Add BOLT12 support to LSPS2 via custom Router implementation

fuzz/src/lsps_message.rs

@@ -88,6 +88,7 @@ pub fn do_test(data: &[u8]) {
 			Arc::clone(&tx_broadcaster),
 			None,
 			None,
+			None,
 		)
 		.unwrap(),
 	);

lightning-background-processor/src/lib.rs

@@ -2519,6 +2519,7 @@ mod tests {
 					Arc::clone(&tx_broadcaster),
 					None,
 					None,
+					None,
 				)
 				.unwrap(),
 			);

lightning-liquidity/src/lsps2/event.rs

@@ -49,7 +49,17 @@ pub enum LSPS2ClientEvent {
 	/// When the invoice is paid, the LSP will open a channel with the previously agreed upon
 	/// parameters to you.
 	///
+	/// For BOLT11 JIT invoices, `intercept_scid` and `cltv_expiry_delta` can be used in a route
+	/// hint.
+	///
+	/// For BOLT12 JIT flows, register these parameters for your offer id on an
+	/// [`LSPS2BOLT12Router`] and then proceed with the regular BOLT12 offer
+	/// flow. The router will inject the LSPS2-specific blinded payment path when creating the
+	/// invoice.
+	///
 	/// **Note: ** This event will *not* be persisted across restarts.
+	///
+	/// [`LSPS2BOLT12Router`]: crate::lsps2::router::LSPS2BOLT12Router
 	InvoiceParametersReady {
 		/// The identifier of the issued bLIP-52 / LSPS2 `buy` request, as returned by
 		/// [`LSPS2ClientHandler::select_opening_params`].

lightning-liquidity/src/lsps2/mod.rs

@@ -13,5 +13,6 @@ pub mod client;
 pub mod event;
 pub mod msgs;
 pub(crate) mod payment_queue;
+pub mod router;
 pub mod service;
 pub mod utils;