fix(web): show ai route fallback evidence

apps/web/messages/en.json

@@ -253,7 +253,19 @@
       "humanGap": "Human gap",
       "humanGapDetail": "{gate} missing {count}",
       "modelRoute": "Model route",
-      "routeDetail": "{model}; fallback {fallback}",
+      "routeDetail": "{model}; current {selected}; {primary}={primaryStatus}; fallback {fallback}",
+      "routeReasonSeparator": "; ",
+      "routeReason": "Reason: {reason}",
+      "routeErrorDetail": "Route check failed: {error}",
+      "routeNoFallback": "none",
+      "routeHealth": {
+        "healthy": "healthy",
+        "slow": "slow",
+        "degraded": "degraded",
+        "offline": "offline",
+        "not_checked": "standby",
+        "unknown": "unknown"
+      },
       "topGap": "Largest current gap: {gate}, {count} items."
     }
   },

apps/web/messages/zh-TW.json

@@ -254,7 +254,19 @@
       "humanGap": "人工缺口",
       "humanGapDetail": "{gate} 缺 {count} 筆",
       "modelRoute": "模型路由",
-      "routeDetail": "{model}；備援 {fallback}",
+      "routeDetail": "{model}；目前 {selected}；{primary}={primaryStatus}；備援 {fallback}",
+      "routeReasonSeparator": "；",
+      "routeReason": "原因：{reason}",
+      "routeErrorDetail": "路由檢查失敗：{error}",
+      "routeNoFallback": "無",
+      "routeHealth": {
+        "healthy": "健康",
+        "slow": "偏慢",
+        "degraded": "降級",
+        "offline": "離線",
+        "not_checked": "待命",
+        "unknown": "未知"
+      },
       "topGap": "目前最大缺口：{gate}，共 {count} 筆。"
     }
   },

apps/web/src/components/dashboard/automation-evidence-card.tsx

@@ -79,12 +79,27 @@ interface RunsResponse {
   items?: RunSummary[]
 }
 
+interface AiRoutePolicyItem {
+  provider_name: string
+  role?: string | null
+  runtime?: string | null
+}
+
+interface AiRouteHealthItem {
+  status?: string | null
+  latency_ms?: number | null
+  reason?: string | null
+  checked?: boolean
+}
+
 interface AiRouteStatusResponse {
+  policy_order?: AiRoutePolicyItem[]
   selected_provider?: string | null
   selected_model?: string | null
-  fallback_chain?: Array<{
+  fallback_chain?: AiRoutePolicyItem[]
-    provider_name: string
+  route_reason?: string | null
-  }>
+  route_error?: string | null
+  health?: Record<string, AiRouteHealthItem>
 }
 
 interface EvidenceSnapshot {
@@ -137,6 +152,42 @@ function gateLabelKey(gate?: string) {
   }
 }
 
+function routeHealthLabelKey(status?: string | null) {
+  if (
+    status === 'healthy' ||
+    status === 'slow' ||
+    status === 'degraded' ||
+    status === 'offline' ||
+    status === 'not_checked'
+  ) {
+    return `routeHealth.${status}`
+  }
+  return 'routeHealth.unknown'
+}
+
+function providerDisplayName(provider?: string | null) {
+  switch (provider) {
+    case 'ollama_gcp_a':
+      return 'GCP-A'
+    case 'ollama_gcp_b':
+      return 'GCP-B'
+    case 'ollama_local':
+      return '111'
+    case 'gemini':
+      return 'Gemini'
+    default:
+      return provider || '--'
+  }
+}
+
+function routeTone(route: AiRouteStatusResponse | null): Tone {
+  if (!route?.selected_provider || route.route_error) return 'warn'
+  const primaryProvider = route.policy_order?.[0]?.provider_name
+  if (primaryProvider && route.selected_provider !== primaryProvider) return 'warn'
+  const primaryStatus = primaryProvider ? route.health?.[primaryProvider]?.status : null
+  return primaryStatus === 'healthy' ? 'good' : 'warn'
+}
+
 async function fetchJson<T>(path: string, signal: AbortSignal): Promise<T | null> {
   const response = await fetch(`${API_BASE}${path}`, { signal })
   if (!response.ok) return null
@@ -254,10 +305,26 @@ export function AutomationEvidenceCard() {
 
     const topGate = quality?.gate_failures?.[0]
     const claimReady = Boolean(quality?.production_claim?.can_claim_full_auto_repair)
-    const selectedProvider = snapshot?.route?.selected_provider ?? '--'
+    const route = snapshot?.route ?? null
-    const fallback = snapshot?.route?.fallback_chain
+    const primaryProvider = route?.policy_order?.[0]?.provider_name ?? null
+    const primaryStatus = primaryProvider ? route?.health?.[primaryProvider]?.status : null
+    const selectedProvider = providerDisplayName(route?.selected_provider)
+    const fallback = route?.fallback_chain
       ?.map((item) => item.provider_name)
+      .map(providerDisplayName)
       .join(' -> ')
+    const routeSummary = route?.route_error
+      ? t('routeErrorDetail', { error: route.route_error })
+      : t('routeDetail', {
+        model: route?.selected_model ?? '--',
+        selected: selectedProvider,
+        primary: providerDisplayName(primaryProvider),
+        primaryStatus: t(routeHealthLabelKey(primaryStatus) as never),
+        fallback: fallback || t('routeNoFallback'),
+      })
+    const routeDetail = route?.route_reason && !route.route_error
+      ? `${routeSummary}${t('routeReasonSeparator')}${t('routeReason', { reason: route.route_reason })}`
+      : routeSummary
 
     return {
       quality,
@@ -268,8 +335,10 @@ export function AutomationEvidenceCard() {
       claimReady,
       selectedProvider,
       fallback,
+      routeDetail,
+      routeTone: routeTone(route),
     }
-  }, [snapshot])
+  }, [snapshot, t])
 
   const hasData = Boolean(snapshot?.quality || snapshot?.coverage || snapshot?.recurrence)
 
@@ -365,11 +434,8 @@ export function AutomationEvidenceCard() {
             <EvidenceMetric
               label={t('modelRoute')}
               value={derived.selectedProvider}
-              detail={t('routeDetail', {
+              detail={derived.routeDetail}
-                model: snapshot?.route?.selected_model ?? '--',
+              tone={derived.routeTone}
-                fallback: derived.fallback || '--',
-              })}
-              tone="neutral"
               icon={Route}
             />
           </div>