diff --git a/tests/unit/test_jobs.py b/tests/unit/test_jobs.py
new file mode 100755
index 000000000..61ba82790
--- /dev/null
+++ b/tests/unit/test_jobs.py
@@ -0,0 +1,578 @@
+"""
+Job 应用层用例单元测试（第十八波）
+
+覆盖：
+- CreateJobUseCase
+- SubmitJobUseCase
+- UpdateJobProgressUseCase
+- CompleteJobUseCase
+- FailJobUseCase
+- RetryJobUseCase
+- CancelJobUseCase
+- GetJobUseCase
+- ListJobsUseCase
+- GetJobStatisticsUseCase
+"""
+
+from unittest.mock import MagicMock
+
+import pytest
+
+from packages.application.jobs import (
+    CancelJobUseCase,
+    CompleteJobCommand,
+    CompleteJobUseCase,
+    CreateJobCommand,
+    CreateJobUseCase,
+    FailJobCommand,
+    FailJobUseCase,
+    GetJobStatisticsUseCase,
+    GetJobUseCase,
+    ListJobsUseCase,
+    RetryJobUseCase,
+    SubmitJobUseCase,
+    UpdateJobProgressCommand,
+    UpdateJobProgressUseCase,
+)
+from packages.domain.job import Job, JobStatus, JobType
+
+
+@pytest.fixture
+def mock_repo():
+    return MagicMock()
+
+
+def make_job(
+    status=JobStatus.PENDING,
+    job_type=JobType.VIDEO_COMPOSE,
+    project_id="proj-1",
+    **kwargs,
+):
+    job = Job.create(
+        project_id=project_id,
+        job_type=job_type,
+        **kwargs,
+    )
+    # 绕过状态机直接设置状态（测试构造用）
+    if status != JobStatus.PENDING:
+        object.__setattr__(job, "status", status)
+    return job
+
+
+# ============================================================
+# CreateJobUseCase
+# ============================================================
+
+
+class TestCreateJobUseCase:
+    """CreateJobUseCase 创建任务"""
+
+    def test_create_success(self, mock_repo):
+        """正常创建任务"""
+        mock_repo.create.side_effect = lambda j: j
+
+        cmd = CreateJobCommand(
+            project_id="proj-1",
+            job_type=JobType.VIDEO_COMPOSE,
+            payload={"key": "val"},
+            source_id="src-1",
+            created_by_user_id="user-1",
+            max_retries=5,
+        )
+        uc = CreateJobUseCase(mock_repo)
+        job = uc.execute(cmd)
+
+        assert job.project_id == "proj-1"
+        assert job.job_type == JobType.VIDEO_COMPOSE
+        assert job.payload == {"key": "val"}
+        assert job.source_id == "src-1"
+        assert job.created_by_user_id == "user-1"
+        assert job.max_retries == 5
+        assert job.status == JobStatus.PENDING
+        assert job.progress == 0.0
+        mock_repo.create.assert_called_once()
+
+    def test_create_default_values(self, mock_repo):
+        """默认参数"""
+        mock_repo.create.side_effect = lambda j: j
+
+        cmd = CreateJobCommand(project_id="proj-1", job_type="video_compose")
+        uc = CreateJobUseCase(mock_repo)
+        job = uc.execute(cmd)
+
+        assert job.payload == {}
+        assert job.source_id == ""
+        assert job.created_by_user_id == ""
+        assert job.max_retries == 3
+
+    def test_create_string_job_type(self, mock_repo):
+        """字符串类型的 job_type 也支持"""
+        mock_repo.create.side_effect = lambda j: j
+
+        cmd = CreateJobCommand(project_id="proj-1", job_type="asset_ingest")
+        uc = CreateJobUseCase(mock_repo)
+        job = uc.execute(cmd)
+
+        assert job.job_type == JobType.ASSET_INGEST
+
+
+# ============================================================
+# SubmitJobUseCase
+# ============================================================
+
+
+class TestSubmitJobUseCase:
+    """SubmitJobUseCase 提交任务"""
+
+    def test_submit_success(self, mock_repo):
+        """正常提交 pending 任务"""
+        job = make_job(status=JobStatus.PENDING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        uc = SubmitJobUseCase(mock_repo)
+        result = uc.execute(job.id, celery_task_id="celery-123")
+
+        assert result.status == JobStatus.RUNNING
+        assert result.celery_task_id == "celery-123"
+        assert result.current_stage == "已提交，等待执行"
+        assert result.started_at is not None
+        mock_repo.update.assert_called_once()
+
+    def test_submit_job_not_found(self, mock_repo):
+        """任务不存在"""
+        mock_repo.get.return_value = None
+
+        uc = SubmitJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="任务不存在"):
+            uc.execute("nonexistent")
+
+    def test_submit_already_running(self, mock_repo):
+        """已经是 running 状态不能再提交"""
+        job = make_job(status=JobStatus.RUNNING)
+        mock_repo.get.return_value = job
+
+        uc = SubmitJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="只有 pending 状态"):
+            uc.execute(job.id)
+
+    def test_submit_without_celery_id(self, mock_repo):
+        """不传 celery_task_id 也可以"""
+        job = make_job(status=JobStatus.PENDING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        uc = SubmitJobUseCase(mock_repo)
+        result = uc.execute(job.id)
+
+        assert result.status == JobStatus.RUNNING
+        assert result.celery_task_id == ""
+
+
+# ============================================================
+# UpdateJobProgressUseCase
+# ============================================================
+
+
+class TestUpdateJobProgressUseCase:
+    """UpdateJobProgressUseCase 更新进度"""
+
+    def test_update_progress_success(self, mock_repo):
+        """正常更新进度"""
+        job = make_job(status=JobStatus.RUNNING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        cmd = UpdateJobProgressCommand(
+            job_id=job.id, progress=50.0, current_stage="处理中"
+        )
+        uc = UpdateJobProgressUseCase(mock_repo)
+        result = uc.execute(cmd)
+
+        assert result.progress == 50.0
+        assert result.current_stage == "处理中"
+        mock_repo.update.assert_called_once()
+
+    def test_update_progress_job_not_found(self, mock_repo):
+        """任务不存在"""
+        mock_repo.get.return_value = None
+
+        cmd = UpdateJobProgressCommand(job_id="nope", progress=50.0)
+        uc = UpdateJobProgressUseCase(mock_repo)
+        with pytest.raises(ValueError, match="任务不存在"):
+            uc.execute(cmd)
+
+    def test_update_progress_not_running(self, mock_repo):
+        """非 running 状态不能更新进度"""
+        job = make_job(status=JobStatus.PENDING)
+        mock_repo.get.return_value = job
+
+        cmd = UpdateJobProgressCommand(job_id=job.id, progress=50.0)
+        uc = UpdateJobProgressUseCase(mock_repo)
+        with pytest.raises(ValueError, match="只有 running 状态"):
+            uc.execute(cmd)
+
+
+# ============================================================
+# CompleteJobUseCase
+# ============================================================
+
+
+class TestCompleteJobUseCase:
+    """CompleteJobUseCase 完成任务"""
+
+    def test_complete_from_running(self, mock_repo):
+        """从 running 状态完成"""
+        job = make_job(status=JobStatus.RUNNING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        cmd = CompleteJobCommand(job_id=job.id, result={"output": "ok"})
+        uc = CompleteJobUseCase(mock_repo)
+        result = uc.execute(cmd)
+
+        assert result.status == JobStatus.SUCCESS
+        assert result.progress == 100.0
+        assert result.result == {"output": "ok"}
+        assert result.completed_at is not None
+        mock_repo.update.assert_called_once()
+
+    def test_complete_from_pending(self, mock_repo):
+        """从 pending 状态也可以直接完成"""
+        job = make_job(status=JobStatus.PENDING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        cmd = CompleteJobCommand(job_id=job.id)
+        uc = CompleteJobUseCase(mock_repo)
+        result = uc.execute(cmd)
+
+        assert result.status == JobStatus.SUCCESS
+        assert result.progress == 100.0
+
+    def test_complete_job_not_found(self, mock_repo):
+        """任务不存在"""
+        mock_repo.get.return_value = None
+
+        cmd = CompleteJobCommand(job_id="nope")
+        uc = CompleteJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="任务不存在"):
+            uc.execute(cmd)
+
+    def test_complete_already_failed(self, mock_repo):
+        """已失败的任务不能直接标记完成"""
+        job = make_job(status=JobStatus.FAILED)
+        job.error_message = "some error"
+        mock_repo.get.return_value = job
+
+        cmd = CompleteJobCommand(job_id=job.id)
+        uc = CompleteJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="只有 running/pending"):
+            uc.execute(cmd)
+
+
+# ============================================================
+# FailJobUseCase
+# ============================================================
+
+
+class TestFailJobUseCase:
+    """FailJobUseCase 失败任务"""
+
+    def test_fail_from_running(self, mock_repo):
+        """从 running 状态失败"""
+        job = make_job(status=JobStatus.RUNNING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        cmd = FailJobCommand(job_id=job.id, error_message="网络超时")
+        uc = FailJobUseCase(mock_repo)
+        result = uc.execute(cmd)
+
+        assert result.status == JobStatus.FAILED
+        assert result.error_message == "网络超时"
+        assert result.current_stage == "失败"
+        assert result.completed_at is not None
+        mock_repo.update.assert_called_once()
+
+    def test_fail_pending_rejected_by_domain(self, mock_repo):
+        """pending 状态不能直接失败（领域状态机约束）"""
+        job = make_job(status=JobStatus.PENDING)
+        mock_repo.get.return_value = job
+
+        cmd = FailJobCommand(job_id=job.id, error_message="资源不足")
+        uc = FailJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="非法状态转换"):
+            uc.execute(cmd)
+
+    def test_fail_job_not_found(self, mock_repo):
+        """任务不存在"""
+        mock_repo.get.return_value = None
+
+        cmd = FailJobCommand(job_id="nope", error_message="err")
+        uc = FailJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="任务不存在"):
+            uc.execute(cmd)
+
+
+# ============================================================
+# RetryJobUseCase
+# ============================================================
+
+
+class TestRetryJobUseCase:
+    """RetryJobUseCase 重试任务"""
+
+    def test_retry_success(self, mock_repo):
+        """失败任务重试成功"""
+        job = make_job(status=JobStatus.FAILED, max_retries=3)
+        job.retry_count = 0
+        job.error_message = "timeout"
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        uc = RetryJobUseCase(mock_repo)
+        result = uc.execute(job.id)
+
+        assert result.status == JobStatus.PENDING
+        assert result.retry_count == 1
+        assert result.progress == 0.0
+        assert result.error_message == ""
+        assert result.started_at is None
+        assert result.completed_at is None
+        assert result.celery_task_id == ""
+        mock_repo.update.assert_called_once()
+
+    def test_retry_job_not_found(self, mock_repo):
+        """任务不存在"""
+        mock_repo.get.return_value = None
+
+        uc = RetryJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="任务不存在"):
+            uc.execute("nope")
+
+    def test_retry_exceeds_max_retries(self, mock_repo):
+        """超过最大重试次数不可重试"""
+        job = make_job(status=JobStatus.FAILED, max_retries=3)
+        job.retry_count = 3
+        mock_repo.get.return_value = job
+
+        uc = RetryJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="不可重试"):
+            uc.execute(job.id)
+
+
+# ============================================================
+# CancelJobUseCase
+# ============================================================
+
+
+class TestCancelJobUseCase:
+    """CancelJobUseCase 取消任务"""
+
+    def test_cancel_pending(self, mock_repo):
+        """取消 pending 任务"""
+        job = make_job(status=JobStatus.PENDING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        uc = CancelJobUseCase(mock_repo)
+        result = uc.execute(job.id)
+
+        assert result.status == JobStatus.CANCELLED
+        assert result.current_stage == "已取消"
+        mock_repo.update.assert_called_once()
+
+    def test_cancel_running(self, mock_repo):
+        """取消 running 任务"""
+        job = make_job(status=JobStatus.RUNNING)
+        mock_repo.get.return_value = job
+        mock_repo.update.side_effect = lambda j: j
+
+        uc = CancelJobUseCase(mock_repo)
+        result = uc.execute(job.id)
+
+        assert result.status == JobStatus.CANCELLED
+
+    def test_cancel_job_not_found(self, mock_repo):
+        """任务不存在"""
+        mock_repo.get.return_value = None
+
+        uc = CancelJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="任务不存在"):
+            uc.execute("nope")
+
+    def test_cancel_already_success(self, mock_repo):
+        """已成功的任务不能取消"""
+        job = make_job(status=JobStatus.SUCCESS)
+        mock_repo.get.return_value = job
+
+        uc = CancelJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="终态"):
+            uc.execute(job.id)
+
+    def test_cancel_already_failed(self, mock_repo):
+        """已失败的任务不能取消（走重试）"""
+        job = make_job(status=JobStatus.FAILED)
+        job.error_message = "err"
+        mock_repo.get.return_value = job
+
+        uc = CancelJobUseCase(mock_repo)
+        with pytest.raises(ValueError, match="终态"):
+            uc.execute(job.id)
+
+
+# ============================================================
+# GetJobUseCase
+# ============================================================
+
+
+class TestGetJobUseCase:
+    """GetJobUseCase 获取任务"""
+
+    def test_get_existing(self, mock_repo):
+        """获取存在的任务"""
+        job = make_job()
+        mock_repo.get.return_value = job
+
+        uc = GetJobUseCase(mock_repo)
+        result = uc.execute(job.id)
+
+        assert result is job
+        mock_repo.get.assert_called_once_with(job.id)
+
+    def test_get_not_found(self, mock_repo):
+        """获取不存在的任务返回 None"""
+        mock_repo.get.return_value = None
+
+        uc = GetJobUseCase(mock_repo)
+        result = uc.execute("nope")
+
+        assert result is None
+
+
+# ============================================================
+# ListJobsUseCase
+# ============================================================
+
+
+class TestListJobsUseCase:
+    """ListJobsUseCase 列出任务"""
+
+    def test_list_by_project(self, mock_repo):
+        """按项目列出"""
+        jobs = [make_job(), make_job()]
+        mock_repo.list_by_project.return_value = jobs
+
+        uc = ListJobsUseCase(mock_repo)
+        result = uc.execute(project_id="proj-1")
+
+        assert len(result) == 2
+        mock_repo.list_by_project.assert_called_once()
+
+    def test_list_by_project_with_filters(self, mock_repo):
+        """按项目 + 类型 + 状态过滤"""
+        mock_repo.list_by_project.return_value = []
+
+        uc = ListJobsUseCase(mock_repo)
+        uc.execute(
+            project_id="proj-1",
+            job_type=JobType.VIDEO_COMPOSE,
+            status=JobStatus.RUNNING,
+            limit=20,
+            offset=10,
+        )
+
+        mock_repo.list_by_project.assert_called_once_with(
+            "proj-1",
+            job_type=JobType.VIDEO_COMPOSE,
+            status=JobStatus.RUNNING,
+            limit=20,
+            offset=10,
+        )
+
+    def test_list_by_user(self, mock_repo):
+        """按用户列出"""
+        jobs = [make_job()]
+        mock_repo.list_by_user.return_value = jobs
+
+        uc = ListJobsUseCase(mock_repo)
+        result = uc.execute(user_id="user-1")
+
+        assert len(result) == 1
+        mock_repo.list_by_user.assert_called_once()
+
+    def test_list_no_filter_raises(self, mock_repo):
+        """不指定 project_id 或 user_id 报错"""
+        uc = ListJobsUseCase(mock_repo)
+        with pytest.raises(ValueError, match="必须指定"):
+            uc.execute()
+
+    def test_list_project_takes_precedence(self, mock_repo):
+        """同时传 project_id 和 user_id，优先按项目查"""
+        mock_repo.list_by_project.return_value = []
+
+        uc = ListJobsUseCase(mock_repo)
+        uc.execute(project_id="proj-1", user_id="user-1")
+
+        mock_repo.list_by_project.assert_called_once()
+        mock_repo.list_by_user.assert_not_called()
+
+
+# ============================================================
+# GetJobStatisticsUseCase
+# ============================================================
+
+
+class TestGetJobStatisticsUseCase:
+    """GetJobStatisticsUseCase 任务统计"""
+
+    def test_stats_counts(self, mock_repo):
+        """统计各状态数量"""
+        mock_repo.count_by_project.side_effect = lambda pid, status=None: {
+            None: 10,  # total
+            JobStatus.PENDING: 2,
+            JobStatus.RUNNING: 3,
+            JobStatus.SUCCESS: 4,
+            JobStatus.FAILED: 1,
+        }[status]
+
+        uc = GetJobStatisticsUseCase(mock_repo)
+        stats = uc.execute("proj-1")
+
+        assert stats["project_id"] == "proj-1"
+        assert stats["total"] == 10
+        assert stats["pending"] == 2
+        assert stats["running"] == 3
+        assert stats["success"] == 4
+        assert stats["failed"] == 1
+        # 总共调用 5 次 count_by_project
+        assert mock_repo.count_by_project.call_count == 5
+
+
+# ============================================================
+# Command 对象
+# ============================================================
+
+
+class TestCommandObjects:
+    """命令对象基本属性"""
+
+    def test_create_job_command_defaults(self):
+        cmd = CreateJobCommand(project_id="p1", job_type=JobType.VIDEO_COMPOSE)
+        assert cmd.payload == {}
+        assert cmd.source_id == ""
+        assert cmd.created_by_user_id == ""
+        assert cmd.max_retries == 3
+
+    def test_update_progress_command_defaults(self):
+        cmd = UpdateJobProgressCommand(job_id="j1", progress=50.0)
+        assert cmd.current_stage == ""
+
+    def test_complete_job_command_defaults(self):
+        cmd = CompleteJobCommand(job_id="j1")
+        assert cmd.result == {}
+
+    def test_fail_job_command(self):
+        cmd = FailJobCommand(job_id="j1", error_message="err")
+        assert cmd.error_message == "err"