Add support for recognizing lightning param in BIP 21 QR codes

[sbddesign]

Background

An issue more broadly in the Bitcoin ecosystem is situations where the user must choose whether to generate an on-chain Bitcoin address or a lightning invoice. Bitcoin Beach wallet falls into this category since it supports both on-chain and lightning.

While Bitcoin Beach will scan a QR code of a BIP 21 payment URI, it will only recognize the on-chain address and not a lightning parameter containing a BOLT 11 invoice. I would love it if Bitcoin Beach wallet could support scanning a BIP-21 QR with a lightning param.

Steps to Replicate

bitcoin:bc1qylh3u67j673h6y6alv70m0pl2yz53tzhvxgg7u?amount=0.00001&label=sbddesign%3A%20For%20lunch%20Tuesday&message=For%20lunch%20Tuesday&lightning=lnbc10u1p3pj257pp5yztkwjcz5ftl5laxkav23zmzekaw37zk6kmv80pk4xaev5qhtz7qdpdwd3xger9wd5kwm36yprx7u3qd36kucmgyp282etnv3shjcqzpgxqyz5vqsp5usyc4lk9chsfp53kvcnvq456ganh60d89reykdngsmtj6yw3nhvq9qyyssqjcewm5cjwz4a6rfjx77c490yced6pemk0upkxhy89cmm7sct66k8gneanwykzgdrwrfje69h9u5u0w57rrcsysas7gadwmzxc8c6t0spjazup6

• Open Bitcoin Beach wallet
• Scan the above QR code
• Results: it takes me to the payment screen and fills the To field with the on-chain address.
• Expected results: it should instead fill the To field with the BOLT 11 invoice from the lightning param in the QR code (or, it could prompt the user to choose which to use, but I think it would be easier on the user if it defaulted to lightning).

See this website for more background information.

Screenshots

[nicolasburtey]

great feedback. we should indeed select the lightning invoice.

a more complex logic would be to suggest a payment on chain if the lightning payment were to fail.

[openoms]

Agree with the OP, the default should be the LNpayment, but the best would be the choice between paying on LN and onchain if both are offered (LN still as default).

BTCPay v1.7.0 introduced BIP21 payment codes eg on signet from: https://signet.demo.btcpayserver.org/apps/2SCdQhwFm464BcHxXn44kRVg3iCr/pos

bitcoin:TB1QXL9JKN9NV04SMTNJ3KTTY8ZSCXY9YLFMHET6JP?amount=0.00005824&lightning=LNTBS58240N1P3C3X4TPP5ZXNH9CF84G32GX7JUTP56DZ5E4V4R8GTQ46M2W60URYV8MVEP9DQDRD2PSKJEPQW3HJQ5MFVAHX2APQW3JHXAPQ9P8HYER9WGSYJ3P6YPCX7UEDV9C8QHEJ2DPKG5TGWARX6DPKX3PXXJRCTPHRGDRT2FTXWVMFGDEZJCQZPGXQZURSP5ZKV7LQ4RSDCU280KC67EUSUT66RG233NFGZQAQU8TAC8H7Y76NZS9QYYSSQCL7ACMDQF2CZ5EEMD9M8LDCAFXMKEZ33KJ3G5TUKVF2G5EY7LTSH976GZ7DJYXXTUR9DYE5YKT6QV0PRDE5N4LCK8GDFVLD5ERU9WSQQKS3RMP

Also the new Zeus v0.7.0 release candidate offers to show BIP21/unifiedQRcode links: https://github.com/ZeusLN/zeus/releases

A good table of wallet compatibility here https://bitcoinqr.dev/ from @agbegin.

Jan 2023 update: Muun Wallet adds Unified QR codes - not by default, can chosse to use in Settings - Advanced settings - Lightning Network - Receiving protocol