🔗 @makerchecker/connector-langchain

Put a governance gate in front of every LangChain tool call.

Wrap a LangChain StructuredTool and every invoke() runs a deny-by-default check before the tool body and records the result to the hash-chained audit log. Same name, same schema — it drops straight into your agent.

governLangChainTool returns a tool with the original name and schema. Every invoke() runs a check before the tool body and records the result to the hash-chained audit log; a denied check throws GovernanceDeniedError before the tool body runs.

Install

pnpm add @makerchecker/connector-langchain @makerchecker/sdk @langchain/core

@langchain/core (^1.0.0) is a peer dependency. The MakerChecker SDK is a direct dependency.

Use

import { tool } from "@langchain/core/tools";
import { z } from "zod";
import { createClient } from "@makerchecker/sdk";
import {
  governLangChainTool,
  GovernanceDeniedError,
} from "@makerchecker/connector-langchain";

const client = createClient({ baseUrl: "http://localhost:3000", apiKey: "mk_..." });

const matchTxns = tool(async ({ statement }) => ({ matched: statement.length }), {
  name: "match_txns",
  description: "Match statement transactions against the ledger.",
  schema: z.object({ statement: z.array(z.string()) }),
});

const { session } = await client.proxy.openSession({ label: "langchain-run" });

const governed = governLangChainTool(
  client,
  { sessionId: session.id, agentName: "recon-preparer", skillRef: "txn-match@1" },
  matchTxns,
);

try {
  await governed.invoke({ statement: ["t1", "t2"] }); // checks, runs, records
} catch (err) {
  if (err instanceof GovernanceDeniedError) console.error(`${err.code}: ${err.reason}`);
  else throw err;
}

await client.proxy.closeSession(session.id);

governed carries the original name and schema, so it drops into a ToolNode or an agent executor in place of matchTxns.

API

governLangChainTool(client, context, tool): DynamicStructuredTool
  context: { sessionId, agentName, skillRef }

governToolkit(client, context, tools, skillRefs): DynamicStructuredTool[]
  context: { sessionId, agentName }
  skillRefs: (tool) => skillRef  |  Record<toolName, skillRef>

governToolkit wraps an array of tools under one session and agent. An unmapped tool throws rather than running ungoverned. GovernanceDeniedError is re-exported from @makerchecker/sdk with fields code and reason.

A runnable example is in examples/connectors/langchain/governed-langchain-demo.mjs.

License

Apache-2.0. See LICENSE.