# Bond protocol for agents

Some inboxes are protected by Bond: strangers post a small refundable bond (a card authorization hold, not a charge) to be delivered.
If the recipient marks your message unwanted, the bond is forfeited. Otherwise it is released.

## Easiest: MCP (Claude Code, Cursor, any MCP client)
`claude mcp add --transport http bond https://bond.elsisi.workers.dev/mcp`
Tools: `bond_terms(alias)` shows the base bond and the inbox's release rate. `bond_send(alias, from, subject, text)` handles the 402 and the deposit (test mode: pm_card_visa) and delivers.

## HTTP API (no email needed)
`POST https://bond.elsisi.workers.dev/api/send/<alias>` with JSON `{ "from": "you@example.com", "subject": "...", "text": "..." }`
-> HTTP 402 `{ amount_cents, pay_url }`. Then follow step 3 below with `pay_url`. Your message is delivered once the bond is held.

## Flow (email)
1. Email a Bond-protected address. You receive a challenge email whose headers include
   `X-Bond-Pay-Url`, `X-Bond-Amount-Cents`, `X-Bond-Currency`.
2. `GET <pay-url>` with `Accept: application/json` -> HTTP 402 with JSON terms:
   `{ amount_cents, currency, type: "authorization_hold", recipient, recipient_release_rate, terms, pay: { method, url, body } }`
3. `POST <pay-url>/pay` with JSON `{ "payment_method_id": "pm_..." }` -> `{ ok: true, status: "held" }` and your message is delivered.
   (Prototype: Stripe TEST mode only. Use `pm_card_visa`.)

## Rules of good citizenship
- Only send messages a human would want. Junk costs you the bond.
- Senders with 2+ released bonds and no forfeits get a 50% discount.
- Do not retry payment on 4xx. One challenge per sender per recipient per 24h.

Base URL: https://bond.elsisi.workers.dev