Accept splice and RBF warning disconnects in chanmon_consistency

The HandleError assertion only accepted "timeout awaiting response"
warnings. However, the fuzzer can deliver messages in unusual orders that
trigger legitimate splice and RBF validation failures (e.g., attempting
RBF after splice_locked, splicing before quiescence, or splicing a
channel that is not live). These produce DisconnectPeerWithWarning with
different messages that the assertion needs to accept.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jkczyz

fuzz/src/chanmon_consistency.rs

@@ -894,18 +894,25 @@ fn send_mpp_hop_payment(
 }
 
 #[inline]
-fn assert_action_timeout_awaiting_response(action: &msgs::ErrorAction) {
-	// Since sending/receiving messages may be delayed, `timer_tick_occurred` may cause a node to
-	// disconnect their counterparty if they're expecting a timely response.
-	assert!(
-		matches!(
-			action,
-			msgs::ErrorAction::DisconnectPeerWithWarning { msg }
+fn assert_action_disconnect_with_warning(action: &msgs::ErrorAction) {
+	match action {
+		msgs::ErrorAction::DisconnectPeerWithWarning { msg }
 			if msg.data.contains("Disconnecting due to timeout awaiting response")
-		),
-		"Expected timeout disconnect, got: {:?}",
-		action,
-	);
+				|| msg.data.contains("cannot RBF")
+				|| msg.data.contains("before RBF")
+				|| msg.data.contains("needed for RBF")
+				|| msg.data.contains("splice to RBF")
+				|| msg.data.contains("candidates to RBF")
+				|| msg.data.contains("candidates for RBF")
+				|| msg.data.contains("before spliced")
+				|| msg.data.contains("needed to splice")
+				|| msg.data.contains("a splice pending")
+				|| msg.data.contains("cannot be spliced")
+				|| msg.data.contains("Splicing requested on a channel that is not live")
+				|| msg.data.contains("funding negotiation already in progress") =>
+		{},
+		_ => panic!("Unexpected error action: {:?}", action),
+	}
 }
 
 enum ChanType {
@@ -1658,7 +1665,7 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(data: &[u8], out: Out) {
 							*node_id == a_id
 						},
 						MessageSendEvent::HandleError { ref action, ref node_id } => {
-							assert_action_timeout_awaiting_response(action);
+							assert_action_disconnect_with_warning(action);
 							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
 							*node_id == a_id
 						},
@@ -1888,7 +1895,7 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(data: &[u8], out: Out) {
 							}
 						},
 						MessageSendEvent::HandleError { ref action, .. } => {
-							assert_action_timeout_awaiting_response(action);
+							assert_action_disconnect_with_warning(action);
 						},
 						MessageSendEvent::SendChannelReady { .. } => {
 							// Can be generated as a reestablish response
@@ -1941,7 +1948,7 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(data: &[u8], out: Out) {
 							MessageSendEvent::SendAnnouncementSignatures { .. } => {},
 							MessageSendEvent::SendChannelUpdate { .. } => {},
 							MessageSendEvent::HandleError { ref action, .. } => {
-								assert_action_timeout_awaiting_response(action);
+								assert_action_disconnect_with_warning(action);
 							},
 							_ => panic!("Unhandled message event"),
 						}
@@ -1963,7 +1970,7 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(data: &[u8], out: Out) {
 							MessageSendEvent::SendAnnouncementSignatures { .. } => {},
 							MessageSendEvent::SendChannelUpdate { .. } => {},
 							MessageSendEvent::HandleError { ref action, .. } => {
-								assert_action_timeout_awaiting_response(action);
+								assert_action_disconnect_with_warning(action);
 							},
 							_ => panic!("Unhandled message event"),
 						}