This NIP describes a way for clients to access a remote Lightning wallet through a standardized protocol. Custodians may implement this, or the user may run a bridge that bridges their wallet/node and the Nostr Wallet Connect protocol.
The info event should be a replaceable event that is published by the **wallet service** on the relay to indicate which commands it supports. The content should be
a plaintext string with the supported commands, space-seperated, eg. `pay_invoice get_balance`. Only the `pay_invoice` command is described in this NIP, but other commands might be defined in different NIPs.
Both the request and response events SHOULD contain one `p` tag, containing the public key of the **wallet service** if this is a request, and the public key of the **client** if this is a response. The response event SHOULD contain an `e` tag with the id of the request event it is responding to.
The content of requests and responses is encrypted with [NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md), and is a JSON-RPCish object with a semi-fixed structure:
The `result_type` field MUST contain the name of the method that this event is responding to.
The `error` field MUST contain a `message` field with a human readable error message and a `code` field with the error code if the command was not succesful.
If the command was succesful, the `error` field must be null.
**client** discovers **wallet service** by scanning a QR code, handling a deeplink or pasting in a URI.
The **wallet service** generates this connection URI with protocol `nostr+walletconnect:` and base path it's hex-encoded `pubkey` with the following query string parameters:
-`relay` Required. URL of the relay where the **wallet service** is connected and will be listening for events. May be more than one.
-`secret` Required. 32-byte randomly generated hex encoded string. The **client** MUST use this to sign events and encrypt payloads when communicating with the **wallet service**.
The **client** should then store this connection and use it when the user wants to perform actions like paying an invoice. Due to this NIP using ephemeral events, it is recommended to pick relays that do not close connections on inactivity to not drop events.
0. The user scans the QR code generated by the **wallet service** with their **client** application, they follow a `nostr+walletconnect:` deeplink or configure the connection details manually.
1.**client** sends an event to with **wallet service** service with kind `23194`. The content is a `pay_invoice` request. The private key is the secret from the connection string above.
2.**wallet service** verifies that the author's key is authorized to perform the payment, decrypts the payload and sends the payment.
3.**wallet service** responds to the event by sending an event with kind `23195` and content being a response either containing an error message or a preimage.
This NIP does not specify any requirements on the type of relays used. However, if the user is using a custodial service it might make sense to use a relay that is hosted by the custodial service. The relay may then enforce authentication to prevent metadata leaks. Not depending on a 3rd party relay would also improve reliability in this case.