diff --git a/backend/cmd/server/VERSION b/backend/cmd/server/VERSION
index 2858d7c5..5a7989b0 100644
--- a/backend/cmd/server/VERSION
+++ b/backend/cmd/server/VERSION
@@ -1 +1 @@
-0.1.90.3
+0.1.90.4
diff --git a/backend/internal/repository/claude_usage_service.go b/backend/internal/repository/claude_usage_service.go
index f6054828..e33f2e50 100644
--- a/backend/internal/repository/claude_usage_service.go
+++ b/backend/internal/repository/claude_usage_service.go
@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"time"
 
+	infraerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/httpclient"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 )
@@ -95,7 +96,8 @@ func (s *claudeUsageService) FetchUsageWithOptions(ctx context.Context, opts *se
 
 	if resp.StatusCode != http.StatusOK {
 		body, _ := io.ReadAll(resp.Body)
-		return nil, fmt.Errorf("API returned status %d: %s", resp.StatusCode, string(body))
+		msg := fmt.Sprintf("API returned status %d: %s", resp.StatusCode, string(body))
+		return nil, infraerrors.New(resp.StatusCode, "UPSTREAM_ERROR", msg)
 	}
 
 	var usageResp service.ClaudeUsageResponse
diff --git a/frontend/src/components/account/AccountUsageCell.vue b/frontend/src/components/account/AccountUsageCell.vue
index 859bd7c9..24851afb 100644
--- a/frontend/src/components/account/AccountUsageCell.vue
+++ b/frontend/src/components/account/AccountUsageCell.vue
@@ -278,11 +278,12 @@
 </template>
 
 <script setup lang="ts">
-import { ref, computed, onMounted } from 'vue'
+import { ref, computed, onMounted, onBeforeUnmount } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { adminAPI } from '@/api/admin'
 import type { Account, AccountUsageInfo, GeminiCredentials, WindowStats } from '@/types'
 import { resolveCodexUsageWindow } from '@/utils/codexUsage'
+import { enqueueUsageRequest } from '@/utils/usageLoadQueue'
 import UsageProgressBar from './UsageProgressBar.vue'
 import AccountQuotaInfo from './AccountQuotaInfo.vue'
 
@@ -292,6 +293,9 @@ const props = defineProps<{
 
 const { t } = useI18n()
 
+const unmounted = ref(false)
+onBeforeUnmount(() => { unmounted.value = true })
+
 const loading = ref(false)
 const error = ref<string | null>(null)
 const usageInfo = ref<AccountUsageInfo | null>(null)
@@ -701,12 +705,30 @@ const loadUsage = async () => {
   error.value = null
 
   try {
-    usageInfo.value = await adminAPI.accounts.getUsage(props.account.id)
+    const fetchFn = () => adminAPI.accounts.getUsage(props.account.id)
+    let result: AccountUsageInfo
+    // Only throttle Anthropic OAuth/setup-token accounts to avoid upstream 429
+    if (
+      props.account.platform === 'anthropic' &&
+      (props.account.type === 'oauth' || props.account.type === 'setup-token')
+    ) {
+      result = await enqueueUsageRequest(
+        props.account.platform,
+        'claude_code',
+        props.account.proxy_id,
+        fetchFn
+      )
+    } else {
+      result = await fetchFn()
+    }
+    if (!unmounted.value) usageInfo.value = result
   } catch (e: any) {
-    error.value = t('common.error')
-    console.error('Failed to load usage:', e)
+    if (!unmounted.value) {
+      error.value = t('common.error')
+      console.error('Failed to load usage:', e)
+    }
   } finally {
-    loading.value = false
+    if (!unmounted.value) loading.value = false
   }
 }
 
diff --git a/frontend/src/components/account/__tests__/AccountUsageCell.spec.ts b/frontend/src/components/account/__tests__/AccountUsageCell.spec.ts
index 0b61b3bd..64f15fc9 100644
--- a/frontend/src/components/account/__tests__/AccountUsageCell.spec.ts
+++ b/frontend/src/components/account/__tests__/AccountUsageCell.spec.ts
@@ -14,6 +14,10 @@ vi.mock('@/api/admin', () => ({
   }
 }))
 
+vi.mock('@/utils/usageLoadQueue', () => ({
+  enqueueUsageRequest: (_p: string, _t: string, _id: unknown, fn: () => Promise<unknown>) => fn()
+}))
+
 vi.mock('vue-i18n', async () => {
   const actual = await vi.importActual<typeof import('vue-i18n')>('vue-i18n')
   return {
diff --git a/frontend/src/utils/__tests__/usageLoadQueue.spec.ts b/frontend/src/utils/__tests__/usageLoadQueue.spec.ts
new file mode 100644
index 00000000..24cebec8
--- /dev/null
+++ b/frontend/src/utils/__tests__/usageLoadQueue.spec.ts
@@ -0,0 +1,87 @@
+import { describe, expect, it, vi } from 'vitest'
+import { enqueueUsageRequest } from '../usageLoadQueue'
+
+function delay(ms: number) {
+  return new Promise((r) => setTimeout(r, ms))
+}
+
+describe('usageLoadQueue', () => {
+  it('同组请求串行执行，间隔 >= 1s', async () => {
+    const timestamps: number[] = []
+    const makeFn = () => async () => {
+      timestamps.push(Date.now())
+      return 'ok'
+    }
+
+    const p1 = enqueueUsageRequest('anthropic', 'oauth', 1, makeFn())
+    const p2 = enqueueUsageRequest('anthropic', 'oauth', 1, makeFn())
+    const p3 = enqueueUsageRequest('anthropic', 'oauth', 1, makeFn())
+
+    await Promise.all([p1, p2, p3])
+
+    expect(timestamps).toHaveLength(3)
+    // 随机 1-1.5s 间隔，至少 950ms（留一点误差）
+    expect(timestamps[1] - timestamps[0]).toBeGreaterThanOrEqual(950)
+    expect(timestamps[1] - timestamps[0]).toBeLessThan(1600)
+    expect(timestamps[2] - timestamps[1]).toBeGreaterThanOrEqual(950)
+    expect(timestamps[2] - timestamps[1]).toBeLessThan(1600)
+  })
+
+  it('不同组请求并行执行', async () => {
+    const timestamps: Record<string, number> = {}
+    const makeTracked = (key: string) => async () => {
+      timestamps[key] = Date.now()
+      return key
+    }
+
+    const p1 = enqueueUsageRequest('anthropic', 'oauth', 1, makeTracked('group1'))
+    const p2 = enqueueUsageRequest('anthropic', 'oauth', 2, makeTracked('group2'))
+    const p3 = enqueueUsageRequest('gemini', 'oauth', 1, makeTracked('group3'))
+
+    await Promise.all([p1, p2, p3])
+
+    // 不同组应几乎同时启动（差距 < 50ms）
+    const values = Object.values(timestamps)
+    const spread = Math.max(...values) - Math.min(...values)
+    expect(spread).toBeLessThan(50)
+  })
+
+  it('请求失败时 reject，后续任务继续执行', async () => {
+    const results: string[] = []
+
+    const p1 = enqueueUsageRequest('anthropic', 'oauth', 99, async () => {
+      throw new Error('fail')
+    })
+    const p2 = enqueueUsageRequest('anthropic', 'oauth', 99, async () => {
+      results.push('second')
+      return 'ok'
+    })
+
+    await expect(p1).rejects.toThrow('fail')
+    await p2
+    expect(results).toEqual(['second'])
+  })
+
+  it('返回值正确透传', async () => {
+    const result = await enqueueUsageRequest('test', 'oauth', null, async () => {
+      return { usage: 42 }
+    })
+    expect(result).toEqual({ usage: 42 })
+  })
+
+  it('proxy_id 为 null 的账号归为同一组', async () => {
+    const order: number[] = []
+    const makeFn = (n: number) => async () => {
+      order.push(n)
+      return n
+    }
+
+    const p1 = enqueueUsageRequest('anthropic', 'oauth', null, makeFn(1))
+    const p2 = enqueueUsageRequest('anthropic', 'oauth', null, makeFn(2))
+
+    await Promise.all([p1, p2])
+
+    // 同组串行，按入队顺序执行
+    expect(order).toEqual([1, 2])
+  })
+})
diff --git a/frontend/src/utils/usageLoadQueue.ts b/frontend/src/utils/usageLoadQueue.ts
new file mode 100644
index 00000000..97549b15
--- /dev/null
+++ b/frontend/src/utils/usageLoadQueue.ts
@@ -0,0 +1,72 @@
+/**
+ * Usage request queue that throttles API calls by group.
+ *
+ * Accounts sharing the same upstream (platform + type + proxy) are placed
+ * into a single serial queue with a configurable delay between requests,
+ * preventing upstream 429 rate-limit errors.
+ *
+ * Different groups run in parallel since they hit different upstreams.
+ */
+
+const GROUP_DELAY_MIN_MS = 1000
+const GROUP_DELAY_MAX_MS = 1500
+
+type Task<T> = {
+  fn: () => Promise<T>
+  resolve: (value: T) => void
+  reject: (reason: unknown) => void
+}
+
+const queues = new Map<string, Task<unknown>[]>()
+const running = new Set<string>()
+
+function buildGroupKey(platform: string, type: string, proxyId: number | null): string {
+  return `${platform}:${type}:${proxyId ?? 'direct'}`
+}
+
+async function drain(groupKey: string) {
+  if (running.has(groupKey)) return
+  running.add(groupKey)
+
+  const queue = queues.get(groupKey)
+  while (queue && queue.length > 0) {
+    const task = queue.shift()!
+    try {
+      const result = await task.fn()
+      task.resolve(result)
+    } catch (err) {
+      task.reject(err)
+    }
+    // Wait a random 1–1.5s before next request in the same group
+    if (queue.length > 0) {
+      const jitter = GROUP_DELAY_MIN_MS + Math.random() * (GROUP_DELAY_MAX_MS - GROUP_DELAY_MIN_MS)
+      await new Promise((r) => setTimeout(r, jitter))
+    }
+  }
+
+  running.delete(groupKey)
+  queues.delete(groupKey)
+}
+
+/**
+ * Enqueue a usage fetch call. Returns a promise that resolves when the
+ * request completes (after waiting its turn in the group queue).
+ */
+export function enqueueUsageRequest<T>(
+  platform: string,
+  type: string,
+  proxyId: number | null,
+  fn: () => Promise<T>
+): Promise<T> {
+  const key = buildGroupKey(platform, type, proxyId)
+
+  return new Promise<T>((resolve, reject) => {
+    let queue = queues.get(key)
+    if (!queue) {
+      queue = []
+      queues.set(key, queue)
+    }
+    queue.push({ fn, resolve, reject } as Task<unknown>)
+    drain(key)
+  })
+}