f: add hold_outbound_htlcs_at_next_hop flag

Author: joostjager

src/config.rs

@@ -181,6 +181,11 @@ pub struct Config {
 	pub route_parameters: Option<RouteParametersConfig>,
 	/// Whether to enable the static invoice service to support async payment reception for clients.
 	pub async_payment_services_enabled: bool,
+	/// If this is set to true, then if we as an often-offline payer receive a [`StaticInvoice`] to
+	/// pay, we will attempt to hold the corresponding outbound HTLCs with our next-hop channel
+	/// counterparty(s) that support the `htlc_hold` feature. This allows our node to go offline once
+	/// the HTLCs are locked in even though the recipient may not yet be online to receive them.
+	pub hold_outbound_htlcs_at_next_hop: bool,
 }
 
 impl Default for Config {
@@ -196,6 +201,7 @@ impl Default for Config {
 			route_parameters: None,
 			node_alias: None,
 			async_payment_services_enabled: false,
+			hold_outbound_htlcs_at_next_hop: false,
 		}
 	}
 }
@@ -333,6 +339,9 @@ pub(crate) fn default_user_config(config: &Config) -> UserConfig {
 	if config.async_payment_services_enabled {
 		user_config.enable_htlc_hold = true;
 	}
+	if config.hold_outbound_htlcs_at_next_hop {
+		user_config.hold_outbound_htlcs_at_next_hop = true;
+	}
 
 	user_config
 }

tests/integration_tests_rust.rs

@@ -1139,6 +1139,7 @@ fn async_payment() {
 	let mut config_sender = random_config(true);
 	config_sender.node_config.listening_addresses = None;
 	config_sender.node_config.node_alias = None;
+	config_sender.node_config.hold_outbound_htlcs_at_next_hop = true;
 	config_sender.log_writer =
 		TestLogWriter::Custom(Arc::new(MultiNodeLogger::new("sender      ".to_string())));
 	let node_sender = setup_node(&chain_source, config_sender, None);