From cf5082d8077212669b8cb91f2cc3c814007f02e8 Mon Sep 17 00:00:00 2001
From: Tanishq <74068132+tanishqbaweja@users.noreply.github.com>
Date: Mon, 26 Oct 2026 01:34:04 +0530
Subject: [PATCH] fix(router): tolerate null deployment metadata in cost
 callbacks

---
 litellm/router_strategy/lowest_cost.py        |  4 +--
 .../unit/router_strategy/test_lowest_cost.py  | 33 +++++++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/litellm/router_strategy/lowest_cost.py b/litellm/router_strategy/lowest_cost.py
index 5894da9cb4f..4862e52f5c6 100644
--- a/litellm/router_strategy/lowest_cost.py
+++ b/litellm/router_strategy/lowest_cost.py
@@ -58,7 +58,7 @@ class LowestCostLoggingHandler(CustomLogger):
             else:
                 model_group: Final = kwargs["litellm_params"]["metadata"].get("model_group", None)
 
-                id = kwargs["litellm_params"].get("model_info", {}).get("id", None)
+                id = (kwargs["litellm_params"].get("model_info") or {}).get("id", None)
                 if model_group is None or id is None:
                     return
                 elif isinstance(id, int):
@@ -134,7 +134,7 @@ class LowestCostLoggingHandler(CustomLogger):
             else:
                 model_group: Final = kwargs["litellm_params"]["metadata"].get("model_group", None)
 
-                id = kwargs["litellm_params"].get("model_info", {}).get("id", None)
+                id = (kwargs["litellm_params"].get("model_info") or {}).get("id", None)
                 if model_group is None or id is None:
                     return
                 elif isinstance(id, int):
diff --git a/tests/unit/router_strategy/test_lowest_cost.py b/tests/unit/router_strategy/test_lowest_cost.py
index e3fdcd69499..c44d318501c 100644
--- a/tests/unit/router_strategy/test_lowest_cost.py
+++ b/tests/unit/router_strategy/test_lowest_cost.py
@@ -1,5 +1,7 @@
 import asyncio, copy, importlib, os, time
+import logging
 from datetime import datetime
+from typing import Final
 
 import pytest
 
@@ -36,6 +38,37 @@ def _recorded_minute_counters(cache: DualCache) -> dict[str, int]:
     return next(iter(minute_buckets.values()))
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize("use_async", [False, True], ids=["sync", "async"])
+@pytest.mark.parametrize(
+    "deployment_params",
+    [{}, {"model_info": None}, {"model_info": {}}, {"model_info": {"id": None}}],
+    ids=["omitted", "null", "empty", "null-id"],
+)
+async def test_success_without_a_deployment_id_skips_cost_accounting_without_errors(
+    caplog: pytest.LogCaptureFixture,
+    use_async: bool,
+    deployment_params: dict[str, dict[str, str | None] | None],
+) -> None:
+    cache: Final = DualCache()
+    handler: Final = LowestCostLoggingHandler(router_cache=cache)
+    call_args: Final = {
+        "kwargs": {"litellm_params": {"metadata": {"model_group": "gpt-5.5-pool"}, **deployment_params}},
+        "response_obj": _chat_response_with_no_completion_tokens(),
+        "start_time": datetime(2026, 1, 1, 12, 0, 0),
+        "end_time": datetime(2026, 1, 1, 12, 0, 2),
+    }
+
+    with caplog.at_level(logging.ERROR, logger="LiteLLM"):
+        if use_async:
+            await handler.async_log_success_event(**call_args)
+        else:
+            handler.log_success_event(**call_args)
+
+    assert cache.get_cache(key=COST_KEY) is None
+    assert caplog.record_tuples == []
+
+
 def test_log_success_event_counts_a_response_with_no_completion_tokens():
     cache = DualCache()
     handler = LowestCostLoggingHandler(router_cache=cache)