Add test for sequential RBF splice attempts

Add test_splice_rbf_sequential that exercises three consecutive RBF
rounds on the same splice (initial → RBF #1 → RBF #2) to verify:
- Each round requires the 25/24 feerate increase (253 → 264 → 275)
- DiscardFunding events reference the correct funding txid from each
  replaced candidate
- The final RBF splice can be mined and splice_locked successfully

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jkczyz

lightning/src/ln/splicing_tests.rs

@@ -5030,3 +5030,216 @@ fn test_splice_rbf_recontributes_feerate_too_high() {
 		other => panic!("Expected HandleError/DisconnectPeerWithWarning, got {:?}", other),
 	}
 }
+
+#[test]
+fn test_splice_rbf_sequential() {
+	// Three consecutive RBF rounds on the same splice (initial → RBF #1 → RBF #2).
+	// Node 0 is the quiescence initiator; node 1 is the acceptor with no contribution.
+	// Verifies:
+	// - Each round satisfies the 25/24 feerate rule
+	// - DiscardFunding events reference the correct txids from previous rounds
+	// - The final RBF can be mined and splice_locked successfully
+	let chanmon_cfgs = create_chanmon_cfgs(2);
+	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+	let node_id_0 = nodes[0].node.get_our_node_id();
+	let node_id_1 = nodes[1].node.get_our_node_id();
+
+	let initial_channel_value_sat = 100_000;
+	let (_, _, channel_id, _) =
+		create_announced_chan_between_nodes_with_value(&nodes, 0, 1, initial_channel_value_sat, 0);
+
+	let added_value = Amount::from_sat(50_000);
+	provide_utxo_reserves(&nodes, 2, added_value * 2);
+
+	// Save the pre-splice funding outpoint.
+	let original_funding_outpoint = nodes[0]
+		.chain_monitor
+		.chain_monitor
+		.get_monitor(channel_id)
+		.map(|monitor| (monitor.get_funding_txo(), monitor.get_funding_script()))
+		.unwrap();
+
+	// --- Round 0: Initial splice-in from node 0 at floor feerate (253). ---
+	let funding_contribution = do_initiate_splice_in(&nodes[0], &nodes[1], channel_id, added_value);
+	let (splice_tx_0, new_funding_script) =
+		splice_channel(&nodes[0], &nodes[1], channel_id, funding_contribution);
+
+	// Feerate progression: 253 → ceil(253*25/24) = 264 → ceil(264*25/24) = 275
+	let feerate_1_sat_per_kwu = (FEERATE_FLOOR_SATS_PER_KW as u64 * 25 + 23) / 24; // 264
+	let feerate_2_sat_per_kwu = (feerate_1_sat_per_kwu * 25 + 23) / 24; // 275
+
+	// --- Round 1: RBF #1 at feerate 264. ---
+	provide_utxo_reserves(&nodes, 2, added_value * 2);
+
+	let rbf_feerate_1 = FeeRate::from_sat_per_kwu(feerate_1_sat_per_kwu);
+	let funding_template =
+		nodes[0].node.rbf_channel(&channel_id, &node_id_1, rbf_feerate_1).unwrap();
+	let wallet = WalletSync::new(Arc::clone(&nodes[0].wallet_source), nodes[0].logger);
+	let funding_contribution_1 = funding_template.splice_in_sync(added_value, &wallet).unwrap();
+	nodes[0]
+		.node
+		.funding_contributed(&channel_id, &node_id_1, funding_contribution_1.clone(), None)
+		.unwrap();
+
+	let stfu_a = get_event_msg!(nodes[0], MessageSendEvent::SendStfu, node_id_1);
+	nodes[1].node.handle_stfu(node_id_0, &stfu_a);
+	let stfu_b = get_event_msg!(nodes[1], MessageSendEvent::SendStfu, node_id_0);
+	nodes[0].node.handle_stfu(node_id_1, &stfu_b);
+
+	let tx_init_rbf = get_event_msg!(nodes[0], MessageSendEvent::SendTxInitRbf, node_id_1);
+	assert_eq!(tx_init_rbf.feerate_sat_per_1000_weight, feerate_1_sat_per_kwu as u32);
+	nodes[1].node.handle_tx_init_rbf(node_id_0, &tx_init_rbf);
+	let tx_ack_rbf = get_event_msg!(nodes[1], MessageSendEvent::SendTxAckRbf, node_id_0);
+	nodes[0].node.handle_tx_ack_rbf(node_id_1, &tx_ack_rbf);
+
+	complete_interactive_funding_negotiation(
+		&nodes[0],
+		&nodes[1],
+		channel_id,
+		funding_contribution_1,
+		new_funding_script.clone(),
+	);
+	let (splice_tx_1, splice_locked) = sign_interactive_funding_tx(&nodes[0], &nodes[1], false);
+	assert!(splice_locked.is_none());
+	expect_splice_pending_event(&nodes[0], &node_id_1);
+	expect_splice_pending_event(&nodes[1], &node_id_0);
+
+	// --- Round 2: RBF #2 at feerate 275. ---
+	provide_utxo_reserves(&nodes, 2, added_value * 2);
+
+	let rbf_feerate_2 = FeeRate::from_sat_per_kwu(feerate_2_sat_per_kwu);
+	let funding_template =
+		nodes[0].node.rbf_channel(&channel_id, &node_id_1, rbf_feerate_2).unwrap();
+	let wallet = WalletSync::new(Arc::clone(&nodes[0].wallet_source), nodes[0].logger);
+	let funding_contribution_2 = funding_template.splice_in_sync(added_value, &wallet).unwrap();
+	nodes[0]
+		.node
+		.funding_contributed(&channel_id, &node_id_1, funding_contribution_2.clone(), None)
+		.unwrap();
+
+	let stfu_a = get_event_msg!(nodes[0], MessageSendEvent::SendStfu, node_id_1);
+	nodes[1].node.handle_stfu(node_id_0, &stfu_a);
+	let stfu_b = get_event_msg!(nodes[1], MessageSendEvent::SendStfu, node_id_0);
+	nodes[0].node.handle_stfu(node_id_1, &stfu_b);
+
+	let tx_init_rbf = get_event_msg!(nodes[0], MessageSendEvent::SendTxInitRbf, node_id_1);
+	assert_eq!(tx_init_rbf.feerate_sat_per_1000_weight, feerate_2_sat_per_kwu as u32);
+	nodes[1].node.handle_tx_init_rbf(node_id_0, &tx_init_rbf);
+	let tx_ack_rbf = get_event_msg!(nodes[1], MessageSendEvent::SendTxAckRbf, node_id_0);
+	nodes[0].node.handle_tx_ack_rbf(node_id_1, &tx_ack_rbf);
+
+	complete_interactive_funding_negotiation(
+		&nodes[0],
+		&nodes[1],
+		channel_id,
+		funding_contribution_2,
+		new_funding_script.clone(),
+	);
+	let (rbf_tx_final, splice_locked) = sign_interactive_funding_tx(&nodes[0], &nodes[1], false);
+	assert!(splice_locked.is_none());
+	expect_splice_pending_event(&nodes[0], &node_id_1);
+	expect_splice_pending_event(&nodes[1], &node_id_0);
+
+	// --- Mine and lock the final RBF. ---
+	mine_transaction(&nodes[0], &rbf_tx_final);
+	mine_transaction(&nodes[1], &rbf_tx_final);
+
+	connect_blocks(&nodes[0], ANTI_REORG_DELAY - 1);
+	connect_blocks(&nodes[1], ANTI_REORG_DELAY - 1);
+
+	let splice_locked_b = get_event_msg!(nodes[0], MessageSendEvent::SendSpliceLocked, node_id_1);
+	nodes[1].node.handle_splice_locked(node_id_0, &splice_locked_b);
+
+	let mut msg_events = nodes[1].node.get_and_clear_pending_msg_events();
+	assert_eq!(msg_events.len(), 2, "{msg_events:?}");
+	let splice_locked_a =
+		if let MessageSendEvent::SendSpliceLocked { msg, .. } = msg_events.remove(0) {
+			msg
+		} else {
+			panic!("Expected SendSpliceLocked, got {:?}", msg_events[0]);
+		};
+	let announcement_sigs_b =
+		if let MessageSendEvent::SendAnnouncementSignatures { msg, .. } = msg_events.remove(0) {
+			msg
+		} else {
+			panic!("Expected SendAnnouncementSignatures");
+		};
+	nodes[0].node.handle_splice_locked(node_id_1, &splice_locked_a);
+	nodes[0].node.handle_announcement_signatures(node_id_1, &announcement_sigs_b);
+
+	// --- Verify DiscardFunding events for both replaced candidates. ---
+	let splice_tx_0_txid = splice_tx_0.compute_txid();
+	let splice_tx_1_txid = splice_tx_1.compute_txid();
+
+	// Node 0 (initiator): ChannelReady + 2 DiscardFunding.
+	let events_a = nodes[0].node.get_and_clear_pending_events();
+	assert_eq!(events_a.len(), 3, "{events_a:?}");
+	assert!(matches!(events_a[0], Event::ChannelReady { .. }));
+	let discard_txids_a: Vec<_> = events_a[1..]
+		.iter()
+		.map(|e| match e {
+			Event::DiscardFunding { funding_info: FundingInfo::Tx { transaction }, .. } => {
+				transaction.compute_txid()
+			},
+			Event::DiscardFunding { funding_info: FundingInfo::OutPoint { outpoint }, .. } => {
+				outpoint.txid
+			},
+			other => panic!("Expected DiscardFunding, got {:?}", other),
+		})
+		.collect();
+	assert!(discard_txids_a.contains(&splice_tx_0_txid), "Missing discard for initial splice");
+	assert!(discard_txids_a.contains(&splice_tx_1_txid), "Missing discard for RBF #1");
+	check_added_monitors(&nodes[0], 1);
+
+	// Node 1 (acceptor): ChannelReady + 2 DiscardFunding.
+	let events_b = nodes[1].node.get_and_clear_pending_events();
+	assert_eq!(events_b.len(), 3, "{events_b:?}");
+	assert!(matches!(events_b[0], Event::ChannelReady { .. }));
+	let discard_txids_b: Vec<_> = events_b[1..]
+		.iter()
+		.map(|e| match e {
+			Event::DiscardFunding { funding_info: FundingInfo::Tx { transaction }, .. } => {
+				transaction.compute_txid()
+			},
+			Event::DiscardFunding { funding_info: FundingInfo::OutPoint { outpoint }, .. } => {
+				outpoint.txid
+			},
+			other => panic!("Expected DiscardFunding, got {:?}", other),
+		})
+		.collect();
+	assert!(discard_txids_b.contains(&splice_tx_0_txid), "Missing discard for initial splice");
+	assert!(discard_txids_b.contains(&splice_tx_1_txid), "Missing discard for RBF #1");
+	check_added_monitors(&nodes[1], 1);
+
+	// Complete the announcement exchange.
+	let mut msg_events = nodes[0].node.get_and_clear_pending_msg_events();
+	assert_eq!(msg_events.len(), 2, "{msg_events:?}");
+	if let MessageSendEvent::SendAnnouncementSignatures { msg, .. } = msg_events.remove(0) {
+		nodes[1].node.handle_announcement_signatures(node_id_0, &msg);
+	} else {
+		panic!("Expected SendAnnouncementSignatures");
+	}
+	assert!(matches!(msg_events.remove(0), MessageSendEvent::BroadcastChannelAnnouncement { .. }));
+
+	let mut msg_events = nodes[1].node.get_and_clear_pending_msg_events();
+	assert_eq!(msg_events.len(), 1, "{msg_events:?}");
+	assert!(matches!(msg_events.remove(0), MessageSendEvent::BroadcastChannelAnnouncement { .. }));
+
+	// Clean up old watched outpoints.
+	let (orig_outpoint, orig_script) = original_funding_outpoint;
+	let splice_funding_idx = |tx: &Transaction| {
+		tx.output.iter().position(|o| o.script_pubkey == new_funding_script).unwrap()
+	};
+	let outpoint_0 =
+		OutPoint { txid: splice_tx_0_txid, index: splice_funding_idx(&splice_tx_0) as u16 };
+	let outpoint_1 =
+		OutPoint { txid: splice_tx_1_txid, index: splice_funding_idx(&splice_tx_1) as u16 };
+	for node in &nodes {
+		node.chain_source.remove_watched_txn_and_outputs(orig_outpoint, orig_script.clone());
+		node.chain_source.remove_watched_txn_and_outputs(outpoint_0, new_funding_script.clone());
+		node.chain_source.remove_watched_txn_and_outputs(outpoint_1, new_funding_script.clone());
+	}
+}