Demo of a LangChain agent using Grantex-scoped tools and automatic audit logging.

1. Registers an agent with calendar:read and email:send scopes
2. Gets a grant token via the sandbox flow (no consent UI)
3. Creates two scoped tools using createGrantexTool (calendar read + email send)
4. Sets up GrantexAuditHandler for automatic tool invocation logging
5. Invokes tools and logs each action to the audit trail
6. Demonstrates scope enforcement — attempting to create a tool with an unauthorized scope fails immediately

• Node.js 18+
• Docker (for the local Grantex stack)

Optional: Set OPENAI_API_KEY to use a real LLM. Without it, the example invokes tools directly to demonstrate the Grantex integration.

# Start the local Grantex stack (from repo root)
docker compose up -d

# Run the example
cd examples/langchain-agent
npm install
npm start

Agent registered: ag_01...
Grant token received, grantId: grnt_01...
Tools created: read_calendar, send_email
Audit handler configured

--- Invoking read_calendar ---
Result: {"events":[{"title":"Team standup","time":"9:00 AM",...}]}

--- Invoking send_email ---
Result: Email sent successfully: "Meeting summary: ..."

--- Testing scope enforcement ---
Scope check blocked unauthorized tool: Grantex: agent is not authorized for scope 'account:delete'. ...

--- Audit trail ---
  [success] tool:read_calendar — 2026-02-27T...
  [success] tool:send_email — 2026-02-27T...

Done! LangChain integration demo complete.