diff --git a/backend/__tests__/integration/oidcSso.test.js b/backend/__tests__/integration/oidcSso.test.js
index a1b6e0b7..19d3299f 100644
--- a/backend/__tests__/integration/oidcSso.test.js
+++ b/backend/__tests__/integration/oidcSso.test.js
@@ -222,6 +222,21 @@ describe('OIDC SSO (#798)', () => {
     expect(cfg.clientSecret).toBe(idp.clientSecret);
   });
 
+  it('refuses local password login for OIDC-owned accounts', async () => {
+    // Give the JIT admin a KNOWN password hash directly in the DB — the
+    // auth_provider check must reject the login even with valid credentials
+    // (otherwise a password reset would mint an IdP-bypassing local login).
+    await db('admin_users').where({ id: agentCookies.jitAdminId }).update({
+      password_hash: await bcrypt.hash('KnownPass123', 4),
+    });
+    const row = await db('admin_users').where({ id: agentCookies.jitAdminId }).first();
+
+    const res = await request(app)
+      .post('/api/auth/admin/login')
+      .send({ username: row.email, password: 'KnownPass123' });
+    expect(res.status).toBe(401);
+  });
+
   it('returns 404 from /sso/login when SSO is disabled', async () => {
     await oidcService.saveOidcSettings({ oidc_enabled: false });
     await request(app).get('/api/auth/admin/sso/login').expect(404);
diff --git a/backend/__tests__/routes/authSession.symmetry.test.js b/backend/__tests__/routes/authSession.symmetry.test.js
index 50ba848f..7b78e61e 100644
--- a/backend/__tests__/routes/authSession.symmetry.test.js
+++ b/backend/__tests__/routes/authSession.symmetry.test.js
@@ -32,9 +32,17 @@ jest.mock('../../src/database/db', () => {
     if (table === 'admin_users') {
       let rowFilter = () => true;
       return {
+        // The session route joins roles for the adminUser payload (#798);
+        // fake rows carry no role fields, so the join is a pass-through.
+        leftJoin() {
+          return this;
+        },
         where(criteria) {
           rowFilter = (row) => {
-            return Object.entries(criteria).every(([k, v]) => {
+            return Object.entries(criteria).every(([rawKey, v]) => {
+              // Joined queries prefix columns ('admin_users.id') — the fake
+              // rows use bare names.
+              const k = rawKey.replace(/^admin_users\./, '');
               if (k === 'is_active') return Boolean(row.is_active) === Boolean(v);
               return row[k] === v;
             });
@@ -50,7 +58,12 @@ jest.mock('../../src/database/db', () => {
           if (!row) return undefined;
           if (!this._cols) return row;
           const out = {};
-          for (const c of this._cols) out[c] = row[c];
+          for (const c of this._cols) {
+            // Support 'table.col' and 'table.col as alias' shapes.
+            const [source, alias] = c.split(/\s+as\s+/i);
+            const bare = source.includes('.') ? source.split('.').pop() : source;
+            out[alias || bare] = row[bare];
+          }
           return out;
         },
       };
diff --git a/backend/src/routes/auth.js b/backend/src/routes/auth.js
index 32299f81..31e9c9c6 100644
--- a/backend/src/routes/auth.js
+++ b/backend/src/routes/auth.js
@@ -143,8 +143,11 @@ router.post('/admin/login', [
       )
       .first();
 
-    // Use generic error to prevent user enumeration
-    if (!admin || !await bcrypt.compare(password, admin.password_hash)) {
+    // Use generic error to prevent user enumeration. OIDC-owned accounts
+    // (#798) never authenticate locally — their random hash is unusable by
+    // design, and the explicit check keeps that true even if a hash ever
+    // gets set through some other path.
+    if (!admin || admin.auth_provider === 'oidc' || !await bcrypt.compare(password, admin.password_hash)) {
       await trackFailedAttempt(username, ipAddress, userAgent);
       return res.status(401).json({ error: getGenericAuthError() });
     }
@@ -654,12 +657,22 @@ router.get('/session', async (req, res) => {
       // or the gallery event was archived/deleted. Mirror those checks
       // here so the session endpoint is always at least as strict as
       // what the protected endpoints will enforce next.
+      // Full user payload for admin sessions — the SSO callback establishes
+      // the session via redirect (no JSON response the SPA could store), so
+      // session restoration must be able to hydrate the user object (#798).
+      let adminUser = null;
+
       if (decoded.type === 'admin') {
         let admin = null;
         try {
           admin = await db('admin_users')
-            .where({ id: decoded.id, is_active: formatBoolean(true) })
-            .select('id', 'username', 'email', 'password_changed_at')
+            .leftJoin('roles', 'roles.id', 'admin_users.role_id')
+            .where({ 'admin_users.id': decoded.id, 'admin_users.is_active': formatBoolean(true) })
+            .select(
+              'admin_users.id', 'admin_users.username', 'admin_users.email',
+              'admin_users.password_changed_at', 'admin_users.must_change_password',
+              'roles.name as role_name', 'roles.display_name as role_display_name'
+            )
             .first();
         } catch (lookupErr) {
           // admin_users table not present (test fixture, fresh DB) — fall
@@ -698,6 +711,19 @@ router.get('/session', async (req, res) => {
           // Helper lookup failed (test stub may not export it) — fall through
           // and trust the token. Real deployments always have the middleware.
         }
+
+        if (admin) {
+          adminUser = {
+            id: admin.id,
+            username: admin.username,
+            email: admin.email,
+            mustChangePassword: admin.must_change_password || false,
+            role: admin.role_name ? {
+              name: admin.role_name,
+              displayName: admin.role_display_name
+            } : null
+          };
+        }
       } else if (decoded.type === 'gallery') {
         try {
           const event = await db('events')
@@ -729,7 +755,11 @@ router.get('/session', async (req, res) => {
         expiresIn: Math.floor(remainingTime),
         user: decoded.username || decoded.eventSlug,
         eventSlug: decoded.eventSlug,
-        adminUsername: decoded.username
+        adminUsername: decoded.username,
+        // Full admin payload (or null) — lets the SPA hydrate its user
+        // state after a redirect-established session (SSO, #798) where no
+        // login JSON response ever reached it.
+        adminUser
       });
     } catch (err) {
       res.json({
@@ -894,7 +924,11 @@ router.get('/admin/sso/login', async (req, res) => {
       return res.status(404).json({ error: 'SSO is not enabled' });
     }
     logger.error('OIDC login initiation failed', { error: error.message });
-    return res.redirect('/admin/login?sso_error=config');
+    // Absolute like the callback's redirects: in split-origin deployments a
+    // relative path would resolve on the API origin and 404.
+    const { getFrontendBaseUrl } = require('../utils/frontendUrl');
+    const frontendBase = (await getFrontendBaseUrl().catch(() => '')) || '';
+    return res.redirect(`${frontendBase}/admin/login?sso_error=config`);
   }
 });
 
diff --git a/backend/src/services/userManagementService.js b/backend/src/services/userManagementService.js
index fc51a34f..dc95dee9 100644
--- a/backend/src/services/userManagementService.js
+++ b/backend/src/services/userManagementService.js
@@ -459,6 +459,13 @@ async function resetAdminPassword(id, resetById) {
     throw new NotFoundError('Admin user', id);
   }
 
+  // OIDC-owned accounts (#798) have no usable local password by design —
+  // minting one here would hand out a login that bypasses the IdP's MFA
+  // and access policies.
+  if (user.auth_provider === 'oidc') {
+    throw new ValidationError('This account is managed by your identity provider (SSO) — reset the password there.');
+  }
+
   const newPassword = generateReadablePassword();
   const passwordHash = await bcrypt.hash(newPassword, getBcryptRounds());
 
diff --git a/docker-compose.yml b/docker-compose.yml
index 786c6652..978cd902 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -60,6 +60,9 @@ services:
       - SMTP_PASS=${SMTP_PASS}
       - EMAIL_FROM=${EMAIL_FROM:-noreply@picpeak.local}
       - FRONTEND_URL=${FRONTEND_URL:-http://localhost:3000}
+      # Public API origin for split-origin deployments (#798 SSO redirect_uri).
+      # Empty = same origin as FRONTEND_URL (the standard proxied setup).
+      - API_URL=${API_URL:-}
       - ADMIN_URL=${ADMIN_URL:-http://localhost:3001}
       - TZ=${TZ:-UTC}
       - STORAGE_PATH=/app/storage
diff --git a/frontend/src/contexts/AdminAuthContext.tsx b/frontend/src/contexts/AdminAuthContext.tsx
index 4f71bc87..6b943397 100644
--- a/frontend/src/contexts/AdminAuthContext.tsx
+++ b/frontend/src/contexts/AdminAuthContext.tsx
@@ -50,12 +50,19 @@ export const AdminAuthProvider: React.FC<AdminAuthProviderProps> = ({ children }
           }
         }
 
-        const response = await api.get<{ valid: boolean; type: string; adminUsername?: string; user?: string }>(
+        const response = await api.get<{ valid: boolean; type: string; adminUsername?: string; user?: string; adminUser?: AdminUser | null }>(
           '/auth/session'
         );
 
         if (response.data?.valid && response.data.type === 'admin') {
           setIsAuthenticated(true);
+          // Redirect-established sessions (SSO, #798) never went through
+          // login(), so sessionStorage has no user — hydrate from the
+          // session payload. Server truth also refreshes stale local copies.
+          if (response.data.adminUser) {
+            setUser(response.data.adminUser);
+            sessionStorage.setItem('admin_user', JSON.stringify(response.data.adminUser));
+          }
         } else {
           sessionStorage.removeItem('admin_user');
           setIsAuthenticated(false);