Agent Observability Python Framework Module: LangChain

agento11y-langchain provides callback handlers that map LangChain lifecycle events into agento11y generation recorder lifecycles.

Installation

pip install agento11y agento11y-langchain
pip install langchain-openai

Usage

from agento11y import Client
from agento11y_langchain import with_agento11y_langchain_callbacks

client = Client()
config = with_agento11y_langchain_callbacks(None, client=client, provider_resolver="auto")

End-to-end example (invoke + stream)

from langchain_openai import ChatOpenAI
from agento11y import Client
from agento11y_langchain import Agento11yLangChainHandler, with_agento11y_langchain_callbacks

client = Client()
handler = Agento11yLangChainHandler(
    client=client,
    provider_resolver="auto",
    agent_name="langchain-example",
    agent_version="1.0.0",
)

llm = ChatOpenAI(model="gpt-4o-mini", temperature=0)

# Non-stream call -> SYNC generation mode.
result = llm.invoke(
    "Summarize why retry budgets matter.",
    config=with_agento11y_langchain_callbacks(None, client=client, provider_resolver="auto"),
)
print(result.content)

# Stream call -> STREAM generation mode + TTFT tracking.
for chunk in llm.stream(
    "Give me three short reliability tips.",
    config=with_agento11y_langchain_callbacks(None, client=client, provider_resolver="auto"),
):
    if chunk.content:
        print(chunk.content, end="", flush=True)
print()

# Advanced usage: explicit handler wiring remains supported.
_ = llm.invoke("manual handler wiring", config={"callbacks": [handler]})

client.shutdown()

Conversation grouping

The handler resolves the conversation id per invocation, in this order:

1. conversation_id / session_id / group_id in the callback metadata, invocation params, or configurable
2. A thread_id in the same places
3. The handler's conversation_id constructor argument
4. A synthetic per-run id

Pass conversation_id on the constructor when your application owns the conversation identity. Per-invocation identity still wins, so a handler built once per process cannot override it.

handler = Agento11yLangChainHandler(
    client=client,
    agent_name="my-chain",
    conversation_id=request.conversation_id,
)

Without any of these, each run becomes its own conversation.

Behavior

• Lifecycle mapping:
  • on_llm_start / on_chat_model_start -> generation recorder
  • System and developer messages passed to on_chat_model_start are lifted out of the input message list into system_prompt (joined with a blank line when there are several), since the wire format has no system role. An explicit invocation_params["system_prompt"] wins.
  • on_tool_start / on_tool_end / on_tool_error -> start_tool_execution
  • on_chain_start / on_chain_end / on_chain_error -> framework chain spans
  • on_retriever_start / on_retriever_end / on_retriever_error -> framework retriever spans
  • on_llm_new_token -> first-token timestamp for stream mode
• Mode mapping: non-stream -> SYNC, stream -> STREAM.
• Provider resolver parity:
  • explicit provider metadata when available
  • model-name inference (gpt-/o1/o3/o4 -> openai, claude- -> anthropic, gemini- -> gemini)
  • fallback -> custom
• Framework tags/metadata are always set:
  • agento11y.framework.name=langchain
  • agento11y.framework.source=handler
  • agento11y.framework.language=python
  • metadata["agento11y.framework.run_id"]=<run id>
  • metadata["agento11y.framework.thread_id"]=<thread id> (when present in callback metadata/config)
  • metadata["agento11y.framework.parent_run_id"] (when available)
  • metadata["agento11y.framework.component_name"] (serialized component identity)
  • metadata["agento11y.framework.run_type"] (llm, chat, tool, chain, retriever)
  • metadata["agento11y.framework.tags"] (normalized callback tags)
  • metadata["agento11y.framework.retry_attempt"] (when available)
  • generation span attributes mirror low-cardinality framework metadata keys

Call client.shutdown() during teardown to flush buffered telemetry.