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

backend/alembic/versions/014_task_status_failed.py

@@ -0,0 +1,34 @@
+"""014 generation_tasks.status ENUM 补 failed 终态（B6 错误态）
+
+Revision ID: 014
+Revises: 013
+Create Date: 2026-06-16
+
+status 是 MySQL ENUM,原7值无失败终态。Celery生成彻底失败(重试耗尽)时
+要落 failed,区分"没跑(pending)"和"跑挂了(failed)"。不补 ENUM 会 Data truncated。
+"""
+from alembic import op
+
+revision = "014"
+down_revision = "013"
+branch_labels = None
+depends_on = None
+
+_ENUM_WITH_FAILED = (
+    "ENUM('pending','generating','pending_selection','pending_review',"
+    "'approved','rejected','archived','failed') NOT NULL DEFAULT 'pending'"
+)
+_ENUM_ORIG = (
+    "ENUM('pending','generating','pending_selection','pending_review',"
+    "'approved','rejected','archived') NOT NULL DEFAULT 'pending'"
+)
+
+
+def upgrade():
+    op.execute(f"ALTER TABLE generation_tasks MODIFY COLUMN status {_ENUM_WITH_FAILED}")
+
+
+def downgrade():
+    # 回退前先把 failed 行归位到 pending,避免越界
+    op.execute("UPDATE generation_tasks SET status='pending' WHERE status='failed'")
+    op.execute(f"ALTER TABLE generation_tasks MODIFY COLUMN status {_ENUM_ORIG}")

backend/app/constants/enums.py

@@ -23,6 +23,7 @@ class TaskStatus(str, Enum):
     APPROVED = "approved"
     REJECTED = "rejected"
     ARCHIVED = "archived"
+    FAILED = "failed"  # 生成彻底失败终态(重试耗尽):区分"没跑"和"跑挂了"(B6)
 
 
 # ── 审核状态（generation_tasks 平铺字段）──────────────────

backend/app/workers/tasks.py

@@ -140,16 +140,21 @@ def run_generation_pipeline(self, task_id: int) -> dict:
 
     except Exception as exc:
         logger.error("run_generation_pipeline failed: task_id=%s err=%s", task_id, exc)
+        # 重试耗尽才落 FAILED 终态;还能重试则保持 GENERATING(别伪装成"待开始")。
+        # B6:失败要可见,区分"没跑(pending)"和"跑挂了(failed)"。
+        exhausted = self.request.retries >= self.max_retries
         try:
             from app.models.task import GenerationTask as GT
             from app.constants.enums import TaskStatus as TS
             t = db.query(GT).filter(GT.id == task_id).first()
             if t:
-                t.status = TS.PENDING
+                t.status = TS.FAILED if exhausted else TS.GENERATING
                 db.commit()
         except Exception:
             pass
         _push_event_sync(task_id, workspace_id, "error", {"code": 50001, "message": str(exc)}, seq + 1)
+        if exhausted:
+            return {"task_id": task_id, "status": "failed", "error": str(exc)}
         raise self.retry(exc=exc)
     finally:
         db.close()