Taking a sell range order

If the order fiat amount is a range like 10-20 the buyer must indicate a fiat amount to take the order, buyer will send a message in a Nostr event kind 4 to Mostro with the following content:

{
  "order": {
    "version": 1,
    "id": "ede61c96-4c13-4519-bf3a-dcf7f1e9d842",
    "pubkey": "0000147e939bef2b81c27af4c1b702c90c3843f7212a34934bff1e049b7f1427",
    "action": "take-sell",
    "content": {
      "amount": 15
    }
  }
}

Mostro response

In order to continue the buyer needs to send a lightning network invoice to Mostro, in this case the amount of the order is 0, so Mostro will need to calculate the amount of sats for this order, then Mostro will send back a message asking for a LN invoice indicating the correct amount of sats that the invoice should have, here the unencrypted content of the message:

{
  "order": {
    "version": 1,
    "id": "ede61c96-4c13-4519-bf3a-dcf7f1e9d842",
    "pubkey": null,
    "action": "add-invoice",
    "content": {
      "order": {
        "id": "ede61c96-4c13-4519-bf3a-dcf7f1e9d842",
        "amount": 7851,
        "fiat_code": "VES",
        "min_amount": 10,
        "max_amount": 20,
        "fiat_amount": 15,
        "payment_method": "face to face",
        "premium": 1,
        "master_buyer_pubkey": null,
        "master_seller_pubkey": null,
        "buyer_invoice": null,
        "created_at": null,
        "expires_at": null
      }
    }
  }
}

Mostro updates the nip 33 event with d tag ede61c96-4c13-4519-bf3a-dcf7f1e9d842 to change the status to waiting-buyer-invoice:

[
  "EVENT",
  "RAND",
  {
    "id": "eb0582360ebd3836c90711f774fbecb27e600f4a5fedf4fc2d16fc852f8380b1",
    "pubkey": "dbe0b1be7aafd3cfba92d7463edbd4e33b2969f61bd554d37ac56f032e13355a",
    "created_at": 1702549437,
    "kind": 38383,
    "tags": [
      ["d", "ede61c96-4c13-4519-bf3a-dcf7f1e9d842"],
      ["k", "sell"],
      ["f", "VES"],
      ["s", "waiting-buyer-invoice"],
      ["amt", "7851"],
      ["fa", "15"],
      ["pm", "face to face"],
      ["premium", "1"],
      ["y", "mostrop2p"],
      ["z", "order"],
      ["expiration", "1716453501"]
    ],
    "content": "",
    "sig": "a835f8620db3ebdd9fa142ae99c599a61da86321c60f7c9fed0cc57169950f4121757ff64a5e998baccf6b68272aa51819c3e688d8ad586c0177b3cd1ab09c0f"
  }
]

Using a lightning address

The buyer can use a lightning address to receive funds and avoid to create and send lightning invoices on each trade, with a range order we set the fiat amount as the third element of the payment_request array, to acomplish this the buyer will send a message in a Nostr event kind 4 to Mostro with the following content:

{
  "order": {
    "version": 1,
    "id": "ede61c96-4c13-4519-bf3a-dcf7f1e9d842",
    "pubkey": "0000147e939bef2b81c27af4c1b702c90c3843f7212a34934bff1e049b7f1427",
    "action": "take-sell",
    "content": {
      "payment_request": [null, "mostro_p2p@ln.tips", 15]
    }
  }
}