diff --git a/src/lib/boss-data.ts b/src/lib/boss-data.ts
index 5ec9db4..f818e24 100644
--- a/src/lib/boss-data.ts
+++ b/src/lib/boss-data.ts
@@ -1742,6 +1742,36 @@ function normalizeDeviceCapabilities(
   };
 }
 
+function refreshDeviceCapabilityLastSeenAt(
+  raw: DeviceCapabilitiesInput | undefined,
+  fallbackLastSeenAt: string,
+  preserveExistingLastSeenAt = true,
+): DeviceCapabilitiesInput | undefined {
+  if (!raw) {
+    return raw;
+  }
+  return {
+    gui: raw.gui
+      ? {
+          ...raw.gui,
+          lastSeenAt:
+            preserveExistingLastSeenAt
+              ? trimToDefined(raw.gui.lastSeenAt) ?? fallbackLastSeenAt
+              : fallbackLastSeenAt,
+        }
+      : raw.gui,
+    cli: raw.cli
+      ? {
+          ...raw.cli,
+          lastSeenAt:
+            preserveExistingLastSeenAt
+              ? trimToDefined(raw.cli.lastSeenAt) ?? fallbackLastSeenAt
+              : fallbackLastSeenAt,
+        }
+      : raw.cli,
+  };
+}
+
 function normalizePreferredExecutionMode(value: unknown): DeviceExecutionMode {
   return value === "gui" ? "gui" : "cli";
 }
@@ -7273,6 +7303,7 @@ export async function updateDevice(deviceId: string, payload: DeviceUpdatePayloa
   const device = await mutateState((state) => {
     const nextDevice = state.devices.find((item) => item.id === deviceId);
     if (!nextDevice) throw new Error("DEVICE_NOT_FOUND");
+    const nextLastSeenAt = nowIso();
 
     if (payload.name) nextDevice.name = payload.name.trim();
     if (payload.avatar) nextDevice.avatar = payload.avatar.trim().slice(0, 2) || nextDevice.avatar;
@@ -7283,21 +7314,23 @@ export async function updateDevice(deviceId: string, payload: DeviceUpdatePayloa
     if (payload.projects) {
       nextDevice.projects = payload.projects.filter(Boolean);
     }
-    if (payload.capabilities) {
-      nextDevice.capabilities = normalizeDeviceCapabilities(
-        {
-          gui: payload.capabilities.gui ?? nextDevice.capabilities?.gui,
-          cli: payload.capabilities.cli ?? nextDevice.capabilities?.cli,
-        },
-        trimToDefined(payload.capabilities.gui?.lastSeenAt) ??
-          trimToDefined(payload.capabilities.cli?.lastSeenAt) ??
-          nextDevice.lastSeenAt,
-      );
-    }
+    nextDevice.capabilities = normalizeDeviceCapabilities(
+      refreshDeviceCapabilityLastSeenAt(
+        payload.capabilities
+          ? {
+              gui: payload.capabilities.gui ?? nextDevice.capabilities?.gui,
+              cli: payload.capabilities.cli ?? nextDevice.capabilities?.cli,
+            }
+          : nextDevice.capabilities,
+        nextLastSeenAt,
+        Boolean(payload.capabilities),
+      ),
+      nextLastSeenAt,
+    );
     if (payload.preferredExecutionMode !== undefined) {
       nextDevice.preferredExecutionMode = normalizePreferredExecutionMode(payload.preferredExecutionMode);
     }
-    nextDevice.lastSeenAt = nowIso();
+    nextDevice.lastSeenAt = nextLastSeenAt;
     return nextDevice;
   });
   publishBossEvent("devices.updated", { deviceId });
@@ -7635,6 +7668,7 @@ export async function upsertDeviceHeartbeat(payload: {
       if (device.token && payload.token && device.token !== payload.token && !claimedEnrollment) {
         throw new Error("DEVICE_TOKEN_MISMATCH");
       }
+      const nextLastSeenAt = nowIso();
       device.name = payload.name;
       device.avatar = payload.avatar;
       device.account = payload.account;
@@ -7643,12 +7677,16 @@ export async function upsertDeviceHeartbeat(payload: {
       device.projects = payload.projects;
       device.quota5h = payload.quota5h;
       device.quota7d = payload.quota7d;
-      device.lastSeenAt = nowIso();
+      device.lastSeenAt = nextLastSeenAt;
       device.endpoint = payload.endpoint ?? device.endpoint;
       device.token = claimedEnrollment?.token ?? payload.token ?? device.token;
       device.capabilities = normalizeDeviceCapabilities(
-        payload.capabilities ?? device.capabilities,
-        device.lastSeenAt,
+        refreshDeviceCapabilityLastSeenAt(
+          payload.capabilities ?? device.capabilities,
+          nextLastSeenAt,
+          Boolean(payload.capabilities),
+        ),
+        nextLastSeenAt,
       );
       if (device.preferredExecutionMode === undefined && payload.preferredExecutionMode !== undefined) {
         device.preferredExecutionMode = normalizePreferredExecutionMode(payload.preferredExecutionMode);
diff --git a/tests/device-gui-cli-capabilities.test.ts b/tests/device-gui-cli-capabilities.test.ts
index 04df0e7..0ea8347 100644
--- a/tests/device-gui-cli-capabilities.test.ts
+++ b/tests/device-gui-cli-capabilities.test.ts
@@ -240,3 +240,56 @@ test("device heartbeat does not overwrite the preferred execution mode chosen in
   assert.ok(device);
   assert.equal(device.preferredExecutionMode, "gui");
 });
+
+test("device heartbeat without capability payload refreshes stale gui cli lastSeenAt", async () => {
+  await setup();
+
+  const staleCapabilityTime = "2026-03-25T11:52:00+08:00";
+  const staleState = await readState();
+  await writeState({
+    ...staleState,
+    devices: staleState.devices.map((device) =>
+      device.id === "mac-studio"
+        ? {
+            ...device,
+            lastSeenAt: staleCapabilityTime,
+            capabilities: {
+              gui: {
+                ...device.capabilities?.gui,
+                connected: true,
+                lastSeenAt: staleCapabilityTime,
+                lastActiveProjectId: "master-agent",
+              },
+              cli: {
+                ...device.capabilities?.cli,
+                connected: true,
+                lastSeenAt: staleCapabilityTime,
+                lastActiveProjectId: "master-agent",
+              },
+            },
+          }
+        : device,
+    ),
+  });
+
+  await upsertDeviceHeartbeat({
+    deviceId: "mac-studio",
+    name: "Mac Studio",
+    avatar: "M",
+    account: "17600003315",
+    status: "online",
+    quota5h: 72,
+    quota7d: 86,
+    preferredExecutionMode: "cli",
+    projects: ["硬件审计协作"],
+    endpoint: "mac://kris.local",
+  });
+
+  const state = await readState();
+  const device = state.devices.find((item) => item.id === "mac-studio");
+
+  assert.ok(device);
+  assert.notEqual(device.lastSeenAt, staleCapabilityTime);
+  assert.equal(device.capabilities?.gui.lastSeenAt, device.lastSeenAt);
+  assert.equal(device.capabilities?.cli.lastSeenAt, device.lastSeenAt);
+});