diff --git a/tests/unit/test_lipsync_gpu_async_task.py b/tests/unit/test_lipsync_gpu_async_task.py
new file mode 100644
index 000000000..59a49f1a5
--- /dev/null
+++ b/tests/unit/test_lipsync_gpu_async_task.py
@@ -0,0 +1,250 @@
+"""Celery 任务 lipsync_gpu_process_async 直接单测 (#1978 异步化).
+
+覆盖 apps/api/app/tasks/lipsync_gpu.py 的全部主路径：
+- 成功：wait_for_result 返回 done → 签名 URL → completed
+- GPU 超时/失败 → MediaKit 兜底（成功/MediaKitError/其他异常）
+- job 不存在 / 状态异常提前返回
+- 主流程异常 → job 标 failed
+- _sign_media_url 各分支
+"""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+import app.tasks.lipsync_gpu as task_mod
+import pytest
+
+
+def _make_job(status="processing"):
+    job = MagicMock()
+    job.id = "job-1"
+    job.user_id = "u1"
+    job.status = status
+    job.video_url = "videos/v.mp4"
+    job.audio_url = "audios/a.wav"
+    job.enable_video_loop = True
+    return job
+
+
+def _make_gpu_task(status="done", result_url="gpu-lipsync/results/t1.mp4", result_duration=11.2):
+    t = MagicMock()
+    t.status = status
+    t.result_url = result_url
+    t.result_duration = result_duration
+    return t
+
+
+@pytest.fixture()
+def db_patch():
+    """patch _get_db_session 返回 MagicMock，并在任务结束后断言 close."""
+    fake_db = MagicMock()
+    with patch.object(task_mod, "_get_db_session", return_value=fake_db):
+        yield fake_db
+
+
+def _patch_gpu_service(final_task):
+    fake_svc = MagicMock()
+    fake_svc.wait_for_result.return_value = final_task
+    return patch(
+        "app.services.gpu_lipsync_service.GpuLipsyncService",
+        return_value=fake_svc,
+    )
+
+
+def _run_task():
+    # @shared_task bind=True：直接调用任务对象会自动注入 self
+    task_mod.lipsync_gpu_process_async("job-1", "u1", "gpu-task-1")
+
+
+class TestHappyPath:
+    def test_gpu_done_marks_completed(self, db_patch):
+        job = _make_job()
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        gpu_task = _make_gpu_task()
+        storage = MagicMock()
+        storage.get_download_url.return_value = "https://signed.example.com/r1.mp4?sig=x"
+        with (
+            _patch_gpu_service(gpu_task),
+            patch.object(task_mod, "get_shared_storage_service", return_value=storage),
+        ):
+            _run_task()
+        assert job.status == "completed"
+        assert job.output_video_url == "https://signed.example.com/r1.mp4?sig=x"
+        assert job.output_duration == 11.2
+        assert job.completed_at is not None
+        db_patch.commit.assert_called_once()
+        db_patch.close.assert_called_once()
+
+    def test_gpu_done_empty_signed_url_keeps_original(self, db_patch):
+        job = _make_job()
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        gpu_task = _make_gpu_task(result_url="gpu/r2.mp4")
+        storage = MagicMock()
+        storage.get_download_url.return_value = ""
+        with (
+            _patch_gpu_service(gpu_task),
+            patch.object(task_mod, "get_shared_storage_service", return_value=storage),
+        ):
+            _run_task()
+        assert job.status == "completed"
+        assert job.output_video_url == "gpu/r2.mp4"
+
+    def test_gpu_done_result_duration_none_defaults_zero(self, db_patch):
+        job = _make_job()
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        gpu_task = _make_gpu_task(result_duration=None)
+        storage = MagicMock()
+        with (
+            _patch_gpu_service(gpu_task),
+            patch.object(task_mod, "get_shared_storage_service", return_value=storage),
+        ):
+            _run_task()
+        assert job.output_duration == 0.0
+
+    def test_sign_failure_uses_original_url(self, db_patch):
+        job = _make_job()
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        gpu_task = _make_gpu_task(result_url="gpu/r3.mp4")
+        with (
+            _patch_gpu_service(gpu_task),
+            patch.object(task_mod, "get_shared_storage_service", side_effect=RuntimeError("oss down")),
+        ):
+            _run_task()
+        assert job.status == "completed"
+        assert job.output_video_url == "gpu/r3.mp4"
+
+
+class TestJobGuards:
+    def test_job_not_found_returns(self, db_patch):
+        db_patch.query.return_value.filter_by.return_value.first.return_value = None
+        _run_task()
+        db_patch.commit.assert_not_called()
+        db_patch.close.assert_called_once()
+
+    def test_job_wrong_status_skipped(self, db_patch):
+        job = _make_job(status="completed")
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        _run_task()
+        db_patch.commit.assert_not_called()
+
+
+class TestGpuFailureFallback:
+    def test_gpu_timeout_falls_back_mediakit_success(self, db_patch):
+        job = _make_job()
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        with (
+            _patch_gpu_service(None),
+            patch.object(task_mod, "_fallback_to_mediakit") as fb,
+        ):
+            _run_task()
+        fb.assert_called_once_with(db_patch, job)
+
+    def test_gpu_failed_status_falls_back(self, db_patch):
+        job = _make_job()
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        gpu_task = _make_gpu_task(status="failed")
+        with (
+            _patch_gpu_service(gpu_task),
+            patch.object(task_mod, "_fallback_to_mediakit") as fb,
+        ):
+            _run_task()
+        fb.assert_called_once_with(db_patch, job)
+
+
+class TestFallbackToMediaKit:
+    def test_mediakit_success_marks_submitted(self, db_patch):
+        job = _make_job()
+        fake_client = MagicMock()
+        fake_client.submit_lipsync.return_value = {"task_id": "mk-99"}
+        with (
+            patch("app.services.mediakit_client.get_mediakit_client", return_value=fake_client),
+            patch.object(task_mod, "_sign_media_url", side_effect=lambda u: u + "?s"),
+        ):
+            task_mod._fallback_to_mediakit(db_patch, job)
+        fake_client.submit_lipsync.assert_called_once()
+        kwargs = fake_client.submit_lipsync.call_args.kwargs
+        assert kwargs["enable_video_loop"] is True
+        assert kwargs["client_token"] == "job-1"
+        assert job.status == "submitted"
+        assert job.mediakit_task_id == "mk-99"
+        db_patch.commit.assert_called_once()
+
+    def test_mediakit_error_marks_failed(self, db_patch):
+        from app.services.mediakit_client import MediaKitError
+
+        job = _make_job()
+        fake_client = MagicMock()
+        fake_client.submit_lipsync.side_effect = MediaKitError("api reject", code="MkReject")
+        with (
+            patch("app.services.mediakit_client.get_mediakit_client", return_value=fake_client),
+            patch.object(task_mod, "_sign_media_url", side_effect=lambda u: u),
+        ):
+            task_mod._fallback_to_mediakit(db_patch, job)
+        assert job.status == "failed"
+        assert job.error_code == "MkReject"
+        db_patch.commit.assert_called_once()
+
+    def test_other_exception_marks_failed(self, db_patch):
+        job = _make_job()
+        with (
+            patch("app.services.mediakit_client.get_mediakit_client", side_effect=RuntimeError("boom")),
+            patch.object(task_mod, "_sign_media_url", side_effect=lambda u: u),
+        ):
+            task_mod._fallback_to_mediakit(db_patch, job)
+        assert job.status == "failed"
+        assert job.error_code == "FallbackFailed"
+        db_patch.commit.assert_called_once()
+
+
+class TestTaskException:
+    def test_unexpected_exception_marks_job_failed(self, db_patch):
+        job = _make_job()
+        # query 第一次返回 job，异常路径里再次 query 也返回 job
+        db_patch.query.return_value.filter_by.return_value.first.return_value = job
+        with patch(
+            "app.services.gpu_lipsync_service.GpuLipsyncService",
+            side_effect=RuntimeError("svc ctor fail"),
+        ):
+            _run_task()
+        assert job.status == "failed"
+        assert job.error_code == "GpuAsyncError"
+
+    def test_exception_handler_failure_swallowed(self, db_patch):
+        # 主流程异常，且异常处理中的 query 也抛异常 → 不应再抛
+        db_patch.query.side_effect = RuntimeError("db totally broken")
+        _run_task()
+        db_patch.close.assert_called_once()
+
+
+class TestSignMediaUrl:
+    def test_empty_url_returned_as_is(self):
+        assert task_mod._sign_media_url("") == ""
+
+    def test_non_own_host_returned_as_is(self):
+        storage = MagicMock()
+        storage.public_url = "https://own-bucket.oss-cn-beijing.aliyuncs.com"
+        with patch.object(task_mod, "get_shared_storage_service", return_value=storage):
+            url = "https://other.example.com/a.wav"
+            assert task_mod._sign_media_url(url) == url
+
+    def test_own_host_signed(self):
+        storage = MagicMock()
+        storage.public_url = "https://own-bucket.oss-cn-beijing.aliyuncs.com"
+        storage.get_download_url.return_value = "https://own-bucket.oss-cn-beijing.aliyuncs.com/a?sig=1"
+        with patch.object(task_mod, "get_shared_storage_service", return_value=storage):
+            out = task_mod._sign_media_url("https://own-bucket.oss-cn-beijing.aliyuncs.com/a.wav")
+        assert out.endswith("?sig=1")
+        storage.get_download_url.assert_called_once()
+
+    def test_missing_public_url_returns_original(self):
+        storage = MagicMock()
+        storage.public_url = ""
+        with patch.object(task_mod, "get_shared_storage_service", return_value=storage):
+            url = "https://own-bucket.oss-cn-beijing.aliyuncs.com/a.wav"
+            assert task_mod._sign_media_url(url) == url
+
+    def test_exception_returns_original(self):
+        with patch.object(task_mod, "get_shared_storage_service", side_effect=RuntimeError("x")):
+            url = "https://own-bucket.oss-cn-beijing.aliyuncs.com/a.wav"
+            assert task_mod._sign_media_url(url) == url
diff --git a/tests/unit/test_lipsync_gpu_integration.py b/tests/unit/test_lipsync_gpu_integration.py
index 60a1412ba..e8e3a0c0a 100644
--- a/tests/unit/test_lipsync_gpu_integration.py
+++ b/tests/unit/test_lipsync_gpu_integration.py
@@ -141,6 +141,46 @@ class TestGpuFallback:
         fake_mediakit.submit_lipsync.assert_called_once()
         assert job.status == "submitted"
 
+    def test_gpu_create_returns_none_falls_back_mediakit(self, fake_db, fake_mediakit):
+        """_submit_to_gpu_create 返回 None（create_task 失败被内部吞掉）→ rollback + MediaKit."""
+        svc = _make_svc(fake_db, fake_mediakit, use_gpu=True)
+        fake_gpu_svc = MagicMock()
+        fake_gpu_svc.has_available_worker.return_value = True
+        with (
+            _patch_storage(),
+            patch("app.services.gpu_lipsync_service.GpuLipsyncService", return_value=fake_gpu_svc),
+            patch.object(svc, "_submit_to_gpu_create", return_value=None) as m_create,
+        ):
+            job = _make_job()
+            svc._submit_audio_direct(job=job)
+        m_create.assert_called_once()
+        fake_db.rollback.assert_called_once()
+        fake_mediakit.submit_lipsync.assert_called_once()
+        assert job.status == "submitted"
+
+    def test_submit_to_gpu_wait_timeout_returns(self, fake_db, fake_mediakit):
+        """降级同步等待：wait_for_result 返回 None → 直接返回，job 保持 processing."""
+        svc = _make_svc(fake_db, fake_mediakit, use_gpu=True)
+        fake_gpu_svc = MagicMock()
+        fake_gpu_svc.wait_for_result.return_value = None
+        job = _make_job()
+        job.status = "processing"
+        svc._submit_to_gpu_wait(job=job, gpu_svc=fake_gpu_svc, gpu_task=MagicMock(id="gpu-task-x"))
+        fake_gpu_svc.wait_for_result.assert_called_once_with("gpu-task-x")
+        fake_db.commit.assert_not_called()
+        assert job.status == "processing"
+
+    def test_submit_to_gpu_wait_failed_status_returns(self, fake_db, fake_mediakit):
+        """降级同步等待：final_task.status != done → 直接返回."""
+        svc = _make_svc(fake_db, fake_mediakit, use_gpu=True)
+        fake_gpu_svc = MagicMock()
+        fake_gpu_svc.wait_for_result.return_value = MagicMock(status="failed", result_url="")
+        job = _make_job()
+        job.status = "processing"
+        svc._submit_to_gpu_wait(job=job, gpu_svc=fake_gpu_svc, gpu_task=MagicMock(id="gpu-task-y"))
+        fake_db.commit.assert_not_called()
+        assert job.status == "processing"
+
     def test_gpu_external_audio_persisted_to_own_oss(self, fake_db, fake_mediakit):
         """Bug2 回归：dashscope 临时音频 URL 在创建 GPU 任务前转存自家 OSS."""
         svc = _make_svc(fake_db, fake_mediakit, use_gpu=True)
@@ -212,6 +252,53 @@ class TestGpuFallback:
         assert fake_gpu_svc.create_task.call_args.kwargs["audio_url"] == dashscope_url
 
 
+class TestRefreshGpuStale:
+    """refresh_job_status 的 GPU 异步 stale 超时分支."""
+
+    def test_stale_gpu_job_marked_failed(self, fake_db):
+        from datetime import UTC, datetime, timedelta
+
+        svc = _make_svc(fake_db, MagicMock(), use_gpu=True)
+        job = MagicMock()
+        job.status = "processing"
+        job.mediakit_task_id = "gpu:gpu-task-stale"
+        job.updated_at = datetime.now(UTC) - timedelta(minutes=31)
+        with patch.object(svc, "get_job", return_value=job):
+            result = svc.refresh_job_status("job-stale", "u1")
+        assert result is job
+        assert job.status == "failed"
+        assert job.error_code == "GpuTimeout"
+        fake_db.commit.assert_called_once()
+
+    def test_fresh_gpu_job_left_processing(self, fake_db):
+        from datetime import UTC, datetime, timedelta
+
+        svc = _make_svc(fake_db, MagicMock(), use_gpu=True)
+        job = MagicMock()
+        job.status = "processing"
+        job.mediakit_task_id = "gpu:gpu-task-fresh"
+        job.updated_at = datetime.now(UTC) - timedelta(minutes=2)
+        with patch.object(svc, "get_job", return_value=job):
+            result = svc.refresh_job_status("job-fresh", "u1")
+        assert result is job
+        assert job.status == "processing"
+        fake_db.commit.assert_not_called()
+
+    def test_naive_updated_at_stale_marked_failed(self, fake_db):
+        """updated_at 为 naive datetime 时按 UTC 补时区后再判定."""
+        from datetime import UTC, datetime, timedelta
+
+        svc = _make_svc(fake_db, MagicMock(), use_gpu=True)
+        job = MagicMock()
+        job.status = "gpu_processing"
+        job.mediakit_task_id = "gpu:gpu-task-naive"
+        job.updated_at = datetime.now(UTC).replace(tzinfo=None) - timedelta(minutes=31)
+        with patch.object(svc, "get_job", return_value=job):
+            svc.refresh_job_status("job-naive", "u1")
+        assert job.status == "failed"
+        assert job.error_code == "GpuTimeout"
+
+
 class TestGpuServiceHelpers:
     """GpuLipsyncService.has_available_worker 测试."""