diff --git a/agents-api/agents_api/queries/docs/list_docs.py b/agents-api/agents_api/queries/docs/list_docs.py
index 852149934..2a1d3f214 100644
--- a/agents-api/agents_api/queries/docs/list_docs.py
+++ b/agents-api/agents_api/queries/docs/list_docs.py
@@ -41,6 +41,7 @@
     AND doc_own.owner_id = $4
 """
 
+
 @rewrap_exceptions(common_db_exceptions("doc", ["list"]))
 @wrap_in_class(
     Doc,
@@ -117,7 +118,9 @@ async def list_docs(
         d.created_at"""
 
     # Add sorting and pagination
-    query += f" ORDER BY {sort_by} {direction} LIMIT ${len(params) + 1} OFFSET ${len(params) + 2}"
+    query += (
+        f" ORDER BY {sort_by} {direction} LIMIT ${len(params) + 1} OFFSET ${len(params) + 2}"
+    )
     params.extend([limit, offset])
 
     return query, params
diff --git a/agents-api/agents_api/queries/executions/create_execution_transition.py b/agents-api/agents_api/queries/executions/create_execution_transition.py
index fb4d0b2b0..98d48e5e9 100644
--- a/agents-api/agents_api/queries/executions/create_execution_transition.py
+++ b/agents-api/agents_api/queries/executions/create_execution_transition.py
@@ -11,7 +11,7 @@
 from ...common.utils.datetime import utcnow
 from ...common.utils.db_exceptions import common_db_exceptions
 from ...metrics.counters import increase_counter
-from ..utils import pg_query, rewrap_exceptions, wrap_in_class
+from ..utils import pg_query, rewrap_exceptions, serialize_model_data, wrap_in_class
 
 # Query to create a transition
 create_execution_transition_query = """
@@ -121,14 +121,7 @@ async def create_execution_transition(
     data.execution_id = execution_id
 
     # Dump to json
-    if isinstance(data.output, list):
-        data.output = [
-            item.model_dump(mode="json") if hasattr(item, "model_dump") else item
-            for item in data.output
-        ]
-
-    elif hasattr(data.output, "model_dump"):
-        data.output = data.output.model_dump(mode="json")
+    data.output = serialize_model_data(data.output)
 
     # Prepare the transition data
     transition_data = data.model_dump(exclude_unset=True, exclude={"id"})
diff --git a/agents-api/agents_api/queries/utils.py b/agents-api/agents_api/queries/utils.py
index b0c7eda45..6ff284f74 100644
--- a/agents-api/agents_api/queries/utils.py
+++ b/agents-api/agents_api/queries/utils.py
@@ -297,3 +297,22 @@ def run_concurrently(
         ]
 
         return [future.result() for future in concurrent.futures.as_completed(futures)]
+
+
+def serialize_model_data(data: Any) -> Any:
+    """
+    Recursively serialize Pydantic models and their nested structures.
+
+    Args:
+        data: Any data structure that might contain Pydantic models
+
+    Returns:
+        JSON-serializable data structure
+    """
+    if hasattr(data, "model_dump"):
+        return data.model_dump(mode="json")
+    if isinstance(data, dict):
+        return {key: serialize_model_data(value) for key, value in data.items()}
+    if isinstance(data, list | tuple):
+        return [serialize_model_data(item) for item in data]
+    return data
diff --git a/agents-api/tests/fixtures.py b/agents-api/tests/fixtures.py
index 1458bf915..cf4fd2f7d 100644
--- a/agents-api/tests/fixtures.py
+++ b/agents-api/tests/fixtures.py
@@ -233,7 +233,7 @@ async def test_doc_with_embedding(dsn=pg_dsn, developer=test_developer, doc=test
     # ensuring it's up-to-date before executing queries.
     # This can be achieved by executing a REINDEX command
     await pool.execute("REINDEX DATABASE")
-    
+
     yield await get_doc(developer_id=developer.id, doc_id=doc.id, connection_pool=pool)
 
 
diff --git a/agents-api/tests/test_docs_queries.py b/agents-api/tests/test_docs_queries.py
index cb52b6df7..dc921b4e9 100644
--- a/agents-api/tests/test_docs_queries.py
+++ b/agents-api/tests/test_docs_queries.py
@@ -145,6 +145,7 @@ async def _(dsn=pg_dsn, developer=test_developer, user=test_user):
     assert any(d.id == doc_user_different_metadata.id for d in docs_list_metadata)
     assert any(d.metadata == {"test": "test2"} for d in docs_list_metadata)
 
+
 @test("query: list agent docs")
 async def _(dsn=pg_dsn, developer=test_developer, agent=test_agent):
     pool = await create_db_pool(dsn=dsn)