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What it does

This example demonstrates the @grantex/langchain integration by building a LangChain agent with Grantex-scoped tools:
  1. Register an agent and obtain a grant token via the sandbox flow
  2. Create scoped tools using createGrantexTool — each tool is bound to a specific scope (calendar:read, email:send)
  3. Attach a GrantexAuditHandler that automatically logs every tool invocation to the Grantex audit trail
  4. Invoke tools directly (or via an LLM if OPENAI_API_KEY is set)
  5. Demonstrate scope enforcement — attempting to create a tool with account:delete (a scope not in the grant) throws immediately
  6. Inspect the audit trail to see the logged actions

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Prerequisites

  • Node.js 18+
  • Docker (Docker Desktop or Docker Engine with Compose)

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Run

Start the local Grantex stack from the repository root: 
docker compose up --build
In a separate terminal, run the example: 
cd examples/langchain-agent
npm install
npm start
To use a real LLM for tool selection instead of direct invocation, set OPENAI_API_KEY: 
OPENAI_API_KEY=sk-... npm start

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Expected output

Agent registered: ag_01HXYZ...
Grant token received, grantId: grnt_01HXYZ...
Tools created: read_calendar, send_email
Audit handler configured

--- Invoking read_calendar ---
Result: {"events":[{"title":"Team standup","time":"9:00 AM","query":"today"},{"title":"Design review","time":"2:00 PM","query":"today"}]}

--- Invoking send_email ---
Result: Email sent successfully: "Meeting summary: standup at 9 AM, design review at 2 PM"

--- Testing scope enforcement ---
Scope check blocked unauthorized tool: Grant token does not include required scope "account:delete". Granted scopes: calendar:read, email:send

--- Audit trail ---
  [success] read_calendar — 2026-02-28T12:00:00.000Z
  [success] send_email — 2026-02-28T12:00:01.000Z

Done! LangChain integration demo complete.

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Environment variables

VariableDefaultDescription
GRANTEX_URLhttp://localhost:3001Base URL of the Grantex auth service
GRANTEX_API_KEYsandbox-api-key-localAPI key. Use a sandbox key for auto-approval
OPENAI_API_KEY(none)Optional. Set to use a real LLM for tool selection

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Source code

The full source is in examples/langchain-agent/src/index.ts.