Merge pull request #4427 from jkczyz/2026-02-splicing-rbf

RBF splice funding transactions

Author: wpaulino

lightning-tests/src/upgrade_downgrade_tests.rs

@@ -466,7 +466,7 @@ fn do_test_0_1_htlc_forward_after_splice(fail_htlc: bool) {
 	}
 
 	let splice_locked = get_event_msg!(nodes[0], MessageSendEvent::SendSpliceLocked, node_b_id);
-	lock_splice(&nodes[0], &nodes[1], &splice_locked, false);
+	lock_splice(&nodes[0], &nodes[1], &splice_locked, false, &[]);
 
 	for node in nodes.iter() {
 		connect_blocks(node, EXTRA_BLOCKS_BEFORE_FAIL - ANTI_REORG_DELAY);

lightning/src/chain/channelmonitor.rs

@@ -4041,9 +4041,16 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 		}
 
 		if let Some(parent_funding_txid) = channel_parameters.splice_parent_funding_txid.as_ref() {
-			// Only one splice can be negotiated at a time after we've exchanged `channel_ready`
-			// (implying our funding is confirmed) that spends our currently locked funding.
-			if !self.pending_funding.is_empty() {
+			// Multiple RBF candidates for the same splice are allowed (they share the same
+			// parent funding txid). A new splice with a different parent while one is pending
+			// is not allowed. This also ensures a dual-funded channel has exchanged
+			// `channel_ready` (implying funding is confirmed) before allowing a splice,
+			// since unconfirmed initial funding has no splice parent.
+			let has_different_parent = self.pending_funding.iter().any(|funding| {
+				funding.channel_parameters.splice_parent_funding_txid.as_ref()
+					!= Some(parent_funding_txid)
+			});
+			if has_different_parent {
 				log_error!(
 					logger,
 					"Negotiated splice while channel is pending channel_ready/splice_locked"