diff --git a/literalai/api/__init__.py b/literalai/api/__init__.py
index 76d49ae..2c8a9f2 100644
--- a/literalai/api/__init__.py
+++ b/literalai/api/__init__.py
@@ -235,9 +235,10 @@ def get_threads(
         before: Optional[str] = None,
         filters: Optional[threads_filters] = None,
         order_by: Optional[threads_order_by] = None,
+        step_types_to_keep: Optional[List[StepType]] = None,
     ):
         return self.gql_helper(
-            *get_threads_helper(first, after, before, filters, order_by)
+            *get_threads_helper(first, after, before, filters, order_by, step_types_to_keep)
         )
 
     def list_threads(
@@ -812,9 +813,10 @@ async def get_threads(
         before: Optional[str] = None,
         filters: Optional[threads_filters] = None,
         order_by: Optional[threads_order_by] = None,
+        step_types_to_keep: Optional[List[StepType]] = None,
     ):
         return await self.gql_helper(
-            *get_threads_helper(first, after, before, filters, order_by)
+            *get_threads_helper(first, after, before, filters, order_by, step_types_to_keep)
         )
 
     async def list_threads(
diff --git a/literalai/api/gql.py b/literalai/api/gql.py
index e6b8e11..f39078e 100644
--- a/literalai/api/gql.py
+++ b/literalai/api/gql.py
@@ -183,6 +183,7 @@
     $first: Int,
     $last: Int,
     $projectId: String,
+    $stepTypesToKeep: [StepType!],
     ) {
     threads(
         after: $after,
@@ -193,6 +194,7 @@
         first: $first,
         last: $last,
         projectId: $projectId,
+        stepTypesToKeep: $stepTypesToKeep,
         ) {
         pageInfo {
             startCursor
diff --git a/literalai/api/thread_helpers.py b/literalai/api/thread_helpers.py
index 631253b..88602d0 100644
--- a/literalai/api/thread_helpers.py
+++ b/literalai/api/thread_helpers.py
@@ -2,6 +2,7 @@
 
 from literalai.filter import threads_filters, threads_order_by
 from literalai.my_types import PaginatedResponse
+from literalai.step import StepType
 from literalai.thread import Thread
 
 from . import gql
@@ -13,6 +14,7 @@ def get_threads_helper(
     before: Optional[str] = None,
     filters: Optional[threads_filters] = None,
     order_by: Optional[threads_order_by] = None,
+    step_types_to_keep: Optional[List[StepType]] = None,
 ):
     variables: Dict[str, Any] = {}
 
@@ -26,6 +28,8 @@ def get_threads_helper(
         variables["filters"] = filters
     if order_by:
         variables["orderBy"] = order_by
+    if step_types_to_keep:
+        variables["stepTypesToKeep"] = step_types_to_keep
 
     def process_response(response):
         processed_response = response["data"]["threads"]
diff --git a/literalai/thread.py b/literalai/thread.py
index 6d2ab97..95c9148 100644
--- a/literalai/thread.py
+++ b/literalai/thread.py
@@ -32,7 +32,7 @@ class Thread:
     tags: Optional[List[str]]
     steps: Optional[List[Step]]
     participant_id: Optional[str]
-    participant_identifier: Optional[str]
+    participant_identifier: Optional[str] = None
     created_at: Optional[str]  # read-only, set by server
     needs_upsert: Optional[bool]
 
@@ -64,7 +64,7 @@ def to_dict(self) -> ThreadDict:
                 id=self.participant_id, identifier=self.participant_identifier
             )
             if self.participant_id
-            else None,
+            else UserDict(),
             "createdAt": getattr(self, "created_at", None),
         }
 
@@ -125,7 +125,7 @@ def upsert(self):
             thread_data_to_upsert["metadata"] = metadata
         if tags := thread_data.get("tags"):
             thread_data_to_upsert["tags"] = tags
-        if participant_id := thread_data.get("participant_id"):
+        if participant_id := thread_data.get("participant", {}).get("id"):
             thread_data_to_upsert["participant_id"] = participant_id
 
         try:
diff --git a/tests/e2e/test_e2e.py b/tests/e2e/test_e2e.py
index ca54a77..bab0a6f 100644
--- a/tests/e2e/test_e2e.py
+++ b/tests/e2e/test_e2e.py
@@ -8,6 +8,7 @@
 from literalai import AsyncLiteralClient, LiteralClient
 from literalai.context import active_steps_var
 from literalai.my_types import ChatGeneration
+from literalai.thread import Thread
 
 """
 End to end tests for the SDK
@@ -573,3 +574,9 @@ async def test_gracefulness(self, broken_client: LiteralClient):
 
         broken_client.flush()
         assert True
+
+    @pytest.mark.timeout(5)
+    async def test_thread_to_dict(self, client: LiteralClient):
+        thread = Thread(id="thread-id", participant_id="participant-id")
+        participant = thread.to_dict().get("participant", {})
+        assert participant and participant["id"] == "participant-id"