chore: introduce write queue for response_store (#3497)

# What does this PR do?
Mirroring the same changes that was used for inference_store:
https://github.com/llamastack/llama-stack/pull/3383

Will follow up with a shared internal API for managing these write
queues.

## Test Plan
existing tests

tests/unit/providers/agents/meta_reference/test_openai_responses.py

@@ -42,10 +42,12 @@ from llama_stack.apis.inference import (
 )
 from llama_stack.apis.tools.tools import Tool, ToolGroups, ToolInvocationResult, ToolParameter, ToolRuntime
 from llama_stack.core.access_control.access_control import default_policy
+from llama_stack.core.datatypes import ResponsesStoreConfig
 from llama_stack.providers.inline.agents.meta_reference.responses.openai_responses import (
     OpenAIResponsesImpl,
 )
 from llama_stack.providers.utils.responses.responses_store import ResponsesStore
+from llama_stack.providers.utils.sqlstore.sqlstore import SqliteSqlStoreConfig
 from tests.unit.providers.agents.meta_reference.fixtures import load_chat_completion_fixture
 
 
@@ -677,7 +679,9 @@ async def test_responses_store_list_input_items_logic():
 
     # Create mock store and response store
     mock_sql_store = AsyncMock()
-    responses_store = ResponsesStore(sql_store_config=None, policy=default_policy())
+    responses_store = ResponsesStore(
+        ResponsesStoreConfig(sql_store_config=SqliteSqlStoreConfig(db_path="mock_db_path")), policy=default_policy()
+    )
     responses_store.sql_store = mock_sql_store
 
     # Setup test data - multiple input items

tests/unit/utils/responses/test_responses_store.py

@@ -67,6 +67,9 @@ async def test_responses_store_pagination_basic():
             input_list = [create_test_response_input(f"Input for {response_id}", f"input-{response_id}")]
             await store.store_response_object(response, input_list)
 
+        # Wait for all queued writes to complete
+        await store.flush()
+
         # Test 1: First page with limit=2, descending order (default)
         result = await store.list_responses(limit=2, order=Order.desc)
         assert len(result.data) == 2
@@ -110,6 +113,9 @@ async def test_responses_store_pagination_ascending():
             input_list = [create_test_response_input(f"Input for {response_id}", f"input-{response_id}")]
             await store.store_response_object(response, input_list)
 
+        # Wait for all queued writes to complete
+        await store.flush()
+
         # Test ascending order pagination
         result = await store.list_responses(limit=1, order=Order.asc)
         assert len(result.data) == 1
@@ -145,6 +151,9 @@ async def test_responses_store_pagination_with_model_filter():
             input_list = [create_test_response_input(f"Input for {response_id}", f"input-{response_id}")]
             await store.store_response_object(response, input_list)
 
+        # Wait for all queued writes to complete
+        await store.flush()
+
         # Test pagination with model filter
         result = await store.list_responses(limit=1, model="model-a", order=Order.desc)
         assert len(result.data) == 1
@@ -192,6 +201,9 @@ async def test_responses_store_pagination_no_limit():
             input_list = [create_test_response_input(f"Input for {response_id}", f"input-{response_id}")]
             await store.store_response_object(response, input_list)
 
+        # Wait for all queued writes to complete
+        await store.flush()
+
         # Test without limit (should use default of 50)
         result = await store.list_responses(order=Order.desc)
         assert len(result.data) == 2
@@ -212,6 +224,9 @@ async def test_responses_store_get_response_object():
         input_list = [create_test_response_input("Test input content", "input-test-resp")]
         await store.store_response_object(response, input_list)
 
+        # Wait for all queued writes to complete
+        await store.flush()
+
         # Retrieve the response
         retrieved = await store.get_response_object("test-resp")
         assert retrieved.id == "test-resp"
@@ -242,6 +257,9 @@ async def test_responses_store_input_items_pagination():
         ]
         await store.store_response_object(response, input_list)
 
+        # Wait for all queued writes to complete
+        await store.flush()
+
         # Verify all items are stored correctly with explicit IDs
         all_items = await store.list_response_input_items("test-resp", order=Order.desc)
         assert len(all_items.data) == 5
@@ -319,6 +337,9 @@ async def test_responses_store_input_items_before_pagination():
         ]
         await store.store_response_object(response, input_list)
 
+        # Wait for all queued writes to complete
+        await store.flush()
+
         # Test before pagination with descending order
         # In desc order: [Fifth, Fourth, Third, Second, First]
         # before="before-3" should return [Fifth, Fourth]