feat(langchain): add model, chain, agent, and streaming callback handlers [4/5]#4453
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nagkumar91 wants to merge 4 commits intoopen-telemetry:mainfrom
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feat(langchain): add model, chain, agent, and streaming callback handlers [4/5]#4453nagkumar91 wants to merge 4 commits intoopen-telemetry:mainfrom
nagkumar91 wants to merge 4 commits intoopen-telemetry:mainfrom
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…nt recording modules Add foundation modules for enhanced LangChain GenAI semantic convention tracing: - semconv_attributes.py: Per-operation attribute matrix based on OTel GenAI semantic conventions. Single source of truth for which attributes apply to which operations (chat, text_completion, invoke_agent, execute_tool, invoke_workflow, retrieval). - operation_mapping.py: Callback-to-semconv operation mapping. Maps each LangChain callback to the correct GenAI semantic convention operation name. Includes heuristic classification for on_chain_start callbacks (agents vs workflows vs internal plumbing) and LangGraph marker recognition. - content_recording.py: Thin integration layer over the shared genai content capture utilities. Provides clear APIs for the callback handler to decide what content should be recorded on spans and events. Part 1 of a series breaking down open-telemetry#4389 into smaller reviewable PRs. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
…propagation utilities Add utility modules for the LangChain instrumentor: - utils.py: Provider name inference from LangChain callback data (ls_provider, base_url, class name, endpoint fields), server address/port extraction, and W3C trace context header extraction and propagation support. - message_formatting.py: Message, tool, and document serialization with content-redaction support. Converts LangChain message objects into the compact JSON format expected by OpenTelemetry GenAI semantic conventions. Part 2 of a series breaking down open-telemetry#4389 into smaller reviewable PRs. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Enhance the span lifecycle manager and add event emission for non-LLM GenAI operations: - span_manager.py: Enhanced with ignored-run walkthrough (re-parenting children of skipped internal runs), per-thread agent stacks for hierarchy tracking, token usage accumulation and propagation to parent agent spans, and LangGraph Command(goto=...) transition support. - event_emitter.py: Emits semantic-convention-aligned log-record events for tool, agent, and retriever spans. All event emission is gated behind the content policy. Uses LogRecord instances linked to the active span context. Part 3 of a series breaking down open-telemetry#4389 into smaller reviewable PRs. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
…h wiring Wire all foundation modules into the callback handler and add comprehensive callback implementations: - callback_handler.py: Enhanced with model start/end/error (improved provider and server inference), chain start/end/error (with operation classification), agent action/finish, LLM new token (streaming chunk timing metrics), tool start/end/error, and retriever start/end/error callbacks. - __init__.py: Wire SpanManager, EventEmitter, and tracer into the instrumentor's _instrument method. - conftest.py: Updated test infrastructure for enhanced callback testing. Part 4 of a series breaking down open-telemetry#4389 into smaller reviewable PRs. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This was referenced Apr 16, 2026
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Description
Wire all foundation modules into the callback handler and implement the core callback methods for LLM model, chain, agent, and streaming operations.
Changes
callback_handler.py(major enhancement)All new callback implementations following GenAI semantic conventions:
on_chat_model_start,on_llm_start,on_llm_end,on_llm_error— enhanced with provider inference, server address extraction, model parameter captureon_chain_start,on_chain_end,on_chain_error— with operation classification (invoke_agent vs invoke_workflow), LangGraph support, ignored-run managementon_agent_action,on_agent_finish— tool call recording, finish reason captureon_llm_new_token— time-to-first-chunk and time-per-output-chunk metricson_tool_start,on_tool_end,on_tool_error— tool name, arguments, results with content redactionon_retriever_start,on_retriever_end,on_retriever_error— query and document capture__init__.py(wiring)_SpanManagerwith a tracer using schema URLV1_37_0EventEmitterwith the logger providerOpenTelemetryLangChainCallbackHandlerconftest.py(test infrastructure)Tests
test_chain_callbacks.py— chain start/end/error, operation classification, LangGraph goto handlingtest_agent_lifecycle.py— agent action/finish, tool call recordingtest_streaming_metrics.py— TTFC/TPOC histogram recording, concurrent streamingtest_llm_call.py— updated for new callback handler signaturePR Series
This is PR 4 of 5 breaking down #4389:
Depends on: #4452 (merge first)
Type of change
Checklist