lnwallet: expose negotiated configs in aux chan state

[GeorgeTsagk]

Description

Pass a populated aux channel state into aux funding so initial custom channel blobs include the negotiated local/remote configs.

This fixes height-0 aux channel state without adding force-close resolution plumbing in lnd.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a mechanism to provide auxiliary resolvers with the initial commitment key ring for channels that are force-closed at height 0. By correctly identifying the commitment keys used before the channel_ready rotation, the changes prevent output misidentification and ensure that auxiliary components function correctly during immediate post-funding force-close events.

Highlights

• Resolution Request Update: Added an InitialKeyRing field to the ResolutionReq struct to support auxiliary resolvers during force-close scenarios.
• Key Derivation Logic: Implemented initialCommitmentKeyRingFromState to derive the correct commitment keys for channels at height 0, distinguishing them from post-channel_ready states.
• Force-Close Integration: Updated NewLocalForceCloseSummary to populate the InitialKeyRing when the local commitment height is 0, ensuring aux resolvers have the necessary context.

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[github-actions]

🔴 PR Severity: CRITICAL

Automated classification | 2 files | 61 lines changed

🔴 Critical (2 files)

• lnwallet/aux_resolutions.go - wallet auxiliary resolution logic (lnwallet/*)
• lnwallet/channel.go - core channel state machine and commitment transaction handling (lnwallet/*)

Analysis

Both changed files reside in the lnwallet package, which is classified as CRITICAL because it encompasses wallet operations, channel funding, signing, and commitment transaction logic — among the most security-sensitive code in the Lightning Network Daemon.

• lnwallet/channel.go is the central channel state machine; changes here can affect commitment transaction construction, fee handling, and the correctness of channel updates.
• lnwallet/aux_resolutions.go handles auxiliary (e.g. custom channel) resolution paths, which feed into on-chain fund recovery.

This PR is small in scope (2 files, 61 lines), so no severity bump was triggered. However, the inherent criticality of lnwallet means expert review is required before merging.

---

_{To override, add a severity-override-{critical,high,medium,low} label.}
<!-- pr-severity-bot -->

[gemini-code-assist]

Code Review

This pull request introduces an InitialKeyRing field to the ResolutionReq struct and implements initialCommitmentKeyRingFromState to derive the key ring for the initial commitment state at height 0. This allows downstream resolvers to correctly distinguish between initial and subsequent commitment states. The reviewer suggested minor documentation improvements to adhere to the repository's style guide, specifically regarding function comment formatting and the requirement for function documentation.

[gemini-code-assist]

This function is missing a comment, which is required by the repository's style guide. Please add a comment that describes its purpose.

Suggested change

	func (lc *LightningChannel) initialCommitmentKeyRing(
	whoseCommit lntypes.ChannelParty) *CommitmentKeyRing {
	return initialCommitmentKeyRingFromState(lc.channelState, whoseCommit)
	}
	// initialCommitmentKeyRing derives the key ring for the initial commitment
	// state at height 0 for the channel.
	func (lc *LightningChannel) initialCommitmentKeyRing(
	whoseCommit lntypes.ChannelParty) *CommitmentKeyRing {
	return initialCommitmentKeyRingFromState(lc.channelState, whoseCommit)
	}

References

1. Every function must be commented with its purpose and assumptions. ^(link)

[jtobin]

I'm pretty sure this one can be simplified dramatically, and I think the simplifications will carry over to the associated tapd PR. I commented on a bunch of stuff, but didn't check any of it myself, so it could be wrong. Seems worth following these Opus-generated instructions to check:

• Drop ResolutionReq.InitialKeyRing; add ResolutionReq.CommitHeight fn.Option[uint64].
• Delete initialCommitmentKeyRingFromState.
• In NewLocalForceCloseSummary, set CommitHeight: fn.Some(chanState.LocalCommitment.CommitHeight).
• In NewUnilateralCloseSummary, set CommitHeight: fn.Some(remoteCommit.CommitHeight).
• Audit the other ResolutionReq construction sites (lnwallet/channel.go:2311, 2394, 7530, 7766, 7903, 8130) and set CommitHeight from the state-num in scope.

[jtobin]

LGTM. 👍 👍

[jtobin]

I may revisit this one. Presently reviewing lightninglabs/taproot-assets#2133, and I think this change may not actually be necessary to solve the issue we encounter in tapd downstream? Will report more when I know more..

[jtobin]

Just a couple of final recos after your last round of changes to lightninglabs/taproot-assets#1933.

[jtobin]

LGTM. 👍 👍

[Roasbeef]

The diff appears to no longer reflect the PR OP desc.

[GeorgeTsagk]

The diff appears to no longer reflect the PR OP desc.

Updated

[ziggie1984]

Change makes sense, wondering why we did not encounter this way earlier on the asset software side, wasn't the config used there form the beginning ?

[jtobin]

wondering why we did not encounter this way earlier on the asset software side

From what I can tell the broken case is just super rare. IIRC one has to force close before any HTLCs have been exchanged.

[ziggie1984]

tests in race mod are failing now due to the ew test

[GeorgeTsagk]

tests in race mod are failing now due to the ew test

taking a look

[litbot-9000]

@Roasbeef: review reminder
@ziggie1984: review reminder
@GeorgeTsagk, remember to re-request review from reviewers when ready

[litbot-9000]

@Roasbeef: review reminder
@ziggie1984: review reminder
@GeorgeTsagk, remember to re-request review from reviewers when ready

[litbot-9000]

@Roasbeef: review reminder
@ziggie1984: review reminder
@GeorgeTsagk, remember to re-request review from reviewers when ready

[litbot-9000]

@Roasbeef: review reminder
@ziggie1984: review reminder
@GeorgeTsagk, remember to re-request review from reviewers when ready