diff --git a/visionA-frontend/src/app/devices/page.tsx b/visionA-frontend/src/app/devices/page.tsx
index 2489561..e717bc7 100644
--- a/visionA-frontend/src/app/devices/page.tsx
+++ b/visionA-frontend/src/app/devices/page.tsx
@@ -19,6 +19,7 @@ import Link from "next/link";
 import { Link2, RefreshCw } from "lucide-react";
 
 import { DeviceList } from "@/components/devices/device-list";
+import { DeviceRescanButton } from "@/components/devices/device-rescan-button";
 import { Button } from "@/components/ui/button";
 import { useT } from "@/lib/i18n/context";
 import { useDeviceStore } from "@/stores/device-store";
@@ -54,6 +55,9 @@ export default function DevicesPage() {
               className={`size-4 ${isLoading ? "animate-spin" : ""}`}
             />
           </Button>
+          {/* 重新掃描 USB（觸發 local agent rescan）— 與上方「刷新列表」不同：
+              刷新只重讀雲端 DB，rescan 讓剛插入的新 USB 裝置被偵測出來。 */}
+          <DeviceRescanButton />
           <Link href="/devices/pair">
             <Button data-testid="devices-pair-cta">
               <Link2 aria-hidden="true" className="mr-2 size-4" />
diff --git a/visionA-frontend/src/components/devices/device-rescan-button.test.tsx b/visionA-frontend/src/components/devices/device-rescan-button.test.tsx
new file mode 100644
index 0000000..38df47c
--- /dev/null
+++ b/visionA-frontend/src/components/devices/device-rescan-button.test.tsx
@@ -0,0 +1,125 @@
+/**
+ * DeviceRescanButton 測試 — 重新掃描 USB 按鈕
+ *
+ * 覆蓋：
+ *   - 有 online 裝置 → 按鈕可點；掃描中 disable + 顯示「掃描中…」
+ *   - 成功 → success toast；失敗 → error toast（帶對應 code 描述）
+ *   - 無 online 裝置（tunnel 離線）→ 按鈕 disable，點不觸發 rescan
+ */
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { LocaleProvider } from "@/lib/i18n/context";
+import type { DeviceSummary } from "@/stores/device-store";
+import { useDeviceStore } from "@/stores/device-store";
+
+import { DeviceRescanButton } from "./device-rescan-button";
+
+// sonner toast mock — 斷言 success / error 呼叫。
+const toastSuccess = vi.fn();
+const toastError = vi.fn();
+vi.mock("sonner", () => ({
+  toast: {
+    success: (...args: unknown[]) => toastSuccess(...args),
+    error: (...args: unknown[]) => toastError(...args),
+  },
+}));
+
+const onlineDevice: DeviceSummary = {
+  id: "dev-1",
+  name: "KL520",
+  type: "kl520",
+  status: "connected",
+  remoteStatus: "online",
+};
+
+const offlineDevice: DeviceSummary = {
+  ...onlineDevice,
+  id: "dev-off",
+  remoteStatus: "offline",
+};
+
+function resetStore(devices: DeviceSummary[]) {
+  useDeviceStore.setState({
+    devices,
+    selectedDevice: null,
+    isLoading: false,
+    connectingId: null,
+    disconnectingId: null,
+    unpairingId: null,
+    registeringId: null,
+    isRescanning: false,
+    error: null,
+  });
+}
+
+function renderButton() {
+  return render(
+    <LocaleProvider>
+      <DeviceRescanButton />
+    </LocaleProvider>,
+  );
+}
+
+beforeEach(() => {
+  toastSuccess.mockClear();
+  toastError.mockClear();
+  resetStore([onlineDevice]);
+});
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+describe("DeviceRescanButton", () => {
+  it("有 online 裝置 → 按鈕可點；成功時呼叫 rescanDevices 並跳 success toast", async () => {
+    const rescan = vi.fn().mockResolvedValue({ ok: true });
+    useDeviceStore.setState({ rescanDevices: rescan });
+
+    renderButton();
+    const btn = screen.getByTestId("device-rescan-btn");
+    expect(btn).toBeEnabled();
+
+    fireEvent.click(btn);
+
+    expect(rescan).toHaveBeenCalledOnce();
+    await waitFor(() => expect(toastSuccess).toHaveBeenCalledOnce());
+    expect(toastError).not.toHaveBeenCalled();
+  });
+
+  it("掃描中（isRescanning=true）→ 按鈕 disable 且顯示「掃描中…」", () => {
+    useDeviceStore.setState({ isRescanning: true });
+    renderButton();
+    const btn = screen.getByTestId("device-rescan-btn");
+    expect(btn).toBeDisabled();
+    expect(btn).toHaveTextContent("掃描中…");
+  });
+
+  it("失敗（TUNNEL_DISCONNECTED）→ 跳 error toast，帶離線描述", async () => {
+    const rescan = vi
+      .fn()
+      .mockResolvedValue({ ok: false, code: "TUNNEL_DISCONNECTED", message: "offline" });
+    useDeviceStore.setState({ rescanDevices: rescan });
+
+    renderButton();
+    fireEvent.click(screen.getByTestId("device-rescan-btn"));
+
+    await waitFor(() => expect(toastError).toHaveBeenCalledOnce());
+    const [, opts] = toastError.mock.calls[0] as [string, { description: string }];
+    expect(opts.description).toContain("local agent");
+    expect(toastSuccess).not.toHaveBeenCalled();
+  });
+
+  it("無 online 裝置（tunnel 離線）→ 按鈕 disable，點了不觸發 rescan", async () => {
+    const rescan = vi.fn().mockResolvedValue({ ok: true });
+    resetStore([offlineDevice]);
+    useDeviceStore.setState({ rescanDevices: rescan });
+
+    renderButton();
+    const btn = screen.getByTestId("device-rescan-btn");
+    expect(btn).toBeDisabled();
+
+    fireEvent.click(btn);
+    expect(rescan).not.toHaveBeenCalled();
+  });
+});
diff --git a/visionA-frontend/src/components/devices/device-rescan-button.tsx b/visionA-frontend/src/components/devices/device-rescan-button.tsx
new file mode 100644
index 0000000..a9b4900
--- /dev/null
+++ b/visionA-frontend/src/components/devices/device-rescan-button.tsx
@@ -0,0 +1,82 @@
+"use client";
+
+/**
+ * DeviceRescanButton — 重新掃描 USB 裝置按鈕
+ *
+ * 動機：
+ *   使用者插入新的 USB 裝置後，雲端網頁抓不到（需重啟 local agent 才會 rescan）。
+ *   後端 rescan 管線全部現成：`POST /api/devices/scan`（雲端 proxy 轉發 local agent
+ *   的 ScanDevices → Rescan，重新偵測 USB 含新插入 / 拔除）。本按鈕補上前端入口：
+ *   點按鈕 → rescanDevices()（打 scan → 成功後 fetchDevices refresh）→ 新裝置就出現。
+ *
+ * 行為：
+ *   - loading：掃描中 disable + spinner + 文案「掃描中…」。
+ *   - 成功：toast「已重新掃描」。
+ *   - 失敗：toast 友善錯誤；tunnel 離線（TUNNEL_DISCONNECTED）給明確提示。
+ *
+ * 離線 gate：
+ *   scan 是 tunnel proxy 操作，無 online agent 時後端必回 502 TUNNEL_DISCONNECTED。
+ *   為避免使用者點了才失敗，這裡在「沒有任何 online 裝置」時直接 disable 按鈕，
+ *   並以 title / aria 提示原因（比照 workspace 對 tunnel 離線的處理精神）。
+ */
+
+import { toast } from "sonner";
+import { RefreshCw } from "lucide-react";
+
+import { Button } from "@/components/ui/button";
+import { useT } from "@/lib/i18n/context";
+import { useDeviceStore } from "@/stores/device-store";
+
+interface DeviceRescanButtonProps {
+  size?: "sm" | "default";
+}
+
+/** rescan 失敗時把 backend code 映射到 i18n key（找不到 → unknown 文案）。 */
+function rescanErrorDesc(t: (k: string) => string, code: string): string {
+  const key = `devices.rescan.error.${code}`;
+  const resolved = t(key);
+  return resolved === key ? t("devices.rescan.error.unknown") : resolved;
+}
+
+export function DeviceRescanButton({ size = "sm" }: DeviceRescanButtonProps) {
+  const t = useT();
+  const rescanDevices = useDeviceStore((s) => s.rescanDevices);
+  const isRescanning = useDeviceStore((s) => s.isRescanning);
+  // 是否至少有一台裝置在線（有 online tunnel）——scan 只有在有 online agent 時才可能成功。
+  const hasOnlineAgent = useDeviceStore((s) =>
+    s.devices.some((d) => d.remoteStatus === "online"),
+  );
+
+  const disabled = isRescanning || !hasOnlineAgent;
+
+  async function handleRescan() {
+    const result = await rescanDevices();
+    if (result.ok) {
+      toast.success(t("devices.rescan.toast.success"));
+    } else {
+      toast.error(t("devices.rescan.error.title"), {
+        description: rescanErrorDesc(t, result.code),
+      });
+    }
+  }
+
+  return (
+    <Button
+      type="button"
+      variant="outline"
+      size={size}
+      onClick={handleRescan}
+      disabled={disabled}
+      data-testid="device-rescan-btn"
+      // 離線時說明為何 disable；線上時給一般 tooltip。
+      title={hasOnlineAgent ? undefined : t("devices.rescan.offlineHint")}
+      aria-label={t("devices.rescan.action")}
+    >
+      <RefreshCw
+        aria-hidden="true"
+        className={`mr-2 size-4 ${isRescanning ? "animate-spin" : ""}`}
+      />
+      {isRescanning ? t("devices.rescan.pending") : t("devices.rescan.action")}
+    </Button>
+  );
+}
diff --git a/visionA-frontend/src/lib/i18n/dictionaries/en.ts b/visionA-frontend/src/lib/i18n/dictionaries/en.ts
index 194be1c..30351d2 100644
--- a/visionA-frontend/src/lib/i18n/dictionaries/en.ts
+++ b/visionA-frontend/src/lib/i18n/dictionaries/en.ts
@@ -106,19 +106,19 @@ export const en: Dictionary = {
   "dashboard.flashes": "Flashes",
   "dashboard.connectedDevices": "Online devices",
   "dashboard.noConnectedDevices":
-    "No devices are online. Pair a Kneron device to start cloud inference.",
+    "No devices are online. Connect your computer to use Kneron devices from the cloud.",
   "dashboard.recentActivity": "Recent activity",
   "dashboard.noActivity":
-    "Nothing here yet. Activity appears after pairing, uploads, or inference runs.",
+    "Nothing here yet. Activity appears after connecting a computer, uploads, or inference runs.",
   "dashboard.quickActions": "Quick actions",
   "dashboard.browseModels": "Browse models",
   "dashboard.manageDevices": "Manage devices",
   "dashboard.uploadModel": "Upload model",
-  "dashboard.pairDevice": "Pair device",
+  "dashboard.pairDevice": "Connect computer",
   "dashboard.empty.title": "No devices yet",
   "dashboard.empty.description":
-    "Pair your first Kneron device to start running inference from anywhere.",
-  "dashboard.empty.action": "Pair a device",
+    "Connect your computer to start using Kneron devices from anywhere.",
+  "dashboard.empty.action": "Connect computer",
   "dashboard.activity.justNow": "just now",
   "dashboard.activity.minutesAgo": "{n} minutes ago",
   "dashboard.activity.hoursAgo": "{n} hours ago",
@@ -131,13 +131,13 @@ export const en: Dictionary = {
   "devices.firmware": "Firmware",
   "devices.flashedModel": "Flashed model",
   "devices.openWorkspace": "Open workspace",
-  "devices.addMore": "Pair a new device",
-  "devices.pairAction": "Pair a new device",
-  "devices.empty.title": "No devices paired yet",
+  "devices.addMore": "Connect a new computer",
+  "devices.pairAction": "Connect a new computer",
+  "devices.empty.title": "No computers connected yet",
   "devices.empty.description":
-    "Run local agent on your computer and complete pairing to access your Kneron devices from anywhere.",
-  "devices.empty.action": "Pair your first device",
-  "devices.empty.secondaryAction": "How pairing works",
+    "Run local agent on your computer and complete the connection to access your Kneron devices from anywhere.",
+  "devices.empty.action": "Connect your computer",
+  "devices.empty.secondaryAction": "How connecting works",
   "devices.detail.id": "ID",
   "devices.detail.type": "Type",
   "devices.detail.firmware": "Firmware",
@@ -146,7 +146,7 @@ export const en: Dictionary = {
   "devices.detail.modelStatus": "Model status",
   "devices.detail.readyForInference": "Ready for inference",
   "devices.detail.noModelFlashed": "No model has been flashed",
-  "devices.detail.pairedAt": "Paired at",
+  "devices.detail.pairedAt": "Connected at",
   "devices.detail.hostName": "Host",
   "devices.detail.lastSeen": "Last seen",
   "devices.detail.offlineBanner.title": "This device is offline",
@@ -165,14 +165,14 @@ export const en: Dictionary = {
   "devices.serial.label": "Serial number",
   "devices.serial.missing": "Serial not reported yet",
   "devices.serial.missingHint":
-    "This device hasn't reported its serial number, so inference-related actions are unavailable. Re-pair it once from local agent to report the serial.",
+    "This device hasn't reported its serial number, so inference-related actions are unavailable. Re-connect once from local agent to report the serial.",
 
   // ── Devices: remove (unpair) ──
   "devices.remove.action": "Remove device",
   "devices.remove.removing": "Removing…",
   "devices.remove.confirm.title": "Remove this device?",
   "devices.remove.confirm.description":
-    "This unpairs “{name}” from your account and revokes its access. To use it again, you'll need to pair it from local agent. This cannot be undone.",
+    "This disconnects “{name}” from your account and revokes its access. To use it again, you'll need to connect it from local agent. This cannot be undone.",
   "devices.remove.confirm.action": "Remove",
   "devices.remove.toast.success": "Device removed",
   "devices.remove.error.title": "Couldn't remove device",
@@ -217,6 +217,16 @@ export const en: Dictionary = {
     "Try a different filter, or clear it to see all your devices.",
   "devices.filter.empty.action": "Clear filter",
 
+  // ── Devices: rescan USB (re-detect newly plugged devices) ──
+  "devices.rescan.action": "Rescan devices",
+  "devices.rescan.pending": "Scanning…",
+  "devices.rescan.toast.success": "Devices rescanned",
+  "devices.rescan.error.title": "Couldn't rescan devices",
+  "devices.rescan.error.TUNNEL_DISCONNECTED":
+    "The local agent is offline. Make sure it's running and connected, then try again.",
+  "devices.rescan.error.unknown": "Something went wrong. Please try again.",
+  "devices.rescan.offlineHint": "Connect a local agent to rescan for USB devices.",
+
   // ── Devices: flash (load model to device) ──
   "devices.flash.flashModel": "Load model",
   "devices.flash.flashToDevice": "Load a model to this device",
@@ -279,7 +289,7 @@ export const en: Dictionary = {
   "models.filters.all": "All",
   "models.empty.title": "No models yet",
   "models.empty.description":
-    "Upload your first .nef model to deploy it to any paired Kneron device.",
+    "Upload your first .nef model to deploy it to any Kneron device on a connected computer.",
   "models.empty.action": "Upload your first model",
   "models.section.preset": "Preset models",
   "models.section.converted": "Converted by you",
@@ -423,7 +433,7 @@ export const en: Dictionary = {
   "workspace.subtitle": "Select an online device to start inference",
   "workspace.empty.title": "No devices are online",
   "workspace.empty.description":
-    "Pair a device and make sure the local agent is connected to the cloud.",
+    "Connect your computer and make sure the local agent is connected to the cloud.",
   "workspace.empty.action": "Go to devices",
   "workspace.header.backToDevices": "Back to devices",
   "workspace.header.title": "Workspace",
@@ -452,7 +462,7 @@ export const en: Dictionary = {
   "workspace.offline.backToList": "Back to devices",
   "workspace.noSerial.title": "This device hasn't reported a serial number",
   "workspace.noSerial.description":
-    "Inference, camera, and media upload need the device serial to route to local agent. Re-pair the device once from local agent; these actions unlock after the serial is reported.",
+    "Inference, camera, and media upload need the device serial to route to local agent. Re-connect once from local agent; these actions unlock after the serial is reported.",
   "workspace.tabs.camera": "Camera",
   "workspace.tabs.image": "Image",
   "workspace.tabs.video": "Video",
@@ -509,35 +519,35 @@ export const en: Dictionary = {
   "settings.advanced.platform": "Platform",
 
   // ── Pairing (F7) ──
-  "pairing.title": "Pair a new device",
+  "pairing.title": "Connect this computer",
   "pairing.subtitle":
-    "Connect your Kneron device to the cloud so you can operate it from anywhere.",
-  "pairing.token.title": "Your pairing token",
+    "Connect this computer to the cloud so its Kneron devices can be operated from anywhere.",
+  "pairing.token.title": "Your connection token",
   "pairing.step1.description":
-    "Copy the token below and paste it into your local agent within 15 minutes.",
+    "Copy the connection token below and paste it into your local agent within 15 minutes.",
   "pairing.copy": "Copy",
   "pairing.copied": "Copied",
   "pairing.regenerate": "Regenerate",
   "pairing.timeRemaining": "{time} remaining",
   "pairing.generatedAt": "Generated at {time}",
-  "pairing.token.expired.label": "This token has expired — please regenerate.",
-  "pairing.regenerateConfirm.title": "Regenerate token?",
+  "pairing.token.expired.label": "This connection token has expired — please regenerate.",
+  "pairing.regenerateConfirm.title": "Regenerate connection token?",
   "pairing.regenerateConfirm.description":
-    "The old token will be invalidated immediately; the new one is valid for 15 minutes.",
+    "The old connection token will be invalidated immediately; the new one is valid for 15 minutes.",
   "pairing.security.warning":
-    "This token is valid for 15 minutes — complete pairing now.",
+    "This connection token is valid for 15 minutes — complete the connection now.",
   "pairing.security.oneTime":
-    "Tokens are single-use and expire automatically after pairing.",
-  "pairing.toast.copied": "Token copied — valid for 15 minutes.",
-  "pairing.toast.generateFailed": "Could not generate token — please retry.",
+    "Connection tokens are single-use and expire automatically after connecting.",
+  "pairing.toast.copied": "Connection token copied — valid for 15 minutes.",
+  "pairing.toast.generateFailed": "Could not generate connection token — please retry.",
   "pairing.toast.expiringSoon":
-    "Token expiring soon — complete pairing or regenerate.",
-  "pairing.toast.pairedSuccess": "Device {deviceName} paired successfully.",
+    "Connection token expiring soon — complete the connection or regenerate.",
+  "pairing.toast.pairedSuccess": "Computer connected — device {deviceName} detected.",
   "pairing.toast.cliCopied": "CLI command copied.",
   "pairing.device.unknown": "Unknown device",
   "pairing.cli.title": "CLI example",
   "pairing.cli.description":
-    "Start local agent on your computer and pass the token to the --relay-token flag.",
+    "Start local agent on your computer and pass the connection token to the --relay-token flag.",
   "pairing.cli.copy": "Copy command",
   "pairing.cli.hint":
     "Once local agent connects to the cloud, this page detects it and forwards you to the device list.",
@@ -545,7 +555,7 @@ export const en: Dictionary = {
   "pairing.step3.elapsed": "Elapsed {time} (max 3 minutes)",
   "pairing.step3.hints.running": "Confirm local agent is running",
   "pairing.step3.hints.token":
-    "Confirm the token was pasted without missing or extra characters",
+    "Confirm the connection token was pasted without missing or extra characters",
   "pairing.step3.hints.network":
     "Confirm your network can reach the cloud endpoint",
   "pairing.step3.success": "Connected!",
diff --git a/visionA-frontend/src/lib/i18n/dictionaries/zh-Hant.ts b/visionA-frontend/src/lib/i18n/dictionaries/zh-Hant.ts
index ecfef89..7f43497 100644
--- a/visionA-frontend/src/lib/i18n/dictionaries/zh-Hant.ts
+++ b/visionA-frontend/src/lib/i18n/dictionaries/zh-Hant.ts
@@ -109,17 +109,17 @@ export const zhHant: Dictionary = {
   "dashboard.connected": "線上裝置",
   "dashboard.flashes": "已燒錄次數",
   "dashboard.connectedDevices": "線上裝置",
-  "dashboard.noConnectedDevices": "目前沒有裝置線上。配對一台 Kneron 裝置開始雲端推論。",
+  "dashboard.noConnectedDevices": "目前沒有裝置線上。連接你的電腦，就能從雲端使用 Kneron 裝置。",
   "dashboard.recentActivity": "近期活動",
-  "dashboard.noActivity": "還沒有任何活動。配對裝置、上傳模型或跑一次推論後就會出現。",
+  "dashboard.noActivity": "還沒有任何活動。連接電腦、上傳模型或跑一次推論後就會出現。",
   "dashboard.quickActions": "快速操作",
   "dashboard.browseModels": "瀏覽模型",
   "dashboard.manageDevices": "管理裝置",
   "dashboard.uploadModel": "上傳模型",
-  "dashboard.pairDevice": "配對裝置",
+  "dashboard.pairDevice": "連接電腦",
   "dashboard.empty.title": "還沒有任何裝置",
-  "dashboard.empty.description": "配對你的第一台 Kneron 裝置，開始雲端推論之旅",
-  "dashboard.empty.action": "配對裝置",
+  "dashboard.empty.description": "連接你的電腦，開始從雲端使用 Kneron 裝置",
+  "dashboard.empty.action": "連接電腦",
   "dashboard.activity.justNow": "剛剛",
   "dashboard.activity.minutesAgo": "{n} 分鐘前",
   "dashboard.activity.hoursAgo": "{n} 小時前",
@@ -132,13 +132,13 @@ export const zhHant: Dictionary = {
   "devices.firmware": "韌體",
   "devices.flashedModel": "已燒錄模型",
   "devices.openWorkspace": "開啟工作區",
-  "devices.addMore": "配對新裝置",
-  "devices.pairAction": "配對新裝置",
-  "devices.empty.title": "還沒有配對的裝置",
+  "devices.addMore": "連接新電腦",
+  "devices.pairAction": "連接新電腦",
+  "devices.empty.title": "還沒有連接任何電腦",
   "devices.empty.description":
-    "在你的電腦上執行 local agent 並完成配對，就能從任何地方存取你的 Kneron 裝置",
-  "devices.empty.action": "配對第一台裝置",
-  "devices.empty.secondaryAction": "查看配對說明",
+    "在你的電腦上執行 local agent 並完成連接，就能從任何地方存取你的 Kneron 裝置",
+  "devices.empty.action": "連接你的電腦",
+  "devices.empty.secondaryAction": "查看連接說明",
   "devices.detail.id": "ID",
   "devices.detail.type": "類型",
   "devices.detail.firmware": "韌體",
@@ -147,7 +147,7 @@ export const zhHant: Dictionary = {
   "devices.detail.modelStatus": "模型狀態",
   "devices.detail.readyForInference": "已就緒，可開始推論",
   "devices.detail.noModelFlashed": "尚未燒錄任何模型",
-  "devices.detail.pairedAt": "配對時間",
+  "devices.detail.pairedAt": "連接時間",
   "devices.detail.hostName": "所在電腦",
   "devices.detail.lastSeen": "最後心跳",
   "devices.detail.offlineBanner.title": "此裝置目前離線",
@@ -166,14 +166,14 @@ export const zhHant: Dictionary = {
   "devices.serial.label": "序號",
   "devices.serial.missing": "尚未回報序號",
   "devices.serial.missingHint":
-    "此裝置尚未回報序號，無法執行推論相關操作。請在 local agent 重新配對一次，序號回報後即可使用。",
+    "此裝置尚未回報序號，無法執行推論相關操作。請在 local agent 重新連接一次，序號回報後即可使用。",
 
   // ── Devices: 移除裝置（unpair） ──
   "devices.remove.action": "移除裝置",
   "devices.remove.removing": "移除中…",
   "devices.remove.confirm.title": "確定要移除此裝置？",
   "devices.remove.confirm.description":
-    "這會解除「{name}」與你帳號的配對並撤銷其存取權限。若要再次使用，需從 local agent 重新配對。此操作無法復原。",
+    "這會解除「{name}」與你帳號的連接並撤銷其存取權限。若要再次使用，需從 local agent 重新連接。此操作無法復原。",
   "devices.remove.confirm.action": "移除",
   "devices.remove.toast.success": "已移除裝置",
   "devices.remove.error.title": "移除裝置失敗",
@@ -216,6 +216,16 @@ export const zhHant: Dictionary = {
   "devices.filter.empty.description": "試試其他篩選條件，或清除篩選以顯示所有裝置。",
   "devices.filter.empty.action": "清除篩選",
 
+  // ── Devices: 重新掃描 USB（偵測新插入的裝置） ──
+  "devices.rescan.action": "重新掃描裝置",
+  "devices.rescan.pending": "掃描中…",
+  "devices.rescan.toast.success": "已重新掃描",
+  "devices.rescan.error.title": "重新掃描失敗",
+  "devices.rescan.error.TUNNEL_DISCONNECTED":
+    "local agent 目前離線。請確認它正在執行並已連線，再試一次。",
+  "devices.rescan.error.unknown": "發生錯誤，請再試一次。",
+  "devices.rescan.offlineHint": "請先連接 local agent，才能重新掃描 USB 裝置。",
+
   // ── Devices: flash（載入模型到裝置） ──
   "devices.flash.flashModel": "載入模型",
   "devices.flash.flashToDevice": "載入模型到此裝置",
@@ -277,7 +287,7 @@ export const zhHant: Dictionary = {
   "models.filters.all": "全部",
   "models.empty.title": "還沒有任何模型",
   "models.empty.description":
-    "上傳你的第一個 .nef 模型到雲端，就能部署到任何一台配對過的 Kneron 裝置",
+    "上傳你的第一個 .nef 模型到雲端，就能部署到任何一台已連接電腦上的 Kneron 裝置",
   "models.empty.action": "上傳第一個模型",
   "models.section.preset": "預設模型",
   "models.section.converted": "我轉檔的",
@@ -412,7 +422,7 @@ export const zhHant: Dictionary = {
   "workspace.title": "推論工作區",
   "workspace.subtitle": "選擇已線上的裝置開始推論",
   "workspace.empty.title": "目前沒有線上裝置",
-  "workspace.empty.description": "請先配對並確認 local agent 已連上雲端",
+  "workspace.empty.description": "請先連接你的電腦並確認 local agent 已連上雲端",
   "workspace.empty.action": "前往裝置管理",
   "workspace.header.backToDevices": "返回裝置",
   "workspace.header.title": "工作區",
@@ -438,7 +448,7 @@ export const zhHant: Dictionary = {
   "workspace.offline.backToList": "返回裝置列表",
   "workspace.noSerial.title": "此裝置尚未回報序號",
   "workspace.noSerial.description":
-    "推論、攝影機與媒體上傳需要裝置序號才能路由到 local agent。請在 local agent 重新配對一次，序號回報後即可操作。",
+    "推論、攝影機與媒體上傳需要裝置序號才能路由到 local agent。請在 local agent 重新連接一次，序號回報後即可操作。",
   "workspace.tabs.camera": "Camera",
   "workspace.tabs.image": "圖片",
   "workspace.tabs.video": "影片",
@@ -494,42 +504,42 @@ export const zhHant: Dictionary = {
   "settings.advanced.platform": "平台",
 
   // ── Pairing（F7 新增）──
-  "pairing.title": "配對新裝置",
-  "pairing.subtitle": "讓你的 Kneron 裝置連上雲端，就能從任何地方遠端操作",
-  "pairing.token.title": "你的 Pairing Token",
+  "pairing.title": "連接這台電腦",
+  "pairing.subtitle": "讓這台電腦連上雲端，之後電腦上的 Kneron 裝置都能從任何地方遠端操作",
+  "pairing.token.title": "你的連接碼",
   "pairing.step1.description":
-    "複製下方 token，在 15 分鐘內貼到 local agent 完成配對",
+    "複製下方連接碼，在 15 分鐘內貼到 local agent 完成連接",
   "pairing.copy": "複製",
   "pairing.copied": "已複製",
   "pairing.regenerate": "重新產生",
   "pairing.timeRemaining": "剩餘 {time}",
   "pairing.generatedAt": "產生時間：{time}",
-  "pairing.token.expired.label": "此 token 已過期，請重新產生",
-  "pairing.regenerateConfirm.title": "確定要重新產生？",
+  "pairing.token.expired.label": "此連接碼已過期，請重新產生",
+  "pairing.regenerateConfirm.title": "確定要重新產生連接碼？",
   "pairing.regenerateConfirm.description":
-    "舊 token 將立即失效，新 token 有效期 15 分鐘",
-  "pairing.security.warning": "這組 token 15 分鐘內有效，請立刻完成配對",
-  "pairing.security.oneTime": "token 是一次性使用，完成配對後自動失效",
-  "pairing.toast.copied": "Token 已複製到剪貼簿，15 分鐘內有效",
-  "pairing.toast.generateFailed": "無法產生 token，請重試",
-  "pairing.toast.expiringSoon": "Token 即將過期，請立刻完成或重新產生",
-  "pairing.toast.pairedSuccess": "裝置 {deviceName} 已成功配對",
+    "舊連接碼將立即失效，新連接碼有效期 15 分鐘",
+  "pairing.security.warning": "這組連接碼 15 分鐘內有效，請立刻完成連接",
+  "pairing.security.oneTime": "連接碼是一次性使用，完成連接後自動失效",
+  "pairing.toast.copied": "連接碼已複製到剪貼簿，15 分鐘內有效",
+  "pairing.toast.generateFailed": "無法產生連接碼，請重試",
+  "pairing.toast.expiringSoon": "連接碼即將過期，請立刻完成或重新產生",
+  "pairing.toast.pairedSuccess": "已成功連接電腦，偵測到裝置 {deviceName}",
   "pairing.toast.cliCopied": "指令已複製到剪貼簿",
   "pairing.device.unknown": "未知裝置",
   "pairing.cli.title": "CLI 指令範例",
   "pairing.cli.description":
-    "在你的電腦啟動 local agent，將 token 貼到指令的 --relay-token 參數",
+    "在你的電腦啟動 local agent，將連接碼貼到指令的 --relay-token 參數",
   "pairing.cli.copy": "複製指令",
   "pairing.cli.hint":
     "local agent 連上雲端後，本頁會自動偵測並跳轉到裝置列表",
   "pairing.step3.waiting": "等待 local agent 連線…",
   "pairing.step3.elapsed": "已等待 {time}（最長 3 分鐘）",
   "pairing.step3.hints.running": "確認 local agent 已啟動",
-  "pairing.step3.hints.token": "確認 token 貼上時無缺字或多餘空白",
+  "pairing.step3.hints.token": "確認連接碼貼上時無缺字或多餘空白",
   "pairing.step3.hints.network": "確認你的網路可連線到雲端",
-  "pairing.step3.success": "已成功連線！",
+  "pairing.step3.success": "已成功連接電腦！",
   "pairing.step3.success.detected": "檢測到的裝置",
-  "pairing.step3.failure.timeout": "連線超時",
+  "pairing.step3.failure.timeout": "連接超時",
   "pairing.step3.failure.reason":
     "超過 3 分鐘沒收到 local agent 連線，可能是 local agent 尚未啟動",
   "pairing.step3.failure.retry": "重新檢查",
diff --git a/visionA-frontend/src/stores/device-store.test.ts b/visionA-frontend/src/stores/device-store.test.ts
index 91ce6fe..73d3336 100644
--- a/visionA-frontend/src/stores/device-store.test.ts
+++ b/visionA-frontend/src/stores/device-store.test.ts
@@ -24,6 +24,7 @@ beforeEach(() => {
     disconnectingId: null,
     unpairingId: null,
     registeringId: null,
+    isRescanning: false,
     error: null,
   });
   // OF2：api.ts 不再需要 token getter（cookie session 由瀏覽器自動帶）
@@ -663,3 +664,101 @@ describe("useDeviceStore.unregisterDevice", () => {
     expect(useDeviceStore.getState().registeringId).toBeNull();
   });
 });
+
+describe("useDeviceStore.rescanDevices", () => {
+  it("成功時打對 scan endpoint（POST）、接著 fetchDevices refresh、回 { ok:true }", async () => {
+    const fetchSpy = vi
+      .spyOn(globalThis, "fetch")
+      // 1) POST /api/devices/scan
+      .mockResolvedValueOnce(jsonResponse({ success: true, data: {} }))
+      // 2) 後續 fetchDevices 的 GET /api/devices（回一台新插入的裝置）
+      .mockResolvedValueOnce(
+        jsonResponse({
+          success: true,
+          data: [
+            {
+              id: "dev-new",
+              name: "KL630",
+              type: "kl630",
+              status: "detected",
+              remote_status: "online",
+            },
+          ],
+        }),
+      );
+
+    const result = await useDeviceStore.getState().rescanDevices();
+
+    expect(result).toEqual({ ok: true });
+    // 第一發是 scan（POST），第二發是 fetchDevices（GET）。
+    expect(String(fetchSpy.mock.calls[0]?.[0])).toContain("/api/devices/scan");
+    expect(fetchSpy.mock.calls[0]?.[1]).toMatchObject({ method: "POST" });
+    expect(String(fetchSpy.mock.calls[1]?.[0])).toContain("/api/devices");
+    // 掃描後列表被 refresh，新裝置出現。
+    const state = useDeviceStore.getState();
+    expect(state.devices.map((d) => d.id)).toEqual(["dev-new"]);
+    expect(state.isRescanning).toBe(false);
+  });
+
+  it("呼叫期間 isRescanning 設為 true（loading 態），完成後清回 false", async () => {
+    let seenDuringScan = false;
+    vi.spyOn(globalThis, "fetch").mockImplementation(async (input) => {
+      // 在 scan 請求進行中觀察 loading 態。
+      if (String(input).includes("/api/devices/scan")) {
+        seenDuringScan = useDeviceStore.getState().isRescanning;
+      }
+      return jsonResponse({ success: true, data: [] });
+    });
+
+    await useDeviceStore.getState().rescanDevices();
+
+    expect(seenDuringScan).toBe(true);
+    expect(useDeviceStore.getState().isRescanning).toBe(false);
+  });
+
+  it("裝置離線（502 TUNNEL_DISCONNECTED）→ 回 { ok:false, code:'TUNNEL_DISCONNECTED' }，不 refresh、不清空列表", async () => {
+    useDeviceStore.setState({
+      devices: [
+        {
+          id: "dev-1",
+          name: "KL520",
+          type: "kl520",
+          status: "connected",
+          remoteStatus: "online",
+        },
+      ],
+    });
+    const fetchSpy = vi.spyOn(globalThis, "fetch").mockResolvedValueOnce(
+      jsonResponse(
+        {
+          success: false,
+          error: { code: "TUNNEL_DISCONNECTED", message: "agent offline" },
+        },
+        502,
+      ),
+    );
+
+    const result = await useDeviceStore.getState().rescanDevices();
+
+    expect(result).toMatchObject({ ok: false, code: "TUNNEL_DISCONNECTED" });
+    // 只打了 scan 一發，沒有接著 fetchDevices（失敗不 refresh）。
+    expect(fetchSpy).toHaveBeenCalledOnce();
+    // 既有列表保留（不清空）。
+    expect(useDeviceStore.getState().devices.map((d) => d.id)).toEqual(["dev-1"]);
+    expect(useDeviceStore.getState().isRescanning).toBe(false);
+    expect(useDeviceStore.getState().error).toBe("agent offline");
+  });
+
+  it("其他錯誤（500）→ 回 { ok:false, code:'INTERNAL_ERROR' }，isRescanning 清回 false", async () => {
+    vi.spyOn(globalThis, "fetch").mockResolvedValueOnce(
+      jsonResponse(
+        { success: false, error: { code: "INTERNAL_ERROR", message: "boom" } },
+        500,
+      ),
+    );
+
+    const result = await useDeviceStore.getState().rescanDevices();
+    expect(result).toMatchObject({ ok: false, code: "INTERNAL_ERROR" });
+    expect(useDeviceStore.getState().isRescanning).toBe(false);
+  });
+});
diff --git a/visionA-frontend/src/stores/device-store.ts b/visionA-frontend/src/stores/device-store.ts
index 608bf9a..14b8eb7 100644
--- a/visionA-frontend/src/stores/device-store.ts
+++ b/visionA-frontend/src/stores/device-store.ts
@@ -203,6 +203,19 @@ export type RegisterResult =
   | { ok: true }
   | { ok: false; code: string; message: string };
 
+/**
+ * rescan（重新掃描 USB 裝置）action 的回傳。
+ *
+ * 採「回 code 而非 boolean」的範式（比照 unpair / register），讓 UI 對不同錯誤分流顯示 toast：
+ *   - scan 是 tunnel proxy 操作（雲端轉發 local agent 的 ScanDevices → Rescan）；
+ *     裝置離線（無 online tunnel）時後端回 502 `TUNNEL_DISCONNECTED`，UI 需針對此顯示
+ *     「請確認 local agent 在線」而非泛用錯誤，故帶 code 出來。
+ * 成功後由呼叫端接著 fetchDevices() refresh 列表（新插入的裝置就會出現）。
+ */
+export type RescanResult =
+  | { ok: true }
+  | { ok: false; code: string; message: string };
+
 interface DeviceState {
   devices: DeviceSummary[];
   selectedDevice: Device | null;
@@ -214,6 +227,8 @@ interface DeviceState {
   unpairingId: string | null;
   /** 註冊 / 取消註冊進行中的裝置 id（UI 顯示 button spinner）；不使用就是 null */
   registeringId: string | null;
+  /** 重新掃描 USB 裝置進行中（UI 顯示按鈕 spinner + disable）；不使用就是 false */
+  isRescanning: boolean;
   error: string | null;
 
   /** 呼叫 `GET /api/devices` */
@@ -246,13 +261,23 @@ interface DeviceState {
    * ⚠️ 取消註冊 ≠ 移除裝置（unpair）：unregister 只清 registeredAt、device 仍在清單顯示為未註冊。
    */
   unregisterDevice: (id: string) => Promise<RegisterResult>;
+  /**
+   * 呼叫 `POST /api/devices/scan`（雲端 proxy 轉發 local agent 的 ScanDevices → Rescan，
+   * 重新偵測 USB：含新插入 / 拔除）。成功後自動接 fetchDevices() 刷新列表，
+   * 讓剛插入的新裝置立即出現（不必重啟 local agent）。
+   *
+   * ⚠️ scan 是 tunnel proxy 操作：無 online tunnel（裝置離線）時後端回 502
+   * `TUNNEL_DISCONNECTED`，回 { ok:false, code:"TUNNEL_DISCONNECTED" } 讓 UI 分流提示。
+   * 失敗時不呼叫 fetchDevices（維持既有列表，不清空）。
+   */
+  rescanDevices: () => Promise<RescanResult>;
   /** 測試 / 雛形用：直接塞 list */
   _setDevices: (devices: DeviceSummary[]) => void;
   /** 測試 / 雛形用：直接塞 selected */
   _setSelected: (device: Device | null) => void;
 }
 
-export const useDeviceStore = create<DeviceState>()((set) => ({
+export const useDeviceStore = create<DeviceState>()((set, get) => ({
   devices: [],
   selectedDevice: null,
   isLoading: false,
@@ -260,6 +285,7 @@ export const useDeviceStore = create<DeviceState>()((set) => ({
   disconnectingId: null,
   unpairingId: null,
   registeringId: null,
+  isRescanning: false,
   error: null,
 
   fetchDevices: async () => {
@@ -416,6 +442,28 @@ export const useDeviceStore = create<DeviceState>()((set) => ({
     }
   },
 
+  rescanDevices: async () => {
+    set({ isRescanning: true, error: null });
+    try {
+      // POST /api/devices/scan：雲端 proxy 透傳 local agent 的 ScanDevices → Rescan。
+      // 回傳的 scan 結果本身不需要（新裝置由後續 fetchDevices 從 DB / tunnel 帶出），
+      // 成功與否由有無 throw 判定（比照 unpair 範式）。
+      await api.post("/api/devices/scan");
+      set({ isRescanning: false });
+      // 掃描完成後 refresh 列表——剛插入的新裝置就會出現。
+      // 這裡 await 讓 UI 的 loading 能延續到列表更新完（fetchDevices 自行管理 isLoading）。
+      await get().fetchDevices();
+      return { ok: true };
+    } catch (err) {
+      // ApiError 帶 backend code（TUNNEL_DISCONNECTED / INTERNAL_ERROR / …）給 UI 分流 toast；
+      // 其他例外（網路層）退化成 unknown。失敗時不呼叫 fetchDevices（維持既有列表）。
+      const message = err instanceof Error ? err.message : String(err);
+      const code = err instanceof ApiError ? err.code : "unknown";
+      set({ isRescanning: false, error: message });
+      return { ok: false, code, message };
+    }
+  },
+
   _setDevices: (devices) => set({ devices }),
   _setSelected: (selectedDevice) => set({ selectedDevice }),
 }));