diff --git a/tests/gateway/test_api_server.py b/tests/gateway/test_api_server.py
index 2be01fc2d1..be1fc63bf4 100644
--- a/tests/gateway/test_api_server.py
+++ b/tests/gateway/test_api_server.py
@@ -220,6 +220,7 @@ def _create_app(adapter: APIServerAdapter) -> web.Application:
     app = web.Application(middlewares=mws)
     app["api_server_adapter"] = adapter
     app.router.add_get("/health", adapter._handle_health)
+    app.router.add_get("/health/detailed", adapter._handle_health_detailed)
     app.router.add_get("/v1/health", adapter._handle_health)
     app.router.add_get("/v1/models", adapter._handle_models)
     app.router.add_post("/v1/chat/completions", adapter._handle_chat_completions)
@@ -277,6 +278,58 @@ class TestHealthEndpoint:
             assert data["platform"] == "hermes-agent"
 
 
+# ---------------------------------------------------------------------------
+# /health/detailed endpoint
+# ---------------------------------------------------------------------------
+
+
+class TestHealthDetailedEndpoint:
+    @pytest.mark.asyncio
+    async def test_health_detailed_returns_ok(self, adapter):
+        """GET /health/detailed returns status, platform, and runtime fields."""
+        app = _create_app(adapter)
+        with patch("gateway.status.read_runtime_status", return_value={
+            "gateway_state": "running",
+            "platforms": {"telegram": {"state": "connected"}},
+            "active_agents": 2,
+            "exit_reason": None,
+            "updated_at": "2026-04-14T00:00:00Z",
+        }):
+            async with TestClient(TestServer(app)) as cli:
+                resp = await cli.get("/health/detailed")
+                assert resp.status == 200
+                data = await resp.json()
+                assert data["status"] == "ok"
+                assert data["platform"] == "hermes-agent"
+                assert data["gateway_state"] == "running"
+                assert data["platforms"] == {"telegram": {"state": "connected"}}
+                assert data["active_agents"] == 2
+                assert isinstance(data["pid"], int)
+                assert "updated_at" in data
+
+    @pytest.mark.asyncio
+    async def test_health_detailed_no_runtime_status(self, adapter):
+        """When gateway_state.json is missing, fields are None."""
+        app = _create_app(adapter)
+        with patch("gateway.status.read_runtime_status", return_value=None):
+            async with TestClient(TestServer(app)) as cli:
+                resp = await cli.get("/health/detailed")
+                assert resp.status == 200
+                data = await resp.json()
+                assert data["status"] == "ok"
+                assert data["gateway_state"] is None
+                assert data["platforms"] == {}
+
+    @pytest.mark.asyncio
+    async def test_health_detailed_does_not_require_auth(self, auth_adapter):
+        """Health detailed endpoint should be accessible without auth, like /health."""
+        app = _create_app(auth_adapter)
+        with patch("gateway.status.read_runtime_status", return_value=None):
+            async with TestClient(TestServer(app)) as cli:
+                resp = await cli.get("/health/detailed")
+                assert resp.status == 200
+
+
 # ---------------------------------------------------------------------------
 # /v1/models endpoint
 # ---------------------------------------------------------------------------
diff --git a/tests/hermes_cli/test_web_server.py b/tests/hermes_cli/test_web_server.py
index ebcb2c95c3..365e3d0fe1 100644
--- a/tests/hermes_cli/test_web_server.py
+++ b/tests/hermes_cli/test_web_server.py
@@ -984,3 +984,195 @@ class TestModelInfoEndpoint:
         assert resp.status_code == 200
         data = resp.json()
         assert data["auto_context_length"] == 0
+
+
+# ---------------------------------------------------------------------------
+# Gateway health probe tests
+# ---------------------------------------------------------------------------
+
+
+class TestProbeGatewayHealth:
+    """Tests for _probe_gateway_health() — cross-container gateway detection."""
+
+    def test_returns_false_when_no_url_configured(self, monkeypatch):
+        """When GATEWAY_HEALTH_URL is unset, the probe returns (False, None)."""
+        import hermes_cli.web_server as ws
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", None)
+        alive, body = ws._probe_gateway_health()
+        assert alive is False
+        assert body is None
+
+    def test_normalizes_url_with_health_suffix(self, monkeypatch):
+        """If the user sets the URL to include /health, it's stripped to base."""
+        import hermes_cli.web_server as ws
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", "http://gw:8642/health")
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_TIMEOUT", 1)
+        # Both paths should fail (no server), but we verify they were constructed
+        # correctly by checking the URLs attempted.
+        calls = []
+        original_urlopen = ws.urllib.request.urlopen
+
+        def mock_urlopen(req, **kwargs):
+            calls.append(req.full_url)
+            raise ConnectionError("mock")
+
+        monkeypatch.setattr(ws.urllib.request, "urlopen", mock_urlopen)
+        alive, body = ws._probe_gateway_health()
+        assert alive is False
+        assert "http://gw:8642/health/detailed" in calls
+        assert "http://gw:8642/health" in calls
+
+    def test_normalizes_url_with_health_detailed_suffix(self, monkeypatch):
+        """If the user sets the URL to include /health/detailed, it's stripped to base."""
+        import hermes_cli.web_server as ws
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", "http://gw:8642/health/detailed")
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_TIMEOUT", 1)
+        calls = []
+
+        def mock_urlopen(req, **kwargs):
+            calls.append(req.full_url)
+            raise ConnectionError("mock")
+
+        monkeypatch.setattr(ws.urllib.request, "urlopen", mock_urlopen)
+        ws._probe_gateway_health()
+        assert "http://gw:8642/health/detailed" in calls
+        assert "http://gw:8642/health" in calls
+
+    def test_successful_detailed_probe(self, monkeypatch):
+        """Successful /health/detailed probe returns (True, body_dict)."""
+        import hermes_cli.web_server as ws
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", "http://gw:8642")
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_TIMEOUT", 1)
+
+        response_body = json.dumps({
+            "status": "ok",
+            "gateway_state": "running",
+            "pid": 42,
+        })
+
+        mock_resp = MagicMock()
+        mock_resp.status = 200
+        mock_resp.read.return_value = response_body.encode()
+        mock_resp.__enter__ = MagicMock(return_value=mock_resp)
+        mock_resp.__exit__ = MagicMock(return_value=False)
+
+        monkeypatch.setattr(ws.urllib.request, "urlopen", lambda req, **kw: mock_resp)
+        alive, body = ws._probe_gateway_health()
+        assert alive is True
+        assert body["status"] == "ok"
+        assert body["pid"] == 42
+
+    def test_detailed_fails_falls_back_to_simple_health(self, monkeypatch):
+        """If /health/detailed fails, falls back to /health."""
+        import hermes_cli.web_server as ws
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", "http://gw:8642")
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_TIMEOUT", 1)
+
+        call_count = [0]
+
+        def mock_urlopen(req, **kwargs):
+            call_count[0] += 1
+            if call_count[0] == 1:
+                raise ConnectionError("detailed failed")
+            mock_resp = MagicMock()
+            mock_resp.status = 200
+            mock_resp.read.return_value = json.dumps({"status": "ok"}).encode()
+            mock_resp.__enter__ = MagicMock(return_value=mock_resp)
+            mock_resp.__exit__ = MagicMock(return_value=False)
+            return mock_resp
+
+        monkeypatch.setattr(ws.urllib.request, "urlopen", mock_urlopen)
+        alive, body = ws._probe_gateway_health()
+        assert alive is True
+        assert body["status"] == "ok"
+        assert call_count[0] == 2
+
+
+class TestStatusRemoteGateway:
+    """Tests for /api/status with remote gateway health fallback."""
+
+    @pytest.fixture(autouse=True)
+    def _setup_test_client(self):
+        try:
+            from starlette.testclient import TestClient
+        except ImportError:
+            pytest.skip("fastapi/starlette not installed")
+
+        from hermes_cli.web_server import app, _SESSION_TOKEN
+        self.client = TestClient(app)
+        self.client.headers["Authorization"] = f"Bearer {_SESSION_TOKEN}"
+
+    def test_status_falls_back_to_remote_probe(self, monkeypatch):
+        """When local PID check fails and remote probe succeeds, gateway shows running."""
+        import hermes_cli.web_server as ws
+
+        monkeypatch.setattr(ws, "get_running_pid", lambda: None)
+        monkeypatch.setattr(ws, "read_runtime_status", lambda: None)
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", "http://gw:8642")
+        monkeypatch.setattr(ws, "_probe_gateway_health", lambda: (True, {
+            "status": "ok",
+            "gateway_state": "running",
+            "platforms": {"telegram": {"state": "connected"}},
+            "pid": 999,
+        }))
+
+        resp = self.client.get("/api/status")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["gateway_running"] is True
+        assert data["gateway_pid"] == 999
+        assert data["gateway_state"] == "running"
+
+    def test_status_remote_probe_not_attempted_when_local_pid_found(self, monkeypatch):
+        """When local PID check succeeds, the remote probe is never called."""
+        import hermes_cli.web_server as ws
+
+        monkeypatch.setattr(ws, "get_running_pid", lambda: 1234)
+        monkeypatch.setattr(ws, "read_runtime_status", lambda: {
+            "gateway_state": "running",
+            "platforms": {},
+        })
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", "http://gw:8642")
+        probe_called = [False]
+        original = ws._probe_gateway_health
+
+        def track_probe():
+            probe_called[0] = True
+            return original()
+
+        monkeypatch.setattr(ws, "_probe_gateway_health", track_probe)
+
+        resp = self.client.get("/api/status")
+        assert resp.status_code == 200
+        assert not probe_called[0]
+
+    def test_status_remote_probe_not_attempted_when_no_url(self, monkeypatch):
+        """When GATEWAY_HEALTH_URL is unset, no probe is attempted."""
+        import hermes_cli.web_server as ws
+
+        monkeypatch.setattr(ws, "get_running_pid", lambda: None)
+        monkeypatch.setattr(ws, "read_runtime_status", lambda: None)
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", None)
+
+        resp = self.client.get("/api/status")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["gateway_running"] is False
+
+    def test_status_remote_running_null_pid(self, monkeypatch):
+        """Remote gateway running but PID not in response — pid should be None."""
+        import hermes_cli.web_server as ws
+
+        monkeypatch.setattr(ws, "get_running_pid", lambda: None)
+        monkeypatch.setattr(ws, "read_runtime_status", lambda: None)
+        monkeypatch.setattr(ws, "_GATEWAY_HEALTH_URL", "http://gw:8642")
+        monkeypatch.setattr(ws, "_probe_gateway_health", lambda: (True, {
+            "status": "ok",
+        }))
+
+        resp = self.client.get("/api/status")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["gateway_running"] is True
+        assert data["gateway_pid"] is None
+        assert data["gateway_state"] == "running"