diff --git a/litellm/types/management_endpoints/router_settings_endpoints.py b/litellm/types/management_endpoints/router_settings_endpoints.py
index dfb513cdd5f..72d1cd2f30d 100644
--- a/litellm/types/management_endpoints/router_settings_endpoints.py
+++ b/litellm/types/management_endpoints/router_settings_endpoints.py
@@ -243,13 +243,15 @@ ROUTER_SETTINGS_FIELDS: List[RouterSettingsField] = [
             "that cached the prompt."
         ),
         field_default=[],
+        # "forward_client_headers_by_model_group" is excluded: it's a literal in the
+        # OptionalPreCallChecks type union, but add_optional_pre_call_checks has no
+        # handler for it, so selecting it from the UI would silently do nothing.
         options=[
             "prompt_caching",
             "router_budget_limiting",
             "responses_api_deployment_check",
             "deployment_affinity",
             "session_affinity",
-            "forward_client_headers_by_model_group",
             "enforce_model_rate_limits",
             "encrypted_content_affinity",
         ],
diff --git a/tests/test_litellm/proxy/management_endpoints/test_router_settings_endpoints.py b/tests/test_litellm/proxy/management_endpoints/test_router_settings_endpoints.py
index 348d74a36fd..a924e2a49b8 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_router_settings_endpoints.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_router_settings_endpoints.py
@@ -97,6 +97,27 @@ class TestRouterSettingsEndpoints:
         assert field is not None
         assert "prompt_caching" in field["options"]
 
+    @pytest.mark.asyncio
+    async def test_get_router_fields_excludes_unimplemented_forward_client_headers_check(self):
+        """
+        Regression test: "forward_client_headers_by_model_group" is a literal in the
+        OptionalPreCallChecks type union, but Router.add_optional_pre_call_checks has
+        no handler for it - selecting it from the Admin UI's multi-select would save
+        successfully and show as enabled while doing nothing. It must not be offered
+        as an option until it's actually implemented.
+        """
+        response = client.get(
+            "/router/fields", headers={"Authorization": "Bearer sk-1234"}
+        )
+        assert response.status_code == 200
+
+        fields = response.json()["fields"]
+        field = next(
+            (f for f in fields if f["field_name"] == "optional_pre_call_checks"), None
+        )
+        assert field is not None
+        assert "forward_client_headers_by_model_group" not in field["options"]
+
     @pytest.mark.asyncio
     async def test_get_router_settings_includes_routing_groups_from_live_router(
         self, monkeypatch