diff --git a/litellm/proxy/auth/auth_utils.py b/litellm/proxy/auth/auth_utils.py
index e7b80538ab6..7fd05ac7664 100644
--- a/litellm/proxy/auth/auth_utils.py
+++ b/litellm/proxy/auth/auth_utils.py
@@ -13,7 +13,7 @@ from typing import (
     Literal,
     Protocol,
     TypeAlias,
-    cast,  # noqa: TID251  # cast-ok: key metadata is an untyped JSON blob, narrowed by TypeAdapter right after
+    cast,  # noqa: TID251  # narrows the untyped key metadata blob in _key_customer_limit_map
 )
 
 from fastapi import HTTPException, Request, status
@@ -1651,7 +1651,7 @@ def get_key_tag_rpm_limit(
     return None
 
 
-_CUSTOMER_LIMIT_MAP: Final[TypeAdapter[dict[str, int]]] = TypeAdapter(dict[str, int])
+_CUSTOMER_LIMIT_MAP: Final[TypeAdapter[Mapping[str, int]]] = TypeAdapter(Mapping[str, int])
 
 
 def _key_customer_limit_map(user_api_key_dict: UserAPIKeyAuth, field: str) -> Mapping[str, int]:
diff --git a/litellm/types/proxy/management_endpoints/request_base.py b/litellm/types/proxy/management_endpoints/request_base.py
index 6f8cf5b0bfc..326d570e44d 100644
--- a/litellm/types/proxy/management_endpoints/request_base.py
+++ b/litellm/types/proxy/management_endpoints/request_base.py
@@ -1,3 +1,4 @@
+from collections.abc import Mapping
 from typing import Any  # noqa: TID251  # metadata and models stay Any so existing callers keep type-checking
 
 from pydantic import ConfigDict, NonNegativeInt, field_validator
@@ -52,8 +53,8 @@ class GenerateRequestBase(LiteLLMPydanticObjectBase):
     model_tpm_limit: dict[object, object] | None = None
     mcp_rpm_limit: dict[str, int] | None = None
     tag_rpm_limit: dict[str, int] | None = None
-    customer_rpm_limit: dict[str, NonNegativeInt] | None = None
-    customer_tpm_limit: dict[str, NonNegativeInt] | None = None
+    customer_rpm_limit: Mapping[str, NonNegativeInt] | None = None
+    customer_tpm_limit: Mapping[str, NonNegativeInt] | None = None
     guardrails: list[str] | None = None
     policies: list[str] | None = None
     prompts: list[str] | None = None