diff --git a/static/cortex-os/runtime-health/runtime_health.css b/static/cortex-os/runtime-health/runtime_health.css
index 8ac21c6..9bd83de 100644
--- a/static/cortex-os/runtime-health/runtime_health.css
+++ b/static/cortex-os/runtime-health/runtime_health.css
@@ -9,6 +9,10 @@
   font: 14px/1.45 system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
 }
 
+main.main:not(.svrnty-showing-cortex-os) .cortex-os-runtime-health {
+  display: none;
+}
+
 .cortex-os-runtime-health h2 {
   margin: 0 0 8px;
   font-size: 15px;
diff --git a/static/cortex-os/runtime-health/runtime_health.js b/static/cortex-os/runtime-health/runtime_health.js
index 5a5399f..c9795f7 100644
--- a/static/cortex-os/runtime-health/runtime_health.js
+++ b/static/cortex-os/runtime-health/runtime_health.js
@@ -42,7 +42,10 @@
     panel.appendChild(summary);
     panel.appendChild(list);
 
-    var target = document.querySelector("main") || document.body;
+    var target = document.querySelector("main.main");
+    if (!target) {
+      return panel;
+    }
     target.appendChild(panel);
     return panel;
   }
@@ -99,9 +102,17 @@
       });
   }
 
-  if (document.readyState === "loading") {
-    document.addEventListener("DOMContentLoaded", loadRuntimeHealth, { once: true });
-  } else {
+  function handlePanelSwitch(event) {
+    var detail = (event && event.detail) || {};
+    if (detail.name === "cortex-os") {
+      loadRuntimeHealth();
+    }
+  }
+
+  window.addEventListener("svrnty:panel-switch", handlePanelSwitch);
+
+  var main = document.querySelector("main.main");
+  if (main && main.classList.contains("svrnty-showing-cortex-os")) {
     loadRuntimeHealth();
   }
 })();
diff --git a/static/svrnty_nav.js b/static/svrnty_nav.js
index 3570bfb..c1a0c2b 100644
--- a/static/svrnty_nav.js
+++ b/static/svrnty_nav.js
@@ -24,11 +24,14 @@
       '<path d="M12 2l1.8 5.6L19.4 9.4l-4.5 3.3 1.7 5.7L12 15l-4.6 3.4 1.7-5.7L4.6 9.4l5.6-1.8L12 2z"/>',
     canvas:
       '<rect x="3" y="3" width="18" height="18" rx="2"/><path d="M8 3v18M16 3v18M3 8h18M3 16h18"/>',
+    "cortex-os":
+      '<path d="M4 7h16M4 12h16M4 17h10"/><circle cx="17" cy="17" r="3"/>',
   };
   const TABS = [
     { id: "adwright", label: "Adwright", tooltip: "Adwright — marketing intelligence" },
     { id: "bte",      label: "BTE",      tooltip: "BTE — brand creative studio" },
     { id: "canvas",   label: "Canvas",   tooltip: "Canvas — sovereign UI design" },
+    { id: "cortex-os", label: "Cortex OS", tooltip: "Cortex OS — Runtime Health" },
   ];
 
   function _svg(iconPath, size, stroke) {
diff --git a/tests/unit/test_cortex_os_runtime_health_static.py b/tests/unit/test_cortex_os_runtime_health_static.py
index 0fd32a6..c75f5a3 100644
--- a/tests/unit/test_cortex_os_runtime_health_static.py
+++ b/tests/unit/test_cortex_os_runtime_health_static.py
@@ -22,6 +22,18 @@ def test_runtime_health_display_has_no_hidden_write_surface():
         "localStorage",
         "sessionStorage",
         "document.cookie",
+        "indexedDB",
+        "caches",
+        "navigator.sendBeacon",
+        "WebSocket",
+        "EventSource",
+        "BroadcastChannel",
+        "SharedWorker",
+        "ServiceWorker",
+        "window.open",
+        "eval(",
+        "new Function",
+        "innerHTML",
         "<form",
         ".submit(",
         "POST",
@@ -43,3 +55,15 @@ def test_runtime_health_css_is_scoped_to_panel():
     assert ".cortex-os-runtime-health" in css
     assert "body {" not in css
     assert "#app" not in css
+
+
+def test_runtime_health_mounts_only_in_cortex_os_panel_context():
+    js = JS.read_text(encoding="utf-8")
+
+    assert 'window.addEventListener("svrnty:panel-switch", handlePanelSwitch)' in js
+    assert 'detail.name === "cortex-os"' in js
+    assert 'document.querySelector("main.main")' in js
+    assert "document.body" not in js
+    assert 'document.addEventListener("DOMContentLoaded", loadRuntimeHealth' not in js
+    assert "loadRuntimeHealth();" in js
+    assert js.count("/api/cortex-os/runtime-health") == 1
diff --git a/tests/unit/test_svrnty_nav_js.py b/tests/unit/test_svrnty_nav_js.py
index b3153f9..d876f48 100644
--- a/tests/unit/test_svrnty_nav_js.py
+++ b/tests/unit/test_svrnty_nav_js.py
@@ -23,3 +23,11 @@ def test_canvas_tab_is_registered():
     src = NAV_JS.read_text()
     assert '{ id: "canvas"' in src
     assert "svrnty-showing-\" + id" in src
+
+
+def test_cortex_os_tab_is_registered_once():
+    src = NAV_JS.read_text()
+    assert src.count('id: "cortex-os"') == 1
+    assert '"cortex-os":' in src
+    for tab_id in ['id: "adwright"', 'id: "bte"', 'id: "canvas"']:
+        assert tab_id in src