diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/NodeParams.scala b/eclair-core/src/main/scala/fr/acinq/eclair/NodeParams.scala
index 59d0dfca9..755e71222 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/NodeParams.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/NodeParams.scala
@@ -134,7 +134,7 @@ case class NodeParams(nodeKeyManager: NodeKeyManager,
       min = (commitmentFeerate * feerateTolerance.ratioLow).max(minimumFeerate),
       max = (commitmentFormat match {
         case Transactions.DefaultCommitmentFormat => commitmentFeerate * feerateTolerance.ratioHigh
-        case _: Transactions.AnchorOutputsCommitmentFormat => (commitmentFeerate * feerateTolerance.ratioHigh).max(feerateTolerance.anchorOutputMaxCommitFeerate)
+        case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat => (commitmentFeerate * feerateTolerance.ratioHigh).max(feerateTolerance.anchorOutputMaxCommitFeerate)
       }).max(minimumFeerate),
     )
     RecommendedFeerates(chainHash, fundingFeerate, commitmentFeerate, TlvStream(fundingRange, commitmentRange))
diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/blockchain/fee/OnChainFeeConf.scala b/eclair-core/src/main/scala/fr/acinq/eclair/blockchain/fee/OnChainFeeConf.scala
index 874bdbd08..5b9f6bff4 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/blockchain/fee/OnChainFeeConf.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/blockchain/fee/OnChainFeeConf.scala
@@ -121,7 +121,7 @@ case class OnChainFeeConf(feeTargets: FeeTargets,
 
     commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => networkFeerate
-      case _: Transactions.AnchorOutputsCommitmentFormat =>
+      case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat =>
         val targetFeerate = networkFeerate.min(feerateToleranceFor(remoteNodeId).anchorOutputMaxCommitFeerate)
         // We make sure the feerate is always greater than the propagation threshold.
         targetFeerate.max(networkMinFee * 1.25)
diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/channel/Helpers.scala b/eclair-core/src/main/scala/fr/acinq/eclair/channel/Helpers.scala
index a3c6d163f..4d31cbb55 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/channel/Helpers.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/channel/Helpers.scala
@@ -357,20 +357,22 @@ object Helpers {
   }
 
   object Funding {
-    def makeFundingPubKeyScript(localFundingKey: PublicKey, remoteFundingKey: PublicKey, commitmentFormat: CommitmentFormat): ByteVector = if (commitmentFormat.useTaproot) {
-      write(Taproot.musig2FundingScript(localFundingKey, remoteFundingKey))
-    } else {
-      write(pay2wsh(multiSig2of2(localFundingKey, remoteFundingKey)))
+    def makeFundingPubKeyScript(localFundingKey: PublicKey, remoteFundingKey: PublicKey, commitmentFormat: CommitmentFormat): ByteVector = commitmentFormat match {
+      case SimpleTaprootChannelCommitmentFormat =>
+        write(Taproot.musig2FundingScript(localFundingKey, remoteFundingKey))
+      case _ =>
+        write(pay2wsh(multiSig2of2(localFundingKey, remoteFundingKey)))
     }
 
-    def makeFundingInputInfo(fundingTxId: TxId, fundingTxOutputIndex: Int, fundingSatoshis: Satoshi, fundingPubkey1: PublicKey, fundingPubkey2: PublicKey, commitmentFormat: CommitmentFormat): InputInfo = if (commitmentFormat.useTaproot) {
-      val fundingScript = Taproot.musig2FundingScript(fundingPubkey1, fundingPubkey2)
-      val fundingTxOut = TxOut(fundingSatoshis, fundingScript)
-      InputInfo.TaprootInput(OutPoint(fundingTxId, fundingTxOutputIndex), fundingTxOut, Taproot.musig2Aggregate(fundingPubkey1, fundingPubkey2), None)
-    } else {
-      val fundingScript = multiSig2of2(fundingPubkey1, fundingPubkey2)
-      val fundingTxOut = TxOut(fundingSatoshis, pay2wsh(fundingScript))
-      InputInfo.SegwitInput(OutPoint(fundingTxId, fundingTxOutputIndex), fundingTxOut, write(fundingScript))
+    def makeFundingInputInfo(fundingTxId: TxId, fundingTxOutputIndex: Int, fundingSatoshis: Satoshi, fundingPubkey1: PublicKey, fundingPubkey2: PublicKey, commitmentFormat: CommitmentFormat): InputInfo = commitmentFormat match {
+      case SimpleTaprootChannelCommitmentFormat =>
+        val fundingScript = Taproot.musig2FundingScript(fundingPubkey1, fundingPubkey2)
+        val fundingTxOut = TxOut(fundingSatoshis, fundingScript)
+        InputInfo.TaprootInput(OutPoint(fundingTxId, fundingTxOutputIndex), fundingTxOut, Taproot.musig2Aggregate(fundingPubkey1, fundingPubkey2), None)
+      case _ =>
+        val fundingScript = multiSig2of2(fundingPubkey1, fundingPubkey2)
+        val fundingTxOut = TxOut(fundingSatoshis, pay2wsh(fundingScript))
+        InputInfo.SegwitInput(OutPoint(fundingTxId, fundingTxOutputIndex), fundingTxOut, write(fundingScript))
     }
 
     /**
@@ -661,7 +663,7 @@ object Helpers {
           case DefaultCommitmentFormat =>
             // we "MUST set fee_satoshis less than or equal to the base fee of the final commitment transaction"
             requestedFeerate.min(commitment.localCommit.spec.commitTxFeerate)
-          case _: AnchorOutputsCommitmentFormat => requestedFeerate
+          case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => requestedFeerate
         }
         // NB: we choose a minimum fee that ensures the tx will easily propagate while allowing low fees since we can
         // always use CPFP to speed up confirmation if necessary.
@@ -892,18 +894,18 @@ object Helpers {
       def claimAnchors(keyManager: ChannelKeyManager, commitment: FullCommitment, lcp: LocalCommitPublished, confirmationTarget: ConfirmationTarget)(implicit log: LoggingAdapter): LocalCommitPublished = {
         if (shouldUpdateAnchorTxs(lcp.claimAnchorTxs, confirmationTarget)) {
           val localFundingPubKey = keyManager.fundingPublicKey(commitment.localParams.fundingKeyPath, commitment.fundingTxIndex).publicKey
-          val localPaymentKey = if (commitment.params.commitmentFormat.useTaproot) {
-            val channelKeyPath = keyManager.keyPath(commitment.localParams, commitment.params.channelConfig)
-            val localPerCommitmentPoint = keyManager.commitmentPoint(channelKeyPath, commitment.localCommit.index)
-            val localDelayedPaymentPubkey = Generators.derivePubKey(keyManager.delayedPaymentPoint(channelKeyPath).publicKey, localPerCommitmentPoint)
-            localDelayedPaymentPubkey
-          } else {
-            localFundingPubKey
+          val localPaymentKey = commitment.params.commitmentFormat match {
+            case SimpleTaprootChannelCommitmentFormat =>
+              val channelKeyPath = keyManager.keyPath(commitment.localParams, commitment.params.channelConfig)
+              val localPerCommitmentPoint = keyManager.commitmentPoint(channelKeyPath, commitment.localCommit.index)
+              val localDelayedPaymentPubkey = Generators.derivePubKey(keyManager.delayedPaymentPoint(channelKeyPath).publicKey, localPerCommitmentPoint)
+              localDelayedPaymentPubkey
+            case _ =>
+              localFundingPubKey
           }
-          val remotePaymentKey = if (commitment.params.commitmentFormat.useTaproot) {
-            commitment.remoteParams.paymentBasepoint
-          } else {
-            commitment.remoteFundingPubKey
+          val remotePaymentKey = commitment.params.commitmentFormat match {
+            case SimpleTaprootChannelCommitmentFormat => commitment.remoteParams.paymentBasepoint
+            case _ => commitment.remoteFundingPubKey
           }
           val claimAnchorTxs = List(
             withTxGenerationLog("local-anchor") {
@@ -1028,17 +1030,19 @@ object Helpers {
           val localFundingPubkey = keyManager.fundingPublicKey(commitment.localParams.fundingKeyPath, commitment.fundingTxIndex).publicKey
 
           // taproot channels do not re-use the funding pubkeys for anchor outputs
-          val localPaymentKey = if (commitment.params.commitmentFormat.useTaproot) {
-            val channelKeyPath = keyManager.keyPath(commitment.localParams, commitment.params.channelConfig)
-            commitment.localParams.walletStaticPaymentBasepoint.getOrElse(keyManager.paymentPoint(channelKeyPath).publicKey)
-          } else {
-            localFundingPubkey
+          val localPaymentKey = commitment.params.commitmentFormat match {
+            case SimpleTaprootChannelCommitmentFormat =>
+              val channelKeyPath = keyManager.keyPath(commitment.localParams, commitment.params.channelConfig)
+              commitment.localParams.walletStaticPaymentBasepoint.getOrElse(keyManager.paymentPoint(channelKeyPath).publicKey)
+            case _ =>
+              localFundingPubkey
           }
-          val remotePaymentKey = if (commitment.params.commitmentFormat.useTaproot) {
-            val remoteDelayedPaymentPubkey = Generators.derivePubKey(commitment.remoteParams.delayedPaymentBasepoint, commitment.remoteCommit.remotePerCommitmentPoint)
-            remoteDelayedPaymentPubkey
-          } else {
-            commitment.remoteFundingPubKey
+          val remotePaymentKey = commitment.params.commitmentFormat match {
+            case SimpleTaprootChannelCommitmentFormat =>
+              val remoteDelayedPaymentPubkey = Generators.derivePubKey(commitment.remoteParams.delayedPaymentBasepoint, commitment.remoteCommit.remotePerCommitmentPoint)
+              remoteDelayedPaymentPubkey
+            case _ =>
+              commitment.remoteFundingPubKey
           }
           val claimAnchorTxs = List(
             withTxGenerationLog("local-anchor") {
@@ -1078,7 +1082,7 @@ object Helpers {
                 Transactions.addSigs(claimMain, localPubkey, sig)
               })
             }
-            case _: AnchorOutputsCommitmentFormat => withTxGenerationLog("remote-main-delayed") {
+            case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => withTxGenerationLog("remote-main-delayed") {
               Transactions.makeClaimRemoteDelayedOutputTx(tx, params.localParams.dustLimit, localPaymentPoint, finalScriptPubKey, feeratePerKwMain).map(claimMain => {
                 val sig = keyManager.sign(claimMain, keyManager.paymentPoint(channelKeyPath), TxOwner.Local, params.commitmentFormat)
                 Transactions.addSigs(claimMain, sig)
@@ -1214,7 +1218,7 @@ object Helpers {
                 Transactions.addSigs(claimMain, localPaymentPubkey, sig)
               })
             }
-            case _: AnchorOutputsCommitmentFormat => withTxGenerationLog("remote-main-delayed") {
+            case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => withTxGenerationLog("remote-main-delayed") {
               Transactions.makeClaimRemoteDelayedOutputTx(commitTx, localParams.dustLimit, localPaymentPoint, finalScriptPubKey, feerateMain).map(claimMain => {
                 val sig = keyManager.sign(claimMain, keyManager.paymentPoint(channelKeyPath), TxOwner.Local, commitmentFormat)
                 Transactions.addSigs(claimMain, sig)
diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/channel/fsm/ErrorHandlers.scala b/eclair-core/src/main/scala/fr/acinq/eclair/channel/fsm/ErrorHandlers.scala
index a13e8ea34..a0c9d2c15 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/channel/fsm/ErrorHandlers.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/channel/fsm/ErrorHandlers.scala
@@ -237,7 +237,7 @@ trait ErrorHandlers extends CommonHandlers {
       case Transactions.DefaultCommitmentFormat =>
         val redeemableHtlcTxs = htlcTxs.values.flatten.map(tx => PublishFinalTx(tx, tx.fee, Some(commitTx.txid)))
         List(PublishFinalTx(commitTx, commitment.commitInput.outPoint, commitment.capacity, "commit-tx", Closing.commitTxFee(commitment.commitInput, commitTx, localPaysCommitTxFees), None)) ++ (claimMainDelayedOutputTx.map(tx => PublishFinalTx(tx, tx.fee, None)) ++ redeemableHtlcTxs ++ claimHtlcDelayedTxs.map(tx => PublishFinalTx(tx, tx.fee, None)))
-      case _: Transactions.AnchorOutputsCommitmentFormat =>
+      case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat =>
         val redeemableHtlcTxs = htlcTxs.values.flatten.map(tx => PublishReplaceableTx(tx, commitment, commitTx))
         val claimLocalAnchor = claimAnchorTxs.collect { case tx: Transactions.ClaimLocalAnchorOutputTx if !localCommitPublished.isConfirmed => PublishReplaceableTx(tx, commitment, commitTx) }
         List(PublishFinalTx(commitTx, commitment.commitInput.outPoint, commitment.capacity, "commit-tx", Closing.commitTxFee(commitment.commitInput, commitTx, localPaysCommitTxFees), None)) ++ claimLocalAnchor ++ claimMainDelayedOutputTx.map(tx => PublishFinalTx(tx, tx.fee, None)) ++ redeemableHtlcTxs ++ claimHtlcDelayedTxs.map(tx => PublishFinalTx(tx, tx.fee, None))
diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Scripts.scala b/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Scripts.scala
index b8969f469..9d19fbdf5 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Scripts.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Scripts.scala
@@ -23,7 +23,7 @@ import fr.acinq.bitcoin.TxIn.{SEQUENCE_LOCKTIME_DISABLE_FLAG, SEQUENCE_LOCKTIME_
 import fr.acinq.bitcoin.scalacompat.Crypto.{PublicKey, XonlyPublicKey}
 import fr.acinq.bitcoin.scalacompat.Script._
 import fr.acinq.bitcoin.scalacompat._
-import fr.acinq.eclair.transactions.Transactions.{AnchorOutputsCommitmentFormat, CommitmentFormat, DefaultCommitmentFormat}
+import fr.acinq.eclair.transactions.Transactions.{AnchorOutputsCommitmentFormat, CommitmentFormat, DefaultCommitmentFormat, SimpleTaprootChannelCommitmentFormat}
 import fr.acinq.eclair.{BlockHeight, CltvExpiry, CltvExpiryDelta}
 import scodec.bits.ByteVector
 
@@ -44,7 +44,7 @@ object Scripts {
 
   private def htlcRemoteSighash(commitmentFormat: CommitmentFormat): Int = commitmentFormat match {
     case DefaultCommitmentFormat => SIGHASH_ALL
-    case _: AnchorOutputsCommitmentFormat => SIGHASH_SINGLE | SIGHASH_ANYONECANPAY
+    case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => SIGHASH_SINGLE | SIGHASH_ANYONECANPAY
   }
 
   /** Sort public keys using lexicographic ordering. */
@@ -191,6 +191,7 @@ object Scripts {
     val addCsvDelay = commitmentFormat match {
       case DefaultCommitmentFormat => false
       case _: AnchorOutputsCommitmentFormat => true
+      case SimpleTaprootChannelCommitmentFormat => true
     }
     // @formatter:off
     // To you with revocation key
@@ -243,6 +244,7 @@ object Scripts {
     val addCsvDelay = commitmentFormat match {
       case DefaultCommitmentFormat => false
       case _: AnchorOutputsCommitmentFormat => true
+      case SimpleTaprootChannelCommitmentFormat => true
     }
     // @formatter:off
     // To you with revocation key
diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Transactions.scala b/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Transactions.scala
index cc6e1e3ac..0769a81f9 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Transactions.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/transactions/Transactions.scala
@@ -52,7 +52,6 @@ object Transactions {
     def htlcSuccessWeight: Int
     def htlcTimeoutInputWeight: Int
     def htlcSuccessInputWeight: Int
-    def useTaproot: Boolean = false
     // @formatter:on
   }
 
@@ -98,9 +97,13 @@ object Transactions {
    */
   case object ZeroFeeHtlcTxAnchorOutputsCommitmentFormat extends AnchorOutputsCommitmentFormat
 
-  case object SimpleTaprootChannelCommitmentFormat extends AnchorOutputsCommitmentFormat {
+  case object SimpleTaprootChannelCommitmentFormat extends CommitmentFormat {
     override val commitWeight = 968
-    override val useTaproot = true
+    override val htlcOutputWeight = 172
+    override val htlcTimeoutWeight = 666
+    override val htlcSuccessWeight = 706
+    override val htlcTimeoutInputWeight = 452
+    override val htlcSuccessInputWeight = 491
   }
 
   // @formatter:off
@@ -144,7 +147,10 @@ object Transactions {
       Satoshi(FeeratePerKw.MinimumRelayFeeRate * vsize / 1000)
     }
     /** Sighash flags to use when signing the transaction. */
-    def sighash(txOwner: TxOwner, commitmentFormat: CommitmentFormat): Int = if (input.isP2tr) SIGHASH_DEFAULT else SIGHASH_ALL
+    def sighash(txOwner: TxOwner, commitmentFormat: CommitmentFormat): Int = commitmentFormat match {
+      case SimpleTaprootChannelCommitmentFormat => SIGHASH_DEFAULT
+      case _ => SIGHASH_ALL
+    }
 
     def sign(key: PrivateKey, txOwner: TxOwner, commitmentFormat: CommitmentFormat): ByteVector64 = {
       sign(key, sighash(txOwner, commitmentFormat))
@@ -218,6 +224,10 @@ object Transactions {
         case TxOwner.Local => SIGHASH_ALL
         case TxOwner.Remote => SIGHASH_SINGLE | SIGHASH_ANYONECANPAY
       }
+      case SimpleTaprootChannelCommitmentFormat => txOwner match {
+        case TxOwner.Local => SIGHASH_DEFAULT
+        case TxOwner.Remote => SIGHASH_SINGLE | SIGHASH_ANYONECANPAY
+      }
     }
     override def confirmationTarget: ConfirmationTarget.Absolute
   }
@@ -228,7 +238,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(scriptTree: ScriptTree.Branch) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY, KotlinUtils.kmp2scala(scriptTree.getRight.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(scriptTree.getRight.hash()))
       case _: InputInfo.SegwitInput =>
         super.sign(privateKey, txOwner, commitmentFormat)
     }
@@ -236,9 +246,8 @@ object Transactions {
     override def checkSig(sig:  ByteVector64, pubKey:  PublicKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): Boolean = input match {
       case t: InputInfo.TaprootInput =>
         import KotlinUtils._
-        val sighash = this.sighash(txOwner, commitmentFormat)
         val Some(scriptTree: ScriptTree.Branch) = t.scriptTree_opt
-        val data = Transaction.hashForSigningTaprootScriptPath(tx, inputIndex = 0, Seq(input.txOut), sighash, scriptTree.getRight.hash())
+        val data = Transaction.hashForSigningTaprootScriptPath(tx, inputIndex = 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), scriptTree.getRight.hash())
         Crypto.verifySignatureSchnorr(data, sig, pubKey.xOnly)
       case _: InputInfo.SegwitInput =>
         super.checkSig(sig, pubKey, txOwner, commitmentFormat)
@@ -251,7 +260,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(scriptTree: ScriptTree.Branch) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY, KotlinUtils.kmp2scala(scriptTree.getLeft.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(scriptTree.getLeft.hash()))
       case _: InputInfo.SegwitInput =>
         super.sign(privateKey, txOwner, commitmentFormat)
     }
@@ -259,9 +268,8 @@ object Transactions {
     override def checkSig(sig:  ByteVector64, pubKey:  PublicKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): Boolean = input match {
       case t: InputInfo.TaprootInput =>
         import KotlinUtils._
-        val sighash = this.sighash(txOwner, commitmentFormat)
         val Some(scriptTree: ScriptTree.Branch) = t.scriptTree_opt
-        val data = Transaction.hashForSigningTaprootScriptPath(tx, inputIndex = 0, Seq(input.txOut), sighash, scriptTree.getLeft.hash())
+        val data = Transaction.hashForSigningTaprootScriptPath(tx, inputIndex = 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), scriptTree.getLeft.hash())
         Crypto.verifySignatureSchnorr(data, sig, pubKey.xOnly)
       case _: InputInfo.SegwitInput =>
         super.checkSig(sig, pubKey, txOwner, commitmentFormat)
@@ -273,7 +281,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(scriptTree: ScriptTree.Leaf) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, KotlinUtils.kmp2scala(scriptTree.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(scriptTree.hash()))
       case _: InputInfo.SegwitInput =>
         super.sign(privateKey, txOwner, commitmentFormat)
     }
@@ -290,7 +298,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(htlcTree: ScriptTree.Branch) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, KotlinUtils.kmp2scala(htlcTree.getRight.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(htlcTree.getRight.hash()))
       case _: InputInfo.SegwitInput =>
         super.sign(privateKey, txOwner, commitmentFormat)
     }
@@ -301,7 +309,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(htlcTree: ScriptTree.Branch) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, KotlinUtils.kmp2scala(htlcTree.getLeft.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(htlcTree.getLeft.hash()))
       case _: InputInfo.SegwitInput =>
         super.sign(privateKey, txOwner, commitmentFormat)
     }
@@ -312,7 +320,7 @@ object Transactions {
     override def desc: String = "local-anchor"
 
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
-      case _: InputInfo.TaprootInput => Transaction.signInputTaprootKeyPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, Some(Scripts.Taproot.anchorScriptTree))
+      case _: InputInfo.TaprootInput => Transaction.signInputTaprootKeyPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), Some(Scripts.Taproot.anchorScriptTree))
       case _: InputInfo.SegwitInput => super.sign(privateKey, txOwner, commitmentFormat)
     }
   }
@@ -326,7 +334,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(toRemoteScriptTree: ScriptTree.Leaf) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, KotlinUtils.kmp2scala(toRemoteScriptTree.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(toRemoteScriptTree.hash()))
       case _: InputInfo.SegwitInput => {
         super.sign(privateKey, txOwner, commitmentFormat)
       }
@@ -339,7 +347,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(toLocalScriptTree: ScriptTree.Branch) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, KotlinUtils.kmp2scala(toLocalScriptTree.getLeft.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(toLocalScriptTree.getLeft.hash()))
       case _: InputInfo.SegwitInput => {
         super.sign(privateKey, txOwner, commitmentFormat)
       }
@@ -352,7 +360,7 @@ object Transactions {
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
         val Some(toLocalScriptTree: ScriptTree.Branch) = t.scriptTree_opt
-        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, KotlinUtils.kmp2scala(toLocalScriptTree.getRight.hash()))
+        Transaction.signInputTaprootScriptPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), KotlinUtils.kmp2scala(toLocalScriptTree.getRight.hash()))
       case _: InputInfo.SegwitInput => {
         super.sign(privateKey, txOwner, commitmentFormat)
       }
@@ -364,7 +372,7 @@ object Transactions {
 
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
-        Transaction.signInputTaprootKeyPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, t.scriptTree_opt)
+        Transaction.signInputTaprootKeyPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), t.scriptTree_opt)
       case _: InputInfo.SegwitInput => {
         super.sign(privateKey, txOwner, commitmentFormat)
       }
@@ -376,7 +384,7 @@ object Transactions {
 
     override def sign(privateKey:  PrivateKey, txOwner:  TxOwner, commitmentFormat:  CommitmentFormat): ByteVector64 = input match {
       case t: InputInfo.TaprootInput =>
-        Transaction.signInputTaprootKeyPath(privateKey, tx, 0, Seq(input.txOut), SigHash.SIGHASH_DEFAULT, t.scriptTree_opt)
+        Transaction.signInputTaprootKeyPath(privateKey, tx, 0, Seq(input.txOut), sighash(txOwner, commitmentFormat), t.scriptTree_opt)
       case _: InputInfo.SegwitInput => {
         super.sign(privateKey, txOwner, commitmentFormat)
       }
@@ -384,8 +392,6 @@ object Transactions {
   }
 
   case class ClosingTx(input: InputInfo, tx: Transaction, toLocalOutput: Option[OutputInfo]) extends TransactionWithInputInfo {
-    // these nonces are generated on the fly at during a "simple" closing session and can be forgotten once the session ends
-    // @volatile var localNonce_opt: Option[(SecretNonce, IndividualNonce)] = None
     override def desc: String = "closing"
   }
 
@@ -529,7 +535,7 @@ object Transactions {
     // This is not technically a fee (it doesn't go to miners) but it also has to be deduced from the channel initiator's main output.
     val anchorsCost = commitmentFormat match {
       case DefaultCommitmentFormat => Satoshi(0)
-      case _: AnchorOutputsCommitmentFormat => AnchorOutputsCommitmentFormat.anchorAmount * 2
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => AnchorOutputsCommitmentFormat.anchorAmount * 2
     }
     txFee + anchorsCost
   }
@@ -583,7 +589,7 @@ object Transactions {
 
   def getHtlcTxInputSequence(commitmentFormat: CommitmentFormat): Long = commitmentFormat match {
     case DefaultCommitmentFormat => 0 // htlc txs immediately spend the commit tx
-    case _: AnchorOutputsCommitmentFormat => 1 // htlc txs have a 1-block delay to allow CPFP carve-out on anchors
+    case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => 1 // htlc txs have a 1-block delay to allow CPFP carve-out on anchors
   }
 
   /**
@@ -645,8 +651,8 @@ object Transactions {
     val outputs = collection.mutable.ArrayBuffer.empty[CommitmentOutputLink[CommitmentOutput]]
 
     trimOfferedHtlcs(localDustLimit, spec, commitmentFormat).foreach { htlc =>
-      commitmentFormat.useTaproot match {
-        case true =>
+      commitmentFormat match {
+        case SimpleTaprootChannelCommitmentFormat =>
           val offeredHtlcTree = Scripts.Taproot.offeredHtlcScriptTree(localHtlcPubkey, remoteHtlcPubkey, htlc.add.paymentHash)
           outputs.append(CommitmentOutputLink(
             TxOut(htlc.add.amountMsat.truncateToSatoshi, pay2tr(localRevocationPubkey.xOnly, Some(offeredHtlcTree))), localRevocationPubkey.xOnly, offeredHtlcTree, OutHtlc(htlc)
@@ -658,8 +664,8 @@ object Transactions {
     }
 
     trimReceivedHtlcs(localDustLimit, spec, commitmentFormat).foreach { htlc =>
-      commitmentFormat.useTaproot match {
-        case true =>
+      commitmentFormat match {
+        case SimpleTaprootChannelCommitmentFormat =>
           val receivedHtlcTree = Scripts.Taproot.receivedHtlcScriptTree(localHtlcPubkey, remoteHtlcPubkey, htlc.add.paymentHash, htlc.add.cltvExpiry)
           outputs.append(CommitmentOutputLink(
             TxOut(htlc.add.amountMsat.truncateToSatoshi, pay2tr(localRevocationPubkey.xOnly, Some(receivedHtlcTree))), localRevocationPubkey.xOnly, receivedHtlcTree, InHtlc(htlc)
@@ -679,13 +685,14 @@ object Transactions {
     } // NB: we don't care if values are < 0, they will be trimmed if they are < dust limit anyway
 
     if (toLocalAmount >= localDustLimit) {
-      if (commitmentFormat.useTaproot) {
+      commitmentFormat match {
+        case SimpleTaprootChannelCommitmentFormat =>
         val toLocalScriptTree = Scripts.Taproot.toLocalScriptTree(localRevocationPubkey, toLocalDelay, localDelayedPaymentPubkey)
         outputs.append(CommitmentOutputLink(
           TxOut(toLocalAmount, pay2tr(XonlyPublicKey(NUMS_POINT), Some(toLocalScriptTree))),
           NUMS_POINT.xOnly, toLocalScriptTree,
           ToLocal))
-      } else {
+        case _ =>
         outputs.append(CommitmentOutputLink(
           TxOut(toLocalAmount, pay2wsh(toLocalDelayed(localRevocationPubkey, toLocalDelay, localDelayedPaymentPubkey))),
           toLocalDelayed(localRevocationPubkey, toLocalDelay, localDelayedPaymentPubkey),
@@ -695,7 +702,7 @@ object Transactions {
 
     if (toRemoteAmount >= localDustLimit) {
       commitmentFormat match {
-        case _ if commitmentFormat.useTaproot =>
+        case SimpleTaprootChannelCommitmentFormat =>
           val toRemoteScriptTree = Scripts.Taproot.toRemoteScriptTree(remotePaymentPubkey)
           outputs.append(CommitmentOutputLink(
             TxOut(toRemoteAmount, pay2tr(XonlyPublicKey(NUMS_POINT), Some(toRemoteScriptTree))),
@@ -713,7 +720,7 @@ object Transactions {
     }
 
     commitmentFormat match {
-      case _ if commitmentFormat.useTaproot =>
+      case SimpleTaprootChannelCommitmentFormat =>
         if (toLocalAmount >= localDustLimit || hasHtlcs) {
           outputs.append(
             CommitmentOutputLink.TaprootLink(
@@ -1456,8 +1463,7 @@ object Transactions {
       case t: InputInfo.TaprootInput =>
         t.scriptTree_opt match {
           case Some(htlcTree: ScriptTree.Branch) =>
-            val sigHash = (SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY).toByte
-            Script.witnessScriptPathPay2tr(t.internalKey, htlcTree.getRight.asInstanceOf[ScriptTree.Leaf], ScriptWitness(Seq(remoteSig :+ sigHash, localSig :+ sigHash, paymentPreimage)), htlcTree)
+            Script.witnessScriptPathPay2tr(t.internalKey, htlcTree.getRight.asInstanceOf[ScriptTree.Leaf], ScriptWitness(Seq(Taproot.encodeSig(remoteSig, SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY), Taproot.encodeSig(localSig, SIGHASH_DEFAULT), paymentPreimage)), htlcTree)
           case _ => throw new IllegalArgumentException("unexpected script tree leaf when building htlc successTx tx")
         }
     }
@@ -1470,8 +1476,7 @@ object Transactions {
       case t: InputInfo.TaprootInput =>
         t.scriptTree_opt match {
           case Some(htlcTree: ScriptTree.Branch) =>
-            val sigHash = (SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY).toByte
-            Script.witnessScriptPathPay2tr(t.internalKey, htlcTree.getLeft.asInstanceOf[ScriptTree.Leaf], ScriptWitness(Seq(remoteSig :+ sigHash, localSig :+ sigHash)), htlcTree)
+            Script.witnessScriptPathPay2tr(t.internalKey, htlcTree.getLeft.asInstanceOf[ScriptTree.Leaf], ScriptWitness(Seq(Taproot.encodeSig(remoteSig, SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY), Taproot.encodeSig(localSig, SIGHASH_DEFAULT))), htlcTree)
           case _ => throw new IllegalArgumentException("unexpected script tree leaf when building htlc timeout tx")
         }
     }
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/channel/publish/ReplaceableTxPublisherSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/channel/publish/ReplaceableTxPublisherSpec.scala
index 20768d649..a0c99f9cc 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/channel/publish/ReplaceableTxPublisherSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/channel/publish/ReplaceableTxPublisherSpec.scala
@@ -1572,7 +1572,7 @@ class ReplaceableTxPublisherSpec extends TestKitBaseClass with AnyFunSuiteLike w
     val remoteCommitTx = bob.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.fullySignedLocalCommitTx(bob.underlyingActor.nodeParams.channelKeyManager)
     bob.stateData.asInstanceOf[DATA_NORMAL].commitments.params.commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => assert(remoteCommitTx.tx.txOut.size == 4)
-      case _: AnchorOutputsCommitmentFormat => assert(remoteCommitTx.tx.txOut.size == 6)
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => assert(remoteCommitTx.tx.txOut.size == 6)
     }
     probe.send(alice, WatchFundingSpentTriggered(remoteCommitTx.tx))
 
@@ -1583,7 +1583,7 @@ class ReplaceableTxPublisherSpec extends TestKitBaseClass with AnyFunSuiteLike w
 
     bob.stateData.asInstanceOf[DATA_NORMAL].commitments.params.commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => ()
-      case _: AnchorOutputsCommitmentFormat => alice2blockchain.expectMsgType[PublishReplaceableTx] // claim anchor
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => alice2blockchain.expectMsgType[PublishReplaceableTx] // claim anchor
     }
     if (!bob.stateData.asInstanceOf[DATA_NORMAL].commitments.params.channelFeatures.paysDirectlyToWallet) alice2blockchain.expectMsgType[PublishFinalTx] // claim main output
     val claimHtlcSuccess = alice2blockchain.expectMsgType[PublishReplaceableTx]
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala
index c9c2b4800..0638180c5 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala
@@ -590,7 +590,7 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
         // all htlcs success/timeout should be published as-is, without claiming their outputs
         s2blockchain.expectMsgAllOf(localCommitPublished.htlcTxs.values.toSeq.collect { case Some(tx) => TxPublisher.PublishFinalTx(tx, tx.fee, Some(commitTx.txid)) }: _*)
         assert(localCommitPublished.claimHtlcDelayedTxs.isEmpty)
-      case _: Transactions.AnchorOutputsCommitmentFormat =>
+      case _: Transactions.AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat =>
         // all htlcs success/timeout should be published as replaceable txs, without claiming their outputs
         val htlcTxs = localCommitPublished.htlcTxs.values.collect { case Some(tx: HtlcTx) => tx }
         val publishedTxs = htlcTxs.map(_ => s2blockchain.expectMsgType[TxPublisher.PublishReplaceableTx])
@@ -629,7 +629,7 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
 
     // If anchor outputs is used, we use the anchor output to bump the fees if necessary.
     closingData.commitments.params.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat =>
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat =>
         val anchorTx = s2blockchain.expectMsgType[PublishReplaceableTx]
         assert(anchorTx.txInfo.isInstanceOf[ClaimLocalAnchorOutputTx])
       case Transactions.DefaultCommitmentFormat => ()
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForDualFundingSignedStateSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForDualFundingSignedStateSpec.scala
index ceb7082d2..47d31ea7c 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForDualFundingSignedStateSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForDualFundingSignedStateSpec.scala
@@ -55,7 +55,7 @@ class WaitForDualFundingSignedStateSpec extends TestKitBaseClass with FixtureAny
     val (initiatorPushAmount, nonInitiatorPushAmount) = if (test.tags.contains("both_push_amount")) (Some(TestConstants.initiatorPushAmount), Some(TestConstants.nonInitiatorPushAmount)) else (None, None)
     val commitFeerate = channelType.commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => TestConstants.feeratePerKw
-      case _: Transactions.AnchorOutputsCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
+      case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
     }
     val aliceListener = TestProbe()
     val bobListener = TestProbe()
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForFundingSignedStateSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForFundingSignedStateSpec.scala
index fd778546c..65229afd7 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForFundingSignedStateSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/b/WaitForFundingSignedStateSpec.scala
@@ -61,7 +61,7 @@ class WaitForFundingSignedStateSpec extends TestKitBaseClass with FixtureAnyFunS
     val (aliceParams, bobParams, channelType) = computeFeatures(setup, test.tags, channelFlags)
     val commitFeerate = channelType.commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => TestConstants.feeratePerKw
-      case _: Transactions.AnchorOutputsCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
+      case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
     }
     val aliceInit = Init(aliceParams.initFeatures)
     val bobInit = Init(bobParams.initFeatures)
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForChannelReadyStateSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForChannelReadyStateSpec.scala
index 7c7bf41f5..21e3f2ffa 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForChannelReadyStateSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForChannelReadyStateSpec.scala
@@ -53,7 +53,7 @@ class WaitForChannelReadyStateSpec extends TestKitBaseClass with FixtureAnyFunSu
     val (aliceParams, bobParams, channelType) = computeFeatures(setup, test.tags, channelFlags)
     val commitFeerate = channelType.commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => TestConstants.feeratePerKw
-      case _: Transactions.AnchorOutputsCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
+      case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
     }
     val pushMsat = if (test.tags.contains(ChannelStateTestsTags.NoPushAmount)) None else Some(TestConstants.initiatorPushAmount)
     val aliceInit = Init(aliceParams.initFeatures)
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForDualFundingConfirmedStateSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForDualFundingConfirmedStateSpec.scala
index d3af777ed..b863cb810 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForDualFundingConfirmedStateSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/c/WaitForDualFundingConfirmedStateSpec.scala
@@ -72,7 +72,7 @@ class WaitForDualFundingConfirmedStateSpec extends TestKitBaseClass with Fixture
     val (aliceParams, bobParams, channelType) = computeFeatures(setup, test.tags, channelFlags)
     val commitFeerate = channelType.commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => TestConstants.feeratePerKw
-      case _: Transactions.AnchorOutputsCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
+      case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat => TestConstants.anchorOutputsFeeratePerKw
     }
     val aliceInit = Init(aliceParams.initFeatures)
     val bobInit = Init(bobParams.initFeatures)
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/h/ClosingStateSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/h/ClosingStateSpec.scala
index 52f7f8a04..869f4533b 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/h/ClosingStateSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/channel/states/h/ClosingStateSpec.scala
@@ -990,7 +990,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
     // Bob publishes the latest commit tx.
     val bobCommitTx = bob.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit.commitTxAndRemoteSig.commitTx.tx
     channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => assert(bobCommitTx.txOut.length == 7) // two main outputs + two anchors + 3 HTLCs
+      case _: AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat => assert(bobCommitTx.txOut.length == 7) // two main outputs + two anchors + 3 HTLCs
       case DefaultCommitmentFormat => assert(bobCommitTx.txOut.length == 5) // two main outputs + 3 HTLCs
     }
     val closingState = remoteClose(bobCommitTx, alice, alice2blockchain)
@@ -1124,7 +1124,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
     // Bob publishes the next commit tx.
     val bobCommitTx = bob.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit.commitTxAndRemoteSig.commitTx.tx
     channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => assert(bobCommitTx.txOut.length == 7) // two main outputs + two anchors + 3 HTLCs
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => assert(bobCommitTx.txOut.length == 7) // two main outputs + two anchors + 3 HTLCs
       case DefaultCommitmentFormat => assert(bobCommitTx.txOut.length == 5) // two main outputs + 3 HTLCs
     }
     val closingState = remoteClose(bobCommitTx, alice, alice2blockchain)
@@ -1319,7 +1319,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
     // bob is nice and publishes its commitment
     val bobCommitTx = bob.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit.commitTxAndRemoteSig.commitTx.tx
     channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => assert(bobCommitTx.txOut.length == 6) // two main outputs + two anchors + 2 HTLCs
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => assert(bobCommitTx.txOut.length == 6) // two main outputs + two anchors + 2 HTLCs
       case DefaultCommitmentFormat => assert(bobCommitTx.txOut.length == 4) // two main outputs + 2 HTLCs
     }
     alice ! WatchFundingSpentTriggered(bobCommitTx)
@@ -1393,7 +1393,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
     // Bob's first commit tx doesn't contain any htlc
     val localCommit1 = bob.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit
     channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => assert(localCommit1.commitTxAndRemoteSig.commitTx.tx.txOut.size == 4) // 2 main outputs + 2 anchors
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => assert(localCommit1.commitTxAndRemoteSig.commitTx.tx.txOut.size == 4) // 2 main outputs + 2 anchors
       case DefaultCommitmentFormat => assert(localCommit1.commitTxAndRemoteSig.commitTx.tx.txOut.size == 2) // 2 main outputs
     }
 
@@ -1409,7 +1409,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
 
     assert(alice.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit.commitTxAndRemoteSig.commitTx.tx.txOut.size == localCommit2.commitTxAndRemoteSig.commitTx.tx.txOut.size)
     channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => assert(localCommit2.commitTxAndRemoteSig.commitTx.tx.txOut.size == 6)
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => assert(localCommit2.commitTxAndRemoteSig.commitTx.tx.txOut.size == 6)
       case DefaultCommitmentFormat => assert(localCommit2.commitTxAndRemoteSig.commitTx.tx.txOut.size == 4)
     }
 
@@ -1425,7 +1425,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
 
     assert(alice.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit.commitTxAndRemoteSig.commitTx.tx.txOut.size == localCommit3.commitTxAndRemoteSig.commitTx.tx.txOut.size)
     channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => assert(localCommit3.commitTxAndRemoteSig.commitTx.tx.txOut.size == 8)
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => assert(localCommit3.commitTxAndRemoteSig.commitTx.tx.txOut.size == 8)
       case DefaultCommitmentFormat => assert(localCommit3.commitTxAndRemoteSig.commitTx.tx.txOut.size == 6)
     }
 
@@ -1439,7 +1439,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
 
     assert(alice.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit.commitTxAndRemoteSig.commitTx.tx.txOut.size == localCommit4.commitTxAndRemoteSig.commitTx.tx.txOut.size)
     channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => assert(localCommit4.commitTxAndRemoteSig.commitTx.tx.txOut.size == 4)
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => assert(localCommit4.commitTxAndRemoteSig.commitTx.tx.txOut.size == 4)
       case DefaultCommitmentFormat => assert(localCommit4.commitTxAndRemoteSig.commitTx.tx.txOut.size == 2)
     }
 
@@ -1820,7 +1820,7 @@ class ClosingStateSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike with
     import f._
     assert(alice.stateData.asInstanceOf[DATA_NORMAL].commitments.params.channelFeatures == channelFeatures)
     val initOutputCount = channelFeatures.commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => 4
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => 4
       case DefaultCommitmentFormat => 2
     }
     assert(bob.stateData.asInstanceOf[DATA_NORMAL].commitments.latest.localCommit.commitTxAndRemoteSig.commitTx.tx.txOut.size == initOutputCount)
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/integration/ChannelIntegrationSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/integration/ChannelIntegrationSpec.scala
index 8b6c93940..a1adc8c1e 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/integration/ChannelIntegrationSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/integration/ChannelIntegrationSpec.scala
@@ -35,7 +35,7 @@ import fr.acinq.eclair.payment.receive.MultiPartHandler.ReceiveStandardPayment
 import fr.acinq.eclair.payment.receive.{ForwardHandler, PaymentHandler}
 import fr.acinq.eclair.payment.send.PaymentInitiator.SendPaymentToNode
 import fr.acinq.eclair.router.Router
-import fr.acinq.eclair.transactions.Transactions.{AnchorOutputsCommitmentFormat, CommitmentFormat, DefaultCommitmentFormat, TxOwner}
+import fr.acinq.eclair.transactions.Transactions.{AnchorOutputsCommitmentFormat, CommitmentFormat, DefaultCommitmentFormat, SimpleTaprootChannelCommitmentFormat, TxOwner}
 import fr.acinq.eclair.transactions.{OutgoingHtlc, Scripts, Transactions}
 import fr.acinq.eclair.wire.protocol._
 import fr.acinq.eclair.{MilliSatoshi, MilliSatoshiLong, randomBytes32}
@@ -181,7 +181,7 @@ abstract class ChannelIntegrationSpec extends IntegrationSpec {
     generateBlocks(25, Some(minerAddress))
     val expectedTxCountC = 1 // C should have 1 recv transaction: its main output
     val expectedTxCountF = commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => 2 // F should have 2 recv transactions: the redeemed htlc and its main output
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => 2 // F should have 2 recv transactions: the redeemed htlc and its main output
       case Transactions.DefaultCommitmentFormat => 1 // F's main output uses static_remotekey
     }
     awaitCond({
@@ -221,7 +221,7 @@ abstract class ChannelIntegrationSpec extends IntegrationSpec {
     // we then generate enough blocks so that F gets its htlc-success delayed output
     generateBlocks(25, Some(minerAddress))
     val expectedTxCountC = commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => 1 // C should have 1 recv transaction: its main output
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => 1 // C should have 1 recv transaction: its main output
       case Transactions.DefaultCommitmentFormat => 0 // C's main output uses static_remotekey
     }
     val expectedTxCountF = 2 // F should have 2 recv transactions: the redeemed htlc and its main output
@@ -275,7 +275,7 @@ abstract class ChannelIntegrationSpec extends IntegrationSpec {
     generateBlocks(25, Some(minerAddress))
     val expectedTxCountC = 2 // C should have 2 recv transactions: its main output and the htlc timeout
     val expectedTxCountF = commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => 1 // F should have 1 recv transaction: its main output
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => 1 // F should have 1 recv transaction: its main output
       case Transactions.DefaultCommitmentFormat => 0 // F's main output uses static_remotekey
     }
     awaitCond({
@@ -330,7 +330,7 @@ abstract class ChannelIntegrationSpec extends IntegrationSpec {
     // we then generate enough blocks to confirm all delayed transactions
     generateBlocks(25, Some(minerAddress))
     val expectedTxCountC = commitmentFormat match {
-      case _: AnchorOutputsCommitmentFormat => 2 // C should have 2 recv transactions: its main output and the htlc timeout
+      case _: AnchorOutputsCommitmentFormat | SimpleTaprootChannelCommitmentFormat => 2 // C should have 2 recv transactions: its main output and the htlc timeout
       case Transactions.DefaultCommitmentFormat => 1 // C's main output uses static_remotekey
     }
     val expectedTxCountF = 1 // F should have 1 recv transaction: its main output
@@ -405,7 +405,7 @@ abstract class ChannelIntegrationSpec extends IntegrationSpec {
     val localCommitF = commitmentsF.latest.localCommit
     commitmentFormat match {
       case Transactions.DefaultCommitmentFormat => assert(localCommitF.commitTxAndRemoteSig.commitTx.tx.txOut.size == 6)
-      case _: Transactions.AnchorOutputsCommitmentFormat => assert(localCommitF.commitTxAndRemoteSig.commitTx.tx.txOut.size == 8)
+      case _: Transactions.AnchorOutputsCommitmentFormat | Transactions.SimpleTaprootChannelCommitmentFormat => assert(localCommitF.commitTxAndRemoteSig.commitTx.tx.txOut.size == 8)
     }
     val outgoingHtlcExpiry = localCommitF.spec.htlcs.collect { case OutgoingHtlc(add) => add.cltvExpiry }.max
     val htlcTimeoutTxs = localCommitF.htlcTxsAndRemoteSigs.collect { case h@HtlcTxAndRemoteSig(_: Transactions.HtlcTimeoutTx, _) => h }
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/transactions/TransactionsSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/transactions/TransactionsSpec.scala
index 4ae3689ce..2028d1159 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/transactions/TransactionsSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/transactions/TransactionsSpec.scala
@@ -770,14 +770,15 @@ class TransactionsSpec extends AnyFunSuite with Logging {
       val commitTxNumber = 0x404142434445L
       val outputs = makeCommitTxOutputs(localPaysCommitTxFees = true, localDustLimit, localRevocationPriv.publicKey, toLocalDelay, localDelayedPaymentPriv.publicKey, remotePaymentPriv.publicKey, localHtlcPriv.publicKey, remoteHtlcPriv.publicKey, localFundingPriv.publicKey, remoteFundingPriv.publicKey, spec, commitmentFormat)
       val txInfo = makeCommitTx(commitInput, commitTxNumber, localPaymentPriv.publicKey, remotePaymentPriv.publicKey, localIsChannelOpener = true, outputs)
-      val commitTx = if (commitmentFormat.useTaproot) {
+      val commitTx = commitmentFormat match {
+        case SimpleTaprootChannelCommitmentFormat =>
         val Right(sig) = for {
           localPartialSig <- Musig2.signTaprootInput(localFundingPriv, txInfo.tx, 0, Seq(fundingOutput), publicKeys, secretLocalNonce, publicNonces, None)
           remotePartialSig <- Musig2.signTaprootInput(remoteFundingPriv, txInfo.tx, 0, Seq(fundingOutput), publicKeys, secretRemoteNonce, publicNonces, None)
           sig <- Musig2.aggregateTaprootSignatures(Seq(localPartialSig, remotePartialSig), txInfo.tx, 0, Seq(fundingOutput), publicKeys, publicNonces, None)
         } yield sig
         Transactions.addAggregatedSignature(txInfo, sig)
-      } else {
+        case _ =>
         val localSig = txInfo.sign(localPaymentPriv, TxOwner.Local, commitmentFormat)
         val remoteSig = txInfo.sign(remotePaymentPriv, TxOwner.Remote, commitmentFormat)
         Transactions.addSigs(txInfo, localFundingPriv.publicKey, remoteFundingPriv.publicKey, localSig, remoteSig)
@@ -815,10 +816,9 @@ class TransactionsSpec extends AnyFunSuite with Logging {
     }
     {
       // local spends local anchor
-      val anchorKey = if (commitmentFormat.useTaproot) {
-        localDelayedPaymentPriv
-      } else {
-        localFundingPriv
+      val anchorKey = commitmentFormat match {
+        case SimpleTaprootChannelCommitmentFormat => localDelayedPaymentPriv
+        case _ => localFundingPriv
       }
       val Right(claimAnchorOutputTx) = makeClaimLocalAnchorOutputTx(commitTx.tx, anchorKey.publicKey, ConfirmationTarget.Absolute(BlockHeight(0)))
       assert(checkSpendable(claimAnchorOutputTx).isFailure)
@@ -828,10 +828,9 @@ class TransactionsSpec extends AnyFunSuite with Logging {
     }
     {
       // remote spends remote anchor
-      val anchorKey = if (commitmentFormat.useTaproot) {
-        remotePaymentPriv
-      } else {
-        remoteFundingPriv
+      val anchorKey = commitmentFormat match {
+        case SimpleTaprootChannelCommitmentFormat => remotePaymentPriv
+        case _ => remoteFundingPriv
       }
       val Right(claimAnchorOutputTx) = makeClaimLocalAnchorOutputTx(commitTx.tx, anchorKey.publicKey, ConfirmationTarget.Absolute(BlockHeight(0)))
       assert(checkSpendable(claimAnchorOutputTx).isFailure)
@@ -950,10 +949,11 @@ class TransactionsSpec extends AnyFunSuite with Logging {
       val Some(htlcOutputIndex) = commitTxOutputs.map(_.filter[OutHtlc]).zipWithIndex.collectFirst {
         case (Some(co), outputIndex) if co.commitmentOutput.outgoingHtlc.add.id == htlc1.id => outputIndex
       }
-      val Right(htlcPenaltyTx) = if (commitmentFormat.useTaproot) {
+      val Right(htlcPenaltyTx) = commitmentFormat match {
+        case SimpleTaprootChannelCommitmentFormat =>
         val scriptTree = Taproot.offeredHtlcScriptTree(localHtlcPriv.publicKey, remoteHtlcPriv.publicKey, htlc1.paymentHash)
         makeHtlcPenaltyTx(commitTx.tx, htlcOutputIndex, localRevocationPriv.publicKey.xOnly, Some(scriptTree), localDustLimit, finalPubKeyScript, feeratePerKw)
-      } else {
+        case _ =>
         val script = Script.write(Scripts.htlcOffered(localHtlcPriv.publicKey, remoteHtlcPriv.publicKey, localRevocationPriv.publicKey, Crypto.ripemd160(htlc1.paymentHash), commitmentFormat))
         makeHtlcPenaltyTx(commitTx.tx, htlcOutputIndex, script, localDustLimit, finalPubKeyScript, feeratePerKw)
       }
@@ -967,10 +967,11 @@ class TransactionsSpec extends AnyFunSuite with Logging {
         val Some(htlcOutputIndex) = commitTxOutputs.map(_.filter[InHtlc]).zipWithIndex.collectFirst {
           case (Some(co), outputIndex) if co.commitmentOutput.incomingHtlc.add.id == htlc.id => outputIndex
         }
-        val Right(htlcPenaltyTx) = if (commitmentFormat.useTaproot) {
+        val Right(htlcPenaltyTx) = commitmentFormat match {
+          case SimpleTaprootChannelCommitmentFormat =>
           val scriptTree = Taproot.receivedHtlcScriptTree(localHtlcPriv.publicKey, remoteHtlcPriv.publicKey, htlc.paymentHash, htlc.cltvExpiry)
           makeHtlcPenaltyTx(commitTx.tx, htlcOutputIndex, localRevocationPriv.publicKey.xOnly, Some(scriptTree), localDustLimit, finalPubKeyScript, feeratePerKw)
-        } else {
+          case _ =>
           val script = Script.write(Scripts.htlcReceived(localHtlcPriv.publicKey, remoteHtlcPriv.publicKey, localRevocationPriv.publicKey, Crypto.ripemd160(htlc.paymentHash), htlc.cltvExpiry, commitmentFormat))
           makeHtlcPenaltyTx(commitTx.tx, htlcOutputIndex, script, localDustLimit, finalPubKeyScript, feeratePerKw)
         }
@@ -1120,9 +1121,8 @@ class TransactionsSpec extends AnyFunSuite with Logging {
         txOut = TxOut(25_000.sat, Taproot.htlcDelayed(localDelayedPaymentPriv.publicKey, toLocalDelay, localRevocationPriv.publicKey)) :: Nil,
         lockTime = 300)
       val scriptTree = Taproot.offeredHtlcScriptTree(localHtlcPriv.publicKey, remoteHtlcPriv.publicKey, paymentHash)
-      val sigHash = SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY
-      val localSig = Taproot.encodeSig(Transaction.signInputTaprootScriptPath(localHtlcPriv, tx, 0, Seq(commitTx.txOut(4)), sigHash, scriptTree.getLeft.hash()), sigHash)
-      val remoteSig = Taproot.encodeSig(Transaction.signInputTaprootScriptPath(remoteHtlcPriv, tx, 0, Seq(commitTx.txOut(4)), sigHash, scriptTree.getLeft.hash()), sigHash)
+      val localSig = Taproot.encodeSig(Transaction.signInputTaprootScriptPath(localHtlcPriv, tx, 0, Seq(commitTx.txOut(4)), SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY, scriptTree.getLeft.hash()), SigHash.SIGHASH_SINGLE | SigHash.SIGHASH_ANYONECANPAY)
+      val remoteSig = Taproot.encodeSig(Transaction.signInputTaprootScriptPath(remoteHtlcPriv, tx, 0, Seq(commitTx.txOut(4)), SigHash.SIGHASH_DEFAULT, scriptTree.getLeft.hash()), SigHash.SIGHASH_DEFAULT)
       val witness = Script.witnessScriptPathPay2tr(localRevocationPriv.xOnlyPublicKey(), scriptTree.getLeft.asInstanceOf[ScriptTree.Leaf], ScriptWitness(Seq(remoteSig, localSig)), scriptTree)
       tx.updateWitness(0, witness)
     }