From 59c2ce4fe61f8466d935fa3d21ae179c57783c7f Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Sat, 19 Sep 2026 18:40:43 -0700
Subject: [PATCH] fix(interactions): carry a missing model through the
 settlement context for agent-only background creates

An interaction created with an agent and no model reaches the poll with no model name, exactly as on main. The settlement context now stores that None instead of rejecting the create, which answered the client with a 500 after the provider had already accepted it.
---
 .../interactions/background_cost_polling.py   |  4 +--
 .../test_background_cost_polling.py           | 32 +++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/litellm/interactions/background_cost_polling.py b/litellm/interactions/background_cost_polling.py
index a4aa3a8a9f7..d1a3fccaac5 100644
--- a/litellm/interactions/background_cost_polling.py
+++ b/litellm/interactions/background_cost_polling.py
@@ -83,7 +83,7 @@ class BackgroundInteractionCreateContext(BaseModel):
 
     model_config = ConfigDict(frozen=True)
 
-    model: str
+    model: str | None
     call_type: str
     litellm_call_id: str
     function_id: str
@@ -275,7 +275,7 @@ def _rebuild_logging_obj(create_context: BackgroundInteractionCreateContext) ->
     from litellm.litellm_core_utils.litellm_logging import Logging
 
     logging_obj: Final = Logging(
-        model=create_context.model,
+        model=create_context.model,  # pyright: ignore[reportArgumentType]  # function_setup builds the live object with the same None for an agent-only create
         messages=None,
         stream=False,
         call_type=create_context.call_type,
diff --git a/tests/test_litellm/interactions/test_background_cost_polling.py b/tests/test_litellm/interactions/test_background_cost_polling.py
index 9dbb2c2f279..40d63090054 100644
--- a/tests/test_litellm/interactions/test_background_cost_polling.py
+++ b/tests/test_litellm/interactions/test_background_cost_polling.py
@@ -9,6 +9,7 @@ import pytest
 from litellm.interactions.background_cost_polling import (
     _create_context,
     _poll_intervals,
+    _rebuild_logging_obj,
     BackgroundInteractionPollContext,
     InMemoryBackgroundSettlementStore,
     maybe_schedule_background_interaction_cost_polling,
@@ -270,6 +271,37 @@ async def test_schedule_creates_poll_task_for_in_progress_create():
         await task
 
 
+@pytest.mark.asyncio
+async def test_schedule_registers_an_agent_only_create_that_names_no_model():
+    logging_obj = LitellmLogging(
+        model=None,
+        messages=None,
+        stream=False,
+        call_type="acreate_interaction",
+        start_time=time.time(),
+        litellm_call_id="bg-agent-call-id",
+        function_id="bg-agent-fn-id",
+    )
+    logging_obj.update_environment_variables(litellm_params={}, optional_params={}, custom_llm_provider="gemini")
+    store = InMemoryBackgroundSettlementStore()
+
+    task = await maybe_schedule_background_interaction_cost_polling(
+        response=_response("in_progress", with_usage=False),
+        create_kwargs={"litellm_logging_obj": logging_obj},
+        custom_llm_provider="gemini",
+        store=store,
+    )
+
+    assert isinstance(task, asyncio.Task)
+    task.cancel()
+    with pytest.raises(asyncio.CancelledError):
+        await task
+    pending = await store.pending("interactions/bg-abc")
+    assert pending is not None
+    assert pending.create_context.model is None
+    assert _rebuild_logging_obj(pending.create_context).model is None
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     "response,create_kwargs",