sell-this

name

sell-this

description

Turn a resource (a file, an answer, an API endpoint, a piece of work) into a paid endpoint by minting an L402 challenge that charges sats for access, then verifying payment before delivering. Use when the user wants to SELL or monetize access to something to another agent or person over Lightning ("charge for this", "sell access to this", "put this behind a paywall", "monetize this"). This is the PRODUCER side of L402. Requires a Lightning Enable API key with an Agentic Commerce subscription.

Sell this

Make the agent a seller, not just a buyer. Point at a resource, set a price in sats, and mint an L402 challenge that anyone (human or agent) must pay to access. When they pay and present the token, verify it before you hand over the goods. This is the other half of agentic commerce — agents that can both buy and sell.

What you need

• Lightning Enable MCP with LIGHTNING_ENABLE_API_KEY set (Agentic Commerce subscription) — the producer tools create_l402_challenge and verify_l402_payment require it.
• A resource to sell and a price the user sets.

Flow

1. Create the challenge (the paywall)

Use create_l402_challenge:

• resource — a URL, service name, or description of what you're selling.
• priceSats — the price in satoshis (the user decides).
• description — optional, shown on the Lightning invoice.

It returns a Lightning invoice + a macaroon. Together these are the 402 challenge you present to the buyer:

"402 Payment Required — pay this invoice, then send back the token <macaroon>:<preimage>."

Share the invoice + macaroon with the buyer (paste them, or hand them to the requesting agent).

2. Verify payment before delivering

When the buyer pays, they get a preimage (proof of payment) and send you the token macaroon:preimage. Verify it with verify_l402_payment:

• macaroon — the base64 macaroon from the token.
• preimage — the hex preimage from the token.

Only deliver the resource if verification succeeds. If it fails, do not hand anything over — they haven't paid (or the token is forged/expired).

3. Deliver

On a verified token, deliver the resource (send the file, return the answer, grant the access). Done — you just sold something over Lightning, no account or card on either side.

Safety rules

• Never deliver before verify_l402_payment succeeds. The preimage is the proof; no valid preimage = no payment = no delivery.
• Set the price with the user; don't guess what to charge.
• Don't leak the resource in the challenge description or resource fields — those are public on the invoice. Describe what's for sale, don't include the payload.
• One token proves one payment; don't accept a reused/forged token.

Example

User: "Charge 100 sats for this market summary I wrote."

1. create_l402_challenge(resource="market-summary-2026-06", priceSats=100, description="Daily market summary") → invoice + macaroon.
2. Share: "Pay this invoice, then send me <macaroon>:<preimage>."
3. Buyer pays → sends token. verify_l402_payment(macaroon, preimage) → valid.
4. Deliver the summary.