-        assert "access_token" in resp.json()
+        assert resp.status_code == 401
+
+    def test_token_rejected_for_oauth_only_user(self, client):
+        """OAuth-only user (no password_hash) must not receive a token via /auth/token."""
+        resp = client.post("/auth/token", json={"email": "ml@test.com"})
+        assert resp.status_code == 401
+        assert "external authentication" in resp.json()["detail"]
 
     def test_token_unknown_user_rejected(self, client):
         """Unknown email must return 401."""

tests/test_bootstrap.py

@@ -64,18 +64,31 @@ class TestBootstrap:
         assert "already exist" in resp.json()["detail"]
 
     def test_bootstrap_then_login(self, fresh_client):
-        """After bootstrap, normal /auth/token login works."""
-        # Bootstrap
+        """After bootstrap with password, /auth/token login works; without password it requires OAuth."""
+        # Bootstrap with a password
+        fresh_client.post("/auth/bootstrap", json={
+            "email": "admin@test.com",
+            "password": "adminpass123",
+        })
+
+        # Normal password login succeeds
+        resp = fresh_client.post("/auth/token", json={
+            "email": "admin@test.com",
+            "password": "adminpass123",
+        })
+        assert resp.status_code == 200
+        assert resp.json()["role"] == "admin"
+
+    def test_bootstrap_no_password_token_rejected(self, fresh_client):
+        """After passwordless bootstrap, /auth/token must reject the user (OAuth-only flow)."""
         fresh_client.post("/auth/bootstrap", json={
             "email": "admin@test.com",
         })
 
-        # Normal login
         resp = fresh_client.post("/auth/token", json={
             "email": "admin@test.com",
         })
-        assert resp.status_code == 200
-        assert resp.json()["role"] == "admin"
+        assert resp.status_code == 401
 
     def test_bootstrap_second_call_fails(self, fresh_client):
         """Second bootstrap call fails — endpoint self-deactivates."""