fix(intelligent-eval): settle stale tasks of finished evals

任务队列出现'评估已 completed 却有待认领/执行中任务'的残留：评估离开
executing 后，其 pending/assigned 任务无人清理（requeue_stale_assigned_tasks
只处理 executing 评估的 assigned，评估结束被跳过）。

- 新增 task_queue.settle_tasks_for_finished_evals：评估非 executing 时，
  其 pending/assigned 任务回收为 completed；executing 评估的任务保留
- scan loop 每 60s 在 requeue+scan 后调用清理
测试：+1（已结束评估的 pending/assigned 回收、executing 保留、幂等），901 passed

backend/agenteval/intelligent_eval/task_queue.py

@@ -277,6 +277,44 @@ def requeue_stale_assigned_tasks(session: Session) -> int:
     return requeued
 
 
+def settle_tasks_for_finished_evals(session: Session) -> int:
+    """Mark pending/assigned tasks of finished (non-executing) evals as completed.
+
+    评估离开 executing（completed/failed/cancelled）后，其待认领/执行中任务不再
+    需要执行，应回收为 completed，否则会永久残留（requeue_stale_assigned_tasks
+    只处理 executing 评估的 assigned 任务，评估结束后被跳过 → 队列里出现
+    "已完成评估却有待认领/执行中任务"）。
+
+    Returns:
+        清理的任务数。
+    """
+    from sqlmodel import select
+
+    from agenteval.intelligent_eval.models import IntelligentEvalStatus
+    from agenteval.storage.db import IntelligentEvalTaskQueueDB
+
+    tasks = session.exec(
+        select(IntelligentEvalTaskQueueDB).where(
+            IntelligentEvalTaskQueueDB.status.in_(["pending", "assigned"])
+        )
+    ).all()
+
+    settled = 0
+    for task in tasks:
+        ev = session.get(IntelligentEvalDB, task.eval_id)
+        if ev is None or ev.status == IntelligentEvalStatus.EXECUTING.value:
+            continue  # executing 评估的任务正常流转，不清理
+        task.status = "completed"
+        task.completed_at = utc_now()
+        task.error = "评估已结束，任务不再需要执行"
+        task.updated_at = utc_now()
+        settled += 1
+
+    if settled:
+        session.commit()
+    return settled
+
+
 # ---------------------------------------------------------------------------
 # 任务队列监控（方案③可视化）：列表 + 状态分布
 # ---------------------------------------------------------------------------

backend/agenteval/web/app.py

@@ -297,6 +297,7 @@ async def _intelligent_eval_scan_loop() -> None:
                 from agenteval.intelligent_eval.task_queue import (
                     requeue_stale_assigned_tasks,
                     scan_and_enqueue_tasks,
+                    settle_tasks_for_finished_evals,
                 )
 
                 r = requeue_stale_assigned_tasks(session)
@@ -305,6 +306,10 @@ async def _intelligent_eval_scan_loop() -> None:
                 n = scan_and_enqueue_tasks(session)
                 if n:
                     _logger.info("智能评估扫描：入队 %d 个 Worker 任务", n)
+                # 清理：评估已结束（非 executing）的 pending/assigned 任务回收为 completed
+                settled = settle_tasks_for_finished_evals(session)
+                if settled:
+                    _logger.info("任务回收：%d 个已结束评估的任务标记完成", settled)
                 # 审计兜底：agent 未上报决策日志时，平台按评估状态补录
                 added = _supplement_decision_logs(session)
                 if added:

tests/unit/test_intelligent_eval_task_queue.py

@@ -292,3 +292,54 @@ def test_complete_task(db_session: Session):
     db_session.refresh(task2)
     assert task2.status == "failed"
     assert task2.error == "test error"
+
+
+def test_settle_tasks_for_finished_evals(db_session: Session):
+    """评估已结束（completed/failed/cancelled）时，其 pending/assigned 任务应回收为 completed。
+
+    回归：t480 队列出现"评估已 completed 却有待认领/执行中任务"的残留。
+    """
+    # 已结束的评估（completed）：pending + assigned 任务都应被清理
+    done_eval = IntelligentEvalDB(
+        name="done", target_id="t1",
+        status=IntelligentEvalStatus.COMPLETED.value, started_at=utc_now(),
+    )
+    db_session.add(done_eval)
+    db_session.commit()
+
+    pending_task = IntelligentEvalTaskQueueDB(
+        eval_id=done_eval.id, status="pending", priority=1, reason="slot_due",
+    )
+    assigned_task = IntelligentEvalTaskQueueDB(
+        eval_id=done_eval.id, status="assigned", priority=1, reason="slot_due",
+        assigned_cron_id="cron1",
+    )
+    db_session.add_all([pending_task, assigned_task])
+    db_session.commit()
+
+    # 仍在执行中的评估：任务应保留（正常流转）
+    running_eval = IntelligentEvalDB(
+        name="running", target_id="t1",
+        status=IntelligentEvalStatus.EXECUTING.value, started_at=utc_now(),
+    )
+    db_session.add(running_eval)
+    db_session.commit()
+    live_task = IntelligentEvalTaskQueueDB(
+        eval_id=running_eval.id, status="assigned", priority=1, reason="slot_due",
+        assigned_cron_id="cron2",
+    )
+    db_session.add(live_task)
+    db_session.commit()
+
+    settled = task_queue.settle_tasks_for_finished_evals(db_session)
+    assert settled == 2  # 只清理已结束评估的 2 个任务
+
+    db_session.refresh(pending_task)
+    db_session.refresh(assigned_task)
+    db_session.refresh(live_task)
+    assert pending_task.status == "completed"
+    assert assigned_task.status == "completed"
+    assert live_task.status == "assigned"  # executing 评估的任务保留
+
+    # 幂等：再跑一次不再清理
+    assert task_queue.settle_tasks_for_finished_evals(db_session) == 0