Agent Context API

A small paid API for coding agents that need a deterministic context preflight before sending repository text to an LLM. It counts GPT-family tokens, applies an optional model-aware budget, and redacts likely credentials.

Local development

npm install
npm test
X402_FACILITATOR=https://facilitator.openx402.ai npm start

The service listens on http://localhost:8787 by default. GET /health is free. POST /v1/context-preflight returns an x402 402 Payment Required response until the caller supplies a valid Base USDC payment.

API example

curl -X POST http://localhost:8787/v1/context-preflight \
  -H 'content-type: application/json' \
  -d '{"text":"const token = \"sk-example\";","model":"claude-sonnet","token_budget":1000}'

The default price is $0.005 per request. Set PAY_TO to change the public payout address and X402_FACILITATOR to select a compatible facilitator. Do not put private keys or facilitator credentials in this repository; the service does not need a signing key to receive payments.

MCP integration

The repository also includes a local stdio MCP server for Cline and other MCP clients:

npm run start:mcp

The preflight_context tool provides a free local tier up to 12,000 characters. Larger inputs return the paid HTTP endpoint and its x402 price. Set PAID_ENDPOINT to the currently deployed endpoint when launching the MCP server. See llms-install.md for a copy-paste client configuration.

Design notes

• server.js contains the Express app, x402 payment middleware, discovery metadata, and analysis logic.
• test/server.test.js covers redaction, budgets, and the health route.
• The API intentionally does not send submitted text to a third party; processing is local.
• This is an experiment. Revenue must be verified from settlement records, not inferred from 402 responses, requests, or directory listings.