diff --git a/src/components/CloudAccountCard.tsx b/src/components/CloudAccountCard.tsx
index a548a61..2253dce 100644
--- a/src/components/CloudAccountCard.tsx
+++ b/src/components/CloudAccountCard.tsx
@@ -37,6 +37,7 @@ import {
 import { useState } from 'react';
 import { useSetAccountProxy } from '@/hooks/useCloudAccounts';
 import { isValidProxyUrl } from '@/utils/url';
+import { getValidationBlockedStatusLabel } from '@/components/accountValidationStatus';
 
 type ModelQuotaEntry = [string, CloudQuotaModelInfo];
 
@@ -336,6 +337,12 @@ export function CloudAccountCard({
     }
   };
 
+  const validationBlockedStatusLabel = getValidationBlockedStatusLabel(
+    account.status,
+    account.status_reason,
+    t,
+  );
+
   return (
     <Card
       className={`group bg-card hover:border-primary/40 flex h-full flex-col overflow-hidden border transition-all duration-200 hover:shadow-sm ${isSelected ? 'ring-primary border-primary/50 ring-2' : ''}`}
@@ -474,7 +481,11 @@ export function CloudAccountCard({
         <div className="mb-3 flex items-center justify-between">
           <div className="flex items-center gap-2">
             <Badge
-              variant={account.status === 'rate_limited' ? 'destructive' : 'outline'}
+              variant={
+                account.status === 'rate_limited' || account.status === 'expired'
+                  ? 'destructive'
+                  : 'outline'
+              }
               className="text-xs"
             >
               {account.provider.toUpperCase()}
@@ -484,9 +495,9 @@ export function CloudAccountCard({
                 {t('cloud.card.active')}
               </Badge>
             )}
-            {account.status === 'rate_limited' && (
+            {validationBlockedStatusLabel && (
               <span className="text-destructive text-xs font-medium">
-                {t('cloud.card.rateLimited')}
+                {validationBlockedStatusLabel}
               </span>
             )}
           </div>
@@ -636,6 +647,12 @@ export function CompactCloudAccountCard({
     }
   };
 
+  const validationBlockedStatusLabel = getValidationBlockedStatusLabel(
+    account.status,
+    account.status_reason,
+    t,
+  );
+
   return (
     <div className="group bg-card hover:border-primary/40 flex items-center gap-3 rounded-lg border px-3 py-2 transition-all duration-200">
       {account.avatar_url ? (
@@ -656,7 +673,11 @@ export function CompactCloudAccountCard({
             {account.name || t('cloud.card.unknown')}
           </span>
           <Badge
-            variant={account.status === 'rate_limited' ? 'destructive' : 'outline'}
+            variant={
+              account.status === 'rate_limited' || account.status === 'expired'
+                ? 'destructive'
+                : 'outline'
+            }
             className="shrink-0 text-[10px]"
           >
             {account.provider.toUpperCase()}
@@ -673,6 +694,9 @@ export function CompactCloudAccountCard({
 
         <div className="text-muted-foreground flex items-center gap-3 text-xs">
           <span className="truncate">{account.email}</span>
+          {validationBlockedStatusLabel && (
+            <span className="text-destructive shrink-0 font-medium">{validationBlockedStatusLabel}</span>
+          )}
 
           {shouldShowAiCredits && aiCredits && (
             <span className="shrink-0 text-amber-500">
diff --git a/src/services/CloudMonitorService.ts b/src/services/CloudMonitorService.ts
index 27378cc..9de4abc 100644
--- a/src/services/CloudMonitorService.ts
+++ b/src/services/CloudMonitorService.ts
@@ -3,6 +3,16 @@ import { CloudAccountRepo } from '../ipc/database/cloudHandler';
 import { GoogleAPIService } from './GoogleAPIService';
 import { AutoSwitchService } from './AutoSwitchService';
 import { logger } from '../utils/logger';
+import { classifyAccountStatusFromError } from '../utils/account-status';
+
+function hasReusableCachedQuota(account: {
+  quota?: { models?: Record<string, unknown> };
+}): boolean {
+  if (!account.quota || !account.quota.models) {
+    return false;
+  }
+  return Object.keys(account.quota.models).length > 0;
+}
 
 export class CloudMonitorService {
   private static intervalId: NodeJS.Timeout | null = null;
@@ -106,14 +116,23 @@ export class CloudMonitorService {
               const newToken = await GoogleAPIService.refreshAccessToken(
                 account.token.refresh_token,
                 account.proxy_url,
+                account.token.oauth_client_key,
               );
               account.token.access_token = newToken.access_token;
               account.token.expires_in = newToken.expires_in;
               account.token.expiry_timestamp = now + newToken.expires_in;
+              account.token.oauth_client_key = GoogleAPIService.normalizeRefreshedOAuthClientKey(
+                account.token,
+                newToken.oauth_client_key,
+              );
               await CloudAccountRepo.updateToken(account.id, account.token);
               accessToken = newToken.access_token;
             } catch (refreshError) {
               logger.error(`Monitor: Token refresh failed for ${account.email}`, refreshError);
+              const classified = classifyAccountStatusFromError(refreshError);
+              if (classified) {
+                await CloudAccountRepo.setAccountStatus(account.id, classified.status, classified.reason);
+              }
               continue;
             }
           }
@@ -139,9 +158,18 @@ export class CloudMonitorService {
           // 3. Update DB
           await CloudAccountRepo.updateQuota(account.id, quota);
           await CloudAccountRepo.updateLastUsed(account.id);
+          await CloudAccountRepo.setAccountStatus(account.id, 'active', null);
         } catch (error) {
           logger.error(`Monitor: Failed to update ${account.email}`, error);
-          // Could mark status as 'error' or 'rate_limited' if 429
+          const classified = classifyAccountStatusFromError(error);
+          if (classified) {
+            await CloudAccountRepo.setAccountStatus(account.id, classified.status, classified.reason);
+            if (classified.status === 'rate_limited' && hasReusableCachedQuota(account)) {
+              logger.warn(
+                `Monitor: Quota request rate-limited for ${account.email}, keeping cached quota as fallback.`,
+              );
+            }
+          }
         }
       }
 
diff --git a/src/tests/unit/cloud-monitor.test.ts b/src/tests/unit/cloud-monitor.test.ts
index 9025815..3351f6b 100644
--- a/src/tests/unit/cloud-monitor.test.ts
+++ b/src/tests/unit/cloud-monitor.test.ts
@@ -61,7 +61,7 @@ describe('CloudMonitorService', () => {
     await pollPromise;
 
     expect(CloudAccountRepo.getAccounts).toHaveBeenCalled();
-    expect(GoogleAPIService.fetchQuota).toHaveBeenCalledWith('valid_token');
+    expect(GoogleAPIService.fetchQuota).toHaveBeenCalledWith('valid_token', undefined);
     expect(CloudAccountRepo.updateQuota).toHaveBeenCalledWith('acc1', expect.anything());
     expect(CloudAccountRepo.updateLastUsed).toHaveBeenCalledWith('acc1');
     expect(AutoSwitchService.checkAndSwitchIfNeeded).toHaveBeenCalled();
@@ -93,9 +93,13 @@ describe('CloudMonitorService', () => {
     await vi.advanceTimersByTimeAsync(1000);
     await pollPromise;
 
-    expect(GoogleAPIService.refreshAccessToken).toHaveBeenCalledWith('ref_token');
+    expect(GoogleAPIService.refreshAccessToken).toHaveBeenCalledWith(
+      'ref_token',
+      undefined,
+      undefined,
+    );
     expect(CloudAccountRepo.updateToken).toHaveBeenCalled();
-    expect(GoogleAPIService.fetchQuota).toHaveBeenCalledWith('new_token');
+    expect(GoogleAPIService.fetchQuota).toHaveBeenCalledWith('new_token', undefined);
   });
 
   describe('handleAppFocus (Smart Refresh)', () => {
diff --git a/src/utils/account-status.ts b/src/utils/account-status.ts
new file mode 100644
index 0000000..92c1b32
--- /dev/null
+++ b/src/utils/account-status.ts
@@ -0,0 +1,73 @@
+export const RATE_LIMIT_HINTS = [
+  'resource_exhausted',
+  'too many requests',
+  '429',
+  'rate limit',
+  'rate-limited',
+  'risk control',
+  'risk-controlled',
+  'frozen',
+] as const;
+
+export const OAUTH_HINTS = [
+  'unauthorized_client',
+  'invalid_client',
+  'invalid_grant',
+  'oauth client',
+  'not authorized',
+  'token expired',
+  'reauth',
+  'verify your account',
+  'further action is required',
+  'validation required',
+  'validation_url',
+  'appeal_url',
+] as const;
+
+function includesAny(text: string, hints: readonly string[]): boolean {
+  return hints.some((hint) => text.includes(hint));
+}
+
+export function isRateLimitReason(reason: string): boolean {
+  return includesAny(reason.toLowerCase(), RATE_LIMIT_HINTS);
+}
+
+export function isOAuthReauthReason(reason: string): boolean {
+  return includesAny(reason.toLowerCase(), OAUTH_HINTS);
+}
+
+export function extractErrorMessage(error: unknown): string {
+  if (error instanceof Error) {
+    return error.message;
+  }
+  if (typeof error === 'string') {
+    return error;
+  }
+  return String(error);
+}
+
+export function classifyAccountStatusFromError(
+  error: unknown,
+): { status: 'rate_limited' | 'expired'; reason: string } | null {
+  const reason = extractErrorMessage(error).trim();
+  if (!reason) {
+    return null;
+  }
+
+  const normalizedReason = reason.toLowerCase();
+  if (isRateLimitReason(normalizedReason)) {
+    return { status: 'rate_limited', reason };
+  }
+  if (isOAuthReauthReason(normalizedReason)) {
+    return { status: 'expired', reason };
+  }
+
+  if (normalizedReason.includes('forbidden')) {
+    return { status: 'rate_limited', reason };
+  }
+  if (normalizedReason.includes('unauthorized')) {
+    return { status: 'expired', reason };
+  }
+
+  return null;
+}