Expose local scheduling failures in usage UI

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

@@ -547,6 +547,38 @@
       </Card>
     </div>
 
+    <!-- Local Scheduling Failure State -->
+    <Card
+      v-else-if="schedulingFailureNotice"
+      class="border-red-200 dark:border-red-800"
+    >
+      <div class="p-4 space-y-2">
+        <div class="flex flex-wrap items-center gap-2">
+          <Badge variant="destructive">
+            调度失败
+          </Badge>
+          <h4 class="text-sm font-semibold text-red-950 dark:text-red-100">
+            {{ schedulingFailureNotice.title }}
+          </h4>
+        </div>
+        <p class="text-sm leading-6 text-red-900 dark:text-red-100">
+          {{ schedulingFailureNotice.message }}
+        </p>
+        <div
+          v-if="schedulingFailureNotice.meta.length > 0"
+          class="flex flex-wrap gap-1.5"
+        >
+          <span
+            v-for="item in schedulingFailureNotice.meta"
+            :key="item"
+            class="rounded-full border border-red-200 bg-white/70 px-2 py-0.5 text-[11px] font-mono text-red-700 dark:border-red-900 dark:bg-red-950/50 dark:text-red-200"
+          >
+            {{ item }}
+          </span>
+        </div>
+      </div>
+    </Card>
+
     <!-- Empty State -->
     <Card
       v-else
@@ -575,6 +607,7 @@ import { parseApiError } from '@/utils/errorParser'
 import { formatApiFormat } from '@/api/endpoints/types/api-format'
 import { useDarkMode } from '@/composables/useDarkMode'
 import { resolveTimelineFinalStatus } from '../utils/status'
+import type { RequestSchedulingFailure } from '@/api/dashboard'
 import {
   buildPoolGroupVisibleAttempts,
   buildPoolParticipatedCandidates,
@@ -637,6 +670,8 @@ const props = defineProps<{
   usageData?: UsageData | null
   /** 请求元数据（用于号池调度组装） */
   requestMetadata?: Record<string, unknown> | null
+  /** 本地调度失败摘要；用于没有 trace candidate 时替代空态 */
+  schedulingFailure?: RequestSchedulingFailure | null
   /** 已获取的追踪数据；传入时不再内部拉取 */
   traceData?: RequestTrace | null
 }>()
@@ -812,6 +847,62 @@ const computedFinalStatus = computed(() => {
   })
 })
 
+const nonEmptyNoticeString = (value: string | null | undefined): string | null => {
+  const trimmed = value?.trim()
+  return trimmed ? trimmed : null
+}
+
+const uniqueNoticeMeta = (values: Array<string | null | undefined>): string[] => {
+  return Array.from(new Set(values.map(value => value?.trim()).filter((value): value is string => Boolean(value))))
+}
+
+const isUnknownProviderHint = (value: string | null): boolean => {
+  const normalized = value?.trim().toLowerCase()
+  return !normalized || ['unknown', 'unknow', 'pending'].includes(normalized)
+}
+
+const schedulingFailureProviderHint = (failure: RequestSchedulingFailure): string | null => {
+  const name = nonEmptyNoticeString(failure.provider_hint?.name)
+  if (name && !isUnknownProviderHint(name)) return name
+
+  const id = nonEmptyNoticeString(failure.provider_hint?.id)
+  if (id && !isUnknownProviderHint(id)) return id
+
+  return null
+}
+
+const schedulingFailureEndpointHint = (failure: RequestSchedulingFailure): string | null => {
+  return nonEmptyNoticeString(failure.endpoint_hint?.api_format)
+    ?? nonEmptyNoticeString(failure.endpoint_hint?.id)
+}
+
+const schedulingFailureNotice = computed(() => {
+  const failure = props.schedulingFailure
+  if (!failure) return null
+
+  const title = nonEmptyNoticeString(failure.title) ?? '本地调度失败'
+  const message = nonEmptyNoticeString(failure.message)
+    ?? nonEmptyNoticeString(failure.reason_summary)
+    ?? nonEmptyNoticeString(failure.reason_label)
+    ?? nonEmptyNoticeString(failure.reason)
+    ?? '本地调度阶段没有选出可用上游提供商'
+
+  return {
+    title,
+    message,
+    meta: uniqueNoticeMeta([
+      schedulingFailureProviderHint(failure),
+      schedulingFailureEndpointHint(failure),
+      nonEmptyNoticeString(failure.requested_model),
+      nonEmptyNoticeString(failure.reason_summary),
+      nonEmptyNoticeString(failure.reason_label),
+      nonEmptyNoticeString(failure.reason),
+      typeof failure.status_code === 'number' ? `HTTP ${failure.status_code}` : null,
+      failure.no_upstream_attempt ? '未进入上游执行' : null,
+    ]),
+  }
+})
+
 const compareBySchedulingOrder = (a: CandidateRecord, b: CandidateRecord): number => {
   if (a.candidate_index !== b.candidate_index) {
     return a.candidate_index - b.candidate_index