diff --git a/litellm/proxy/spend_tracking/savings.py b/litellm/proxy/spend_tracking/savings.py
index 07563e494dc..075f15b4fdb 100644
--- a/litellm/proxy/spend_tracking/savings.py
+++ b/litellm/proxy/spend_tracking/savings.py
@@ -8,6 +8,7 @@ are known) and summed into the daily tables; tokens cannot be priced after they
 have been aggregated across models.
 """
 
+from collections.abc import Mapping
 from typing import NamedTuple
 
 import litellm
@@ -172,7 +173,7 @@ def compute_autorouter_savings(
     return baseline_cost - selected_cost
 
 
-def _usage_from_spend_log(usage_object: dict | None) -> Usage | None:
+def _usage_from_spend_log(usage_object: Mapping[str, object] | None) -> Usage | None:
     """Rebuild the request's ``Usage`` from the copy the spend log recorded."""
     if not usage_object:
         return None
@@ -192,7 +193,7 @@ def compute_savings_spend(
     compression_saved_tokens: int,
     cache_read_input_tokens: int,
     baseline_model: str | None = None,
-    usage_object: dict | None = None,
+    usage_object: Mapping[str, object] | None = None,
 ) -> SavingsSpend:
     """
     Dollar savings for one request, split by optimization driver.
diff --git a/litellm/router.py b/litellm/router.py
index 58efeceb5aa..ff7735e355e 100644
--- a/litellm/router.py
+++ b/litellm/router.py
@@ -11191,7 +11191,7 @@ class Router:
     @staticmethod
     def _record_routing_decision(
         request_kwargs: dict,
-        pre_routing_hook_response: Optional[PreRoutingHookResponse],
+        pre_routing_hook_response: PreRoutingHookResponse | None,
     ) -> None:
         """Make the request's metadata describe THIS routing attempt, and only this one.
 
@@ -11210,15 +11210,23 @@ class Router:
         routing_decision = pre_routing_hook_response.routing_decision if pre_routing_hook_response else None
         baseline_model = pre_routing_hook_response.savings_baseline_model if pre_routing_hook_response else None
 
-        recorded: dict[str, Any] = {}
-        if routing_decision is not None:
-            recorded["routing_decision"] = Router._redact_prompt_text_if_needed(
-                request_kwargs=request_kwargs, routing_decision=routing_decision
+        recorded = {
+            key: value
+            for key, value in (
+                (
+                    "routing_decision",
+                    Router._redact_prompt_text_if_needed(
+                        request_kwargs=request_kwargs, routing_decision=routing_decision
+                    )
+                    if routing_decision is not None
+                    else None,
+                ),
+                ("auto_router_savings_baseline_model", baseline_model),
             )
-        if baseline_model is not None:
-            recorded["auto_router_savings_baseline_model"] = baseline_model
+            if value is not None
+        }
 
-        cleared = {"routing_decision", "auto_router_savings_baseline_model"} - recorded.keys()
+        cleared = frozenset({"routing_decision", "auto_router_savings_baseline_model"}) - recorded.keys()
         for bucket in (request_kwargs.get("metadata"), request_kwargs.get("litellm_metadata")):
             if isinstance(bucket, dict):
                 for key in cleared: