feat(client): add task hub name filter to orchestration queries (#295)

Closes #222.

- Adds 	ask_hub_names: list[str] | None = None to OrchestrationQuery.
- Serializes 	ask_hub_names into InstanceQuery.taskHubNames as 
epeated google.protobuf.StringValue in �uild_query_instances_req().
- Updates unit tests covering 	ask_hub_names serialization independently, combined with instance_id_prefix, and verifying positional argument order preservation.
- Documents the addition in CHANGELOG.md under Unreleased.

Author: hardikkaurani

CHANGELOG.md

@@ -7,6 +7,11 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+ADDED
+
+- Added `OrchestrationQuery.task_hub_names` to filter orchestration instances
+by one or more task hubs.
+
 FIXED
 
 - Large-payload externalization now checks every eligible payload's maximum

durabletask/client.py

@@ -197,6 +197,7 @@ class OrchestrationQuery:
     max_instance_count: int | None = (1 << 31) - 1
     fetch_inputs_and_outputs: bool = False
     instance_id_prefix: str | None = None
+    task_hub_names: list[str] | None = None
 
 
 @dataclass

durabletask/internal/client_helpers.py

@@ -103,6 +103,7 @@ def build_query_instances_req(
             runtimeStatus=[status.value for status in orchestration_query.runtime_status] if orchestration_query.runtime_status else None,
             createdTimeFrom=helpers.new_timestamp(orchestration_query.created_time_from) if orchestration_query.created_time_from else None,
             createdTimeTo=helpers.new_timestamp(orchestration_query.created_time_to) if orchestration_query.created_time_to else None,
+            taskHubNames=[wrappers_pb2.StringValue(value=name) for name in orchestration_query.task_hub_names] if orchestration_query.task_hub_names else None,
             instanceIdPrefix=helpers.get_string_value(orchestration_query.instance_id_prefix),
             maxInstanceCount=orchestration_query.max_instance_count,
             fetchInputsAndOutputs=orchestration_query.fetch_inputs_and_outputs,

tests/durabletask/test_batch_actions.py

@@ -197,12 +197,36 @@ def test_orchestration_query_serializes_instance_id_prefix():
     assert request.query.instanceIdPrefix.value == "prefix-"
 
 
+def test_orchestration_query_serializes_task_hub_names():
+    request = build_query_instances_req(
+        client.OrchestrationQuery(task_hub_names=["hub1", "hub2"]),
+        continuation_token=None,
+    )
+
+    assert [name.value for name in request.query.taskHubNames] == ["hub1", "hub2"]
+
+
+def test_orchestration_query_serializes_task_hub_names_and_instance_id_prefix():
+    request = build_query_instances_req(
+        client.OrchestrationQuery(
+            instance_id_prefix="prefix-",
+            task_hub_names=["hub1"],
+        ),
+        continuation_token=None,
+    )
+
+    assert request.query.HasField("instanceIdPrefix")
+    assert request.query.instanceIdPrefix.value == "prefix-"
+    assert [name.value for name in request.query.taskHubNames] == ["hub1"]
+
+
 def test_orchestration_query_preserves_positional_argument_order():
     query = client.OrchestrationQuery(None, None, None, None, True)
 
     assert query.max_instance_count is None
     assert query.fetch_inputs_and_outputs is True
     assert query.instance_id_prefix is None
+    assert query.task_hub_names is None
 
 
 def test_get_orchestration_state_pagination_succeeds(backend):