# bLIP 10 - A Lightning TLV record for carrying v4v payment metadata

```text
Original Author: Satoshis Stream <satoshisstream@pm.me>
Created: 2022-01-24
License: CC0
```

<br>

## Purpose

Using Value 4 Value apps, listeners can send sats to the podcasts they listen to. A per-minute payment is
called a `stream`, a manually triggered payment is called a `boost` and an automatically recurring (i.e. scheduled)
payment is called an `auto` payment. If there is a message to the podcaster included in a `boost` it is referred to as
a `boostagram`.

The payload is a simple JSON structure that is encoded as a TLV in the Lightning payment when it is sent. This
structure is explained in this document.

Simple Example:

```json
{
  "podcast": "Podcasting 2.0",
  "feedID": 920666,
  "episode": "Episode 127: Fortress of Freedom",
  "action": "boost",
  "ts": 33
}
```

<br>

## Specification

The sender of a bLIP-10 payment (i.e. - the podcast app) needs to include some metadata so the podcast host can
identify for whom the payment is for. Most fields are optional.

<br>

### Formatting and encoding

A flat, key-value json structure is used where the keys listed below can be set. The json string is then encoded
into `utf8` and attached to the Lightning payment. Most of the time, the payment will be a `keysend` payment, but this
TLV data can be used in standard BOLT11 and BOLT12 payments also. Receivers of messages must be aware that there
is no guarantee for the order of the keys.

A more complex example:

```json
{
  "app_name": "Castamatic",
  "app_version": "8.0.6",
  "value_msat_total": 49960,
  "url": "https://feeds.buzzsprout.com/1844352.rss",
  "podcast": "Mere Mortals",
  "action": "stream",
  "episode": "The Art Of NFT's & Aimless Wandering",
  "episode_guid": "Buzzsprout-9931017",
  "value_msat": 97940,
  "ts": 574,
  "name": "Podcaster",
  "sender_name": "Peter"
}
```

Treated as `utf-8`, the hex value of the above json record would be:

```base64
7b226170705f6e616d65223a202243617374616d61746963222c20226170705f76657273696f6e223a2022382e302e36222c202276616c75655f
6d7361745f746f74616c223a2034393936302c202275726c223a202268747470733a2f2f66656564732e62757a7a7370726f75742e636f6d2f31
3834343335322e727373222c2022706f6463617374223a20224d657265204d6f7274616c73222c2022616374696f6e223a202273747265616d22
2c2022657069736f6465223a202254686520417274204f66204e4654277320262041696d6c6573732057616e646572696e67222c202265706973
6f64655f67756964223a202242757a7a7370726f75742d39393331303137222c202276616c75655f6d736174223a2039373934302c2022747322
3a203537342c20226e616d65223a2022506f64636173746572222c202273656e6465725f6e616d65223a20225065746572227d0a
```

<br>

### Types

If a field is indicated to be a `str` in the fields-list, that means it is a JSON string (within quotes). An `int` is
a plain number.

<br>

### Fields

Identifying the podcast **required**: use one or more of `podcast`, `guid`, `feedID` and/or `url`. **guid preferred**

* `guid` (
  str) [The `<podcast:guid>` tag](https://github.com/Podcastindex-org/podcast-namespace/blob/main/docs/1.0.md#guid).
* `podcast` (str) Title of the podcast
* `feedID` (int) ID of podcast in PodcastIndex.org directory
* `url` (str) RSS feed URL of podcast

<br>

Identifying the episode **recommended**: use any of `episode`, `itemID` and/or `episode_guid`. **episode_guid
preferred**

* `episode` (str) Title of the podcast episode
* `itemID` (int) ID of episode in PodcastIndex.org directory
* `episode_guid` (str) The GUID of the episode

<br>

Information about time within the episode **recommended**: use one of `ts` or `time`. **ts preferred**

* `ts` (int) Timestamp of when the payment was sent, in seconds, as an offset from zero (i.e. - playback position)
* `time` (str) Timestamp of when the payment was sent, in HH:MM:SS notation, as an offset from 00:00:00
  (i.e. - playback position)

<br>

Other fields that are strongly recommended:

* `action` **recommended**: (str) "boost", "stream" or "auto". See Appending B of the
  [value](/value.md#appendix-b---payment-actions) spec for details.
* `app_name`: **recommended** (str) Name of sending app
* `sender_name` **recommended** (str) Name of the sender (free text, not validated in any way)
* `value_msat_total`: **recommended** (int) TOTAL Number of millisats for the payment before any fees are subtracted.
  This should be the number the listener entered into the app. Preserving
  this value is important for numerology reasons. Certain numeric values can
  have significance to the sender and/or receiver, so giving a way to show
  this is critical.

<br>

Other optional fields:

* `message` (str) Text message to add to the payment. When this field is present, the payment is known as a
  "boostagram".
* `app_version`: (str) Version of sending app
* `boost_link`: (str) App specific URL containing route to podcast, episode, and/or timestamp at time of the action.
  The use case for this is sending a link along with the payment that will take the recipient to
  the exact playback position within the episode where the payment was sent.
* `name` (str) Name for this split in value tag
* `sender_id` (str) Static random identifier for users, not displayed by apps to prevent abuse. Apps can set this
  per-feed or app-wide. A GUID-like random identifier or a hash works well. Max 32 bytes (64 ascii
  characters). This can be a Nostr hex encoded pubkey (not NIP-19) for purposes of sender attribution.
* `signature` (str) Optionally, this field can contain a signature for the payment, to be able to verify that the
  user who sent it is actually who they claim in the `sender_id` field. If the `sender_id` contains
  a Nostr public key, this field should contain a Nostr `sig` value as a 64-byte encoded hex string.  
  For the purpose of generating the Nostr signature, the following data should be serialized:
  [0,`sender_id`,`ts`,1,[],`message`] to conform to the
  [NIP-01](https://github.com/nostr-protocol/nips/blob/master/01.md) specification. The resulting
  serialized string should be hashed with `sha256` to obtain the value.
* `speed` (str) Speed in which the podcast was playing, in decimal notation at the time the payment was sent. So 0.5
  is half speed and 2 is double speed.
* `uuid` (str) Unique UUID of the payment.
* `reply_address` (str) The pubkey of the lightning node that can receive payments for the sender. The node given
  must be capable of receiving keysend payments. If this field contains an "@" symbol, it should
  be interpreted as a
  "[lightning address](https://github.com/andrerfneves/lightning-address/blob/master/README.md#tldr)".
* `reply_custom_key` (int) The custom key for routing a reply payment to the sender. This field should not be present
  if it is not required for payment routing.
* `reply_custom_value` (str) The custom value for routing a reply payment to the sender. This field should not be
  present if it is not required for payment routing.
* `remote_feed_guid` (str) Sometimes a payment will be sent to a feed's value block because a different feed referenced
  it in a `<podcast:valueTimeSplit>` tag. When that happens, this field will contain the guid of the referencing feed.
* `remote_item_guid` (str) Sometimes a payment will be sent to an episode's value block because a different feed
  referenced it in a `<podcast:valueTimeSplit>` tag. When that happens, this field will contain the guid of the 
  referencing feed's `<item>`.

<br>

## Reference Implementations

*

Breez: <https://github.com/breez/breezmobile/blob/4cf057c066d03c155964f0c4db43476cd70a57ab/lib/bloc/podcast_payments/podcast_payments_bloc.dart>

*

Podverse: <https://github.com/podverse/podverse-shared/blob/fff84c0143dea4fa01241109b8666d4c0b9a6ffc/src/satoshiStream.ts>

* PodStation: <https://github.com/podStation/podStation/pull/249>
* Helipad: <https://github.com/Podcastindex-org/helipad/blob/203e72dafb65e4f9e89540fbe4fc07a456a9907a/src/main.rs>
* Rust-V4V: <https://github.com/Conshax/Rust-V4V/blob/master/src/boostagram.rs>

## Examples & App Specifics

### Podverse

Podverse cuts the episode name short and `stream` actions are sent as `streaming`.

#### Boost

```json
{
  "podcast": "Test Podcast Anchor",
  "feedID": 6015671,
  "episode": "this is a very very very very very very very very very very ",
  "episode_guid": "12b4df54-af38-4c53-8099-82f9caacdcd5",
  "ts": 24,
  "action": "boost",
  "speed": "1",
  "pubkey": "podverse-pubkey",
  "value_msat_total": 100000,
  "uuid": "75758d19-c4af-4da2-80ce-a5c84a0f1642",
  "app_name": "Podverse",
  "name": "Alby Test User PUT",
  "sender_name": "Alwin_Conshax",
  "message": "test"
}
```

#### Stream

```json
{
  "podcast": "Test Podcast Anchor",
  "feedID": 6015671,
  "episode": "this is a very very very very very very very very very very ",
  "episode_guid": "12b4df54-af38-4c53-8099-82f9caacdcd5",
  "ts": 315,
  "action": "streaming",
  "speed": "1",
  "pubkey": "podverse-pubkey",
  "value_msat_total": 100000,
  "uuid": "654072b5-9825-4792-b502-31ee9f1ec6aa",
  "app_name": "Podverse",
  "name": "Alby Test User PUT",
  "sender_name": "Alwin_Conshax"
}
```

### Castamatic

Castamatic sends `value_msat_total` only on boosts not on streams.

#### Boost

```json
{
  "message": "test",
  "app_name": "Castamatic",
  "app_version": "8.6.0",
  "value_msat_total": 100000,
  "url": "https://anchor.fm/s/da6b03c0/podcast/rss",
  "podcast": "Test Podcast Anchor",
  "action": "boost",
  "episode": "this is a very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very long episode name!!!",
  "episode_guid": "12b4df54-af38-4c53-8099-82f9caacdcd5",
  "feedID": 6015671,
  "value_msat": 95049,
  "ts": 0,
  "name": "Alby Test User PUT",
  "sender_name": "Alwin_Conshax"
}
```

#### Stream

```json
{
  "app_name": "Castamatic",
  "app_version": "8.6.0",
  "url": "https://anchor.fm/s/da6b03c0/podcast/rss",
  "podcast": "Test Podcast Anchor",
  "action": "stream",
  "episode": "this is a very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very long episode name!!!",
  "episode_guid": "12b4df54-af38-4c53-8099-82f9caacdcd5",
  "feedID": 6015671,
  "value_msat": 50940,
  "ts": 254,
  "name": "Test User Peppe the first",
  "sender_name": "Alwin_Conshax"
}
```

### Fountain

Fountain sends the itemID as a string, not an int.

#### Boost

```json
{
  "app_name": "Fountain",
  "value_msat_total": 100000,
  "name": "Alby Test User PUT",
  "podcast": "Test Podcast Anchor",
  "feedID": 6015671,
  "action": "boost",
  "sender_id": "nSiq7id78JAdH9uY1pIy",
  "sender_name": "@alwin_conshax",
  "message": "test",
  "itemID": "14934154309",
  "boost_link": "https://fountain.fm/episode/14934154309",
  "episode": "this is a very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very long episode name!!!",
  "ts": 15,
  "time": "00:00:15"
}
```

#### Stream

```json
{
  "app_name": "Fountain",
  "value_msat_total": 50000,
  "name": "Alby Test User PUT",
  "podcast": "Test Podcast Anchor",
  "feedID": 6015671,
  "action": "stream",
  "sender_id": "pqwMfFdkCwtj8LKm0tNu",
  "sender_name": "@moritz_conshax",
  "message": null,
  "itemID": "14934154309",
  "boost_link": "https://fountain.fm/episode/14934154309",
  "episode": "this is a very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very long episode name!!!",
  "ts": 62,
  "time": "00:01:02"
}
```

### Breez

Breez sends the guid on the itemID field and the sender_name is an empty string on streams.
Besides that Breez takes its fee from the total instead on top of the total as fountain does, this results in the
received value of a split being less than it should calculated from the total.

#### Boost

```json
{
  "podcast": "Test Podcast Anchor",
  "episode": "this is a very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very long episode name!!!",
  "action": "boost",
  "time": "00:00:24",
  "feedID": 6015671,
  "itemID": "12b4df54-af38-4c53-8099-82f9caacdcd5",
  "app_name": "Breez",
  "value_msat_total": 100000,
  "sender_name": "Jade Monkey",
  "message": "test"
}

```

#### Stream

```json
{
  "podcast": "Test Podcast Anchor",
  "episode": "this is a very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very long episode name!!!",
  "action": "stream",
  "time": "00:02:37",
  "feedID": 6015671,
  "itemID": "12b4df54-af38-4c53-8099-82f9caacdcd5",
  "app_name": "Breez",
  "value_msat_total": 100000,
  "sender_name": ""
}
```
