dmux · Oct 31, 2026 · Oct 26, 2026 · Oct 31, 2026 · Oct 31, 2026
diff --git a/src/minilake/services/jobs.py b/src/minilake/services/jobs.py
@@ -201,7 +201,12 @@ async def update_job(req: UpdateJobRequest) -> dict:
     job = _state["jobs"][req.job_id]
     new_settings = dict(job["settings"])
     if req.new_settings is not None:
-        new_settings.update(req.new_settings.model_dump(exclude_none=True))
+        # Merge only the top-level fields the request actually sent. A plain dump also
+        # carries model defaults (name="Untitled"), which would overwrite stored values the
+        # caller never touched. exclude_unset is not used because it would also strip the
+        # nested defaults (e.g. a task's run_if) that create_job stores.
+        sent = req.new_settings.model_fields_set
+        new_settings.update(req.new_settings.model_dump(exclude_none=True, include=sent))
     for field in req.fields_to_remove or []:
         new_settings.pop(field, None)
     _validate_task_graph(_tasks_from_settings(new_settings))

diff --git a/tests/test_jobs.py b/tests/test_jobs.py
@@ -14,6 +14,7 @@
 from databricks.sdk.errors import DatabricksError
 from databricks.sdk.service.compute import ClusterSpec
 from databricks.sdk.service.jobs import (
+    JobEmailNotifications,
     JobSettings,
     NotebookTask,
     RunIf,
@@ -73,6 +74,76 @@ def test_job_list_includes_created(workspace_client: WorkspaceClient):
     print(f"✓ Job {job.job_id} appears in job list")
 
 
+@pytest.mark.crud
+@pytest.mark.parametrize(
+    "new_settings",
+    [
+        JobSettings(tags={"team": "qa"}),
+        JobSettings(timeout_seconds=600),
+        JobSettings(),
+    ],
+    ids=["tags-only", "timeout-only", "empty"],
+)
+def test_job_partial_update_keeps_omitted_fields(workspace_client: WorkspaceClient, new_settings: JobSettings):
+    """Test: jobs/update only changes the fields it sends; the name and tasks survive."""
+    job = workspace_client.jobs.create(
+        name="valuable name",
+        tasks=[Task(task_key="main", notebook_task=NotebookTask(notebook_path="/Shared/nb"))],
+    )
+
+    workspace_client.jobs.update(job_id=job.job_id, new_settings=new_settings)
+
+    settings = workspace_client.jobs.get(job_id=job.job_id).settings
+    assert settings.name == "valuable name"
+    assert [t.task_key for t in settings.tasks] == ["main"]
+    if new_settings.tags is not None:
+        assert settings.tags == new_settings.tags
+    if new_settings.timeout_seconds is not None:
+        assert settings.timeout_seconds == new_settings.timeout_seconds
+
+    print(f"✓ Partial update kept name and tasks of job {job.job_id}")
+
+
+@pytest.mark.crud
+def test_job_update_with_name_renames(workspace_client: WorkspaceClient):
+    """Test: a name sent in jobs/update still replaces the stored one."""
+    job = workspace_client.jobs.create(name="old name", tasks=[])
+
+    workspace_client.jobs.update(job_id=job.job_id, new_settings=JobSettings(name="new name"))
+
+    assert workspace_client.jobs.get(job_id=job.job_id).settings.name == "new name"
+
+    print(f"✓ Job {job.job_id} renamed via update")
+
+
+@pytest.mark.crud
+def test_job_partial_update_keeps_and_replaces_extra_fields(workspace_client: WorkspaceClient):
+    """Test: a setting outside the declared model (email_notifications) is kept when omitted
+    from jobs/update and replaced when sent, and the name survives both."""
+    job = workspace_client.jobs.create(
+        name="valuable name",
+        email_notifications=JobEmailNotifications(on_failure=["oncall@example.com"]),
+        tasks=[],
+    )
+
+    workspace_client.jobs.update(job_id=job.job_id, new_settings=JobSettings(tags={"team": "qa"}))
+    settings = workspace_client.jobs.get(job_id=job.job_id).settings
+    assert settings.name == "valuable name"
+    assert settings.email_notifications.on_failure == ["oncall@example.com"]
+
+    workspace_client.jobs.update(
+        job_id=job.job_id,
+        new_settings=JobSettings(email_notifications=JobEmailNotifications(on_success=["team@example.com"])),
+    )
+    settings = workspace_client.jobs.get(job_id=job.job_id).settings
+    assert settings.name == "valuable name"
+    assert settings.tags == {"team": "qa"}
+    assert settings.email_notifications.on_success == ["team@example.com"]
+    assert not settings.email_notifications.on_failure  # a sent top-level field replaces it whole
+
+    print(f"✓ Partial updates kept and replaced email_notifications of job {job.job_id}")
+
+
 @pytest.mark.crud
 def test_job_delete(workspace_client: WorkspaceClient):
     """Test: Deleting a job removes it; get then raises NOT_FOUND."""