@atbash/atbash-langchain

@atbash/atbash-langchain

Guard LangChain tools with Atbash.

This is the lightest Atbash integration — a single function that wraps a DynamicStructuredTool and adds a safety check before the tool runs. No graph changes, no framework lifecycle, just a guarded tool boundary.

Installation

npm install @atbash/atbash-langchain

Peer dependency:

npm install @langchain/core

When To Use It

Use this package when:

• you already use DynamicStructuredTool
• you want minimal ceremony
• you only need Atbash at the tool execution boundary

Use @atbash/langgraph instead when you need graph-level pause/resume on HOLD.

Quick Start

import { createAtbashClient, loadAgent } from "@atbash/sdk";
import { DynamicStructuredTool } from "@langchain/core/tools";
import { withAtbashGuard } from "@atbash/atbash-langchain";
import { z } from "zod";

const agent = loadAgent(process.env.ATBASH_AGENT_PRIVKEY);
const client = createAtbashClient({
  keyPair: { privKey: agent.privkey, pubKey: agent.pubkey },
});

const tool = new DynamicStructuredTool({
  name: "send_bank_transfer",
  description: "Send a bank transfer to an external vendor account",
  schema: z.object({ request: z.string() }),
  func: async (input) => `Executed: ${input.request}`,
});

withAtbashGuard(tool, client);

try {
  const result = await tool.invoke({ request: "Transfer $25 to vendor" });
  console.log(result);
} catch (error) {
  // BLOCK or ERROR — surface error.message to the operator
  console.error(error.message);
}

API

withAtbashGuard(tool, client)

Mutates tool.func in-place. The original tool instance is returned for chaining.

Parameter	Type	Description
tool	DynamicStructuredTool	The tool to guard
client	AtbashClient	SDK client created with createAtbashClient()

Returns the same tool instance with its func wrapped.

Verdict Handling

Verdict	Behavior
ALLOW	Original tool func runs normally
HOLD	Original tool func runs (HOLD treated as ALLOW)
BLOCK	Throws Error with the policy reason
ERROR	Throws Error with the API error message

Because blocked and errored calls throw, wrap tool invocations in try/catch and handle the error deliberately — do not treat all exceptions as generic crashes.

Creating the Client

Create AtbashClient once at startup and reuse it for every guarded tool:

import { createAtbashClient, loadAgent } from "@atbash/sdk";

const agent = loadAgent(process.env.ATBASH_AGENT_PRIVKEY);
const client = createAtbashClient({
  keyPair: { privKey: agent.privkey, pubKey: agent.pubkey },
  judge: process.env.ATBASH_ENDPOINT
    ? { endpoint: process.env.ATBASH_ENDPOINT }
    : undefined,
});

Environment Variables

Variable	Required	Description
ATBASH_AGENT_PRIVKEY	Yes	Your Atbash agent private key
ATBASH_ENDPOINT	No	Override the default Atbash endpoint (https://atbash.ai)

What This Package Does Not Do

• It does not manage a review queue.
• It does not pause and resume execution (use @atbash/langgraph for that).
• It does not guard arbitrary business code — only code behind a wrapped DynamicStructuredTool.

Example

A runnable example is in examples/langchain-runtime-agent/.

npm install && npm run build
cd examples/langchain-runtime-agent && npm install && cd ../..
ATBASH_AGENT_PRIVKEY=your_key_here node examples/langchain-runtime-agent/run.mjs