If a user has an open Lightning channel, their Electrum wallet file gets destroyed, and they restore their Electrum wallet from seed phrase, will the Lightning channel be recoverable or will it be lost?
It depends, it's only possible if you've enabled the setting "
Create recoverable channels" when you created the channel.
The setting can be found in the small setting icon on the upper-right hand of Open channel window.
It can't be enabled (
grayed-out) if you're using hardware wallet, using BIP39 seed or have a nodeID before the feature implementation (
v4.1.0):
In case you want to check if your channels are recoverable from seed, the channel's icon on the left side of channels tab shouldn't have a "
crossed-out blue cloud" icon.
Another indication is by checking the "
open channel" transaction if it has a "
SCRIPT" output containing
OP_RETURN encrypted data from your lightning nodeID.
However, just like a manual channel backup, it's only a "
static backup" which can't be used to spend or receive,
the only thing you can do to it is to request to force-close the channel to retrieve the funds.