diff --git a/backend/services/maintenance.py b/backend/services/maintenance.py
index 2602ffb..28eabcc 100644
--- a/backend/services/maintenance.py
+++ b/backend/services/maintenance.py
@@ -702,14 +702,25 @@ def hermes_update_job() -> dict:
     py = os.path.join(path, "venv", "bin", "python")
     backup = os.path.join(_REPO_ROOT, "deploy", "backup.sh")
     postcheck = os.path.join(_REPO_ROOT, "deploy", "hermes-postcheck.sh")
-    # Backup → update → Gateway-Neustart → Gehirn-Check (Job wird rot, wenn Mem0/Plugin kaputt).
-    # Backup → update → doctor (Config/Deps-Diagnose der NEUEN Version) → Gateway-Neustart →
-    # Gehirn-Check (erweitert um Config-Drift-Scan, Tool- und Voice-Smoke — Lehre aus v0.18:
-    # 'approvals.mode auto' wurde still ungültig und legte alle Tools in pending_approval).
+    # Backup → Stop UI (verhindert Crash durch Löschen der Sourcen) → update → doctor → 
+    # UI-Build mit MC2-Basepath (/hermes-ui/) → Gateway + UI-Neustart → Smoke-Test.
+    hui_web = os.path.join(path, "web")
+    hui_dist = os.path.join(path, "hermes_cli", "web_dist")
+    npm_path = os.path.expanduser("~/.hermes/node/bin")
+    
+    build_cmd = (
+        f"if [ -d {hui_web} ]; then "
+        f"cd {hui_web} && PATH={npm_path}:$PATH npx --no-install vite build --base=/hermes-ui/ --outDir /tmp/h-build --emptyOutDir "
+        f"&& rm -rf {hui_dist} && cp -r /tmp/h-build {hui_dist}; fi"
+    )
+
     cmd = (f"bash {backup} || true; "
+           f"systemctl --user stop hermes-builtin-ui || true; "
            f"cd {path} && {py} -m hermes_cli.main update --yes "
            f"&& {py} -m hermes_cli.main doctor "
-           f"&& systemctl --user restart hermes-gateway "
+           f"&& {build_cmd} "
+           f"&& systemctl --user reset-failed hermes-builtin-ui || true; "
+           f"systemctl --user restart hermes-gateway hermes-builtin-ui "
            f"&& sleep 6 && bash {postcheck}")
 
     def on_done():