event: expose paid BOLT12 invoice in PaymentSuccessful

Expose the paid BOLT12 invoice on successful outbound payments so API users can access the invoice alongside the payment preimage.

This keeps the event surface needed for follow-up storage and payer-proof work.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
AI-assisted-by: Codex

Author: vincenzopalazzo

src/event.rs

@@ -15,6 +15,8 @@ use bitcoin::blockdata::locktime::absolute::LockTime;
 use bitcoin::secp256k1::PublicKey;
 use bitcoin::{Amount, OutPoint};
 use lightning::events::bump_transaction::BumpTransactionEvent;
+#[cfg(not(feature = "uniffi"))]
+use lightning::events::PaidBolt12Invoice;
 use lightning::events::{
 	ClosureReason, Event as LdkEvent, FundingInfo, PaymentFailureReason, PaymentPurpose,
 	ReplayEvent,
@@ -37,6 +39,8 @@ use crate::config::{may_announce_channel, Config};
 use crate::connection::ConnectionManager;
 use crate::data_store::DataStoreUpdateResult;
 use crate::fee_estimator::ConfirmationTarget;
+#[cfg(feature = "uniffi")]
+use crate::ffi::PaidBolt12Invoice;
 use crate::io::{
 	EVENT_QUEUE_PERSISTENCE_KEY, EVENT_QUEUE_PERSISTENCE_PRIMARY_NAMESPACE,
 	EVENT_QUEUE_PERSISTENCE_SECONDARY_NAMESPACE,
@@ -79,6 +83,17 @@ pub enum Event {
 		payment_preimage: Option<PaymentPreimage>,
 		/// The total fee which was spent at intermediate hops in this payment.
 		fee_paid_msat: Option<u64>,
+		/// The BOLT12 invoice that was paid.
+		///
+		/// This is useful for proof of payment. A third party can verify that the payment was made
+		/// by checking that the `payment_hash` in the invoice matches `sha256(payment_preimage)`.
+		///
+		/// Will be `None` for non-BOLT12 payments.
+		///
+		/// Note that static invoices (indicated by [`PaidBolt12Invoice::StaticInvoice`], used for
+		/// async payments) do not support proof of payment as the payment hash is not derived
+		/// from a preimage known only to the recipient.
+		bolt12_invoice: Option<PaidBolt12Invoice>,
 	},
 	/// A sent payment has failed.
 	PaymentFailed {
@@ -268,6 +283,7 @@ impl_writeable_tlv_based_enum!(Event,
 		(1, fee_paid_msat, option),
 		(3, payment_id, option),
 		(5, payment_preimage, option),
+		(7, bolt12_invoice, option),
 	},
 	(1, PaymentFailed) => {
 		(0, payment_hash, option),
@@ -1028,6 +1044,7 @@ where
 				payment_preimage,
 				payment_hash,
 				fee_paid_msat,
+				bolt12_invoice,
 				..
 			} => {
 				let payment_id = if let Some(id) = payment_id {
@@ -1073,6 +1090,7 @@ where
 					payment_hash,
 					payment_preimage: Some(payment_preimage),
 					fee_paid_msat,
+					bolt12_invoice: bolt12_invoice.map(Into::into),
 				};
 
 				match self.event_queue.add_event(event).await {

src/ffi/types.rs

@@ -10,6 +10,7 @@
 //
 // Make sure to add any re-exported items that need to be used in uniffi below.
 
+use std::collections::HashMap;
 use std::convert::TryInto;
 use std::ops::Deref;
 use std::str::FromStr;
@@ -22,17 +23,20 @@ use bitcoin::hashes::Hash;
 use bitcoin::secp256k1::PublicKey;
 pub use bitcoin::{Address, BlockHash, FeeRate, Network, OutPoint, ScriptBuf, Txid};
 pub use lightning::chain::channelmonitor::BalanceSource;
+use lightning::events::PaidBolt12Invoice as LdkPaidBolt12Invoice;
 pub use lightning::events::{ClosureReason, PaymentFailureReason};
 use lightning::ln::channelmanager::PaymentId;
+use lightning::ln::msgs::DecodeError;
 pub use lightning::ln::types::ChannelId;
 use lightning::offers::invoice::Bolt12Invoice as LdkBolt12Invoice;
 pub use lightning::offers::offer::OfferId;
 use lightning::offers::offer::{Amount as LdkAmount, Offer as LdkOffer};
 use lightning::offers::refund::Refund as LdkRefund;
+use lightning::offers::static_invoice::StaticInvoice as LdkStaticInvoice;
 use lightning::onion_message::dns_resolution::HumanReadableName as LdkHumanReadableName;
 pub use lightning::routing::gossip::{NodeAlias, NodeId, RoutingFees};
 pub use lightning::routing::router::RouteParametersConfig;
-use lightning::util::ser::Writeable;
+use lightning::util::ser::{Readable, Writeable, Writer};
 use lightning_invoice::{Bolt11Invoice as LdkBolt11Invoice, Bolt11InvoiceDescriptionRef};
 pub use lightning_invoice::{Description, SignedRawBolt11Invoice};
 pub use lightning_liquidity::lsps0::ser::LSPSDateTime;
@@ -41,10 +45,10 @@ pub use lightning_liquidity::lsps1::msgs::{
 };
 pub use lightning_types::payment::{PaymentHash, PaymentPreimage, PaymentSecret};
 pub use lightning_types::string::UntrustedString;
-use std::collections::HashMap;
-
-use vss_client::headers::VssHeaderProvider as VssClientHeaderProvider;
-use vss_client::headers::VssHeaderProviderError as VssClientHeaderProviderError;
+use vss_client::headers::{
+	VssHeaderProvider as VssClientHeaderProvider,
+	VssHeaderProviderError as VssClientHeaderProviderError,
+};
 
 /// Errors around providing headers for each VSS request.
 #[derive(Debug, uniffi::Error)]
@@ -775,6 +779,95 @@ impl AsRef<LdkBolt12Invoice> for Bolt12Invoice {
 	}
 }
 
+/// A static invoice used for async payments.
+///
+/// Static invoices are a special type of BOLT12 invoice where proof of payment is not possible,
+/// as the payment hash is not derived from a preimage known only to the recipient.
+#[derive(Debug, Clone, PartialEq, Eq, uniffi::Object)]
+pub struct StaticInvoice {
+	pub(crate) inner: LdkStaticInvoice,
+}
+
+#[uniffi::export]
+impl StaticInvoice {
+	/// The amount for a successful payment of the invoice, if specified.
+	pub fn amount(&self) -> Option<OfferAmount> {
+		self.inner.amount().map(|amount| amount.into())
+	}
+}
+
+impl From<LdkStaticInvoice> for StaticInvoice {
+	fn from(invoice: LdkStaticInvoice) -> Self {
+		StaticInvoice { inner: invoice }
+	}
+}
+
+impl Deref for StaticInvoice {
+	type Target = LdkStaticInvoice;
+	fn deref(&self) -> &Self::Target {
+		&self.inner
+	}
+}
+
+impl AsRef<LdkStaticInvoice> for StaticInvoice {
+	fn as_ref(&self) -> &LdkStaticInvoice {
+		self.deref()
+	}
+}
+
+/// The BOLT12 invoice that was paid, surfaced in [`Event::PaymentSuccessful`].
+///
+/// [`Event::PaymentSuccessful`]: crate::Event::PaymentSuccessful
+#[derive(Debug, Clone, PartialEq, Eq, uniffi::Enum)]
+pub enum PaidBolt12Invoice {
+	/// The BOLT12 invoice, allowing the user to perform proof of payment.
+	Bolt12(Arc<Bolt12Invoice>),
+	/// The static invoice, used in async payments, where the user cannot perform proof of
+	/// payment.
+	Static(Arc<StaticInvoice>),
+}
+
+impl From<LdkPaidBolt12Invoice> for PaidBolt12Invoice {
+	fn from(ldk: LdkPaidBolt12Invoice) -> Self {
+		match ldk {
+			LdkPaidBolt12Invoice::Bolt12Invoice(invoice) => {
+				PaidBolt12Invoice::Bolt12(Arc::new(Bolt12Invoice::from(invoice)))
+			},
+			LdkPaidBolt12Invoice::StaticInvoice(invoice) => {
+				PaidBolt12Invoice::Static(Arc::new(StaticInvoice::from(invoice)))
+			},
+		}
+	}
+}
+
+impl From<PaidBolt12Invoice> for LdkPaidBolt12Invoice {
+	fn from(wrapper: PaidBolt12Invoice) -> Self {
+		match wrapper {
+			PaidBolt12Invoice::Bolt12(invoice) => {
+				LdkPaidBolt12Invoice::Bolt12Invoice(invoice.inner.clone())
+			},
+			PaidBolt12Invoice::Static(invoice) => {
+				LdkPaidBolt12Invoice::StaticInvoice(invoice.inner.clone())
+			},
+		}
+	}
+}
+
+impl Writeable for PaidBolt12Invoice {
+	fn write<W: Writer>(&self, w: &mut W) -> Result<(), lightning::io::Error> {
+		// TODO: Find way to avoid cloning invoice data.
+		let ldk_type: LdkPaidBolt12Invoice = self.clone().into();
+		ldk_type.write(w)
+	}
+}
+
+impl Readable for PaidBolt12Invoice {
+	fn read<R: lightning::io::Read>(r: &mut R) -> Result<Self, DecodeError> {
+		let ldk_type = LdkPaidBolt12Invoice::read(r)?;
+		Ok(ldk_type.into())
+	}
+}
+
 uniffi::custom_type!(OfferId, String, {
 	remote,
 	try_lift: |val| {

tests/common/mod.rs

@@ -953,7 +953,17 @@ pub(crate) async fn do_channel_full_cycle<E: ElectrumApi>(
 	});
 	assert_eq!(inbound_payments_b.len(), 1);
 
-	expect_event!(node_a, PaymentSuccessful);
+	// Verify bolt12_invoice is None for BOLT11 payments
+	match node_a.next_event_async().await {
+		ref e @ Event::PaymentSuccessful { ref bolt12_invoice, .. } => {
+			println!("{} got event {:?}", node_a.node_id(), e);
+			assert!(bolt12_invoice.is_none(), "bolt12_invoice should be None for BOLT11 payments");
+			node_a.event_handled().unwrap();
+		},
+		ref e => {
+			panic!("{} got unexpected event!: {:?}", std::stringify!(node_a), e);
+		},
+	}
 	expect_event!(node_b, PaymentReceived);
 	assert_eq!(node_a.payment(&payment_id).unwrap().status, PaymentStatus::Succeeded);
 	assert_eq!(node_a.payment(&payment_id).unwrap().direction, PaymentDirection::Outbound);

tests/integration_tests_rust.rs

@@ -1089,7 +1089,19 @@ async fn simple_bolt12_send_receive() {
 		.send(&offer, expected_quantity, expected_payer_note.clone(), None)
 		.unwrap();
 
-	expect_payment_successful_event!(node_a, Some(payment_id), None);
+	let event = node_a.next_event_async().await;
+	match event {
+		ref e @ Event::PaymentSuccessful { payment_id: ref evt_id, ref bolt12_invoice, .. } => {
+			println!("{} got event {:?}", node_a.node_id(), e);
+			assert_eq!(*evt_id, Some(payment_id));
+			assert!(
+				bolt12_invoice.is_some(),
+				"bolt12_invoice should be present for BOLT12 payments"
+			);
+			node_a.event_handled().unwrap();
+		},
+		ref e => panic!("{} got unexpected event!: {:?}", "node_a", e),
+	}
 	let node_a_payments =
 		node_a.list_payments_with_filter(|p| matches!(p.kind, PaymentKind::Bolt12Offer { .. }));
 	assert_eq!(node_a_payments.len(), 1);