From b641a0d9b75ca82a9e0ee702f8c0cf64ff565216 Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Wed, 28 Oct 2026 04:25:44 -0700
Subject: [PATCH] fix(caching): key the response cache by the router's metadata
 bucket only

---
 litellm/caching/caching.py                    |  6 ++--
 .../test_response_cache_model_group_key.py    |  6 ++--
 tests/unit/caching/test_unit_test_caching.py  | 29 +++++++++++++++++++
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/litellm/caching/caching.py b/litellm/caching/caching.py
index 5f5b8210096..7173f941a8d 100644
--- a/litellm/caching/caching.py
+++ b/litellm/caching/caching.py
@@ -456,10 +456,8 @@ class Cache:
         """
         litellm_params: Final[dict] = kwargs.get("litellm_params", {}) or {}
         metadata_sources: Final[tuple[dict, ...]] = (
-            kwargs.get("metadata") or {},
-            kwargs.get("litellm_metadata") or {},
-            litellm_params.get("metadata") or {},
-            litellm_params.get("litellm_metadata") or {},
+            kwargs.get("litellm_metadata" if "litellm_metadata" in kwargs else "metadata") or {},
+            litellm_params.get("litellm_metadata") or litellm_params.get("metadata") or {},
         )
         model_group: Final[str | None] = next(
             (source["model_group"] for source in metadata_sources if source.get("model_group")), None
diff --git a/tests/integration/caching/test_response_cache_model_group_key.py b/tests/integration/caching/test_response_cache_model_group_key.py
index 6f32163481b..9b977adfa9b 100644
--- a/tests/integration/caching/test_response_cache_model_group_key.py
+++ b/tests/integration/caching/test_response_cache_model_group_key.py
@@ -21,7 +21,7 @@ from openai import OpenAI
 from pydantic import JsonValue
 
 from tests.integration._support.client import JSON_OBJECT, Gateway, Scenario, object_value
-from tests.integration._support.process import graceful_stop_seconds, owned_proxy_process
+from tests.integration._support.process import OwnedState, graceful_stop_seconds, owned_proxy_process
 from tests.integration._support.upstream import ScenarioHandle
 from tests.integration.caching.response_cache_case import (
     CHAT,
@@ -175,7 +175,9 @@ def test_groups_in_one_caching_group_on_different_models_share_one_entry(
         first: Final = _configured_group(scenario, endpoint)
         second: Final = _configured_group(scenario, endpoint)
         config: Final = _caching_groups_config(tmp_path, endpoint, first, second)
-        with owned_proxy_process(gateway, tmp_path, {}, config=config, workers=1) as owned:
+        with owned_proxy_process(
+            gateway, tmp_path, {}, config=config, workers=1, state=OwnedState.SHARED_WITH_WORKER
+        ) as owned:
             filled: Final = endpoint.ask(owned.gateway, first.name, text, {})
             await_entry(store, filled)
             assert endpoint.ask(owned.gateway, second.name, text, {}) == filled
diff --git a/tests/unit/caching/test_unit_test_caching.py b/tests/unit/caching/test_unit_test_caching.py
index 83132b5aa1d..06b8a4d9cac 100644
--- a/tests/unit/caching/test_unit_test_caching.py
+++ b/tests/unit/caching/test_unit_test_caching.py
@@ -278,6 +278,35 @@ def test_get_model_param_value_reads_model_group_from_litellm_metadata():
     )
 
 
+def test_get_model_param_value_ignores_a_caller_model_group_outside_the_router_bucket():
+    cache = Cache()
+    request = {"model": "openai/gpt-5.6", "input": "search this text"}
+
+    assert (
+        cache._get_model_param_value(
+            {**request, "metadata": {"model_group": "target"}, "litellm_metadata": {"model_group": "caller"}}
+        )
+        == "caller"
+    )
+    assert (
+        cache._get_model_param_value({**request, "metadata": {"model_group": "target"}, "litellm_metadata": {}})
+        == "openai/gpt-5.6"
+    )
+    assert (
+        cache._get_model_param_value(
+            {
+                **request,
+                "metadata": {"model_group": "target"},
+                "litellm_metadata": {"user_api_key": "hashed"},
+                "litellm_params": {
+                    "metadata": {"model_group": "target"},
+                    "litellm_metadata": {"user_api_key": "hashed"},
+                },
+            }
+        )
+        == "openai/gpt-5.6"
+    )
+
 def test_preset_cache_key():
     """
     Test that the preset cache key is used if it is set in kwargs["litellm_params"]