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RBF Coop Close using sat/kw instead of sat/vb #10425

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1458fa8
lnrpc: add sat/kw in the PendingUpdate message
MPins Nov 26, 2025
80259ab
rpcserver+peer+chancloser: change rbf coop close from sat/vb to sat/kw
MPins Nov 26, 2025
750816e
lntest+itest: adjust tests to work with the RBF coop close changes
MPins Dec 5, 2025
e5afb57
doc: release-notes-0.21.0
MPins Jan 26, 2026
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3 changes: 3 additions & 0 deletions docs/release-notes/release-notes-0.21.0.md
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Expand Up @@ -389,6 +389,9 @@

## Code Health

* [Extends sat/kw support to rbf cooperative channel closes](https://github.com/lightningnetwork/lnd/pull/10425), ensuring consistent fee handling across the
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closing flow and adding `fee_per_kw` to the RPC message `PendingUpdate`.

* [Update taproot detection](https://github.com/lightningnetwork/lnd/pull/10683)
to accommodate buried activation (and modified RPC `getdeploymentinfo`
response) beginning in Bitcoin Core v32.
Expand Down
14 changes: 8 additions & 6 deletions itest/lnd_coop_close_rbf_test.go
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Expand Up @@ -33,7 +33,7 @@ func runRbfCoopCloseTest(st *lntest.HarnessTest,
alicePendingUpdate := aliceCloseUpdate.GetClosePending()
require.NotNil(st, aliceCloseUpdate)
require.Equal(
st, int64(aliceFeeRate), alicePendingUpdate.FeePerVbyte,
st, int64(aliceFeeRate), int64(alicePendingUpdate.FeePerKw/250),
)
require.True(st, alicePendingUpdate.LocalCloseTx)

Expand All @@ -48,7 +48,9 @@ func runRbfCoopCloseTest(st *lntest.HarnessTest,
// Confirm that this new update was at 10 sat/vb.
bobPendingUpdate := bobCloseUpdate.GetClosePending()
require.NotNil(st, bobCloseUpdate)
require.Equal(st, bobPendingUpdate.FeePerVbyte, int64(bobFeeRate))
require.Equal(
st, int64(bobPendingUpdate.FeePerKw/250), int64(bobFeeRate),
)
require.True(st, bobPendingUpdate.LocalCloseTx)

var err error
Expand All @@ -69,11 +71,11 @@ func runRbfCoopCloseTest(st *lntest.HarnessTest,
// calculation for taproot.
require.InDelta(
st, int64(bobFeeRate),
alicePendingUpdate.FeePerVbyte, 1,
int64(alicePendingUpdate.FeePerKw/250), 1,
)
} else {
require.Equal(
st, alicePendingUpdate.FeePerVbyte,
st, int64(alicePendingUpdate.FeePerKw/250),
int64(bobFeeRate),
)
}
Expand All @@ -92,7 +94,7 @@ func runRbfCoopCloseTest(st *lntest.HarnessTest,
alicePendingUpdate = aliceCloseUpdate.GetClosePending()
require.NotNil(st, aliceCloseUpdate)
require.Equal(
st, alicePendingUpdate.FeePerVbyte,
st, int64(alicePendingUpdate.FeePerKw/250),
int64(aliceRejectedFeeRate),
)
require.True(st, alicePendingUpdate.LocalCloseTx)
Expand Down Expand Up @@ -126,7 +128,7 @@ func runRbfCoopCloseTest(st *lntest.HarnessTest,
alicePendingUpdate = aliceCloseUpdate.GetClosePending()
require.NotNil(st, aliceCloseUpdate)
require.Equal(
st, alicePendingUpdate.FeePerVbyte, int64(aliceFeeRate),
st, int64(alicePendingUpdate.FeePerKw/250), int64(aliceFeeRate),
)
require.True(st, alicePendingUpdate.LocalCloseTx)

Expand Down
25 changes: 18 additions & 7 deletions lnrpc/lightning.pb.go
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2 changes: 2 additions & 0 deletions lnrpc/lightning.proto
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Expand Up @@ -2286,7 +2286,9 @@ message CloseStatusUpdate {
message PendingUpdate {
bytes txid = 1;
uint32 output_index = 2;
// The update carries the fee rate in sat/vbyte and sat/kw
int64 fee_per_vbyte = 3;
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uint64 fee_per_kw = 5;
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bool local_close_tx = 4;
}

Expand Down
7 changes: 6 additions & 1 deletion lnrpc/lightning.swagger.json
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Expand Up @@ -7207,7 +7207,12 @@
},
"fee_per_vbyte": {
"type": "string",
"format": "int64"
"format": "int64",
"title": "The update carries the fee rate in sat/vbyte and sat/kw"
},
"fee_per_kw": {
"type": "string",
"format": "uint64"
},
"local_close_tx": {
"type": "boolean"
Expand Down
9 changes: 7 additions & 2 deletions lntest/harness.go
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Expand Up @@ -1348,9 +1348,14 @@ func (h *HarnessTest) CloseChannelAssertPending(hn *node.HarnessNode,
continue
}

notifyRate := pendingClose.ClosePending.FeePerVbyte
// Close pending notification in FeePerKw overwrites
// FeePerVbyte.
notifyRate := uint64(pendingClose.ClosePending.FeePerVbyte)
if pendingClose.ClosePending.FeePerKw != 0 {
notifyRate = pendingClose.ClosePending.FeePerKw / 250
}
if closeOpts.localTxOnly &&
notifyRate != int64(closeReq.SatPerVbyte) {
notifyRate != closeReq.SatPerVbyte {

continue
}
Expand Down
14 changes: 7 additions & 7 deletions lnwallet/chancloser/rbf_coop_states.go
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Expand Up @@ -105,7 +105,7 @@ type SendShutdown struct {

// IdealFeeRate is the ideal fee rate we'd like to use for the closing
// attempt.
IdealFeeRate chainfee.SatPerVByte
IdealFeeRate chainfee.SatPerKWeight

// CloseeNonce is the nonce we'll send in the shutdown message. The
// remote party will use this when they create their closing transaction
Expand Down Expand Up @@ -197,7 +197,7 @@ func (c *ChannelFlushed) protocolSealed() {}
// - toState: LocalOfferSent
type SendOfferEvent struct {
// TargetFeeRate is the fee rate we'll use for the closing transaction.
TargetFeeRate chainfee.SatPerVByte
TargetFeeRate chainfee.SatPerKWeight
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
Expand Down Expand Up @@ -319,7 +319,7 @@ type Environment struct {
// DefaultFeeRate is the fee we'll use for the closing transaction if
// the user didn't specify an ideal fee rate. This may happen if the
// remote party is the one that initiates the co-op close.
DefaultFeeRate chainfee.SatPerVByte
DefaultFeeRate chainfee.SatPerKWeight

// ThawHeight is the height at which the channel will be thawed. If
// this is None, then co-op close can occur at any moment.
Expand Down Expand Up @@ -484,7 +484,7 @@ type ShutdownPending struct {

// IdealFeeRate is the ideal fee rate we'd like to use for the closing
// attempt.
IdealFeeRate fn.Option[chainfee.SatPerVByte]
IdealFeeRate fn.Option[chainfee.SatPerKWeight]

// EarlyRemoteOffer is the offer we received from the remote party
// before we received their shutdown message. We'll stash it to process
Expand Down Expand Up @@ -533,7 +533,7 @@ type ChannelFlushing struct {
// IdealFeeRate is the ideal fee rate we'd like to use for the closing
// transaction. Once the channel has been flushed, we'll use this as
// our target fee rate.
IdealFeeRate fn.Option[chainfee.SatPerVByte]
IdealFeeRate fn.Option[chainfee.SatPerKWeight]

// NonceState tracks the nonces exchanged during shutdown for taproot
// channels.
Expand Down Expand Up @@ -788,7 +788,7 @@ type LocalOfferSent struct {
ProposedFee btcutil.Amount

// ProposedFeeRate is the fee rate we proposed to the remote party.
ProposedFeeRate chainfee.SatPerVByte
ProposedFeeRate chainfee.SatPerKWeight

// LocalSig is the signature we sent to the remote party.
LocalSig lnwire.Sig
Expand Down Expand Up @@ -843,7 +843,7 @@ type ClosePending struct {
*CloseChannelTerms

// FeeRate is the fee rate of the closing transaction.
FeeRate chainfee.SatPerVByte
FeeRate chainfee.SatPerKWeight

// Party indicates which party is at this state. This is used to
// implement the state transition properly, based on ShouldRouteTo.
Expand Down
28 changes: 14 additions & 14 deletions lnwallet/chancloser/rbf_coop_test.go
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Expand Up @@ -988,7 +988,7 @@ func newRbfCloserTestHarness(t *testing.T,
ChanPoint: chanPoint,
ChanID: chanID,
Scid: scid,
DefaultFeeRate: defaultFeeRate.FeePerVByte(),
DefaultFeeRate: defaultFeeRate,
ThawHeight: cfg.thawHeight,
RemoteUpfrontShutdown: cfg.remoteUpfrontAddr,
LocalUpfrontShutdown: cfg.localUpfrontAddr,
Expand Down Expand Up @@ -1069,7 +1069,7 @@ func testInitiatorShutdownRecvOkNonTap(t *testing.T, ctx context.Context,
t.Run("non_taproot", func(t *testing.T) {
firstState := *startingState
firstState.IdealFeeRate = fn.Some(
chainfee.FeePerKwFloor.FeePerVByte(),
chainfee.FeePerKwFloor,
)
firstState.ShutdownScripts = ShutdownScripts{
LocalDeliveryScript: localAddr,
Expand Down Expand Up @@ -1128,7 +1128,7 @@ func testInitiatorShutdownRecvOkTaproot(t *testing.T, ctx context.Context,
t.Run("taproot", func(t *testing.T) {
firstState := *startingState
firstState.IdealFeeRate = fn.Some(
chainfee.FeePerKwFloor.FeePerVByte(),
chainfee.FeePerKwFloor,
)
firstState.ShutdownScripts = ShutdownScripts{
LocalDeliveryScript: localAddr,
Expand Down Expand Up @@ -1377,7 +1377,7 @@ func TestRbfChannelActiveTransitions(t *testing.T) {
localAddr := lnwire.DeliveryAddress(bytes.Repeat([]byte{0x01}, 20))
remoteAddr := lnwire.DeliveryAddress(bytes.Repeat([]byte{0x02}, 20))

feeRate := chainfee.SatPerVByte(1000)
feeRate := chainfee.SatPerKWeight(250_000)

// Test that if a spend event is received, the FSM transitions to the
// CloseFin terminal state.
Expand Down Expand Up @@ -1580,7 +1580,7 @@ func TestRbfShutdownPendingTransitions(t *testing.T) {
t.Run("initiator_shutdown_recv_taproot_no_nonce_fail", func(t *testing.T) { //nolint:ll
firstState := *startingState
firstState.IdealFeeRate = fn.Some(
chainfee.FeePerKwFloor.FeePerVByte(),
chainfee.FeePerKwFloor,
)
firstState.ShutdownScripts = ShutdownScripts{
LocalDeliveryScript: localAddr,
Expand Down Expand Up @@ -1632,7 +1632,7 @@ func TestRbfShutdownPendingTransitions(t *testing.T) {
t.Run("responder_complete", func(t *testing.T) {
firstState := *startingState
firstState.IdealFeeRate = fn.Some(
chainfee.FeePerKwFloor.FeePerVByte(),
chainfee.FeePerKwFloor,
)
firstState.ShutdownScripts = ShutdownScripts{
LocalDeliveryScript: localAddr,
Expand Down Expand Up @@ -1663,7 +1663,7 @@ func TestRbfShutdownPendingTransitions(t *testing.T) {
t.Run("early_remote_offer_shutdown_complete", func(t *testing.T) {
firstState := *startingState
firstState.IdealFeeRate = fn.Some(
chainfee.FeePerKwFloor.FeePerVByte(),
chainfee.FeePerKwFloor,
)
firstState.ShutdownScripts = ShutdownScripts{
LocalDeliveryScript: localAddr,
Expand Down Expand Up @@ -1710,7 +1710,7 @@ func TestRbfShutdownPendingTransitions(t *testing.T) {
t.Run("early_remote_offer_shutdown_received", func(t *testing.T) {
firstState := *startingState
firstState.IdealFeeRate = fn.Some(
chainfee.FeePerKwFloor.FeePerVByte(),
chainfee.FeePerKwFloor,
)
firstState.ShutdownScripts = ShutdownScripts{
LocalDeliveryScript: localAddr,
Expand Down Expand Up @@ -1970,7 +1970,7 @@ func testSendOfferRbfIterationLoopNonTap(t *testing.T,
noDustExpect, false,
)

rbfFeeBump := chainfee.FeePerKwFloor.FeePerVByte() * 10
rbfFeeBump := chainfee.FeePerKwFloor * 10
localOffer := &SendOfferEvent{
TargetFeeRate: rbfFeeBump,
}
Expand Down Expand Up @@ -2033,7 +2033,7 @@ func testSendOfferRbfIterationLoopTaproot(t *testing.T,
lnwire.Musig2Nonce{7, 8, 9},
)

rbfFeeBump := chainfee.FeePerKwFloor.FeePerVByte() * 10
rbfFeeBump := chainfee.FeePerKwFloor * 10
localOffer := &SendOfferEvent{
TargetFeeRate: rbfFeeBump,
}
Expand Down Expand Up @@ -2331,7 +2331,7 @@ func TestRbfCloseClosingNegotiationLocal(t *testing.T) {
}

sendOfferEvent := &SendOfferEvent{
TargetFeeRate: chainfee.FeePerKwFloor.FeePerVByte(),
TargetFeeRate: chainfee.FeePerKwFloor,
}

balanceAfterClose := localBalance.ToSatoshis() - absoluteFee
Expand Down Expand Up @@ -2519,7 +2519,7 @@ func TestRbfCloseClosingNegotiationLocal(t *testing.T) {
// the amount we have in the channel.
closeHarness.expectFeeEstimate(btcutil.SatoshiPerBitcoin, 1)

rbfFeeBump := chainfee.FeePerKwFloor.FeePerVByte()
rbfFeeBump := chainfee.FeePerKwFloor
localOffer := &SendOfferEvent{
TargetFeeRate: rbfFeeBump,
}
Expand Down Expand Up @@ -2960,7 +2960,7 @@ func TestRbfCloseErr(t *testing.T) {
})
defer closeHarness.stopAndAssert()

rbfFeeBump := chainfee.FeePerKwFloor.FeePerVByte()
rbfFeeBump := chainfee.FeePerKwFloor
localOffer := &SendOfferEvent{
TargetFeeRate: rbfFeeBump,
}
Expand Down Expand Up @@ -3293,7 +3293,7 @@ func TestLocalOfferSentUsesStoredSig(t *testing.T) {
localOfferSent := &LocalOfferSent{
CloseChannelTerms: closeTerms,
ProposedFee: btcutil.Amount(1000),
ProposedFeeRate: chainfee.FeePerKwFloor.FeePerVByte(),
ProposedFeeRate: chainfee.FeePerKwFloor,
LocalSig: localSchnorrSig,
LocalMusigSig: fn.Some(lnwallet.MusigPartialSig{}),
}
Expand Down
16 changes: 11 additions & 5 deletions lnwallet/chancloser/rbf_coop_transitions.go
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Expand Up @@ -4,6 +4,7 @@ import (
"bytes"
"fmt"

"github.com/btcsuite/btcd/blockchain"
"github.com/btcsuite/btcd/btcec/v2"
"github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
"github.com/btcsuite/btcd/btcutil"
Expand Down Expand Up @@ -607,7 +608,7 @@ func (c *ChannelFlushing) ProcessEvent(event ProtocolEvent, env *Environment,
localTxOut, remoteTxOut := closeTerms.DeriveCloseTxOuts()
absoluteFee := env.FeeEstimator.EstimateFee(
env.ChanType, localTxOut, remoteTxOut,
idealFeeRate.FeePerKWeight(),
idealFeeRate,
)

chancloserLog.Infof("ChannelPoint(%v): using ideal_fee=%v, "+
Expand Down Expand Up @@ -1119,7 +1120,7 @@ func (l *LocalCloseStart) ProcessEvent(event ProtocolEvent, env *Environment,
localTxOut, remoteTxOut := l.DeriveCloseTxOuts()
absoluteFee := env.FeeEstimator.EstimateFee(
env.ChanType, localTxOut, remoteTxOut,
msg.TargetFeeRate.FeePerKWeight(),
msg.TargetFeeRate,
)

// If we can't actually pay for fees here, then we'll just do a
Expand Down Expand Up @@ -2115,11 +2116,16 @@ func (l *RemoteCloseStart) ProcessEvent(event ProtocolEvent, env *Environment,
// We'll also compute the final fee rate that the remote party
// paid based off the absolute fee and the size of the closing
// transaction.
vSize := mempool.GetTxVirtualSize(btcutil.NewTx(closeTx))
feeRate := chainfee.SatPerVByte(
int64(msg.SigMsg.FeeSatoshis) / vSize,
weight := blockchain.GetTransactionWeight(
btcutil.NewTx(closeTx),
)

// Convert absolute fee to a fee rate in sat/kw, rounding up.
fee := int64(msg.SigMsg.FeeSatoshis)
rate := ((fee * 1000) + weight - 1) / weight
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feeRate := chainfee.SatPerKWeight(rate)

// Now that we've extracted the signature, we'll transition to
// the next state where we'll sign+broadcast the sig.
return &CloseStateTransition{
Expand Down
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