[bug]: Self_Payment Failed

[lukegao209]

Background

Alice(Tapd0.5) Bob(Tapd0.5)
Alice <----1 BTC Channel------>BOB
Alice <----100000 USDT Channel------>BOB

Self_Payment for USDT Channel:
1. Generate 100 USDT Invoice On Alice 
2. Pay invoice on Alice 
3. Success

Self_Payment for BTC Channel:
1. Generate 0.00001 BTC Invoice On Alice 
2. Pay invoice on Alice 
3. Failed

Logs ： logs.txt

I encountered an issue with allow_self_payment. When Alice and Bob have both a BTC-Channel and a TaprootAssets-Channel, creating a BTC invoice on Alice and performing a self-payment on Alice fails. Could this be a bug with self-payment when both Taproot channels and BTC channels coexist? (If a Taproot invoice is generated, self-payment works fine.) Here are the logs for reference.

It’s particularly worth noting whether there is a way to avoid using Taproot channels for small BTC invoices. This is important because using Taproot channels for such payments might result in insufficient local BTC balance in the Taproot channel, making it impossible to pay Taproot invoices.

[Roasbeef]

When Alice and Bob have both a BTC-Channel and a TaprootAssets-Channel, creating a BTC invoice on Alice and performing a self-payment on Alice fails

When you go to make the payment, you can specify the outgoing and incoming scid's.

[Roasbeef]

What's the purpose of the self payment here? Is it to rebalance, or implement user multi-plexing (accounts) over channels? If the latter why does a higher layer keeping track of balances not suffice?

It’s particularly worth noting whether there is a way to avoid using Taproot channels for small BTC invoices.

You can specify the outgoing scid here to avoid using certain channels for normal BTC invoices.

[lukegao209]

What's the purpose of the self payment here? Is it to rebalance, or implement user multi-plexing (accounts) over channels? If the latter why does a higher layer keeping track of balances not suffice?

It’s particularly worth noting whether there is a way to avoid using Taproot channels for small BTC invoices.

You can specify the outgoing scid here to avoid using certain channels for normal BTC invoices.

我们的同一个节点的托管用户之间会产生相互支付invoice的情况，所以会产生selfpayment

[lukegao209]

@Roasbeef @guggero

Alice <---10000USDT--->Bob

When there is a USDT taproot channel between Alice and Bob, is it possible for Alice to transfer funds to Bob by paying an invoice? For example, if Bob issues an invoice for 100 USDT, can Alice pay that invoice using the channel, such that BTC price fluctuations are ignored and Alice can always use exactly 100 USDT to settle Bob’s invoice?

[guggero]

Yes, you can pay an invoice from your edge node directly with USDT. But the on-chain HTLC will always cost an additional 354 sats, which will go away once we implement #888.
See https://github.com/lightninglabs/lightning-terminal/blob/a3ff9f23fde77769b654d4ac8c907fa4daec488b/itest/litd_custom_channels_test.go#L251.

[lukegao209]

Yes, you can pay an invoice from your edge node directly with USDT. But the on-chain HTLC will always cost an additional 354 sats, which will go away once we implement #888. See https://github.com/lightninglabs/lightning-terminal/blob/a3ff9f23fde77769b654d4ac8c907fa4daec488b/itest/litd_custom_channels_test.go#L251.

What I want to confirm is ： When Alice and Bob have a direct taproot channel, can Alice pay Bob’s USDT invoice without being affected by BTC price fluctuations?

[guggero]

Yes.

[guggero]

Did you get this working? Can we close the issue?

[lukegao209]

Did you get this working? Can we close the issue?

still doesnt work for me

[Roasbeef]

@ZZiigguurraatt IIRC you've made succesful self-payments with your test scripts?