fix(usage): calibrate active elapsed clock efficiently

frontend/src/features/usage/components/ElapsedTimeText.vue

@@ -3,25 +3,26 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onUnmounted, ref, watch } from 'vue'
+import { computed } from 'vue'
+import { useActiveElapsedDisplayNowMs } from '../composables/useActiveElapsedDisplayClock'
 
 const props = withDefaults(defineProps<{
   createdAt?: string | null
   status?: string | null
   responseTimeMs?: number | null
+  displayNowMs?: number | null
   precision?: number
 }>(), {
   createdAt: null,
   status: null,
   responseTimeMs: null,
+  displayNowMs: null,
   precision: 2,
 })
 
-const now = ref(Date.now())
 const precision = computed(() => Math.max(0, props.precision))
 const isActive = computed(() => props.status === 'pending' || props.status === 'streaming')
-
-let rafId: number | null = null
+const injectedDisplayNowMs = useActiveElapsedDisplayNowMs()
 
 function parseCreatedAtMs(value: string | null | undefined): number {
   if (!value) return Number.NaN
@@ -30,35 +31,6 @@ function parseCreatedAtMs(value: string | null | undefined): number {
   return new Date(normalized).getTime()
 }
 
-function stopRaf() {
-  if (rafId == null) return
-  cancelAnimationFrame(rafId)
-  rafId = null
-}
-
-function tick() {
-  now.value = Date.now()
-  rafId = requestAnimationFrame(tick)
-}
-
-function startRaf() {
-  stopRaf()
-  now.value = Date.now()
-  rafId = requestAnimationFrame(tick)
-}
-
-watch(isActive, (active) => {
-  if (active) {
-    startRaf()
-  } else {
-    stopRaf()
-  }
-}, { immediate: true })
-
-onUnmounted(() => {
-  stopRaf()
-})
-
 const displayText = computed(() => {
   if (!isActive.value) {
     if (props.responseTimeMs == null) return '-'
@@ -70,7 +42,14 @@ const displayText = computed(() => {
   const createdAtMs = parseCreatedAtMs(props.createdAt)
   if (Number.isNaN(createdAtMs)) return '-'
 
-  const elapsedMs = Math.max(0, now.value - createdAtMs)
+  // 活跃请求里的 response_time_ms 可能只是首字或中间值；终态才使用后端最终耗时。
+  const injectedNowMs = injectedDisplayNowMs?.value
+  const nowMs = typeof props.displayNowMs === 'number' && Number.isFinite(props.displayNowMs)
+    ? props.displayNowMs
+    : typeof injectedNowMs === 'number' && Number.isFinite(injectedNowMs)
+      ? injectedNowMs
+    : Date.now()
+  const elapsedMs = Math.max(0, nowMs - createdAtMs)
   return `${(elapsedMs / 1000).toFixed(precision.value)}s`
 })
 </script>

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

@@ -0,0 +1,79 @@
+import { afterEach, describe, expect, it } from 'vitest'
+import { createApp, nextTick, ref, type App } from 'vue'
+import { ACTIVE_ELAPSED_DISPLAY_NOW_MS_KEY, type ActiveElapsedDisplayNowMsRef } from '../../composables/useActiveElapsedDisplayClock'
+import ElapsedTimeText from '../ElapsedTimeText.vue'
+
+const mountedApps: Array<{ app: App, root: HTMLElement }> = []
+
+function mountElapsedTimeText(
+  props: Record<string, unknown>,
+  options: { providedDisplayNowMs?: ActiveElapsedDisplayNowMsRef } = {}
+) {
+  const root = document.createElement('div')
+  document.body.appendChild(root)
+
+  const app = createApp(ElapsedTimeText, props)
+  if (options.providedDisplayNowMs) {
+    app.provide(ACTIVE_ELAPSED_DISPLAY_NOW_MS_KEY, options.providedDisplayNowMs)
+  }
+  app.mount(root)
+  mountedApps.push({ app, root })
+  return root
+}
+
+afterEach(() => {
+  for (const { app, root } of mountedApps.splice(0)) {
+    app.unmount()
+    root.remove()
+  }
+})
+
+describe('ElapsedTimeText', () => {
+  it('uses the supplied display clock for active requests', () => {
+    const root = mountElapsedTimeText({
+      createdAt: '2026-05-28T12:00:00Z',
+      status: 'streaming',
+      responseTimeMs: 10_000,
+      displayNowMs: Date.parse('2026-05-28T12:00:40Z'),
+    })
+
+    expect(root.textContent).toBe('40.00s')
+  })
+
+  it('uses the injected shared display clock when no prop is supplied', async () => {
+    const displayNowMs = ref(Date.parse('2026-05-28T12:00:40Z'))
+    const root = mountElapsedTimeText({
+      createdAt: '2026-05-28T12:00:00Z',
+      status: 'streaming',
+      responseTimeMs: 10_000,
+    }, { providedDisplayNowMs: displayNowMs })
+
+    expect(root.textContent).toBe('40.00s')
+
+    displayNowMs.value = Date.parse('2026-05-28T12:00:45Z')
+    await nextTick()
+
+    expect(root.textContent).toBe('45.00s')
+  })
+
+  it('keeps terminal requests pinned to the backend final duration', () => {
+    const root = mountElapsedTimeText({
+      createdAt: '2026-05-28T12:00:00Z',
+      status: 'completed',
+      responseTimeMs: 42_340,
+      displayNowMs: Date.parse('2026-05-28T12:01:30Z'),
+    })
+
+    expect(root.textContent).toBe('42.34s')
+  })
+
+  it('clamps active elapsed time at zero when the display clock is behind', () => {
+    const root = mountElapsedTimeText({
+      createdAt: '2026-05-28T12:00:40Z',
+      status: 'pending',
+      displayNowMs: Date.parse('2026-05-28T12:00:00Z'),
+    })
+
+    expect(root.textContent).toBe('0.00s')
+  })
+})

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

@@ -91,8 +91,15 @@ vi.mock('lucide-vue-next', async () => {
 vi.mock('../ElapsedTimeText.vue', () => ({
   default: defineComponent({
     name: 'ElapsedTimeTextStub',
-    setup() {
-      return () => h('span', 'elapsed')
+    props: {
+      displayNowMs: {
+        type: Number,
+      },
+    },
+    setup(props) {
+      return () => h('span', {
+        'data-display-now-ms': props.displayNowMs == null ? 'missing' : String(props.displayNowMs),
+      }, 'elapsed')
     },
   }),
 }))
@@ -243,6 +250,16 @@ describe('UsageRecordsTable', () => {
     expect(root.querySelector('[data-active-latency-state="waiting-first-byte"]')).toBeNull()
   })
 
+  it('leaves shared clock subscription inside active elapsed text', () => {
+    const root = mountUsageRecordsTable([buildRecord({
+      status: 'streaming',
+      response_time_ms: null,
+      first_byte_time_ms: 500,
+    })])
+
+    expect(root.querySelector('[data-display-now-ms="missing"]')).not.toBeNull()
+  })
+
   it('shows failed when Codex image progress fails before the usage record finalizes', () => {
     const root = mountUsageRecordsTable([buildRecord({
       status: 'pending',