refactor(gateway): 重构格式转换候选资格检查并优化测试基础设施

- 将 format_conversion_disabled 的过滤提前到候选遴选阶段，替代原来的 skip_reason 标记机制
- 为测试添加 execution_runtime_sync_override 直接注入支持，避免启动额外 HTTP 服务器
- 将 submit_terminal_event 改为 async record_terminal_event 确保失败用量事件可靠入库
- 新增 test_support 模块封装可重试的 loopback 端口绑定逻辑
- 前端：poolTrace 将 skipped 从隐藏状态移除，新增 buildPoolParticipatedCandidates 统一新旧链路逻辑，并将 skipped 状态色改为 foreground

frontend/src/features/usage/utils/__tests__/poolTrace.spec.ts

@@ -1,7 +1,10 @@
 import { describe, expect, it } from 'vitest'
 
 import type { CandidateRecord } from '@/api/requestTrace'
-import { buildPoolAttemptCandidatesFromAudit } from '@/features/usage/utils/poolTrace'
+import {
+  buildPoolAttemptCandidatesFromAudit,
+  buildPoolParticipatedCandidates,
+} from '@/features/usage/utils/poolTrace'
 
 function buildCandidate(
   overrides: Partial<CandidateRecord> = {},
@@ -19,7 +22,7 @@ function buildCandidate(
 }
 
 describe('poolTrace', () => {
-  it('keeps only actually attempted pool nodes from scheduling audit fallback', () => {
+  it('keeps only pool nodes that actually participated in scheduling audit fallback', () => {
     const attempts = buildPoolAttemptCandidatesFromAudit([], [
       {
         candidate_index: 0,
@@ -63,9 +66,11 @@ describe('poolTrace', () => {
       },
     ], 'req-1')
 
-    expect(attempts).toHaveLength(1)
+    expect(attempts).toHaveLength(2)
     expect(attempts[0].key_id).toBe('key-success')
     expect(attempts[0].status).toBe('success')
+    expect(attempts[1].key_id).toBe('key-skipped')
+    expect(attempts[1].status).toBe('skipped')
   })
 
   it('preserves real trace attempts even when audit status is non-standard', () => {
@@ -111,4 +116,58 @@ describe('poolTrace', () => {
     expect(attempts[0].status).toBe('failed')
     expect(attempts[0].provider_name).toBe('Codex反代')
   })
+
+  it('merges audit-only skipped pool nodes when trace only carries partial pool metadata', () => {
+    const rawTimeline = [
+      buildCandidate({
+        id: 'cand-success',
+        candidate_index: 1,
+        retry_index: 0,
+        provider_id: 'provider-1',
+        provider_name: 'Codex反代',
+        key_id: 'key-success',
+        key_name: 'Success Key',
+        status: 'success',
+        extra_data: { pool_group_id: 'provider-1' },
+        started_at: '2026-04-19T12:00:00.000Z',
+      }),
+      buildCandidate({
+        id: 'cand-skipped',
+        candidate_index: 2,
+        retry_index: 0,
+        provider_id: 'provider-1',
+        provider_name: 'Codex反代',
+        key_id: 'key-skipped',
+        key_name: 'Skipped Key',
+        status: 'skipped',
+      }),
+    ]
+
+    const attempts = buildPoolParticipatedCandidates(rawTimeline, [
+      {
+        candidate_index: 1,
+        retry_index: 0,
+        provider_id: 'provider-1',
+        provider_name: 'Codex反代',
+        key_id: 'key-success',
+        key_name: 'Success Key',
+        status: 'success',
+        pool_group_id: 'provider-1',
+      },
+      {
+        candidate_index: 2,
+        retry_index: 0,
+        provider_id: 'provider-1',
+        provider_name: 'Codex反代',
+        key_id: 'key-skipped',
+        key_name: 'Skipped Key',
+        status: 'skipped',
+        pool_group_id: 'provider-1',
+      },
+    ], 'req-1')
+
+    expect(attempts).toHaveLength(2)
+    expect(attempts.map(item => item.key_id)).toEqual(['key-success', 'key-skipped'])
+    expect(attempts[1].extra_data?.pool_group_id).toBe('provider-1')
+  })
 })

frontend/src/features/usage/utils/poolTrace.ts

@@ -12,10 +12,9 @@ export const TIMELINE_STATUS: CandidateRecord['status'][] = [
   'stream_interrupted',
 ]
 
-const POOL_UNATTEMPTED_STATUS = new Set<CandidateRecord['status']>([
+const POOL_HIDDEN_STATUS = new Set<CandidateRecord['status']>([
   'available',
   'unused',
-  'skipped',
 ])
 
 const PROVIDER_TYPE_LIKE_NAMES = new Set<string>([
@@ -40,8 +39,8 @@ export const makeAttemptKey = (candidateIndex: number, retryIndex: number): stri
   return `${candidateIndex}:${retryIndex}`
 }
 
-export const isPoolAttemptedCandidate = (candidate: CandidateRecord): boolean => {
-  if (POOL_UNATTEMPTED_STATUS.has(candidate.status)) return false
+export const isPoolParticipatedCandidate = (candidate: CandidateRecord): boolean => {
+  if (POOL_HIDDEN_STATUS.has(candidate.status)) return false
   if (candidate.status === 'pending' && !candidate.started_at) return false
   return true
 }
@@ -66,6 +65,38 @@ export const extractPoolGroupId = (
   return text || null
 }
 
+export function buildPoolParticipatedCandidates(
+  rawTimeline: CandidateRecord[],
+  attempts: unknown,
+  requestId?: string | null,
+): CandidateRecord[] {
+  const fromTrace = rawTimeline.filter(
+    candidate => extractPoolGroupId(candidate) !== null && isPoolParticipatedCandidate(candidate),
+  )
+  const fromAudit = buildPoolAttemptCandidatesFromAudit(rawTimeline, attempts, requestId)
+
+  if (fromTrace.length === 0) return fromAudit
+  if (fromAudit.length === 0) return fromTrace
+
+  const traceKeys = new Set(
+    fromTrace.map(candidate => makeAttemptKey(candidate.candidate_index, candidate.retry_index)),
+  )
+  const merged = [...fromTrace]
+  for (const candidate of fromAudit) {
+    const key = makeAttemptKey(candidate.candidate_index, candidate.retry_index)
+    if (!traceKeys.has(key)) {
+      merged.push(candidate)
+    }
+  }
+
+  return merged.sort((a, b) => {
+    if (a.candidate_index !== b.candidate_index) {
+      return a.candidate_index - b.candidate_index
+    }
+    return a.retry_index - b.retry_index
+  })
+}
+
 export function buildPoolAttemptCandidatesFromAudit(
   rawTimeline: CandidateRecord[],
   attempts: unknown,
@@ -154,7 +185,7 @@ export function buildPoolAttemptCandidatesFromAudit(
         }
       }
 
-      return isPoolAttemptedCandidate(merged) ? merged : null
+      return isPoolParticipatedCandidate(merged) ? merged : null
     })
     .filter((item): item is CandidateRecord => item !== null)
 }