@krynix/adapter-langchain

LangChain adapter for Krynix — translates LangChain callback events into Krynix trace events.

Install

npm install @krynix/adapter-langchain

Usage

Zero-friction plugin (recommended)

import { createLangChainTracer } from "@krynix/adapter-langchain";

const { handler, handle } = await createLangChainTracer({
  outputPath: "./traces/run.trace.jsonl",
  agentId: "my-agent",
});

// Pass handler to LangChain — all events captured automatically
const result = await chain.invoke(input, {
  callbacks: [handler],
});

// When done, shut down to finalize the trace file
await handle.shutdown();

Manual adapter (fine-grained control)

import { LangChainAdapter } from "@krynix/adapter-langchain";

const adapter = new LangChainAdapter();
await adapter.initialize({ agentId: "my-agent", sessionId: "s1" });

// Map a LangChain callback event to a Krynix TraceEvent
const traceEvent = adapter.onEvent({
  _callback: "handleToolStart",
  tool: { lc: 1, type: "not_implemented", id: ["langchain", "tools", "Calculator"] },
  input: "query string",
  runId: "run-123",
  runName: "my_calculator",
});

Callbacks Handled

handleLLMStart, handleLLMEnd, handleLLMError, handleToolStart, handleToolEnd, handleToolError, handleChainStart, handleChainEnd, handleChainError, handleAgentAction, handleAgentFinish

Key Behavior

• Zero runtime dependency on LangChain — accepts unknown input, validates shape
• normalizeFinishReason() maps provider-specific strings to canonical finish reasons
• Tool call timing tracked via metadata["tool.duration_ms"] for replay determinism

License

Apache 2.0