diff --git a/tests/test_maintenance.py b/tests/test_maintenance.py
index 72f497d..5c918ea 100644
--- a/tests/test_maintenance.py
+++ b/tests/test_maintenance.py
@@ -76,6 +76,25 @@ def test_apply_creates_backup_and_replaces_file(tmp_path, monkeypatch):
     assert report.results[0].detail["cache_invalidated"] is True
 
 
+def test_source_failure_preserves_existing_file_and_reports_error(tmp_path, monkeypatch):
+    current = _sp500_rows(450)
+    output_path = tmp_path / "data" / "sp500_constituents.csv"
+    _write_constituents(output_path, current)
+    _disable_cache_invalidation(monkeypatch)
+
+    def failing_source():
+        raise RuntimeError("source unavailable")
+
+    runner = _runner(tmp_path, {"sp500_constituents": failing_source})
+
+    report = runner.run(tasks=["sp500_constituents"], dry_run=False)
+
+    assert report.status == "failed"
+    assert "source unavailable" in report.errors
+    assert _read_symbols(output_path) == [r["symbol"] for r in current]
+    assert not (tmp_path / "data" / "backups" / "constituents").exists()
+
+
 def test_validation_failure_preserves_existing_file(tmp_path, monkeypatch):
     current = _sp500_rows(450)
     invalid = _sp500_rows(1)
@@ -107,6 +126,14 @@ def test_maintenance_page_loads(client):
     assert b"System Maintenance" in response.data
 
 
+def test_maintenance_nav_link_registered_in_main_js(client):
+    response = client.get("/static/js/main.js")
+
+    assert response.status_code == 200
+    assert b"/maintenance" in response.data
+    assert b"Maintenance" in response.data
+
+
 def test_maintenance_status_api_loads(client):
     response = client.get("/api/maintenance/status")
 
diff --git a/web/static/js/main.js b/web/static/js/main.js
index 290f9ce..ff9172e 100644
--- a/web/static/js/main.js
+++ b/web/static/js/main.js
@@ -3,6 +3,10 @@
 document.addEventListener('DOMContentLoaded', () => {
   console.log('[TWS Robot] UI ready');
 
+  // Ensure optional/operator pages are discoverable even when the server-side
+  // navbar template has not been expanded yet.
+  _ensureMaintenanceNavLink();
+
   // Auto-enrich symbol cells with company names
   _enrichSymbolNames();
 });
@@ -79,6 +83,38 @@ window.renderMarkdown = function renderMarkdown(text) {
     .replace(/\n/g,           '<br>');
 };
 
+/**
+ * Add the System Maintenance console to the Monitoring dropdown.
+ * This keeps the operator-only page discoverable from the web UI.
+ * @private
+ */
+function _ensureMaintenanceNavLink() {
+  const existing = document.querySelector('a[href="/maintenance"]');
+  if (existing) return;
+
+  const monitoringToggle = Array.from(document.querySelectorAll('.nav-dropdown-toggle'))
+    .find(btn => (btn.textContent || '').includes('Monitoring'));
+  if (!monitoringToggle) return;
+
+  const dropdown = monitoringToggle.closest('.nav-dropdown');
+  const menu = dropdown ? dropdown.querySelector('.nav-dropdown-menu') : null;
+  if (!menu) return;
+
+  const li = document.createElement('li');
+  const isMaintenancePage = window.location.pathname === '/maintenance' ||
+    window.location.pathname.startsWith('/maintenance/');
+  if (isMaintenancePage) {
+    li.className = 'active';
+    dropdown.classList.add('active');
+  }
+
+  const link = document.createElement('a');
+  link.href = '/maintenance';
+  link.textContent = 'Maintenance';
+  li.appendChild(link);
+  menu.appendChild(li);
+}
+
 /**
  * Fetch company names for all ``[data-symbol]`` elements on the page
  * and enrich them with a tooltip (title) and a small subtitle showing