Add details for post-anchor dust_limit_satoshis
#1301
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Since the introduction of `option_anchors`, pre-signed HTLC transactions don't include any fees, and thus don't contribute to trimming. This results in HTLC outputs in the commitment transactions that may be forever uneconomical to spend, and will pollute the utxo set. We should use a `dust_limit_satoshis` that is higher than Bitcoin Core's standard values to take into account the cost of these second-stage txs at a reasonable (TM) feerate.
This was referenced Nov 19, 2025
ziggie1984
approved these changes
Dec 15, 2025
Contributor
ziggie1984
left a comment
ziggie1984
left a comment
There was a problem hiding this comment.
ACK, had some minor comments.
| - pay to script hash (p2sh): 540 satoshis | ||
| - pay to witness pubkey hash (p2wpkh): 294 satoshis | ||
| - pay to witness script hash (p2wsh): 330 satoshis | ||
| - pay to anchor (p2a): 240 satoshis |
Collaborator
Author
There was a problem hiding this comment.
I'd rather have it here since we "mirror" the dust limits set by Bitcoin Core, even for output types we don't use. For example, we don't use p2sh in lightning, but we do list it here for reference.
| second-stage HTLC transactions, to ensure that outputs added to the commitment | ||
| transaction can actually be claimed on-chain, otherwise they may pollute the | ||
| utxo set indefinitely. At a minimum, nodes should allow their peer to use a | ||
| `dust_limit_satoshis` that is higher than the values defined by Bitcoin Core. |
Contributor
There was a problem hiding this comment.
could you maybe also add a note describing that it can basically not be perfect, if the transaction fee of the base-layer stays for example very high for a long period of time HTLCs will be unspendable and on the other hand the dust limit cannot be too high because of the griefing attacks.
As requested by @ziggie1984
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Since the introduction of
option_anchors, pre-signed HTLC transactions don't include any fees, and thus don't contribute to trimming. This results in HTLC outputs in the commitment transactions that may be forever uneconomical to spend, and will pollute the utxo set.We should use a
dust_limit_satoshisthat is higher than Bitcoin Core's standard values to take into account the cost of these second-stage txs at a reasonable (TM) feerate. If we want for example to be able to claim HTLC outputs at20 sat/byte, we need adust_limit_satoshisof around4 000 sats.