ACINQ · remyers · Mar 26, 2025 · Mar 26, 2025
diff --git a/docs/release-notes/eclair-vnext.md b/docs/release-notes/eclair-vnext.md
@@ -10,6 +10,11 @@
 
 - `listoffers` now returns more details about each offer.
 
+
+### Configuration changes
+
+- The default for `eclair.features.option_channel_type` is now  `mandatory` instead of `optional`. This change prepares nodes to always assume the behavior of `option_channel_type` from peers when Bolts PR [#1232](https://github.com/lightning/bolts/pull/1232) is adopted. Until [#1232](https://github.com/lightning/bolts/pull/1232) is adopted you can still set `option_channel_type` to `optional` in your `eclair.conf` file for specific peers that do not yet support this option, see `Configure.md` for more information.
+
 ### Miscellaneous improvements and bug fixes
 
 #### Remove confirmation scaling based on funding amount

diff --git a/eclair-core/src/main/resources/reference.conf b/eclair-core/src/main/resources/reference.conf
@@ -76,7 +76,7 @@ eclair {
     // This feature should only be enabled when acting as an LSP for mobile wallets.
     // When activating this feature, the peer-storage section should be customized to match desired SLAs.
     option_provide_storage = disabled
-    option_channel_type = optional
+    option_channel_type = mandatory
     option_scid_alias = optional
     option_payment_metadata = optional
     // By enabling option_zeroconf, you will be trusting your peer as fundee. You will lose funds if they double spend

diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/TestConstants.scala b/eclair-core/src/test/scala/fr/acinq/eclair/TestConstants.scala
@@ -110,6 +110,7 @@ object TestConstants {
           Features.Quiescence -> FeatureSupport.Optional,
           Features.SplicePrototype -> FeatureSupport.Optional,
           Features.ProvideStorage -> FeatureSupport.Optional,
+          Features.ChannelType -> FeatureSupport.Mandatory
         ),
         unknown = Set(UnknownFeature(TestFeature.optional))
       ),
@@ -295,6 +296,7 @@ object TestConstants {
         Features.AnchorOutputsZeroFeeHtlcTx -> FeatureSupport.Optional,
         Features.Quiescence -> FeatureSupport.Optional,
         Features.SplicePrototype -> FeatureSupport.Optional,
+        Features.ChannelType -> FeatureSupport.Mandatory
       ),
       pluginParams = Nil,
       overrideInitFeatures = Map.empty,

diff --git a/...r-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala b/...r-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala
@@ -82,8 +82,6 @@ object ChannelStateTestsTags {
   val HighDustLimitDifferenceBobAlice = "high_dust_limit_difference_bob_alice"
   /** If set, Alice and Bob will use a very large tolerance for feerate mismatch. */
   val HighFeerateMismatchTolerance = "high_feerate_mismatch_tolerance"
-  /** If set, channels will use option_channel_type. */
-  val ChannelType = "option_channel_type"
   /** If set, channels will use option_zeroconf. */
   val ZeroConf = "zeroconf"
   /** If set, channels will use option_scid_alias. */
@@ -190,7 +188,6 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs))(_.updated(Features.StaticRemoteKey, FeatureSupport.Optional).updated(Features.AnchorOutputs, FeatureSupport.Optional).updated(Features.AnchorOutputsZeroFeeHtlcTx, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ShutdownAnySegwit))(_.updated(Features.ShutdownAnySegwit, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.UpfrontShutdownScript))(_.updated(Features.UpfrontShutdownScript, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ChannelType))(_.updated(Features.ChannelType, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ZeroConf))(_.updated(Features.ZeroConf, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ScidAlias))(_.updated(Features.ScidAlias, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DualFunding))(_.updated(Features.DualFunding, FeatureSupport.Optional))
@@ -202,7 +199,6 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs))(_.updated(Features.StaticRemoteKey, FeatureSupport.Optional).updated(Features.AnchorOutputs, FeatureSupport.Optional).updated(Features.AnchorOutputsZeroFeeHtlcTx, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ShutdownAnySegwit))(_.updated(Features.ShutdownAnySegwit, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.UpfrontShutdownScript))(_.updated(Features.UpfrontShutdownScript, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ChannelType))(_.updated(Features.ChannelType, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ZeroConf))(_.updated(Features.ZeroConf, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ScidAlias))(_.updated(Features.ScidAlias, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DualFunding))(_.updated(Features.DualFunding, FeatureSupport.Optional))

diff --git a/...-core/src/test/scala/fr/acinq/eclair/channel/states/a/WaitForAcceptChannelStateSpec.scala b/...-core/src/test/scala/fr/acinq/eclair/channel/states/a/WaitForAcceptChannelStateSpec.scala
@@ -18,6 +18,7 @@ package fr.acinq.eclair.channel.states.a
 
 import akka.actor.typed.scaladsl.adapter.ClassicActorRefOps
 import akka.testkit.{TestFSMRef, TestProbe}
+import com.softwaremill.quicklens.ModifyPimp
 import fr.acinq.bitcoin.scalacompat.{ByteVector32, SatoshiLong}
 import fr.acinq.eclair.TestConstants.{Alice, Bob}
 import fr.acinq.eclair.blockchain.NoOpOnChainWallet
@@ -114,19 +115,7 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
     aliceOpenReplyTo.expectNoMessage()
   }
 
-  test("recv AcceptChannel (channel type not set)", Tag(ChannelStateTestsTags.AnchorOutputs)) { f =>
-    import f._
-    val accept = bob2alice.expectMsgType[AcceptChannel]
-    assert(accept.channelType_opt.contains(ChannelTypes.AnchorOutputs()))
-    // Alice explicitly asked for an anchor output channel. Bob doesn't support explicit channel type negotiation but
-    // they both activated anchor outputs so it is the default choice anyway.
-    bob2alice.forward(alice, accept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty))))
-    awaitCond(alice.stateName == WAIT_FOR_FUNDING_INTERNAL)
-    assert(alice.stateData.asInstanceOf[DATA_WAIT_FOR_FUNDING_INTERNAL].params.commitmentFormat == UnsafeLegacyAnchorOutputsCommitmentFormat)
-    aliceOpenReplyTo.expectNoMessage()
-  }
-
-  test("recv AcceptChannel (channel type not set but feature bit set)", Tag(ChannelStateTestsTags.ChannelType), Tag(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs)) { f =>
+  test("recv AcceptChannel (channel type not set but feature bit set)", Tag(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs)) { f =>
     import f._
     val accept = bob2alice.expectMsgType[AcceptChannel]
     assert(accept.channelType_opt.contains(ChannelTypes.AnchorOutputsZeroFeeHtlcTx()))
@@ -148,19 +137,6 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
     aliceOpenReplyTo.expectNoMessage()
   }
 
-  test("recv AcceptChannel (non-default channel type not set)", Tag(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs), Tag(StandardChannelType)) { f =>
-    import f._
-    val accept = bob2alice.expectMsgType[AcceptChannel]
-    assert(accept.channelType_opt.contains(ChannelTypes.Standard()))
-    // Alice asked for a standard channel whereas they both support anchor outputs. Bob doesn't support explicit channel
-    // type negotiation so Alice needs to abort because the channel types won't match.
-    bob2alice.forward(alice, accept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty))))
-    alice2bob.expectMsg(Error(accept.temporaryChannelId, "invalid channel_type=anchor_outputs_zero_fee_htlc_tx, expected channel_type=standard"))
-    listener.expectMsgType[ChannelAborted]
-    awaitCond(alice.stateName == CLOSED)
-    aliceOpenReplyTo.expectMsgType[OpenChannelResponse.Rejected]
-  }
-
   test("recv AcceptChannel (anchor outputs channel type without enabling the feature)") { () =>
     val setup = init(Alice.nodeParams, Bob.nodeParams, wallet_opt = Some(new NoOpOnChainWallet()))
     import setup._
@@ -169,7 +145,7 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
     val channelFlags = ChannelFlags(announceChannel = false)
     // Bob advertises support for anchor outputs, but Alice doesn't.
     val aliceParams = Alice.channelParams
-    val bobParams = Bob.channelParams.copy(initFeatures = Features(Features.StaticRemoteKey -> FeatureSupport.Optional, Features.AnchorOutputs -> FeatureSupport.Optional))
+    val bobParams = Bob.channelParams.copy(initFeatures = Features(Features.StaticRemoteKey -> FeatureSupport.Optional, Features.AnchorOutputs -> FeatureSupport.Optional, Features.ChannelType -> FeatureSupport.Mandatory))
     alice ! INPUT_INIT_CHANNEL_INITIATOR(ByteVector32.Zeroes, TestConstants.fundingSatoshis, dualFunded = false, TestConstants.anchorOutputsFeeratePerKw, TestConstants.feeratePerKw, fundingTxFeeBudget_opt = None, Some(TestConstants.initiatorPushAmount), requireConfirmedInputs = false, requestFunding_opt = None, aliceParams, alice2bob.ref, Init(bobParams.initFeatures), channelFlags, channelConfig, ChannelTypes.AnchorOutputs(), replyTo = aliceOpenReplyTo.ref.toTyped)
     bob ! INPUT_INIT_CHANNEL_NON_INITIATOR(ByteVector32.Zeroes, None, dualFunded = false, None, requireConfirmedInputs = false, bobParams, bob2alice.ref, Init(bobParams.initFeatures), channelConfig, ChannelTypes.AnchorOutputs())
     val open = alice2bob.expectMsgType[OpenChannel]
@@ -310,8 +286,11 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
     import f._
     val accept = bob2alice.expectMsgType[AcceptChannel]
     assert(accept.upfrontShutdownScript_opt.contains(bob.stateData.asInstanceOf[DATA_WAIT_FOR_FUNDING_CREATED].params.localParams.upfrontShutdownScript_opt.get))
-    val accept1 = accept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty)))
+    val accept1 = accept
+      .modify(_.tlvStream.records).using(_.filterNot(_.isInstanceOf[ChannelTlv.UpfrontShutdownScriptTlv]))
+      .modify(_.tlvStream.records).using(_ + ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty))
     bob2alice.forward(alice, accept1)
+    alice2bob.expectNoMessage(100 millis)
     awaitCond(alice.stateName == WAIT_FOR_FUNDING_INTERNAL)
     assert(alice.stateData.asInstanceOf[DATA_WAIT_FOR_FUNDING_INTERNAL].params.remoteParams.upfrontShutdownScript_opt.isEmpty)
     aliceOpenReplyTo.expectNoMessage()
@@ -320,9 +299,12 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
   test("recv AcceptChannel (invalid upfront shutdown script)", Tag(ChannelStateTestsTags.UpfrontShutdownScript)) { f =>
     import f._
     val accept = bob2alice.expectMsgType[AcceptChannel]
-    val accept1 = accept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.fromValidHex("deadbeef"))))
+    val accept1 = accept
+      .modify(_.tlvStream.records).using(_.filterNot(_.isInstanceOf[ChannelTlv.UpfrontShutdownScriptTlv]))
+      .modify(_.tlvStream.records).using(_ + ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.fromValidHex("deadbeef")))
     bob2alice.forward(alice, accept1)
     listener.expectMsgType[ChannelAborted]
+    alice2bob.expectMsg(Error(accept.temporaryChannelId, "invalid final script"))
     awaitCond(alice.stateName == CLOSED)
     aliceOpenReplyTo.expectMsgType[OpenChannelResponse.Rejected]
   }

diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/io/OpenChannelInterceptorSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/io/OpenChannelInterceptorSpec.scala
@@ -320,7 +320,7 @@ class OpenChannelInterceptorSpec extends ScalaTestWithActorTestKit(ConfigFactory
     }
   }
 
-  test("don't spawn a channel if channel type is missing with the feature bit set", Tag(ChannelStateTestsTags.ChannelType)) { f =>
+  test("don't spawn a channel if channel type is missing with the feature bit set") { f =>
     import f._
 
     val open = createOpenChannelMessage()

diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/io/PeerConnectionSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/io/PeerConnectionSpec.scala
@@ -21,7 +21,7 @@ import akka.testkit.{TestFSMRef, TestProbe}
 import fr.acinq.bitcoin.scalacompat.Crypto.{PrivateKey, PublicKey}
 import fr.acinq.bitcoin.scalacompat.{Block, ByteVector32}
 import fr.acinq.eclair.FeatureSupport.{Mandatory, Optional}
-import fr.acinq.eclair.Features.{BasicMultiPartPayment, ChannelRangeQueries, PaymentSecret, StaticRemoteKey, VariableLengthOnion}
+import fr.acinq.eclair.Features.{BasicMultiPartPayment, ChannelRangeQueries, ChannelType, PaymentSecret, StaticRemoteKey, VariableLengthOnion}
 import fr.acinq.eclair.TestConstants._
 import fr.acinq.eclair.crypto.TransportHandler
 import fr.acinq.eclair.io.Peer.ConnectionDown
@@ -153,7 +153,7 @@ class PeerConnectionSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike wi
     transport.send(peerConnection, LightningMessageCodecs.initCodec.decode(hex"0000 00050100000000".bits).require.value)
     transport.expectMsgType[TransportHandler.ReadAck]
     probe.expectTerminated(transport.ref)
-    origin.expectMsg(PeerConnection.ConnectionResult.InitializationFailed("incompatible features (unknown_32,payment_secret,var_onion_optin,option_static_remotekey)"))
+    origin.expectMsg(PeerConnection.ConnectionResult.InitializationFailed("incompatible features (option_channel_type,option_static_remotekey,var_onion_optin,unknown_32,payment_secret)"))
     peer.expectMsg(ConnectionDown(peerConnection))
   }
 
@@ -170,7 +170,7 @@ class PeerConnectionSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike wi
     transport.send(peerConnection, LightningMessageCodecs.initCodec.decode(hex"00050100000000 0000".bits).require.value)
     transport.expectMsgType[TransportHandler.ReadAck]
     probe.expectTerminated(transport.ref)
-    origin.expectMsg(PeerConnection.ConnectionResult.InitializationFailed("incompatible features (unknown_32,payment_secret,var_onion_optin,option_static_remotekey)"))
+    origin.expectMsg(PeerConnection.ConnectionResult.InitializationFailed("incompatible features (option_channel_type,option_static_remotekey,var_onion_optin,unknown_32,payment_secret)"))
     peer.expectMsg(ConnectionDown(peerConnection))
   }
 
@@ -211,7 +211,7 @@ class PeerConnectionSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike wi
 
   test("sync when requested") { f =>
     import f._
-    val remoteInit = protocol.Init(Features(ChannelRangeQueries -> Optional, VariableLengthOnion -> Mandatory, PaymentSecret -> Mandatory, StaticRemoteKey -> Mandatory))
+    val remoteInit = protocol.Init(Features(ChannelRangeQueries -> Optional, VariableLengthOnion -> Mandatory, PaymentSecret -> Mandatory, StaticRemoteKey -> Mandatory, ChannelType -> Mandatory))
     connect(nodeParams, remoteNodeId, switchboard, router, connection, transport, peerConnection, peer, remoteInit, doSync = true)
   }
 

diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/io/PeerSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/io/PeerSpec.scala
@@ -70,7 +70,6 @@ class PeerSpec extends FixtureSpec {
 
     import com.softwaremill.quicklens._
     val aliceParams = TestConstants.Alice.nodeParams
-      .modify(_.features).setToIf(testData.tags.contains(ChannelStateTestsTags.ChannelType))(Features(ChannelType -> Optional))
       .modify(_.features).setToIf(testData.tags.contains(ChannelStateTestsTags.StaticRemoteKey))(Features(StaticRemoteKey -> Optional))
       .modify(_.features).setToIf(testData.tags.contains(ChannelStateTestsTags.AnchorOutputs))(Features(StaticRemoteKey -> Optional, AnchorOutputs -> Optional))
       .modify(_.features).setToIf(testData.tags.contains(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs))(Features(StaticRemoteKey -> Optional, AnchorOutputs -> Optional, AnchorOutputsZeroFeeHtlcTx -> Optional))