From 6f0ea1be5f3327b482b5f57f58c968886b345b32 Mon Sep 17 00:00:00 2001
From: Azmi Muwahid <92735014+azmi2409@users.noreply.github.com>
Date: Tue, 20 Oct 2026 18:46:07 +0700
Subject: [PATCH] fix(router): satisfy ruff format check and cover deployments
 without model info

---
 .../complexity_router/complexity_router.py    | 10 +++++---
 .../router_strategy/test_complexity_router.py | 25 +++++++++++++++++++
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/litellm/router_strategy/complexity_router/complexity_router.py b/litellm/router_strategy/complexity_router/complexity_router.py
index 736bb6cc59c..e139206b874 100644
--- a/litellm/router_strategy/complexity_router/complexity_router.py
+++ b/litellm/router_strategy/complexity_router/complexity_router.py
@@ -3456,9 +3456,13 @@ class ComplexityRouter(CustomLogger):
     @staticmethod
     def _deployment_model_id(deployment: Mapping[str, object]) -> str | None:
         model_info: Final = deployment.get("model_info")
-        deployment_id: Final = cast(  # cast-ok: the isinstance check in the condition narrows model_info to a Mapping with str keys
-            "Mapping[str, object]", model_info
-        ).get("id") if isinstance(model_info, Mapping) else None
+        deployment_id: Final = (
+            cast(  # cast-ok: the isinstance check in the condition narrows model_info to a Mapping with str keys
+                "Mapping[str, object]", model_info
+            ).get("id")
+            if isinstance(model_info, Mapping)
+            else None
+        )
         return None if deployment_id is None else str(deployment_id)
 
     def _group_has_deployment_id(self, group: str, model_id: str) -> bool:
diff --git a/tests/unit/router_strategy/test_complexity_router.py b/tests/unit/router_strategy/test_complexity_router.py
index a5c39e616b5..fc54cb120c1 100644
--- a/tests/unit/router_strategy/test_complexity_router.py
+++ b/tests/unit/router_strategy/test_complexity_router.py
@@ -17426,6 +17426,31 @@ class TestPreviousResponseReuse:
         assert decision["cause"] == "previous_response_reuse", decision
         assert decision["conversation_continuing"] is True, decision
 
+    @pytest.mark.asyncio
+    async def test_tool_continuation_skips_deployments_without_model_info(self, mock_router_instance, basic_config):
+        router = self._router(mock_router_instance, basic_config, default_model="gpt-4o")
+        deployments = {
+            "gpt-4o-mini": [
+                {"model_name": "gpt-4o-mini", "litellm_params": {"model": "gpt-4o-mini"}},
+                {
+                    "model_name": "gpt-4o-mini",
+                    "litellm_params": {"model": "gpt-4o-mini"},
+                    "model_info": {"id": "deployment-mini"},
+                },
+            ]
+        }
+        mock_router_instance.get_model_list.side_effect = lambda model_name=None: deployments.get(model_name, [])
+        result = await router.async_pre_routing_hook(
+            model="test-complexity-router",
+            request_kwargs={"previous_response_id": self._encoded_response_id("deployment-mini")},
+            messages=[{"role": "tool", "content": "search results", "tool_call_id": "call_1"}],
+        )
+        assert result is not None
+        assert result.model == "gpt-4o-mini", result.routing_decision
+        decision = result.routing_decision
+        assert decision is not None
+        assert decision["cause"] == "previous_response_reuse", decision
+
     @pytest.mark.asyncio
     async def test_unencoded_previous_response_id_still_falls_back_to_default(
         self, mock_router_instance, basic_config