fix(P0): 修复取消链路断裂，前端取消后 GPU 仍继续推理 (#2009)

Co-authored-by: xiaoxia <dev@xiaoxiajianji.com>
Co-committed-by: xiaoxia <dev@xiaoxiajianji.com>

tests/unit/test_gpu_lipsync_service.py

@@ -173,10 +173,10 @@ def test_timed_out_task_is_redispatched(svc):
 
 
 def test_register_worker_creates_then_updates(svc):
-    w = svc.register_worker("w-1", hostname="pc1", gpu_name="RTX2060", free_vram_mb=3500)
+    w, _cancel = svc.register_worker("w-1", hostname="pc1", gpu_name="RTX2060", free_vram_mb=3500)
     assert w.worker_id == "w-1"
     assert w.gpu_name == "RTX2060"
-    w2 = svc.register_worker("w-1", hostname="pc1", gpu_name="RTX2060", free_vram_mb=2000)
+    w2, _cancel2 = svc.register_worker("w-1", hostname="pc1", gpu_name="RTX2060", free_vram_mb=2000)
     assert w2.free_vram_mb == 2000  # 更新
     assert w2.created_at == w.created_at  # 没新建
 
@@ -195,7 +195,7 @@ def test_register_with_task_id_refreshes_task_heartbeat(svc):
         {"last_heartbeat_at": old_hb - timedelta(seconds=300)}
     )
     svc.db.commit()
-    svc.register_worker("w-1", task_id=t.id)
+    _w, _c = svc.register_worker("w-1", task_id=t.id)
     svc.db.refresh(t)
     assert t.last_heartbeat_at > old_hb
     assert t.status == "processing"  # 心跳不改变状态
@@ -213,7 +213,7 @@ def test_register_task_heartbeat_ignores_finished_or_foreign_task(svc):
     svc.poll_task("w-1")
     done = svc.report_result(t.id, "w-1", success=True, duration_seconds=10.0)
     hb_when_done = done.last_heartbeat_at
-    svc.register_worker("w-1", task_id=t.id)
+    _w, _c = svc.register_worker("w-1", task_id=t.id)
     svc.db.refresh(t)
     assert t.status == "done"
     assert t.last_heartbeat_at == hb_when_done  # 没被改写
@@ -232,17 +232,61 @@ def test_register_task_heartbeat_ignores_finished_or_foreign_task(svc):
         {"last_heartbeat_at": owner_hb - timedelta(seconds=600)}
     )
     svc.db.commit()
-    svc.register_worker("w-1", task_id=t2.id)  # 旧 worker 迟到心跳
+    _w2, _c2 = svc.register_worker("w-1", task_id=t2.id)  # 旧 worker 迟到心跳
     svc.db.refresh(t2)
     assert t2.worker_id == "w-2"
     assert t2.status == "processing"
     assert t2.last_heartbeat_at == owner_hb
 
     # 场景 3：不存在的 task_id 不报错
-    svc.register_worker("w-1", task_id="nonexistent-id")
+    _wn, _cn = svc.register_worker("w-1", task_id="nonexistent-id")
     assert svc.db.get(GpuLipsyncTaskModel, "nonexistent-id") is None
 
 
+def test_register_task_heartbeat_detects_cancelled(svc):
+    """取消链路：任务已 cancelled 时，register 心跳必须返回 cancel_task=True."""
+    t = svc.create_task(video_url="v", audio_url="a")
+    svc.poll_task("w-1")
+    svc.db.refresh(t)
+    # 用户取消：直接把任务置为 cancelled
+    t.status = "cancelled"
+    t.finished_at = datetime.now(UTC)
+    svc.db.commit()
+
+    _w, cancel_task = svc.register_worker("w-1", task_id=t.id)
+    assert cancel_task is True
+    svc.db.refresh(t)
+    assert t.status == "cancelled"  # 心跳不改写已取消状态
+
+
+def test_report_result_cancelled_stays_cancelled(svc):
+    """Worker 终止取消任务后上报失败，report_result 必须保持 cancelled 不回退 pending."""
+    t = svc.create_task(video_url="v", audio_url="a")
+    svc.poll_task("w-1")
+    svc.db.refresh(t)
+    t.status = "cancelled"
+    svc.db.commit()
+
+    result = svc.report_result(t.id, "w-1", success=False, error_msg="推理被终止")
+    assert result.status == "cancelled"
+    assert result.finished_at is not None
+    assert "推理被终止" in (result.error_msg or "")
+
+
+def test_wait_for_result_returns_when_cancelled(svc):
+    """wait_for_result 将 cancelled 视为终态，立即返回，Celery 不回退 MediaKit."""
+    t = svc.create_task(video_url="v", audio_url="a")
+    svc.poll_task("w-1")
+    svc.db.refresh(t)
+    t.status = "cancelled"
+    t.finished_at = datetime.now(UTC)
+    svc.db.commit()
+
+    result = svc.wait_for_result(t.id, timeout_seconds=5, poll_interval=0.1)
+    assert result is not None
+    assert result.status == "cancelled"
+
+
 def test_default_gpu_task_timeout_is_900(svc):
     """#1970 默认超时 300→900，覆盖 RTX2060 长视频推理."""
     assert svc.settings.gpu_task_timeout_seconds == 900