Lightning Specification Meeting 2024/06/03

[t-bast]

The meeting will take place on Monday 2024/06/03 at 8pm UTC (5:30am Adelaide time) on Libera Chat IRC #lightning-dev. It is open to the public.

A video link is available for higher bandwidth communication: https://meet.jit.si/Lightning-Spec-Meeting

Recently Updated Proposals / Seeking Review

This section contains changes that have been opened or updated recently and need feedback from the meeting participants.

• Spec clean-up Clean-up: follow-up on removing spec features #1165
• Optional channel_update in error onions Drop the required channel_update in failure onions #1163
• Offers Offers #798
• Quiescence BOLT 2: quiescence protocol (feature 34/35) option_quiesce #869
  • @rustyrussell can you (or someone else with access to the branch) rebase the PR? We've started cross-compat tests between eclair and lnd, it's looking good, so we should be able to merge it soon
  • there are also a couple of comments asking for some small additions to clarify a few subtleties, but nothing major
• Splicing Splice draft (feature 62/63) #863 Channel Splicing (feature 62/63) #1160
• Liquidity ads option_will_fund: liquidity ads #878 Advertise liquidity ads rates #1145 Extensible Liquidity Ads #1153
• Dynamic Commitments Extension/dynamic commitments #1117 vs Upgrade on Reestablish BOLT 2: upgrade protocol on reestablish #868
• Taproot extension-bolt: simple taproot channels (feature 80/81) #995
• Taproot gossip extension-bolt: taproot gossip (features 32/33) #1059
• Async payments Support async payments in BOLT 12 #1149
• Peer storage backup Peer backup storage (feature 40/41/42/43) #881 or Peer storage for nodes to distribute small encrypted blobs. #1110
• Channel jamming draft: Staking Credentials token issuance/redemption #1043 draft: HTLC Endorsement to Mitigate Channel Jamming #1071 blip-0004: experimental endorsement signaling in update_add_htlc blips#27
• DNS-based offers Define a mechanism for looking up an offer from a user/domain pair #1136
• Attributable errors Attributable errors (feature 36/37) #1044
• Clarify channel_reestablish requirements Clarify channel_reestablish requirements #1049 or Rework channel_reestablish requirements #1051

Stale Proposals

This section contains pending changes that may not need feedback from the meeting participants, unless someone explicitly asks for it during the meeting. These changes are usually waiting for implementation work to happen to drive more feedback.

• Constant size failure onion decryption BOLT04: Add rationale for constant error decryption. #1154
• Inbound fees Inbound routing fees blips#18 and Add a bLIP for backwards-compatible inbound fees blips#22

Waiting for interop

This section contains changes that have been conceptually ACKed and are waiting for at least two implementations to fully interoperate.
They most likely don't need to be covered during the meeting, unless someone asks for updates.

• Simplified mutual close option_simple_close (features 60/61) #1096
• Trampoline routing Trampoline Routing (2021 edition) (Feature 56/57) #829 and Trampoline onion format (Feature 56/57) #836
• Zero reserve Add option_zero_reserve (FEATURE 64/65) #1140 (follow-up on bolt2: relax channel_reserve_satoshis requirements #1133 to include a feature bit)
• Don't force close until error is received after channel_reestablish Nodes shouldn't publish their commitment when receiving outdated channel_reestablish #934

Long Term Updates

This section contains long-term changes that need review, but require a substantial implementation effort.

• Simplified commitment Feature 106/107: option_simplified_update. #867
• lnprototest (https://github.com/rustyrussell/lnprototest)

[carlaKC]

I'm not going to make this meeting - please will somebody record it for transcription!

Only update from me is that lightning/blips#27 is ready for mergo (IMO) and the LND implementation is up to date with current blip.

[Roasbeef]

spec clean up:

• left over sections that ref non-zero fee anchors and pubkey rotation
• now removed
• other interop instance in the wild:
  • CLN stopped setting the TLV onion bit
  • older nodes may still use that value to decide if TLV onion should be used or not
  • new lnd can start to assume bit, old will take some time to update

optional channel update:

• today nodes already treat it as optional in the onion error, spec says it's mandatory, should address that
• can also soften the language

offers:

• BOLT 12 for bundled payments
  • if you recv an invoice request, but don't have the capacity
  • sends two payment hashes: user pays one for chan open, then another for the actual payment
    • downside of 2 payments for the sender, and also needs to actually know of it
    • griefing vector, something up to the pricing of the end user or service

stfu:

• needs some final clarifications
• once those are done, and PR is rebased, then should be g2g
• lnd <-> eclair compat achieved

splicing:

• new PR should be reviewed, matches eclair impl
• main diffs:
  • which TLVs are added to commit sig, revoke and ack, and the other messages
  • ensures some edge cases work properly w/o it, undefined

rbf-coop close:

• lock time cross compat to be interop tested, then g2g

gossip 1.75:

• two independent protocols going forward, all nodes need to advertise both versions