fix(langfuse_otel): keep span export alive when nested request metadata has non-string keys

The content strip validated prompt_management_metadata, mcp_tool_call_metadata
and vector_store_request_metadata items as str-keyed mappings, so an SDK
caller passing one with a non-string key raised inside
exported_request_metadata: OTEL v2 dropped the LLM span for every vendor and
v1 langfuse_otel lost the request metadata and every attribute after it.
Validate those nested mappings with object keys instead. Also hoists the
langfuse_otel imports.

litellm/integrations/langfuse/langfuse_otel.py

@@ -13,6 +13,9 @@ from litellm.integrations.langfuse.langfuse_otel_attributes import (
     LangfuseLLMObsOTELAttributes,
 )
 from litellm.integrations.opentelemetry import OpenTelemetry, OpenTelemetryConfig
+from litellm.integrations.otel.mappers.langfuse import TRACE_IDENTITY_FIELDS
+from litellm.integrations.otel.model.metadata import exported_request_metadata
+from litellm.litellm_core_utils.safe_json_dumps import safe_dumps
 from litellm.litellm_core_utils.safe_json_loads import safe_json_loads
 from litellm.types.integrations.langfuse_otel import (
     LangfuseSpanAttributes,
@@ -135,11 +138,6 @@ class LangfuseOtelLogger(OpenTelemetry):
         span: Span,
         kwargs: dict[str, object],  # mutable-ok: required callback signature accepts kwargs as a dict
     ) -> None:
-        from litellm.integrations.arize._utils import safe_set_attribute
-        from litellm.integrations.otel.mappers.langfuse import TRACE_IDENTITY_FIELDS
-        from litellm.integrations.otel.model.metadata import exported_request_metadata
-        from litellm.litellm_core_utils.safe_json_dumps import safe_dumps
-
         raw_standard_logging_object: Final = kwargs.get("standard_logging_object")
         if not isinstance(raw_standard_logging_object, dict):
             return
@@ -148,7 +146,7 @@ class LangfuseOtelLogger(OpenTelemetry):
             return
         observation_metadata: Final = exported_request_metadata(standard_logging_object)
         if observation_metadata:
-            safe_set_attribute(
+            _utils.safe_set_attribute(
                 span,
                 LangfuseSpanAttributes.OBSERVATION_METADATA.value,
                 safe_dumps(dict(observation_metadata)),
@@ -156,7 +154,7 @@ class LangfuseOtelLogger(OpenTelemetry):
         trace_prefix: Final = LangfuseSpanAttributes.TRACE_METADATA.value
         for field in TRACE_IDENTITY_FIELDS:
             if value := observation_metadata.get(field):
-                safe_set_attribute(span, f"{trace_prefix}.{field}", value)
+                _utils.safe_set_attribute(span, f"{trace_prefix}.{field}", value)
 
     @staticmethod
     def _set_observation_output(span: Span, response_obj):

litellm/integrations/otel/model/metadata.py

@@ -60,6 +60,7 @@ if TYPE_CHECKING:
 _INTERNAL_CALL_ORIGINS: Final[frozenset[str]] = frozenset(get_args(InternalCallOrigin))
 _AUTH_ATTRIBUTE: Final = TypeAdapter(object)
 _REQUEST_METADATA_MAPPING_ADAPTER: Final[TypeAdapter[Mapping[str, object]]] = TypeAdapter(Mapping[str, object])
+_NESTED_METADATA_MAPPING_ADAPTER: Final[TypeAdapter[Mapping[object, object]]] = TypeAdapter(Mapping[object, object])
 _PROMPT_MANAGEMENT_CONTENT_FIELDS: Final[frozenset[str]] = frozenset({"prompt_variables"})
 _MCP_TOOL_CALL_CONTENT_FIELDS: Final[frozenset[str]] = frozenset({"arguments", "result"})
 _VECTOR_STORE_CONTENT_FIELDS: Final[frozenset[str]] = frozenset({"query", "vector_store_search_response"})
@@ -494,7 +495,7 @@ def exported_request_metadata(payload: Mapping[str, object]) -> Mapping[str, obj
 def _without_mapping_content_fields(value: object, content_fields: frozenset[str]) -> object:
     if not isinstance(value, dict):
         return value
-    mapping: Final = _REQUEST_METADATA_MAPPING_ADAPTER.validate_python(value)
+    mapping: Final = _NESTED_METADATA_MAPPING_ADAPTER.validate_python(value)
     return {key: item for key, item in mapping.items() if key not in content_fields}
 
 

tests/unit/integrations/otel/test_otel_v2_vendor_mappers.py

@@ -919,3 +919,24 @@ def test_langfuse_mapper_omits_observation_metadata_without_payload_metadata():
     attrs: Final = LangfuseMapper().map(LLMCallSpanData.from_standard_logging_payload(payload))
 
     assert json.loads(attrs["langfuse.observation.metadata"]) == {"requester_metadata": {}}
+
+
+@pytest.mark.parametrize(
+    "unexpected_shape",
+    [
+        {"prompt_management_metadata": {1: "one", "prompt_id": "prompt-1"}},
+        {"mcp_tool_call_metadata": {1: "one", "name": "lookup_weather"}},
+        {"vector_store_request_metadata": [{1: "one", "vector_store_id": "vs-1"}]},
+    ],
+)
+def test_span_data_builds_from_request_metadata_of_unexpected_shape(unexpected_shape: dict[str, object]) -> None:
+    payload: Final[dict[str, object]] = {
+        "call_type": "acompletion",
+        "custom_llm_provider": "openai",
+        "model": "gpt-4o",
+        "metadata": {**unexpected_shape, "spend_logs_metadata": {"ticket": "LIT-8283"}},
+        "response": {},
+    }
+    attrs: Final = LangfuseMapper().map(LLMCallSpanData.from_standard_logging_payload(payload))
+
+    assert json.loads(attrs["langfuse.observation.metadata"])["spend_logs_metadata"] == {"ticket": "LIT-8283"}

tests/unit/integrations/test_langfuse_otel.py

@@ -644,6 +644,31 @@ class TestLangfuseOtelIntegration:
             assert [key for key in actual if key.startswith("langfuse.trace.metadata")] == ["langfuse.trace.metadata"]
             assert "langfuse.observation.metadata" not in actual
 
+    @pytest.mark.parametrize(
+        "unexpected_shape",
+        [
+            {"prompt_management_metadata": {1: "one", "prompt_id": "prompt-1"}},
+            {"mcp_tool_call_metadata": {1: "one", "name": "lookup_weather"}},
+            {"vector_store_request_metadata": [{1: "one", "vector_store_id": "vs-1"}]},
+        ],
+    )
+    def test_request_metadata_of_unexpected_shape_keeps_the_observation_output(
+        self, unexpected_shape: dict[str, object]
+    ) -> None:
+        kwargs: Final[dict[str, object]] = {
+            "litellm_params": {"metadata": {}},
+            "standard_logging_object": {"metadata": {**unexpected_shape, "spend_logs_metadata": {"env": "prod"}}},
+        }
+        response_obj: Final = {"choices": [{"message": {"role": "assistant", "content": "hello"}}]}
+
+        with patch("litellm.integrations.arize._utils.safe_set_attribute") as mock_safe_set_attribute:
+            LangfuseOtelLogger._set_langfuse_specific_attributes(MagicMock(), kwargs, response_obj)
+
+            actual: Final = {call.args[1]: call.args[2] for call in mock_safe_set_attribute.call_args_list}
+
+            assert json.loads(actual["langfuse.observation.metadata"])["spend_logs_metadata"] == {"env": "prod"}
+            assert json.loads(actual["langfuse.observation.output"]) == {"role": "assistant", "content": "hello"}
+
 
 class TestLangfuseOtelKeyDynamicConfig:
     """Key/team-scoped Langfuse credentials must define the full export target