Lightning Specification Meeting 2025/09/08

[t-bast]

The meeting will take place on Monday 2025/09/08 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.

• Bech32 compatibility with BIP173 BOLT 12: Inconsistent bech32 padding validation across implementations #1281
• Basic security file Add a SECURITY.md #1278
• Bolt 11 low-s requirements bolt11: clarify signature normalization requirements #1284
• Dual funding reconnect commit_sig retransmission Do not unnecessarily retransmit commitment_signed in dual funding #1214
• Allow non-initiator to RBF dual-funded channels Allow either node to send tx_init_rbf in v2 establishment #1236
• Increase spent channel graph removal delay Increase channel close delay to 72 blocks #1270
• Splicing Channel Splicing (feature 62/63) #1160
• Taproot extension-bolt: simple taproot channels (feature 80/81) #995
• Taproot gossip extension-bolt: taproot gossip (features 70/71/72/73/74/75) #1059
• Attributable failures Attribution data (feature 36/37) #1044
• Receiver-side random delays Add recommendations for receiver-side random delays #1263
• Channel jamming Project Updates: Hybrid Channel Jamming Mitigation #1218 Outgoing reputation and HTLC Accountability #1280
• Trampoline routing Trampoline Routing (2021 edition) (Feature 56/57) #829 and Trampoline onion format (Feature 56/57) #836
• Async payments Support async payments in BOLT 12 #1149
• BOLT 12 recurrence BOLT 12: re-add recurrence support. #1240
• Bolt 12 contacts: blip-0042: Bolt 12 Contacts blips#42
• Liquidity ads Extensible Liquidity Ads #1153
• Dynamic Commitments Extension/dynamic commitments #1117
• 0-fee commitments Zero-fee commitments using v3 transactions (feature 40/41) #1228
• Path queries Path queries (feature 66/67) #1259

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.

• 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.

• Don't force close until error is received after channel_reestablish Nodes shouldn't publish their commitment when receiving outdated channel_reestablish #934
• 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)

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)
• Investigate QUIC transport BOLT-0008+BOLT-0007: consider adding QUIC transport #1257

[ariard3]

Opened an issue to ask clarification about some abuse done under the code of conduct: #1287

I'll see to attend this Monday Jitsi meeting and the futures one, until I have answer to the following question from TheBlueMatt:

"Why there was 0 (zero) lessons on ethics and professional conduct during the 2019 residency ?"

I just want to genuinely and naively ask the question.

[Roasbeef]

bip 173 compat:

• not necessarily a BOLT 12 specific issue
• question is: do all our libraries properly impl BIP 173
  • need to double check, contribute extra test vectors re padding if needed

security file:

• needs CLN approval, then we can merge

splicing:

• need cross compat for all the channel reestablish changes
• close to having cross compat
• which feature bit is being used across impls?
  • eclair has a very old feature bit, was pre staging feature bit (+100 pattern)
  • LDK wondering if they should ship under the real feature bit or not
    • should wait for a final cross compat testing round, close to having that all wrapped up

taproot chans:

• should we get the splicing stuff in as another change?
  • minimally can keep the nonce map

attributable errors:

• interop nearing the final portion
• blinded paths issues?
  • there's a field, if ppl aren't using blinded paths, and they use an accurate value
  • then you send another payment, and use that information to tell more
    • so then defensive impls will instead just lie about their values, to protect themselves
  • still unclear what/how sender will use in practice re punishment, etc

receiver side delays

• elias started to work on an impl
  • refactored the way we do forwarding in general in LDK

channel jamming:

• new PR to review: Outgoing reputation and HTLC Accountability #1280
• eclair starting to deploy some data collection for the reputation algorithm
  • will then compare the data to see if they would have dropped this vs not

trampoline:

• LDK making steady progress

async payments:

• LDK been doing more work on async send
• goal to merge the rest of the feature this week

v3 commitments:

• eclair to come back to this after doing taproot chans work
• deprecating non-anchor channels:
  • timeline to doing so
    • stop accepting them (creation+accept)
    • feature bit in the future