fix(proxy): log rejected unknown-model requests under a placeholder model name

A request whose model field matched no configured model was rejected with 400 but its failure row still persisted the raw client string as the model, so a client that concatenated its prompt into the model field wrote that prompt into LiteLLM_SpendLogs and the daily spend tables, where /user/daily/activity/aggregated returned it as a breakdown.models key. The spend log payload now records such rejections under the constant unknown-model, keeping the failed request counted without persisting client input as a model name.

litellm/constants.py

@@ -1999,6 +1999,8 @@ NON_INFERENCE_CALL_TYPES: Final[frozenset[str]] = frozenset(
     }
 )
 
+UNKNOWN_MODEL_SPEND_LOG_MODEL: Final[str] = "unknown-model"
+
 # PTU reservation rollup writes rows to LiteLLM_DailyTeamSpend with this
 # sentinel api_key so PTU flat cost stays distinguishable from real per-request
 # spend under the table's composite unique constraint.

litellm/proxy/spend_tracking/spend_tracking_utils.py

@@ -18,6 +18,7 @@ from litellm.constants import (
     LITTELM_INTERNAL_HEALTH_SERVICE_ACCOUNT_NAME,
     REDACTED_BY_LITELM_STRING,
     SESSION_ID_OMITTED_METADATA_KEY,
+    UNKNOWN_MODEL_SPEND_LOG_MODEL,
 )
 from litellm.constants import (
     MAX_STRING_LENGTH_PROMPT_IN_DB as DEFAULT_MAX_STRING_LENGTH_PROMPT_IN_DB,
@@ -34,6 +35,7 @@ from litellm.litellm_core_utils.litellm_logging import (
 )
 from litellm.litellm_core_utils.safe_json_dumps import safe_dumps, strip_null_bytes
 from litellm.proxy._types import SpendLogsMetadata, SpendLogsPayload, SpendLogsRouterMetadata
+from litellm.proxy.route_llm_request import ProxyModelNotFoundError
 from litellm.proxy.spend_tracking.spend_log_error_logger import spend_log_error
 from litellm.proxy.utils import PrismaClient, hash_token
 from litellm.types.utils import (
@@ -335,6 +337,7 @@ def get_logging_payload(kwargs, response_obj, start_time, end_time) -> SpendLogs
     if kwargs is None:
         kwargs = {}
 
+    rejected_as_unknown_model: Final = isinstance(response_obj, ProxyModelNotFoundError)
     if response_obj is None:
         response_obj = {}
     elif not isinstance(response_obj, BaseModel) and not isinstance(response_obj, dict):
@@ -433,8 +436,11 @@ def get_logging_payload(kwargs, response_obj, start_time, end_time) -> SpendLogs
     )
     raw_model: Final = cast(str, kwargs.get("model") or "")
     model_name: Final = (
-        standard_logging_payload.get("model") if standard_logging_payload is not None else None
-    ) or reconstruct_model_name(raw_model, custom_llm_provider, metadata or {})
+        UNKNOWN_MODEL_SPEND_LOG_MODEL
+        if rejected_as_unknown_model
+        else (standard_logging_payload.get("model") if standard_logging_payload is not None else None)
+        or reconstruct_model_name(raw_model, custom_llm_provider, metadata or {})
+    )
     litellm_call_id: Final = cast(
         str | None,
         kwargs.get("litellm_call_id") or litellm_params.get("litellm_call_id"),

tests/test_litellm/proxy/spend_tracking/test_spend_tracking_utils.py

@@ -17,10 +17,12 @@ from litellm.constants import (
     LITTELM_INTERNAL_HEALTH_SERVICE_ACCOUNT_NAME,
     REDACTED_BY_LITELM_STRING,
     SESSION_ID_OMITTED_METADATA_KEY,
+    UNKNOWN_MODEL_SPEND_LOG_MODEL,
 )
 from litellm.litellm_core_utils.safe_json_dumps import safe_dumps
 from litellm.proxy._types import UserAPIKeyAuth
 from litellm.proxy.litellm_pre_call_utils import LiteLLMProxyRequestSetup
+from litellm.proxy.route_llm_request import ProxyModelNotFoundError
 from litellm.proxy.spend_tracking.spend_tracking_utils import (
     _get_messages_for_spend_logs_payload,
     _get_proxy_server_request_for_spend_logs_payload,
@@ -922,6 +924,39 @@ def test_safe_dumps_complex_metadata_like_object():
     assert parsed["model"] == "gpt-4"
 
 
+_RAW_MODEL_WITH_PROMPT: Final = "opus-4.6 Please summarize my medical records\nPatient has diabetes"
+
+
+@pytest.mark.parametrize(
+    ("rejection", "expected_model"),
+    [
+        (
+            ProxyModelNotFoundError(route="acompletion", model_name=_RAW_MODEL_WITH_PROMPT),
+            UNKNOWN_MODEL_SPEND_LOG_MODEL,
+        ),
+        (ValueError("provider timed out"), _RAW_MODEL_WITH_PROMPT),
+    ],
+)
+def test_get_logging_payload_replaces_model_only_when_router_rejected_it_as_unknown(
+    rejection: Exception, expected_model: str
+):
+    kwargs: Final = {
+        "model": _RAW_MODEL_WITH_PROMPT,
+        "messages": [{"role": "user", "content": "hi"}],
+        "call_type": "acompletion",
+        "litellm_params": {"metadata": {"user_api_key": "sk-test", "status": "failure"}},
+    }
+
+    payload: Final = get_logging_payload(
+        kwargs=kwargs,
+        response_obj=rejection,
+        start_time=datetime.datetime.now(timezone.utc),
+        end_time=datetime.datetime.now(timezone.utc),
+    )
+
+    assert payload["model"] == expected_model
+
+
 @patch("litellm.proxy.proxy_server.master_key", None)
 @patch("litellm.proxy.proxy_server.general_settings", {})
 def test_get_logging_payload_api_key_preserved_when_standard_logging_payload_is_none():