diff --git a/background/steps/create-plus-checkout.js b/background/steps/create-plus-checkout.js
index 6e5d150..905e874 100644
--- a/background/steps/create-plus-checkout.js
+++ b/background/steps/create-plus-checkout.js
@@ -210,13 +210,42 @@
       return Number.isFinite(numeric) ? Math.max(0, Math.floor(numeric)) : null;
     }
 
-    function isGpcAutoModeEnabled(payload = {}) {
-      const rootScope = typeof self !== 'undefined' ? self : globalThis;
-      if (rootScope.GoPayUtils?.isGpcAutoModeEnabled) {
-        return rootScope.GoPayUtils.isGpcAutoModeEnabled(payload);
+    function normalizeGpcAutoModePermissionValue(value) {
+      if (typeof value === 'boolean') {
+        return value;
       }
+      if (typeof value === 'number') {
+        if (value === 1) return true;
+        if (value === 0) return false;
+      }
+      const normalized = String(value ?? '').trim().toLowerCase();
+      if (!normalized) {
+        return null;
+      }
+      if (['true', '1', 'yes', 'y', 'on', 'enabled', 'enable'].includes(normalized)) {
+        return true;
+      }
+      if (['false', '0', 'no', 'n', 'off', 'disabled', 'disable'].includes(normalized)) {
+        return false;
+      }
+      return null;
+    }
+
+    function getGpcAutoModePermission(payload = {}) {
       const data = unwrapGpcResponse(payload);
-      return data?.auto_mode_enabled === true || data?.autoModeEnabled === true;
+      if (!data || typeof data !== 'object' || Array.isArray(data)) {
+        return null;
+      }
+      return normalizeGpcAutoModePermissionValue(
+        data.auto_mode_enabled
+        ?? data.autoModeEnabled
+        ?? data.auto_enabled
+        ?? data.autoEnabled
+      );
+    }
+
+    function isGpcAutoModePermissionDenied(payload = {}) {
+      return getGpcAutoModePermission(payload) === false;
     }
 
     async function assertGpcApiKeyReadyForCreate(state = {}, phoneMode = GPC_HELPER_PHONE_MODE_MANUAL, apiKey = '') {
@@ -244,7 +273,7 @@
       if (remainingUses !== null && remainingUses <= 0) {
         throw new Error('创建 GPC 订单失败：API Key 剩余次数不足。');
       }
-      if (phoneMode === GPC_HELPER_PHONE_MODE_AUTO && !isGpcAutoModeEnabled(balanceData)) {
+      if (phoneMode === GPC_HELPER_PHONE_MODE_AUTO && isGpcAutoModePermissionDenied(balanceData)) {
         throw new Error('创建 GPC 订单失败：当前 GPC API Key 未开通自动模式。');
       }
     }
diff --git a/sidepanel/sidepanel.js b/sidepanel/sidepanel.js
index 2bbb36d..d32e7e0 100644
--- a/sidepanel/sidepanel.js
+++ b/sidepanel/sidepanel.js
@@ -7775,7 +7775,7 @@ async function ensureGpcApiKeyReadyForStart(options = {}) {
     return false;
   }
 
-  if (selectedMode === GPC_HELPER_PHONE_MODE_AUTO && !balanceState.gopayHelperAutoModeEnabled) {
+  if (selectedMode === GPC_HELPER_PHONE_MODE_AUTO && isGpcAutoModePermissionDenied(balanceState)) {
     if (typeof selectGpcHelperPhoneMode !== 'undefined' && selectGpcHelperPhoneMode) {
       selectGpcHelperPhoneMode.value = GPC_HELPER_PHONE_MODE_MANUAL;
     }
@@ -11805,15 +11805,22 @@ btnGpcHelperBalance?.addEventListener('click', async () => {
       gopayHelperAutoModeEnabled: getGpcAutoModeEnabledFromResponse(response),
       gopayHelperApiKeyStatus: response?.apiKeyStatus || response?.data?.status || response?.payload?.data?.status || response?.payload?.status || '',
     };
+    const nextAutoModePermission = getGpcAutoModePermissionFromPayload(nextState.gopayHelperBalancePayload);
+    const nextAutoModeDenied = nextAutoModePermission === false;
+    const nextAutoModeConfirmed = nextAutoModePermission === true || nextState.gopayHelperAutoModeEnabled;
     const selectedModeBeforeBalanceState = getSelectedGpcHelperPhoneMode();
     syncLatestState(nextState);
-    if (!nextState.gopayHelperAutoModeEnabled && selectedModeBeforeBalanceState === GPC_HELPER_PHONE_MODE_AUTO) {
+    if (nextAutoModeDenied && selectedModeBeforeBalanceState === GPC_HELPER_PHONE_MODE_AUTO) {
       selectGpcHelperPhoneMode.value = GPC_HELPER_PHONE_MODE_MANUAL;
       syncLatestState({ gopayHelperPhoneMode: GPC_HELPER_PHONE_MODE_MANUAL });
       await saveSettings({ silent: true, force: true }).catch(() => {});
       showToast('当前 API Key 未开通自动模式，已切回手动模式。', 'warn');
+    } else if (nextAutoModeDenied) {
+      showToast('GPC 余额已更新，当前 API Key 只能使用手动模式。', 'success');
+    } else if (nextAutoModeConfirmed) {
+      showToast('GPC 余额已更新，自动模式可用。', 'success');
     } else {
-      showToast(nextState.gopayHelperAutoModeEnabled ? 'GPC 余额已更新，自动模式可用。' : 'GPC 余额已更新，当前 API Key 只能使用手动模式。', 'success');
+      showToast('GPC 余额已更新，当前接口未返回自动模式权限，已保留所选模式。', 'success');
     }
     updatePlusModeUI();
   } catch (error) {
diff --git a/tests/plus-checkout-create-wait.test.js b/tests/plus-checkout-create-wait.test.js
index 9b3d01a..6c13520 100644
--- a/tests/plus-checkout-create-wait.test.js
+++ b/tests/plus-checkout-create-wait.test.js
@@ -510,6 +510,63 @@ test('GPC auto checkout only sends access token and API Key', async () => {
   assert.equal(events.find((event) => event.type === 'complete')?.step, 6);
 });
 
+test('GPC auto checkout keeps running when balance payload omits auto mode permission', async () => {
+  const events = [];
+  const fetchCalls = [];
+  const executor = api.createPlusCheckoutCreateExecutor({
+    addLog: async () => {},
+    chrome: {
+      tabs: {
+        create: async () => {
+          throw new Error('should not open token tab when direct access token exists');
+        },
+        remove: async () => {},
+      },
+    },
+    completeStepFromBackground: async (step, payload) => events.push({ type: 'complete', step, payload }),
+    ensureContentScriptReadyOnTabUntilStopped: async () => {},
+    fetch: async (url, options = {}) => {
+      fetchCalls.push({ url, options });
+      return {
+        ok: true,
+        status: 200,
+        json: async () => url.endsWith('/api/gp/balance')
+          ? createGpcBalanceResponse({ auto_mode_enabled: undefined, remaining_uses: 998 })
+          : createGpcTaskResponse({
+              task_id: 'task_auto_unknown_permission',
+              status: 'queued',
+              status_text: '排队中',
+              phone_mode: 'auto',
+              api_waiting_for: '',
+            }),
+      };
+    },
+    registerTab: async () => {},
+    sendTabMessageUntilStopped: async () => ({}),
+    setState: async (payload) => events.push({ type: 'set-state', payload }),
+    sleepWithStop: async () => {},
+    waitForTabCompleteUntilStopped: async () => {},
+  });
+
+  await executor.executePlusCheckoutCreate({
+    plusPaymentMethod: 'gpc-helper',
+    gopayHelperPhoneMode: 'auto',
+    gopayHelperApiUrl: 'https://gpc.qlhazycoder.top/',
+    chatgptAccessToken: 'state-access-token',
+    gopayHelperApiKey: 'gpc_auto_123',
+  });
+
+  assert.equal(fetchCalls.length, 2);
+  assert.equal(fetchCalls[0].url, 'https://gpc.qlhazycoder.top/api/gp/balance');
+  assert.equal(fetchCalls[1].url, 'https://gpc.qlhazycoder.top/api/gp/tasks');
+  const helperPayload = JSON.parse(fetchCalls[1].options.body);
+  assert.equal(helperPayload.phone_mode, 'auto');
+  const statePayload = events.find((event) => event.type === 'set-state')?.payload || {};
+  assert.equal(statePayload.gopayHelperTaskId, 'task_auto_unknown_permission');
+  assert.equal(statePayload.gopayHelperPhoneMode, 'auto');
+  assert.equal(events.find((event) => event.type === 'complete')?.step, 6);
+});
+
 test('GPC auto checkout blocks API Keys without auto mode permission', async () => {
   const fetchCalls = [];
   const executor = api.createPlusCheckoutCreateExecutor({
diff --git a/tests/sidepanel-plus-payment-method.test.js b/tests/sidepanel-plus-payment-method.test.js
index 92c0e6b..fdd8e6d 100644
--- a/tests/sidepanel-plus-payment-method.test.js
+++ b/tests/sidepanel-plus-payment-method.test.js
@@ -502,6 +502,70 @@ return { updatePlusModeUI, selectGpcHelperPhoneMode, plusPaymentMethodCaption, r
   assert.match(api.plusPaymentMethodCaption.textContent, /自动/);
 });
 
+test('sidepanel start check keeps GPC auto mode when balance payload omits permission field', async () => {
+  const bundle = [
+    extractFunction('normalizeGpcAutoModePermissionValue'),
+    extractFunction('getGpcAutoModePermissionFromPayload'),
+    extractFunction('isGpcAutoModePermissionDenied'),
+    extractFunction('normalizeGpcRemainingUsesValue'),
+    extractFunction('ensureGpcApiKeyReadyForStart'),
+  ].join('\n');
+
+  const api = new Function(`
+let latestState = { gopayHelperPhoneMode: 'auto' };
+const GPC_HELPER_PHONE_MODE_AUTO = 'auto';
+const GPC_HELPER_PHONE_MODE_MANUAL = 'manual';
+const selectGpcHelperPhoneMode = { value: 'auto' };
+const dialogs = [];
+let saveCalls = 0;
+let updateCalls = 0;
+${bundle}
+function isGpcHelperCheckoutSelected() { return true; }
+function getSelectedGpcHelperPhoneMode() { return selectGpcHelperPhoneMode.value; }
+async function refreshGpcBalanceForStart() {
+  return {
+    gopayHelperRemainingUses: 998,
+    gopayHelperApiKeyStatus: 'active',
+    gopayHelperAutoModeEnabled: false,
+    gopayHelperBalancePayload: {
+      status: 'active',
+      remaining_uses: 998,
+    },
+  };
+}
+async function showGpcStartBlockedDialog(message) {
+  dialogs.push(message);
+}
+function syncLatestState(nextState) {
+  latestState = { ...latestState, ...nextState };
+}
+function updatePlusModeUI() {
+  updateCalls += 1;
+}
+async function saveSettings() {
+  saveCalls += 1;
+}
+function showToast() {}
+return {
+  ensureGpcApiKeyReadyForStart,
+  selectGpcHelperPhoneMode,
+  getDialogs: () => dialogs.slice(),
+  getSaveCalls: () => saveCalls,
+  getUpdateCalls: () => updateCalls,
+  getPersistedPhoneMode: () => latestState.gopayHelperPhoneMode,
+};
+`)();
+
+  const allowed = await api.ensureGpcApiKeyReadyForStart();
+
+  assert.equal(allowed, true);
+  assert.equal(api.selectGpcHelperPhoneMode.value, 'auto');
+  assert.equal(api.getPersistedPhoneMode(), 'auto');
+  assert.equal(api.getSaveCalls(), 0);
+  assert.equal(api.getUpdateCalls(), 0);
+  assert.deepEqual(api.getDialogs(), []);
+});
+
 test('sidepanel resolves pending GoPay manual confirmation from DATA_UPDATED state', async () => {
   const bundle = [
     extractFunction('openPlusManualConfirmationDialog'),