B6/B7: failed终态前端可见 + SSE事件链核实

B6 错误态:
- 后端已加 TaskStatus.FAILED + 异常区分重试中/耗尽(014迁移ALTER status ENUM)
- 前端 TaskStatus 类型加 failed
- RecentTasksBar/history STATUS_LABEL 补 failed 标签
- history 页 HISTORY_STATUSES 纳入 failed(否则失败任务前端找不到)
- FatalErrorBanner + useSse error 不再静默丢弃

B7: 核实 SSE(ticket换JWT) + 事件消费链无缺口,标绿

tsc EXIT=0

frontend/src/app/history/components.tsx

@@ -17,6 +17,7 @@ const STATUS_LABEL: Record<string, { text: string; color: string }> = {
   approved: { text: '已通过', color: 'text-green-600 bg-green-50' },
   archived: { text: '已归档', color: 'text-gray-500 bg-gray-100' },
   rejected: { text: '被打回', color: 'text-red-500 bg-red-50' },
+  failed: { text: '生成失败', color: 'text-red-600 bg-red-50' },
 };
 
 // --- DownloadButton --- 触发打包→轮询→下载 zip

frontend/src/app/history/page.tsx

@@ -11,9 +11,9 @@ import { getErrorAction } from '@/types/errors';
 import { clsx } from 'clsx';
 import { HistoryTable, HistorySkeleton, Pagination } from './components';
 
-const HISTORY_STATUSES = ['approved', 'archived', 'rejected'];
+const HISTORY_STATUSES = ['approved', 'archived', 'rejected', 'failed'];
 const STATUS_LABELS: Record<string, string> = {
-  approved: '已通过', archived: '已归档', rejected: '被打回',
+  approved: '已通过', archived: '已归档', rejected: '被打回', failed: '生成失败',
 };
 const PAGE_SIZE = 20;
 

frontend/src/app/tasks/[id]/images/page.tsx

@@ -7,6 +7,7 @@ import { ImageProgressCardSkeleton } from '@/components/tasks/ImageProgressCard'
 import { ImageProgressHeader } from '@/components/tasks/ImageProgressHeader';
 import { ImageActionBar } from '@/components/tasks/ImageActionBar';
 import { SseStatusBar } from '@/components/tasks/SseStatusBar';
+import { FatalErrorBanner } from '@/components/tasks/FatalErrorBanner';
 import { useSse } from '@/hooks/useSse';
 import { useGenerationStore } from '@/stores/generationStore';
 import { useTaskStore } from '@/stores/taskStore';
@@ -50,6 +51,7 @@ export default function ImageSelectionPage() {
       )}
       <SseStatusBar status={connectionStatus} attempt={reconnectAttempt} />
       <div className="p-6 flex-1 overflow-auto">
+        <FatalErrorBanner />
         <ImageProgressHeader imageTotal={imageTotal} imageDone={imageDone} pendingCount={pendingCount} />
         {/* 图片网格（谁好谁先冒） */}
         <div className="grid grid-cols-3 xl:grid-cols-5 gap-3">

frontend/src/app/tasks/[id]/text/page.tsx

@@ -6,6 +6,7 @@ import { ProgressBar } from '@/components/layout/ProgressBar';
 import { FlywheelBannerFromSse } from '@/components/FlywheelBanner';
 import { TextCandidateCard, TextCandidateCardSkeleton } from '@/components/tasks/TextCandidateCard';
 import { SseStatusBar } from '@/components/tasks/SseStatusBar';
+import { FatalErrorBanner } from '@/components/tasks/FatalErrorBanner';
 import { useSse } from '@/hooks/useSse';
 import { useGenerationStore } from '@/stores/generationStore';
 import { useTaskStore } from '@/stores/taskStore';
@@ -50,6 +51,9 @@ export default function TextSelectionPage() {
           <SseStatusBar status={connectionStatus} attempt={reconnectAttempt} />
         </div>
 
+        {/* 任务级失败提示(B6):生成彻底失败时明确反馈,不再无限转圈 */}
+        <FatalErrorBanner />
+
         {/* SSE 进度提示（生成中且无内容时） */}
         {showSkeleton && (
           <div className="mb-4 bg-brand-cream border border-brand-orange/20 rounded-xl px-4 py-3 text-sm text-text-secondary"

frontend/src/components/tasks/FatalErrorBanner.tsx

@@ -0,0 +1,30 @@
+'use client';
+// FatalErrorBanner — 任务级致命错误提示(B6)。生成彻底失败时给用户明确反馈,
+// 不再让页面无限转圈。从 generationStore.fatalError 读。
+import { useGenerationStore } from '@/stores/generationStore';
+
+export function FatalErrorBanner() {
+  const fatalError = useGenerationStore((s) => s.fatalError);
+  if (!fatalError) return null;
+
+  return (
+    <div
+      className="mb-4 bg-red-50 border border-status-error rounded-xl px-4 py-3"
+      role="alert"
+      aria-live="assertive"
+    >
+      <div className="flex items-start gap-2">
+        <span aria-hidden="true" className="text-status-error">⚠️</span>
+        <div className="flex-1 min-w-0">
+          <p className="text-sm font-medium text-status-error">生成失败</p>
+          <p className="text-xs text-text-secondary mt-0.5 break-words">
+            {fatalError.message || '生成过程出错，请重试或联系管理员'}
+          </p>
+          <p className="text-xs text-text-tertiary mt-1">
+            可在任务列表对该任务重新生成；多次失败请检查 key 配置或网络。
+          </p>
+        </div>
+      </div>
+    </div>
+  );
+}

frontend/src/components/tasks/RecentTasksBar.tsx

@@ -19,6 +19,7 @@ const STATUS_LABELS: Record<TaskStatus, { label: string; color: string }> = {
   approved: { label: '已通过', color: 'text-status-success' },
   rejected: { label: '已打回', color: 'text-status-error' },
   archived: { label: '已归档', color: 'text-text-tertiary' },
+  failed: { label: '生成失败', color: 'text-status-error' },
 };
 
 export function RecentTasksBar() {

frontend/src/hooks/useSse.ts

@@ -121,6 +121,10 @@ function handleEvent(
       break;
 
     case 'error':
+      // 任务级致命错误:不再静默丢弃,落 fatalError 让 UI 提示(B6)
+      store.setFatalError(event.data.code, event.data.message);
+      break;
+
     case 'heartbeat':
     case 'analyze_done':
     case 'task_done':

frontend/src/stores/generationStore.ts

@@ -28,6 +28,9 @@ interface GenerationState {
   imageCandidates: ImageCandidate[];
   failedBatches: FailedBatch[];
 
+  // 任务级致命错误(SSE error事件,生成彻底失败)。区别于图片批次级 failedBatches。
+  fatalError: { code: number; message: string } | null;
+
   // 飞轮注入（飞轮隐形，只显注入提示，无"训练AI"按钮）
   flywheelInjected: {
     recentPreference: string;
@@ -41,6 +44,7 @@ interface GenerationState {
   setImageProgress: (done: number, total: number) => void;
   addImageCandidate: (candidate: ImageCandidate) => void;
   markBatchFailed: (batch: string, reason: string, retryable: boolean) => void;
+  setFatalError: (code: number, message: string) => void;
   setFlywheelInjected: (data: { recentPreference: string; rejectReasons: string[] }) => void;
   hydrateFromTask: (data: {
     textCandidates: TextCandidate[];
@@ -59,6 +63,7 @@ export const useGenerationStore = create<GenerationState>((set) => ({
   imageTotal: 0,
   imageCandidates: [],
   failedBatches: [],
+  fatalError: null,
   flywheelInjected: null,
 
   setConnectionStatus(s, attempt = 0) {
@@ -95,6 +100,10 @@ export const useGenerationStore = create<GenerationState>((set) => ({
     }));
   },
 
+  setFatalError(code, message) {
+    set({ fatalError: { code, message } });
+  },
+
   setFlywheelInjected(data) {
     set({ flywheelInjected: data });
   },
@@ -116,7 +125,7 @@ export const useGenerationStore = create<GenerationState>((set) => ({
       connectionStatus: 'connecting', reconnectAttempt: 0,
       textDone: 0, textTotal: 0, textCandidates: [],
       imageDone: 0, imageTotal: 0, imageCandidates: [],
-      failedBatches: [], flywheelInjected: null,
+      failedBatches: [], fatalError: null, flywheelInjected: null,
     });
   },
 }));

frontend/src/types/dto.tasks.ts

@@ -3,7 +3,7 @@
 // 任务
 export type TaskStatus =
   | 'pending' | 'generating' | 'pending_selection'
-  | 'pending_review' | 'approved' | 'rejected' | 'archived';
+  | 'pending_review' | 'approved' | 'rejected' | 'archived' | 'failed';
 
 export interface TaskListItem {
   id: number;