fix(km): recover primary knowledge readback via direct fallback

apps/web/src/app/[locale]/knowledge-base/page.tsx

@@ -64,6 +64,7 @@ interface ListResponse {
   categories: CategoryCount[]
   asset_taxonomy?: AssetTaxonomyCount[]
   readback_status?: 'ready' | 'degraded' | string
+  primary_readback_ready?: boolean
   degraded_reason_code?: string | null
   operator_stage?: string | null
   next_step?: string | null
@@ -441,8 +442,12 @@ const humanizeSignalTag = (tag: string) => {
 const compactReadbackToken = (value: string | null | undefined) => {
   if (!value) return '--'
   if (value === 'primary_km_db_timeout_or_pool_exhausted') return 'DB pool'
+  if (value === 'ready_direct_connection_after_session_timeout') return 'Direct KM'
+  if (value === 'knowledge_readback_direct_connection_recovered') return '已救回'
+  if (value === 'repair_session_pool_readback_without_hiding_primary_km') return '修復 pool'
   if (value === 'knowledge_readback_source_backed_ai_controlled_repair') return '接管'
   if (value === 'repair_primary_km_db_readback_then_promote_source_backed_receipts_to_persistent_km') return '修復 KM'
+  if (value === 'source_backed_db_empty_direct_connection') return 'Direct 空值'
   if (value === 'primary_km_taxonomy_readback_degraded') return 'Taxonomy 降級'
   if (value === 'knowledge_primary_entries_ready_taxonomy_degraded') return 'Primary 可讀'
   if (value === 'repair_primary_km_taxonomy_readback_without_hiding_entries') return '修復 taxonomy'
@@ -509,7 +514,7 @@ export default function KnowledgeBasePage({
   const [assetTaxonomy, setAssetTaxonomy] = useState<AssetTaxonomyCount[]>(ASSET_TAXONOMY_FALLBACK_COUNTS)
   const [loading, setLoading] = useState(true)
   const [entryFetchError, setEntryFetchError] = useState<string | null>(null)
-  const [entryReadback, setEntryReadback] = useState<Pick<ListResponse, 'readback_status' | 'degraded_reason_code' | 'operator_stage' | 'next_step'> | null>(null)
+  const [entryReadback, setEntryReadback] = useState<Pick<ListResponse, 'readback_status' | 'primary_readback_ready' | 'degraded_reason_code' | 'operator_stage' | 'next_step'> | null>(null)
   const [governanceTelemetry, setGovernanceTelemetry] = useState<KnowledgeGovernanceTelemetry>({
     staleCandidates: null,
     ownerReviews: null,
@@ -554,6 +559,7 @@ export default function KnowledgeBasePage({
         setAssetTaxonomy(data.asset_taxonomy?.length ? data.asset_taxonomy : ASSET_TAXONOMY_FALLBACK_COUNTS)
         setEntryReadback({
           readback_status: data.readback_status ?? 'ready',
+          primary_readback_ready: data.primary_readback_ready ?? false,
           degraded_reason_code: data.degraded_reason_code ?? null,
           operator_stage: data.operator_stage ?? null,
           next_step: data.next_step ?? null,
@@ -701,10 +707,16 @@ export default function KnowledgeBasePage({
   const totalCount = categories.reduce((sum, c) => sum + c.count, 0)
   const isKnowledgeListUnavailable = Boolean(entryFetchError)
   const readbackStatus = entryReadback?.readback_status ?? null
+  const isKnowledgeDirectRecovered = readbackStatus === 'ready_direct_connection_after_session_timeout'
   const isKnowledgeSourceBacked = Boolean(readbackStatus?.startsWith('source_backed'))
-  const isKnowledgeListDegraded = Boolean(readbackStatus && readbackStatus !== 'ready')
+  const isKnowledgeListDegraded = Boolean(readbackStatus && readbackStatus !== 'ready' && !isKnowledgeDirectRecovered)
   const hasKnowledgePayload = entries.length > 0 || total > 0 || categories.some(category => category.count > 0)
   const knowledgeReadbackReady = !loading && !isKnowledgeListUnavailable && (!isKnowledgeListDegraded || hasKnowledgePayload)
+  const showKnowledgeReadbackNotice = Boolean(entryFetchError || isKnowledgeListDegraded || isKnowledgeDirectRecovered)
+  const readbackNoticeTone = isKnowledgeDirectRecovered
+    ? 'border-status-healthy/20 bg-status-healthy/5'
+    : 'border-status-warning/20 bg-status-warning/5'
+  const readbackNoticeTitleTone = isKnowledgeDirectRecovered ? 'text-status-healthy' : 'text-status-warning'
   const localeCode = params.locale === 'en' ? 'en-US' : 'zh-TW'
   const formatCount = useCallback(
     (value: number) => value.toLocaleString(localeCode),
@@ -714,7 +726,11 @@ export default function KnowledgeBasePage({
     () => [
       {
         label: t('dataChain.chip.mode'),
-        value: isKnowledgeSourceBacked ? t('dataChain.mode.sourceBacked') : compactReadbackToken(readbackStatus),
+        value: isKnowledgeSourceBacked
+          ? t('dataChain.mode.sourceBacked')
+          : isKnowledgeDirectRecovered
+            ? t('dataChain.mode.directRecovered')
+            : compactReadbackToken(readbackStatus),
         icon: CheckCircle2,
         tone: 'border-status-healthy/20 bg-status-healthy/10 text-status-healthy',
       },
@@ -757,6 +773,7 @@ export default function KnowledgeBasePage({
       entryReadback?.operator_stage,
       formatCount,
       isKnowledgeSourceBacked,
+      isKnowledgeDirectRecovered,
       readbackStatus,
       t,
       total,
@@ -1485,27 +1502,31 @@ export default function KnowledgeBasePage({
             </button>
           </div>
 
-          {(entryFetchError || isKnowledgeListDegraded) && (
+          {showKnowledgeReadbackNotice && (
             <div className="border-b border-status-warning/20 bg-white px-4 py-2">
-              <div className="flex flex-col gap-2 rounded-md border border-status-warning/20 bg-status-warning/5 px-3 py-2 xl:flex-row xl:items-center xl:justify-between">
+              <div className={cn('flex flex-col gap-2 rounded-md border px-3 py-2 xl:flex-row xl:items-center xl:justify-between', readbackNoticeTone)}>
                 <div className="grid min-w-0 flex-1 gap-2 xl:grid-cols-[minmax(220px,0.8fr)_minmax(0,2fr)] xl:items-center">
                   <div className="min-w-0">
-                    <div className="flex items-center gap-2 text-xs font-label text-status-warning">
+                    <div className={cn('flex items-center gap-2 text-xs font-label', readbackNoticeTitleTone)}>
                       <TriangleAlert className="h-4 w-4 shrink-0" aria-hidden="true" />
                       <span className="truncate">
                         {entryFetchError
                           ? t('dataChain.errorTitle')
-                          : isKnowledgeSourceBacked
-                            ? t('dataChain.sourceBackedTitle')
-                            : t('dataChain.degradedTitle')}
+                          : isKnowledgeDirectRecovered
+                            ? t('dataChain.directRecoveredTitle')
+                            : isKnowledgeSourceBacked
+                              ? t('dataChain.sourceBackedTitle')
+                              : t('dataChain.degradedTitle')}
                       </span>
                     </div>
                     <p className="mt-1 truncate text-[11px] font-body text-muted">
                       {entryFetchError
                         ? t('dataChain.errorDescription', { reason: entryFetchError })
-                        : isKnowledgeSourceBacked
-                          ? t('dataChain.sourceBackedSummary')
-                          : t('dataChain.degradedSummary')}
+                        : isKnowledgeDirectRecovered
+                          ? t('dataChain.directRecoveredSummary')
+                          : isKnowledgeSourceBacked
+                            ? t('dataChain.sourceBackedSummary')
+                            : t('dataChain.degradedSummary')}
                     </p>
                   </div>
                   {!entryFetchError && (