Add rss::payment Metadata

[MerryOscar]

RSS Payment Metadata

Originally the <podcast:value> spec used keysend to facilitate payments. However there is now consensus within the Podcasting 2.0 community that keysend is not a long-term solution because many of the most popular Lightning Wallets such as Strike, CashApp, Primal, Wallet of Satoshi do not support it.

The Lightning Address has also become the de-facto standard for sharing payment information in an easy way.

"Like an email address, but for money" - is an easy to understand concept for anyone even if they are new to Bitcoin, and asking someone to share their Lightning Address is simple.

Because of this the Podcasting 2.0 spec has been updated to use type="lnaddress" - allowing podcasters to simply add one or more Lightning Address into their RSS feed to instruct apps where to send payments:

<podcast:value type="lightning">
  <podcast:valueRecipient
    name="Oscar"
    type="lnaddress"
    address="merryoscar@fountain.fm" 
    split="100"
  />
</podcast:value>

The final piece to the puzzle is how to share payment metadata such as the show / episode info, sender info, and message, as Lightning Address payments have a maximum description size of around 200 characters.

This document outlines a simple spec for sharing RSS payment metadata that will not require any changes from wallets.

---

Goals:

• for sending wallets - should work out of the box without requiring any changes
• for receiving wallets:
  • should give users some basic information about what the payment is related to without the wallet needing to make any changes
  • should allows programmatic parsing of the metadata so that wallets that care about RSS payments (Fountain, Alby, Helipad) can display and aggregate it

---

Spec:

The rss::payment metadata spec uses a prefix in the payment description field, combined with http headers in a linked url, to deliver full payment metadata to services that care about it, whilst giving receiving users on any wallet an easily readable description for the payment:

rss::payment::{action} {url} {truncated message}

rss::payment::boost https://fountain.fm/show/2JCkApiUwyBj2eOG7JJI?payment=DBBhBwUise1bcfoHRCC3 Great episode!

As well as displaying the episode content, the url (https://fountain.fm/show/2JCkApiUwyBj2eOG7JJI?payment=DBBhBwUise1bcfoHRCC3) will also return an x-rss-payment http header, that contains the full structured metadata for the payment as a URI encoded JSON string:

// `x-rss-payment` response header encoded as a uri component
encodeURIComponent({
  "id": "DBBhBwUise1bcfoHRCC3", // payment id (optional)
  "group": "EoL2Qp52RMOSiF1rmGGs", // payment group id (optional)
  
  "action": "boost", // payment action (boost, stream)
  "split": 0.25, // the split as a decimal percentage
  "message": "Great episode!", // message (optional)

  "app_name": "Fountain", // (recommended)
  "app_version": "1.3.10", // (optional)

  "sender_id": "IIaS9X2JuH75yvrRcFoL", // (optional)
  "sender_name": "oscar@fountain.fm", // (optional)

  "recipient_name": "merryoscar@primal.net", // (optional)
  "recipient_address": "merryoscar@primal.net", // (optional)

  "value_msat": 25000, // the amount in millisatoshis
  "value_msat_total": 100000, // the total amount for all splits in millisatoshis
  "value_usd": 0.025797, // the amount in usd (optional)
  "timestamp": "2025-11-05T15:09:10.174Z", // ISO 8601 timestamp
  "position": 120, // episode position in seconds (optional)

  "feed_guid": "",
  "feed_title": "",
  "item_guid": "",
  "item_title": "",
  "publisher_guid": "",
  "publisher_title": "",
  "remote_feed_guid": "",
  "remote_item_guid": "",
  "remote_publisher_guid": ""
})

---

Implementation:

• for apps:
  • add rss::payment::{action} {url} {truncated message} to the BOLT11 description field
  • add the x-rss-payment response header to the url
• for receiving wallets that care about rss payment metadata:
  • look for payments with description fields that start with rss::payment and contain a url
  • load the url and parse the x-rss-payment response header
  • build a sexy analytics dashboard, push messages to irc and nostr, turn on lights at your concert venue etc...

[johnspurlock]

What prevents an app from making up stuff at the url they include in the payment?

[MerryOscar]

What prevents an app from making up stuff at the url they include in the payment?

@johnspurlock - nothing prevents this - apps will have to be trusted based on reputation - in my view that's another reason why having app-hosted urls makes sense

[johnspurlock]

May want to review the blip10 fields and add important missing analogs to your example, for example the app_name, app_version

[MerryOscar]

May want to review the blip10 fields and add important missing analogs to your example, for example the app_name, app_version

@johnspurlock added (9074709) - I've also updated our service to include the app_name - https://fountain.fm/episode/JCIzq3VyFKQVkEzVNA8v?payment=5XIAt66P29Iv6rjSTZUB

[johnspurlock]

May want to review the blip10 fields and add important missing analogs to your example, for example the app_name, app_version

@johnspurlock added (9074709) - I've also updated our service to include the app_name - https://fountain.fm/episode/JCIzq3VyFKQVkEzVNA8v?payment=5XIAt66P29Iv6rjSTZUB

Thanks, can you add it to your example above?

[MerryOscar]

Thanks, can you add it to your example above?

done!

[bumi]

payment description field

should this be the LNURL comment field?
Afaik LNURL does not allow to set a "description" field and comments might not be passed to the bolt11 description.

[bumi]

Suggested change

	- add `rss::payment::{action} {url} {truncated message}` to the BOLT11 description field
	- pass `rss::payment::{action} {url} {truncated message}` to the LNURL comment field

[johnspurlock]

@MerryOscar the truncated message in the invoice comment is coming through as the string undefined when not present. Intentional?

ex: rss::payment::stream https://fountain.fm/episode/u036Q6admhFEQn8ndJpt?payment=e6wsM5cM3Fi4fNobap5P undefined