@sbo3l/langchain

LangChain JS Tool wrapping SBO3L. Drop into any LangChain agent's tool list to gate every payment intent through SBO3L's policy boundary.

⚠ DRAFT (T-1-1): depends on F-9 (@sbo3l/sdk) merging + publishing.

Install

npm install @sbo3l/langchain @sbo3l/sdk

Quick start

import { SBO3LClient } from "@sbo3l/sdk";
import { DynamicTool } from "@langchain/core/tools";
import { sbo3lTool } from "@sbo3l/langchain";

const client = new SBO3LClient({
  endpoint: "http://localhost:8730",
  auth: { kind: "bearer", token: process.env.SBO3L_BEARER_TOKEN! },
});

const tool = new DynamicTool(sbo3lTool({ client }));
// Pass `tool` into your LangChain agent's tool list.

What it does

The agent emits a tool call with a JSON-stringified APRP. The Tool forwards to SBO3LClient.submit() and returns a JSON envelope:

{
  "decision": "allow",
  "deny_code": null,
  "matched_rule_id": "allow-low-risk-x402",
  "execution_ref": "kh-01HTAWX5K3R8YV9NQB7C6P2DGS",
  "audit_event_id": "evt-...",
  "request_hash": "...",
  "policy_hash": "..."
}

On deny, the LLM sees deny_code (policy.budget_exceeded, policy.token_unsupported, etc.) and can self-correct or escalate.

Idempotency

const tool = new DynamicTool(sbo3lTool({
  client,
  idempotencyKey: (aprp) => `${aprp.task_id}-${aprp.nonce}`,
}));

Errors

Transport / auth failures surface as a JSON envelope with error (RFC 7807 domain code, e.g. auth.required) and status.

Compatibility

• Node ≥ 18
• LangChain JS 0.1+ (compatible with DynamicTool, DynamicStructuredTool, or any tool factory)
• SBO3L daemon 0.1+

License

MIT