Mr Mainspring

Installable MCP stdio backend for agent memory, Grimoire secrets and policies, audit trails, Casper hash anchoring, and policy-gated x402 payment receipts.

Install

No global install is required:

npx -y mrmainspring setup

The setup command creates local config, data, logs, a generated agent_id, and a GRIMOIRE_MASTER_KEY under the user's standard app config folder. It also auto-configures detected MCP clients when possible.

Manual MCP config:

{
  "mcpServers": {
    "mainspring": {
      "command": "npx",
      "args": ["-y", "mrmainspring"]
    }
  }
}

Run the server directly:

npx -y mrmainspring

Check the setup:

npx -y mrmainspring doctor

Tools

• agent.whoami
• memory.write
• memory.read
• memory.search
• memory.verify
• grimoire.secret.put
• grimoire.secret.list
• grimoire.policy.set
• grimoire.policy.get
• payment.fetch
• payment.receipt
• audit.tail

Local Development

npm install
npm test
npm run build
npm run demo:stdio

For live TypeScript development:

npm run dev

Casper And x402

Local memory, Grimoire, audit, and payment preflight tools require no environment variables. Real Casper submission and real x402 settlement are gated until explicitly enabled.

Configure a funded Casper testnet wallet with a key stored outside the repository:

npx -y mrmainspring wallet setup <absolute-path-outside-repo>/backend.pem

This writes Casper testnet RPC/account settings and enables:

• CASPER_ENABLE_REAL_SUBMISSION=true
• X402_ENABLE_REAL_SETTLEMENT=true
• X402_SETTLEMENT_MODE=casper-cli

For real x402 resource settlement, also provide the resource and payee values required by your paid resource, such as X402_PAY_TO, X402_RESOURCE_AMOUNT, and X402_ASSET_ID.

Library Entry

import { createSigilServer } from "mrmainspring";

The package also exports mrmainspring/mcp, but importing that entry starts the stdio server. Use the package binary for normal MCP client configuration.

Boundaries

• Secrets are encrypted and returned only as metadata.
• Payment receipts store safe metadata and signed payload hashes, not signed payload bodies.
• Casper memory anchoring stores hashes only.
• The backend returns pending or unavailable states unless real Casper or x402 settlement is configured and verified.