feat(gateway): harden failover and payload handling

Retry pre-response transport failures across candidates with an explicit stop policy, and propagate end-to-end timing into usage records and UI diagnostics.

Remove legacy body, import, cookie, PII, and tunnel replay caps while preserving optional operator-configured gateway limits.

frontend/src/features/usage/components/__tests__/HorizontalRequestTimeline.spec.ts

@@ -181,6 +181,46 @@ afterEach(() => {
 })
 
 describe('HorizontalRequestTimeline', () => {
+  it('uses the trace aggregate latency instead of the successful candidate latency', async () => {
+    const trace = buildTrace([
+      buildCandidate({
+        id: 'cand-transport-timeout',
+        provider_id: 'provider-timeout',
+        provider_name: 'Provider Timeout',
+        key_id: 'key-timeout',
+        key_name: 'Timeout Key',
+        candidate_index: 0,
+        status: 'failed',
+        latency_ms: 10_000,
+        started_at: '2026-05-06T12:00:00.000Z',
+        finished_at: '2026-05-06T12:00:10.000Z',
+      }),
+      buildCandidate({
+        id: 'cand-success-after-failover',
+        provider_id: 'provider-success',
+        provider_name: 'Provider Success',
+        key_id: 'key-success',
+        key_name: 'Success Key',
+        candidate_index: 1,
+        status: 'success',
+        latency_ms: 626,
+        started_at: '2026-05-06T12:00:10.000Z',
+        finished_at: '2026-05-06T12:00:10.626Z',
+      }),
+    ])
+    trace.total_latency_ms = 10_626
+
+    const root = mountTimeline(trace)
+    await nextTick()
+
+    const heading = [...root.querySelectorAll('h4')]
+      .find(element => element.textContent?.trim() === '请求链路追踪')
+    const overview = heading?.parentElement?.parentElement
+    const displayedLatency = overview?.lastElementChild?.textContent?.trim()
+    expect(displayedLatency).toBe('10.63s')
+    expect(displayedLatency).not.toBe('626ms')
+  })
+
   it('keeps attempted keys visible for ordinary provider groups that are not selected', async () => {
     const trace = buildTrace([
       buildCandidate({

frontend/src/features/usage/components/__tests__/RequestDetailDrawer.pricing.spec.ts

@@ -113,6 +113,48 @@ function buildFastTierDetail(): RequestDetail {
 }
 
 describe('RequestDetailDrawer settlement pricing', () => {
+  it('shows end-to-end latency while keeping output TPS scoped to candidate timing', async () => {
+    apiMocks.getRequestDetail.mockResolvedValue({
+      ...buildEmbeddingDetail(),
+      tokens: { input: 100, output: 50, total: 150 },
+      input_tokens: 100,
+      output_tokens: 50,
+      total_tokens: 150,
+      is_stream: true,
+      upstream_is_stream: true,
+      response_time_ms: 626,
+      first_byte_time_ms: 100,
+      end_to_end_time_ms: 10_626,
+      end_to_end_first_byte_time_ms: 10_120,
+    } satisfies RequestDetail)
+
+    let isOpen!: Ref<boolean>
+    const Host = defineComponent({
+      setup() {
+        isOpen = ref(false)
+        return () => h(RequestDetailDrawer, {
+          isOpen: isOpen.value,
+          requestId: 'usage-embedding-1',
+        })
+      },
+    })
+
+    const root = document.createElement('div')
+    document.body.appendChild(root)
+    const app = createApp(Host)
+    app.mount(root)
+    mountedApps.push({ app, root })
+
+    isOpen.value = true
+    await nextTick()
+
+    await vi.waitFor(() => {
+      expect(document.body.textContent).toContain('10.12s / 10.63s')
+      expect(document.body.textContent).toContain('95.1tps')
+      expect(document.body.textContent).not.toContain('98.8tps')
+    })
+  })
+
   it('renders an input-only embedding tier without treating the missing output price as zero', async () => {
     apiMocks.getRequestDetail.mockResolvedValue(buildEmbeddingDetail())
 

frontend/src/features/usage/components/__tests__/UsageRecordsTable.spec.ts

@@ -195,8 +195,10 @@ describe('UsageRecordsTable', () => {
     const titles = [...root.querySelectorAll<HTMLElement>('[title]')]
       .map((element) => element.getAttribute('title'))
     expect(titles).toContain([
-      '首字: 0.50s',
-      '总耗时: 1.00s',
+      '端到端首字: 0.50s',
+      '端到端总耗时: 1.00s',
+      '成功候选首字: 0.50s',
+      '成功候选耗时: 1.00s',
       '生成耗时: 0.50s',
       '输出速度: 100 tokens/s',
     ].join('\n'))
@@ -204,6 +206,55 @@ describe('UsageRecordsTable', () => {
     expect(titles.join('\n')).not.toContain('首字后生成耗时')
   })
 
+  it('shows end-to-end latency while keeping output TPS scoped to the successful candidate', () => {
+    const root = mountUsageRecordsTable([buildRecord({
+      output_tokens: 50,
+      response_time_ms: 626,
+      first_byte_time_ms: 100,
+      end_to_end_time_ms: 10_626,
+      end_to_end_first_byte_time_ms: 10_120,
+    })])
+
+    const performanceCell = root.querySelector('table tbody tr td:last-child') as HTMLElement
+    expect(performanceCell.textContent).toContain('10.12s / 10.63s')
+    expect(performanceCell.textContent).toContain('95.1 tps')
+    expect(performanceCell.textContent).not.toContain('98.8 tps')
+
+    const titles = [...root.querySelectorAll<HTMLElement>('[title]')]
+      .map((element) => element.getAttribute('title'))
+    expect(titles).toContain([
+      '端到端首字: 10.12s',
+      '端到端总耗时: 10.63s',
+      '成功候选首字: 0.10s',
+      '成功候选耗时: 0.63s',
+      '生成耗时: 0.53s',
+      '输出速度: 95.1 tokens/s',
+    ].join('\n'))
+  })
+
+  it('shows end-to-end latency when candidate timing fields are unavailable', () => {
+    const root = mountUsageRecordsTable([buildRecord({
+      response_time_ms: null,
+      first_byte_time_ms: null,
+      end_to_end_time_ms: 10_626,
+      end_to_end_first_byte_time_ms: 10_120,
+    })])
+
+    const performanceCell = root.querySelector('table tbody tr td:last-child') as HTMLElement
+    expect(performanceCell.textContent).toContain('10.12s / 10.63s')
+
+    const titles = [...root.querySelectorAll<HTMLElement>('[title]')]
+      .map((element) => element.getAttribute('title'))
+    expect(titles).toContain([
+      '端到端首字: 10.12s',
+      '端到端总耗时: 10.63s',
+      '成功候选首字: -',
+      '成功候选耗时: -',
+      '生成耗时: -',
+      '输出速度: -',
+    ].join('\n'))
+  })
+
   it('shows an output speed placeholder when the rate is unavailable', () => {
     const root = mountUsageRecordsTable([buildRecord({
       output_tokens: 0,
@@ -218,8 +269,10 @@ describe('UsageRecordsTable', () => {
 
     const titles = [...root.querySelectorAll<HTMLElement>('[title]')].map((element) => element.title)
     expect(titles).toContain([
-      '首字: 0.50s',
-      '总耗时: 1.00s',
+      '端到端首字: 0.50s',
+      '端到端总耗时: 1.00s',
+      '成功候选首字: 0.50s',
+      '成功候选耗时: 1.00s',
       '生成耗时: 0.50s',
       '输出速度: -',
     ].join('\n'))