KaleidoPay

Pay with what you have. Receive what you want.

One reusable BOLT12 QR says which layers the receiver accepts, in order: Bark, Arkade, Lightning, on-chain. The payer's wallet reads it and quotes every route it can pay, directly or through a swap provider found on Nostr. Any other BOLT12 wallet still sees a normal offer.

Built at bitcoin++ Berlin, 1–3 October 2026, by Walter and Mo.

Site, videos and slides: https://kaleidoswap.github.io/kaleido-pay/

How it works

• Receiver: in Rate, connect your LDK node over Nostr Wallet Connect, pick and order the layers you accept, and your node issues one reusable BOLT12 offer carrying that order in an ssps_rails record (SSPS §5.3, type 1000000385). Bark and Arkade entries carry your address; an on-chain address travels next to the offer in a BIP321 link.
• Payer: scan. KaleidoPay shows the receiver's order and quotes every route, fees included: Bark to their Bark address, the offer over Lightning, Bark's on-chain send, or an Electrum swap provider found on Nostr. You pick; nothing moves until you confirm.

Details: docs/ARCHITECTURE.md and docs/bolt12.md.

Beyond Bark: Nostr Lightning Swap Providers

The payer's wallet only needs to read the rails and pay Lightning; Bark is the first wallet wired in. A Nostr Lightning Swap Provider announces on Nostr which rails it delivers to, quotes a swap from Lightning, and locks the receiver's asset on the receiver's rail for the same payment hash, so both sides settle or neither does.

• Live today: Electrum's swap providers (Lightning → on-chain bitcoin), quoted on mainnet in Rate.
• Next: a receiver lists liquid:mainnet/<USDt asset id>, the payer pays sats over Lightning, a provider (for example a KaleidoSwap maker) locks USDt on Liquid, and the claim pays the receiver. The same pattern covers L-BTC, Arkade and RGB assets on Lightning, with Arkade, Spark or any Lightning node as the payer.

This repository

Folder	What
packages/universal-code	The rails record codec, BIP321 + offer, network detection, route planner
packages/swap-market	Client for Electrum's swap providers over Nostr: discover, quote, reverse swap, claim, recovery
signet/	Our offer nodes (LDK fork) and Electrum swap providers on signet and Mutinynet
demo/	Command-line demos, the offer inspector, and the demo videos
site/	The GitHub Pages site and slides

The app lives in kaleidoswap/Rate (branch hack/universal-bolt12), which imports the packages from here. The LDK changes are on branch feat/offer-ssps-rails of our forks of rust-lightning, ldk-node and ldk-server. The spec is kaleidoswap/ssps.

Quick start

npm install
npm test                                                  # offline checks
npm run offers -w @universal-bolt12/swap-market mainnet   # live swap providers on Nostr
npm run offer -- --decode lno1...                         # read an offer's rails

Status

Proven:

• Scan → receiver's order → live quotes for every route, on mainnet in Rate (quotes only).
• The LDK fork issues offers with the receiver's rails over encrypted NWC (regtest, and signet with a real node); a wallet that doesn't know the record still pays the offer.
• Electrum swaps over Nostr fully paid and claimed on Mutinynet (24 s and 19 s) with our own provider.
• Bark pays Lightning and Arkade receives Lightning on mainnet (small amounts).

Not yet:

• A complete payment from Bark through an enriched QR end to end.
• Arkade paying an Arkade address directly (needs a fee estimate from the wallet library).
• A per-payment lock (ssps_lock) from the receiver instead of a static address.

Built at the hackathon

Everything in this repository was written during the event, as were the LDK fork branches, Bark support in wallet-engine and Rate, and KaleidoPay in Rate. Rate, wallet-engine and the SSPS drafts existed before.

License

MIT