From cee2c79a979941a61225778db9c90a65bac340e9 Mon Sep 17 00:00:00 2001
From: yucheng <yucheng@berri.ai>
Date: Mon, 2 Nov 2026 15:05:03 -0800
Subject: [PATCH] fix(proxy): annotate the guardrail headers kept across
 upstream failure logging

---
 .../proxy/pass_through_endpoints/pass_through_endpoints.py    | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/litellm/proxy/pass_through_endpoints/pass_through_endpoints.py b/litellm/proxy/pass_through_endpoints/pass_through_endpoints.py
index 7b28b25ffc6..451d2ae22af 100644
--- a/litellm/proxy/pass_through_endpoints/pass_through_endpoints.py
+++ b/litellm/proxy/pass_through_endpoints/pass_through_endpoints.py
@@ -1446,8 +1446,8 @@ async def _log_passthrough_upstream_failure_keeping_guardrail_headers(
     """Log an upstream error like ``_log_passthrough_upstream_failure`` and return the guardrail response headers,
     read before the failure hooks rebuild ``kwargs``' metadata without the guardrail fields. A successful response
     has no failure hooks to read around, so it returns none."""
-    guardrail_headers: Final = (
-        _guardrail_response_headers(parsed_body, kwargs) if response.status_code >= 400 else MappingProxyType({})
+    guardrail_headers: Final[Mapping[str, str]] = (
+        _guardrail_response_headers(parsed_body, kwargs) if response.status_code >= 400 else {}
     )
     await _log_passthrough_upstream_failure(
         response=response,