fix(billing): 修复 OpenAI fast 档位计费并补齐展示

- 打通 service_tier 在 OpenAI HTTP、WS、passthrough 与 usage 记录中的传递
- 修正 priority/flex 计费逻辑，并将 fast 归一化为 priority
- 在用户端和管理端补齐服务档位与计费明细展示
- 补齐前后端测试，并修复 WS 限流信号重复持久化导致的全量回归失败

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/admin/usage/UsageTable.vue

@@ -228,6 +228,14 @@
               <span class="text-gray-400">{{ t('admin.usage.outputCost') }}</span>
               <span class="font-medium text-white">${{ tooltipData.output_cost.toFixed(6) }}</span>
             </div>
+            <div v-if="tooltipData && tooltipData.input_tokens > 0" class="flex items-center justify-between gap-4">
+              <span class="text-gray-400">{{ t('usage.inputTokenPrice') }}</span>
+              <span class="font-medium text-sky-300">{{ formatTokenPricePerMillion(tooltipData.input_cost, tooltipData.input_tokens) }} {{ t('usage.perMillionTokens') }}</span>
+            </div>
+            <div v-if="tooltipData && tooltipData.output_tokens > 0" class="flex items-center justify-between gap-4">
+              <span class="text-gray-400">{{ t('usage.outputTokenPrice') }}</span>
+              <span class="font-medium text-violet-300">{{ formatTokenPricePerMillion(tooltipData.output_cost, tooltipData.output_tokens) }} {{ t('usage.perMillionTokens') }}</span>
+            </div>
             <div v-if="tooltipData && tooltipData.cache_creation_cost > 0" class="flex items-center justify-between gap-4">
               <span class="text-gray-400">{{ t('admin.usage.cacheCreationCost') }}</span>
               <span class="font-medium text-white">${{ tooltipData.cache_creation_cost.toFixed(6) }}</span>
@@ -238,6 +246,10 @@
             </div>
           </div>
           <!-- Rate and Summary -->
+          <div class="flex items-center justify-between gap-6">
+            <span class="text-gray-400">{{ t('usage.serviceTier') }}</span>
+            <span class="font-semibold text-cyan-300">{{ getUsageServiceTierLabel(tooltipData?.service_tier, t) }}</span>
+          </div>
           <div class="flex items-center justify-between gap-6">
             <span class="text-gray-400">{{ t('usage.rate') }}</span>
             <span class="font-semibold text-blue-400">{{ (tooltipData?.rate_multiplier || 1).toFixed(2) }}x</span>
@@ -271,6 +283,8 @@
 import { ref } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { formatDateTime, formatReasoningEffort } from '@/utils/format'
+import { formatTokenPricePerMillion } from '@/utils/usagePricing'
+import { getUsageServiceTierLabel } from '@/utils/usageServiceTier'
 import { resolveUsageRequestType } from '@/utils/usageRequestType'
 import DataTable from '@/components/common/DataTable.vue'
 import EmptyState from '@/components/common/EmptyState.vue'

frontend/src/components/admin/usage/__tests__/UsageTable.spec.ts

@@ -0,0 +1,111 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest'
+import { mount } from '@vue/test-utils'
+import { nextTick } from 'vue'
+
+import UsageTable from '../UsageTable.vue'
+
+const messages: Record<string, string> = {
+  'usage.costDetails': 'Cost Breakdown',
+  'admin.usage.inputCost': 'Input Cost',
+  'admin.usage.outputCost': 'Output Cost',
+  'admin.usage.cacheCreationCost': 'Cache Creation Cost',
+  'admin.usage.cacheReadCost': 'Cache Read Cost',
+  'usage.inputTokenPrice': 'Input price',
+  'usage.outputTokenPrice': 'Output price',
+  'usage.perMillionTokens': '/ 1M tokens',
+  'usage.serviceTier': 'Service tier',
+  'usage.serviceTierPriority': 'Fast',
+  'usage.serviceTierFlex': 'Flex',
+  'usage.serviceTierStandard': 'Standard',
+  'usage.rate': 'Rate',
+  'usage.accountMultiplier': 'Account rate',
+  'usage.original': 'Original',
+  'usage.userBilled': 'User billed',
+  'usage.accountBilled': 'Account billed',
+}
+
+vi.mock('vue-i18n', async () => {
+  const actual = await vi.importActual<typeof import('vue-i18n')>('vue-i18n')
+  return {
+    ...actual,
+    useI18n: () => ({
+      t: (key: string) => messages[key] ?? key,
+    }),
+  }
+})
+
+const DataTableStub = {
+  props: ['data'],
+  template: `
+    <div>
+      <div v-for="row in data" :key="row.request_id">
+        <slot name="cell-cost" :row="row" />
+      </div>
+    </div>
+  `,
+}
+
+describe('admin UsageTable tooltip', () => {
+  beforeEach(() => {
+    vi.spyOn(HTMLElement.prototype, 'getBoundingClientRect').mockReturnValue({
+      x: 0,
+      y: 0,
+      top: 20,
+      left: 20,
+      right: 120,
+      bottom: 40,
+      width: 100,
+      height: 20,
+      toJSON: () => ({}),
+    } as DOMRect)
+  })
+
+  it('shows service tier and billing breakdown in cost tooltip', async () => {
+    const row = {
+      request_id: 'req-admin-1',
+      actual_cost: 0.092883,
+      total_cost: 0.092883,
+      account_rate_multiplier: 1,
+      rate_multiplier: 1,
+      service_tier: 'priority',
+      input_cost: 0.020285,
+      output_cost: 0.00303,
+      cache_creation_cost: 0,
+      cache_read_cost: 0.069568,
+      input_tokens: 4057,
+      output_tokens: 101,
+    }
+
+    const wrapper = mount(UsageTable, {
+      props: {
+        data: [row],
+        loading: false,
+        columns: [],
+      },
+      global: {
+        stubs: {
+          DataTable: DataTableStub,
+          EmptyState: true,
+          Icon: true,
+          Teleport: true,
+        },
+      },
+    })
+
+    await wrapper.find('.group.relative').trigger('mouseenter')
+    await nextTick()
+
+    const text = wrapper.text()
+    expect(text).toContain('Service tier')
+    expect(text).toContain('Fast')
+    expect(text).toContain('Rate')
+    expect(text).toContain('1.00x')
+    expect(text).toContain('Account rate')
+    expect(text).toContain('User billed')
+    expect(text).toContain('Account billed')
+    expect(text).toContain('$0.092883')
+    expect(text).toContain('$5.0000 / 1M tokens')
+    expect(text).toContain('$30.0000 / 1M tokens')
+    expect(text).toContain('$0.069568')
+  })
+})