diff --git a/litellm/litellm_core_utils/core_helpers.py b/litellm/litellm_core_utils/core_helpers.py
index cecc35ee1c1..49457135915 100644
--- a/litellm/litellm_core_utils/core_helpers.py
+++ b/litellm/litellm_core_utils/core_helpers.py
@@ -168,14 +168,17 @@ def add_missing_spend_metadata_to_litellm_metadata(litellm_metadata: dict, metad
     """
     Helper to get litellm metadata for spend tracking
 
-    PATCH for issue where both `litellm_metadata` and `metadata` are present in the kwargs
-    and user_api_key values are in 'metadata'.
+    Both `litellm_metadata` and `metadata` can be present in the kwargs (e.g. a pre-call
+    guardrail creates `litellm_metadata` while the router populated `metadata`). Spend
+    tracking reads a single bucket, so fill in every key `litellm_metadata` is missing
+    (`model_group`, `model_info`, ...) from `metadata`, and let `metadata` win for the
+    `user_api_key*` keys, which are always the authoritative auth values.
     """
     potential_spend_tracking_metadata_substring = "user_api_key"
-    for key, value in metadata.items():
-        if potential_spend_tracking_metadata_substring in key:
-            litellm_metadata[key] = value
-    return litellm_metadata
+    auth_metadata = {
+        key: value for key, value in metadata.items() if potential_spend_tracking_metadata_substring in key
+    }
+    return {**metadata, **litellm_metadata, **auth_metadata}
 
 
 def get_metadata_variable_name_from_kwargs(
diff --git a/tests/test_litellm/litellm_core_utils/test_core_helpers.py b/tests/test_litellm/litellm_core_utils/test_core_helpers.py
index b4f539da286..6ebdd13cee7 100644
--- a/tests/test_litellm/litellm_core_utils/test_core_helpers.py
+++ b/tests/test_litellm/litellm_core_utils/test_core_helpers.py
@@ -4,6 +4,7 @@ import pytest
 
 from litellm.litellm_core_utils.core_helpers import (
     _FINISH_REASON_MAP,
+    add_missing_spend_metadata_to_litellm_metadata,
     get_or_create_metadata_bucket,
     map_finish_reason,
     reconstruct_model_name,
@@ -242,3 +243,28 @@ class TestRedactNestedMatchAndRegexKeys:
     def test_passes_through_none_and_str(self):
         assert redact_nested_match_and_regex_keys(None) is None
         assert redact_nested_match_and_regex_keys("plain") == "plain"
+
+
+class TestAddMissingSpendMetadataToLitellmMetadata:
+    def test_fills_missing_router_fields_without_clobbering_litellm_metadata(self):
+        merged = add_missing_spend_metadata_to_litellm_metadata(
+            litellm_metadata={"guardrail_added": True, "model_group": "from-litellm-metadata"},
+            metadata={
+                "model_group": "from-metadata",
+                "model_info": {"id": "deployment-123"},
+                "user_api_key_team_id": "team-1",
+            },
+        )
+
+        assert merged["model_info"] == {"id": "deployment-123"}
+        assert merged["user_api_key_team_id"] == "team-1"
+        assert merged["guardrail_added"] is True
+        assert merged["model_group"] == "from-litellm-metadata"
+
+    def test_auth_keys_always_come_from_metadata(self):
+        merged = add_missing_spend_metadata_to_litellm_metadata(
+            litellm_metadata={"user_api_key": "stale"},
+            metadata={"user_api_key": "authoritative"},
+        )
+
+        assert merged["user_api_key"] == "authoritative"
diff --git a/tests/test_litellm/proxy/spend_tracking/test_spend_tracking_utils.py b/tests/test_litellm/proxy/spend_tracking/test_spend_tracking_utils.py
index cc1e2943c8f..6e8938f624e 100644
--- a/tests/test_litellm/proxy/spend_tracking/test_spend_tracking_utils.py
+++ b/tests/test_litellm/proxy/spend_tracking/test_spend_tracking_utils.py
@@ -2902,3 +2902,27 @@ async def test_compression_savings_survive_to_spend_log_payload_metadata(monkeyp
         "tokens_saved": 7000,
         "source": "compression_interception",
     }
+
+
+def test_get_logging_payload_keeps_router_fields_when_guardrail_adds_litellm_metadata():
+    payload = get_logging_payload(
+        kwargs={
+            "model": "gpt-4o-mini",
+            "litellm_params": {
+                "metadata": {
+                    "user_api_key": "test-key",
+                    "user_api_key_team_id": "team-1",
+                    "model_group": "my-model-group",
+                    "model_info": {"id": "deployment-123"},
+                },
+                "litellm_metadata": {"guardrail_added": True},
+            },
+        },
+        response_obj=litellm.ModelResponse(id="chatcmpl-test", choices=[], usage=litellm.Usage()),
+        start_time=datetime.datetime.now(timezone.utc),
+        end_time=datetime.datetime.now(timezone.utc),
+    )
+
+    assert payload["model_group"] == "my-model-group"
+    assert payload["model_id"] == "deployment-123"
+    assert json.loads(payload["metadata"])["user_api_key_team_id"] == "team-1"