feat(tracing)!: remove trace-level input/output setters

langfuse/_client/attributes.py

@@ -32,8 +32,6 @@ class LangfuseOtelSpanAttributes:
     TRACE_TAGS = "langfuse.trace.tags"
     TRACE_PUBLIC = "langfuse.trace.public"
     TRACE_METADATA = "langfuse.trace.metadata"
-    TRACE_INPUT = "langfuse.trace.input"
-    TRACE_OUTPUT = "langfuse.trace.output"
 
     # Langfuse-observation attributes
     OBSERVATION_TYPE = "langfuse.observation.type"
@@ -76,13 +74,9 @@ class LangfuseOtelSpanAttributes:
 
 def create_trace_attributes(
     *,
-    input: Optional[Any] = None,
-    output: Optional[Any] = None,
     public: Optional[bool] = None,
 ) -> dict:
     attributes = {
-        LangfuseOtelSpanAttributes.TRACE_INPUT: _serialize(input),
-        LangfuseOtelSpanAttributes.TRACE_OUTPUT: _serialize(output),
         LangfuseOtelSpanAttributes.TRACE_PUBLIC: public,
     }
 

langfuse/_client/client.py

@@ -38,7 +38,6 @@
     _agnosticcontextmanager,
 )
 from packaging.version import Version
-from typing_extensions import deprecated
 
 from langfuse._client.attributes import (
     LangfuseOtelSpanAttributes,
@@ -213,7 +212,7 @@ class Langfuse:
         release (Optional[str]): Release version/hash of your application. Used for grouping analytics by release.
         media_upload_thread_count (Optional[int]): Number of background threads for handling media uploads. Defaults to 1. Can also be set via LANGFUSE_MEDIA_UPLOAD_THREAD_COUNT environment variable.
         sample_rate (Optional[float]): Sampling rate for traces (0.0 to 1.0). Defaults to 1.0 (100% of traces are sampled). Can also be set via LANGFUSE_SAMPLE_RATE environment variable.
-        mask (Optional[MaskFunction]): Function to mask sensitive data synchronously when Langfuse SDK attributes are created. This applies only to data set through Langfuse SDK APIs such as `start_observation()`, `update()`, and `set_trace_io()`.
+        mask (Optional[MaskFunction]): Function to mask sensitive data synchronously when Langfuse SDK attributes are created. This applies only to data set through Langfuse SDK APIs such as `start_observation()` and `update()`.
         mask_otel_spans (Optional[MaskOtelSpansFunction]): Synchronous export-stage hook for masking raw OpenTelemetry span attributes before this Langfuse client sends them to Langfuse. Use this for spans created by third-party OpenTelemetry instrumentations, or when you need to inspect final span attributes after export filtering and Langfuse media handling. It does not modify spans already exported through other OpenTelemetry exporters.
 
             The hook receives one OpenTelemetry export batch. A batch is not guaranteed to contain a complete trace, request, or Langfuse observation tree. The hook usually runs on the OpenTelemetry batch span processor worker thread; during `flush()` and shutdown it may run on the caller thread. Keep it synchronous, deterministic, and fast.
@@ -1534,55 +1533,6 @@ def update_current_span(
                 status_message=status_message,
             )
 
-    @deprecated(
-        "Trace-level input/output is deprecated. "
-        "For trace attributes (user_id, session_id, tags, etc.), use propagate_attributes() instead. "
-        "This method will be removed in a future major version."
-    )
-    def set_current_trace_io(
-        self,
-        *,
-        input: Optional[Any] = None,
-        output: Optional[Any] = None,
-    ) -> None:
-        """Set trace-level input and output for the current span's trace.
-
-        .. deprecated::
-            This is a legacy method for backward compatibility with Langfuse platform
-            features that still rely on trace-level input/output (e.g., legacy LLM-as-a-judge
-            evaluators). It will be removed in a future major version.
-
-            For setting other trace attributes (user_id, session_id, metadata, tags, version),
-            use :func:`langfuse.propagate_attributes` (top-level import) instead.
-
-        Args:
-            input: Input data to associate with the trace.
-            output: Output data to associate with the trace.
-        """
-        if not self._tracing_enabled:
-            langfuse_logger.debug(
-                "Operation skipped: set_current_trace_io - Tracing is disabled or client is in no-op mode."
-            )
-            return
-
-        current_otel_span = self._get_current_otel_span()
-
-        if current_otel_span is not None and current_otel_span.is_recording():
-            span_class = self._get_span_class(
-                self._get_observation_type_from_otel_span(current_otel_span)
-            )
-            span = span_class(
-                otel_span=current_otel_span,
-                langfuse_client=self,
-                environment=self._environment,
-                release=self._release,
-            )
-
-            span.set_trace_io(
-                input=input,
-                output=output,
-            )
-
     def set_current_trace_as_public(self) -> None:
         """Make the current trace publicly accessible via its URL.
 

langfuse/_client/span.py

@@ -36,7 +36,6 @@
 if TYPE_CHECKING:
     from langfuse._client.client import Langfuse
 
-from typing_extensions import deprecated
 
 from langfuse._client.attributes import (
     LangfuseOtelSpanAttributes,
@@ -226,53 +225,6 @@ def end(self, *, end_time: Optional[int] = None) -> "LangfuseObservationWrapper"
 
         return self
 
-    @deprecated(
-        "Trace-level input/output is deprecated. "
-        "For trace attributes (user_id, session_id, tags, etc.), use propagate_attributes() instead. "
-        "This method will be removed in a future major version."
-    )
-    def set_trace_io(
-        self,
-        *,
-        input: Optional[Any] = None,
-        output: Optional[Any] = None,
-    ) -> "LangfuseObservationWrapper":
-        """Set trace-level input and output for the trace this span belongs to.
-
-        .. deprecated::
-            This is a legacy method for backward compatibility with Langfuse platform
-            features that still rely on trace-level input/output (e.g., legacy LLM-as-a-judge
-            evaluators). It will be removed in a future major version.
-
-            For setting other trace attributes (user_id, session_id, metadata, tags, version),
-            use :func:`langfuse.propagate_attributes` (top-level import) instead.
-
-        Args:
-            input: Input data to associate with the trace.
-            output: Output data to associate with the trace.
-
-        Returns:
-            The span instance for method chaining.
-        """
-        if not self._otel_span.is_recording():
-            return self
-
-        media_processed_input = self._process_media_and_apply_mask(
-            data=input, field="input", span=self._otel_span
-        )
-        media_processed_output = self._process_media_and_apply_mask(
-            data=output, field="output", span=self._otel_span
-        )
-
-        attributes = create_trace_attributes(
-            input=media_processed_input,
-            output=media_processed_output,
-        )
-
-        self._otel_span.set_attributes(attributes)
-
-        return self
-
     def set_trace_as_public(self) -> "LangfuseObservationWrapper":
         """Make this trace publicly accessible via its URL.
 

langfuse/_client/span_exporter.py

@@ -27,7 +27,6 @@
 
 _INPUT_MEDIA_ATTRIBUTE_KEYS = frozenset(
     {
-        LangfuseOtelSpanAttributes.TRACE_INPUT,
         LangfuseOtelSpanAttributes.OBSERVATION_INPUT,
         "ai.prompt.messages",
         "ai.prompt",
@@ -54,7 +53,6 @@
 
 _OUTPUT_MEDIA_ATTRIBUTE_KEYS = frozenset(
     {
-        LangfuseOtelSpanAttributes.TRACE_OUTPUT,
         LangfuseOtelSpanAttributes.OBSERVATION_OUTPUT,
         "ai.response.text",
         "ai.result.text",

tests/e2e/test_core_sdk.py

@@ -549,14 +549,14 @@ def test_create_update_current_trace():
 
     trace_name = create_uuid()
 
-    # Create initial span with trace properties using propagate_attributes and set_current_trace_io
+    # Create initial span with trace properties using propagate_attributes
     with langfuse.start_as_current_observation(name="test-span-current") as span:
         with propagate_attributes(
             trace_name=trace_name,
             user_id="test",
             metadata={"key": "value"},
         ):
-            langfuse.set_current_trace_io(input="test_input")
+            langfuse.update_current_span(input="test_input")
             langfuse.set_current_trace_as_public()
             # Get trace ID for later reference
             trace_id = span.trace_id
@@ -989,7 +989,7 @@ def test_create_trace_and_generation():
     # Create parent span and set trace properties
     with langfuse.start_as_current_observation(name=trace_name) as parent_span:
         with propagate_attributes(trace_name=trace_name, session_id="test-session-id"):
-            parent_span.set_trace_io(input={"key": "value"})
+            parent_span.update(input={"key": "value"})
 
             # Create a generation as child
             generation = parent_span.start_observation(
@@ -1812,23 +1812,23 @@ def test_fetch_traces():
     # First trace
     with langfuse.start_as_current_observation(name="test1") as span:
         with propagate_attributes(trace_name=name, session_id="session-1"):
-            span.set_trace_io(input={"key": "value"}, output="output-value")
+            span.update(input={"key": "value"}, output="output-value")
             trace_ids.append(span.trace_id)
 
     sleep(1)  # Ensure traces have different timestamps
 
     # Second trace
     with langfuse.start_as_current_observation(name="test2") as span:
         with propagate_attributes(trace_name=name, session_id="session-1"):
-            span.set_trace_io(input={"key": "value"}, output="output-value")
+            span.update(input={"key": "value"}, output="output-value")
             trace_ids.append(span.trace_id)
 
     sleep(1)  # Ensure traces have different timestamps
 
     # Third trace
     with langfuse.start_as_current_observation(name="test3") as span:
         with propagate_attributes(trace_name=name, session_id="session-1"):
-            span.set_trace_io(input={"key": "value"}, output="output-value")
+            span.update(input={"key": "value"}, output="output-value")
             trace_ids.append(span.trace_id)
 
     # Ensure data is sent
@@ -2088,11 +2088,11 @@ def mask_func(data):
     # Create a root span with trace properties
     with langfuse.start_as_current_observation(name="test-span") as root_span:
         with propagate_attributes(trace_name="test_trace"):
-            root_span.set_trace_io(input={"sensitive": "data"})
+            root_span.update(input={"sensitive": "data"})
             # Get trace ID for later use
             trace_id = root_span.trace_id
             # Add output to the trace
-            root_span.set_trace_io(output={"more": "sensitive"})
+            root_span.update(output={"more": "sensitive"})
 
             # Create a generation as child
             gen = root_span.start_observation(
@@ -2136,11 +2136,11 @@ def mask_func(data):
     # Create a root span with trace properties
     with langfuse.start_as_current_observation(name="test-span") as root_span:
         with propagate_attributes(trace_name="test_trace"):
-            root_span.set_trace_io(input={"should_raise": "data"})
+            root_span.update(input={"should_raise": "data"})
             # Get trace ID for later use
             trace_id = root_span.trace_id
             # Add output to the trace
-            root_span.set_trace_io(output={"should_raise": "sensitive"})
+            root_span.update(output={"should_raise": "sensitive"})
 
     # Ensure data is sent
     langfuse.flush()

tests/e2e/test_decorators.py

@@ -1071,10 +1071,10 @@ def test_media():
 
     media = LangfuseMedia(content_bytes=pdf_bytes, content_type="application/pdf")
 
-    @observe()
+    @observe(capture_input=False, capture_output=False)
     def main():
         sleep(1)
-        langfuse.set_current_trace_io(
+        langfuse.update_current_span(
             input={
                 "context": {
                     "nested": media,

tests/unit/test_mask_otel_spans.py

@@ -293,7 +293,6 @@ def test_export_stage_media_processes_string_sequence_attributes():
 @pytest.mark.parametrize(
     ("attribute_key", "expected_field"),
     [
-        ("langfuse.trace.input", "input"),
         ("langfuse.observation.input", "input"),
         ("ai.prompt.messages", "input"),
         ("gcp.vertex.agent.tool_call_args", "input"),
@@ -302,7 +301,6 @@ def test_export_stage_media_processes_string_sequence_attributes():
         ("gen_ai.input.messages", "input"),
         ("gen_ai.prompt.0.content", "input"),
         ("llm.input_messages.0.message.content", "input"),
-        ("langfuse.trace.output", "output"),
         ("langfuse.observation.output", "output"),
         ("ai.response.toolCalls", "output"),
         ("gcp.vertex.agent.tool_response", "output"),

tests/unit/test_otel.py

@@ -498,16 +498,16 @@ def test_generation_name_update(self, langfuse_client, memory_exporter):
 
     def test_trace_update(self, langfuse_client, memory_exporter):
         """Test updating trace level attributes."""
-        # Create a span and set trace attributes using propagate_attributes and set_trace_io
-        with langfuse_client.start_as_current_observation(name="trace-span") as span:
+        # Create a span and set trace attributes using propagate_attributes
+        with langfuse_client.start_as_current_observation(name="trace-span"):
             with propagate_attributes(
                 trace_name="updated-trace-name",
                 user_id="test-user",
                 session_id="test-session",
                 tags=["tag1", "tag2"],
                 metadata={"trace-meta": "data"},
             ):
-                span.set_trace_io(input={"trace-input": "value"})
+                pass
 
         # Get the span data
         spans = self.get_spans_by_name(memory_exporter, "trace-span")
@@ -526,12 +526,10 @@ def test_trace_update(self, langfuse_client, memory_exporter):
         else:
             tags = list(attributes[LangfuseOtelSpanAttributes.TRACE_TAGS])
 
-        input_data = json.loads(attributes[LangfuseOtelSpanAttributes.TRACE_INPUT])
         metadata = attributes[f"{LangfuseOtelSpanAttributes.TRACE_METADATA}.trace-meta"]
 
         # Check attribute values
         assert sorted(tags) == sorted(["tag1", "tag2"])
-        assert input_data == {"trace-input": "value"}
         assert metadata == "data"
 
     def test_complex_scenario(self, langfuse_client, memory_exporter):