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Review: Add currency conversion support for BOLT 12 offers #10

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341de05
[feat] Introduce the CurrencyConversion trait
shaavan May 15, 2026
4ecf4bd
[plumb] Thread CurrencyConversion through ChannelManager
shaavan May 16, 2026
9fab1ed
[plumb] Thread CurrencyConversion through offer builders
shaavan May 16, 2026
dff5758
[feat/test] Allow currency-denominated amounts in OfferBuilder
shaavan May 16, 2026
da5290d
[feat/test] Allow invoice requests for currency-denominated offers
shaavan May 16, 2026
4b5bac4
[refactor] Separate explicit and derived InvoiceRequest amounts
shaavan May 15, 2026
ba5432c
[plumb] Thread currency conversion through InvoiceBuilder
shaavan May 16, 2026
811a0d3
[feat] Introduce currency conversion support for InvoiceBuilder
shaavan May 19, 2026
41b267a
[test] Cover currency-denominated offer invoice responses
shaavan May 16, 2026
325c6dd
[feat] Verify invoice amounts for currency-denominated offers
shaavan May 17, 2026
45fdf6c
[test] Cover currency-denominated invoice verification paths
shaavan May 20, 2026
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13 changes: 13 additions & 0 deletions fuzz/src/full_stack.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,9 @@ use lightning::ln::peer_handler::{
};
use lightning::ln::script::ShutdownScript;
use lightning::ln::types::ChannelId;
use lightning::offers::currency::CurrencyConversion;
use lightning::offers::invoice::UnsignedBolt12Invoice;
use lightning::offers::offer::CurrencyCode;
Comment on lines +54 to +56
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@coderabbitai coderabbitai Bot May 20, 2026

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⚠️ Potential issue | 🔴 Critical | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "== CurrencyConversion trait signature =="
rg -n "trait CurrencyConversion|fn conversion_range" lightning/src/offers/currency.rs -A4 -B2

echo
echo "== Imports in fuzz/src/full_stack.rs (currency-related) =="
sed -n '50,60p' fuzz/src/full_stack.rs

echo
echo "== FuzzCurrencyConversion impl snippet =="
sed -n '189,196p' fuzz/src/full_stack.rs

echo
echo "== Check for ExchangeRange import in fuzz/src/full_stack.rs =="
rg -n "use lightning::offers::currency::.*ExchangeRange" fuzz/src/full_stack.rs || true

Repository: shaavan/rust-lightning

Length of output: 1671

Add missing ExchangeRange import to resolve type resolution failure at line 192.

The conversion_range method implementation returns Result<ExchangeRange, ()> but ExchangeRange is not in scope. This is a compile blocker.

Proposed fix 
-use lightning::offers::currency::CurrencyConversion;
+use lightning::offers::currency::{CurrencyConversion, ExchangeRange};
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
use lightning::offers::currency::CurrencyConversion;
use lightning::offers::invoice::UnsignedBolt12Invoice;
use lightning::offers::offer::CurrencyCode;
use lightning::offers::currency::{CurrencyConversion, ExchangeRange};
use lightning::offers::invoice::UnsignedBolt12Invoice;
use lightning::offers::offer::CurrencyCode;
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@fuzz/src/full_stack.rs` around lines 54 - 56, The file is missing an import
for ExchangeRange which causes the return type Result<ExchangeRange, ()> in the
conversion_range function to be unresolved; add the appropriate use statement
(bring ExchangeRange into scope) so the conversion_range function compiles —
locate the conversion_range method in full_stack.rs and add a use for
ExchangeRange (from the same module as CurrencyConversion/CurrencyCode or the
offers::currency module) so the type name resolves.

use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath};
use lightning::routing::gossip::{NetworkGraph, P2PGossipSync};
use lightning::routing::router::{
Expand Down Expand Up @@ -184,6 +186,14 @@ impl MessageRouter for FuzzRouter {
}
}

struct FuzzCurrencyConversion {}

impl CurrencyConversion for FuzzCurrencyConversion {
fn conversion_range(&self, _currency: CurrencyCode) -> Result<ExchangeRange, ()> {
Err(())
}
}

struct TestBroadcaster {
txn_broadcasted: Mutex<Vec<Transaction>>,
}
Expand Down Expand Up @@ -239,6 +249,7 @@ type ChannelMan<'a> = ChannelManager<
Arc<FuzzEstimator>,
&'a FuzzRouter,
&'a FuzzRouter,
&'a FuzzCurrencyConversion,
Arc<dyn Logger + MaybeSend + MaybeSync>,
>;
type PeerMan<'a> = PeerManager<
Expand Down Expand Up @@ -548,6 +559,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger + MaybeSend + MaybeSync>
});
let fee_est = Arc::new(FuzzEstimator { input: input.clone() });
let router = FuzzRouter {};
let conversion = FuzzCurrencyConversion {};

macro_rules! get_slice {
($len: expr) => {
Expand Down Expand Up @@ -613,6 +625,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger + MaybeSend + MaybeSync>
broadcast.clone(),
&router,
&router,
&conversion,
Arc::clone(&logger),
keys_manager.clone(),
keys_manager.clone(),
Expand Down
3 changes: 2 additions & 1 deletion fuzz/src/invoice_request_deser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ use lightning::blinded_path::payment::{
};
use lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA;
use lightning::ln::inbound_payment::ExpandedKey;
use lightning::offers::currency::NullCurrencyConversion;
use lightning::offers::invoice::UnsignedBolt12Invoice;
use lightning::offers::invoice_request::{InvoiceRequest, InvoiceRequestFields};
use lightning::offers::offer::OfferId;
Expand Down Expand Up @@ -144,7 +145,7 @@ fn build_response<T: secp256k1::Signing + secp256k1::Verification>(
.unwrap();

let payment_hash = PaymentHash([42; 32]);
invoice_request.respond_with(vec![payment_path], payment_hash)?.build()
invoice_request.respond_with(&NullCurrencyConversion, vec![payment_path], payment_hash)?.build()
}

pub fn invoice_request_deser_test<Out: test_logger::Output>(data: &[u8], out: Out) {
Expand Down
3 changes: 2 additions & 1 deletion fuzz/src/refund_deser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ use lightning::blinded_path::payment::{
PaymentForwardNode, PaymentRelay, ReceiveTlvs,
};
use lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA;
use lightning::offers::currency::NullCurrencyConversion;
use lightning::offers::invoice::UnsignedBolt12Invoice;
use lightning::offers::parse::Bolt12SemanticError;
use lightning::offers::refund::Refund;
Expand Down Expand Up @@ -109,7 +110,7 @@ fn build_response<T: secp256k1::Signing + secp256k1::Verification>(
.unwrap();

let payment_hash = PaymentHash([42; 32]);
refund.respond_with(vec![payment_path], payment_hash, signing_pubkey)?.build()
refund.respond_with(&NullCurrencyConversion, vec![payment_path], payment_hash, signing_pubkey)?.build()
}

pub fn refund_deser_test<Out: test_logger::Output>(data: &[u8], out: Out) {
Expand Down
8 changes: 8 additions & 0 deletions lightning-background-processor/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -378,6 +378,9 @@ type DynMessageRouter = lightning::onion_message::messenger::DefaultMessageRoute
&'static (dyn EntropySource + Send + Sync),
>;

#[cfg(not(c_bindings))]
type DynCurrencyConversion = lightning::offers::currency::NullCurrencyConversion;

#[cfg(not(c_bindings))]
type DynSignerProvider = dyn lightning::sign::SignerProvider<EcdsaSigner = lightning::sign::InMemorySigner>
+ Send
Expand All @@ -393,6 +396,7 @@ type DynChannelManager = lightning::ln::channelmanager::ChannelManager<
&'static (dyn FeeEstimator + Send + Sync),
&'static DynRouter,
&'static DynMessageRouter,
&'static DynCurrencyConversion,
&'static (dyn Logger + Send + Sync),
>;

Expand Down Expand Up @@ -1949,6 +1953,7 @@ mod tests {
IgnoringMessageHandler, MessageHandler, PeerManager, SocketDescriptor,
};
use lightning::ln::types::ChannelId;
use lightning::offers::currency::NullCurrencyConversion;
use lightning::onion_message::messenger::{DefaultMessageRouter, OnionMessenger};
use lightning::routing::gossip::{NetworkGraph, P2PGossipSync};
use lightning::routing::router::{CandidateRouteHop, DefaultRouter, Path, RouteHop};
Expand Down Expand Up @@ -2044,6 +2049,7 @@ mod tests {
Arc<KeysManager>,
>,
>,
Arc<NullCurrencyConversion>,
Arc<test_utils::TestLogger>,
>;

Expand Down Expand Up @@ -2468,6 +2474,7 @@ mod tests {
Arc::clone(&network_graph),
Arc::clone(&keys_manager),
));
let conversion = Arc::new(NullCurrencyConversion);
let chain_source = Arc::new(test_utils::TestChainSource::new(Network::Bitcoin));
let kv_store =
Arc::new(Persister::new(format!("{}_persister_{}", &persist_dir, i).into()));
Expand All @@ -2494,6 +2501,7 @@ mod tests {
Arc::clone(&tx_broadcaster),
Arc::clone(&router),
Arc::clone(&msg_router),
Arc::clone(&conversion),
Arc::clone(&logger),
Arc::clone(&keys_manager),
Arc::clone(&keys_manager),
Expand Down
6 changes: 5 additions & 1 deletion lightning-block-sync/src/init.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@ where
/// use lightning::chain::chaininterface::BroadcasterInterface;
/// use lightning::chain::chaininterface::FeeEstimator;
/// use lightning::ln::channelmanager::{ChannelManager, ChannelManagerReadArgs};
/// use lightning::offers::currency::CurrencyConversion;
/// use lightning::onion_message::messenger::MessageRouter;
/// use lightning::routing::router::Router;
/// use lightning::sign;
Expand All @@ -74,6 +75,7 @@ where
/// F: FeeEstimator,
/// R: Router,
/// MR: MessageRouter,
/// CC: CurrencyConversion,
/// L: Logger,
/// C: chain::Filter,
/// P: chainmonitor::Persist<SP::EcdsaSigner>,
Expand All @@ -88,6 +90,7 @@ where
/// fee_estimator: &F,
/// router: &R,
/// message_router: &MR,
/// currency_conversion: &CC,
/// logger: &L,
/// persister: &P,
/// ) {
Expand All @@ -108,11 +111,12 @@ where
/// tx_broadcaster,
/// router,
/// message_router,
/// currency_conversion,
/// logger,
/// config,
/// vec![&mut monitor],
/// );
/// <(BestBlock, ChannelManager<&ChainMonitor<SP::EcdsaSigner, &C, &T, &F, &L, &P, &ES>, &T, &ES, &NS, &SP, &F, &R, &MR, &L>)>::read(
/// <(BestBlock, ChannelManager<&ChainMonitor<SP::EcdsaSigner, &C, &T, &F, &L, &P, &ES>, &T, &ES, &NS, &SP, &F, &R, &MR, &CC, &L>)>::read(
/// &mut Cursor::new(&serialized_manager), read_args).unwrap()
/// };
///
Expand Down
19 changes: 16 additions & 3 deletions lightning/src/ln/async_payments_tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ use crate::offers::async_receive_offer_cache::{
TEST_INVOICE_REFRESH_THRESHOLD, TEST_MAX_CACHED_OFFERS_TARGET, TEST_MAX_UPDATE_ATTEMPTS,
TEST_MIN_OFFER_PATHS_RELATIVE_EXPIRY_SECS, TEST_OFFER_REFRESH_THRESHOLD,
};
use crate::offers::currency::NullCurrencyConversion;
use crate::offers::flow::{
TEST_DEFAULT_ASYNC_RECEIVE_OFFER_EXPIRY, TEST_OFFERS_MESSAGE_REQUEST_LIMIT,
TEST_TEMP_REPLY_PATH_RELATIVE_EXPIRY,
Expand Down Expand Up @@ -322,7 +323,11 @@ fn create_static_invoice<T: secp256k1::Signing + secp256k1::Verification>(
let (offer_builder, offer_nonce) = recipient
.node
.flow
.create_async_receive_offer_builder(entropy_source, blinded_paths_to_always_online_node)
.create_async_receive_offer_builder(
entropy_source,
&NullCurrencyConversion,
blinded_paths_to_always_online_node,
)
.unwrap();
let offer = offer_builder.build().unwrap();
let static_invoice =
Expand Down Expand Up @@ -693,7 +698,11 @@ fn static_invoice_unknown_required_features() {
let (offer_builder, nonce) = nodes[2]
.node
.flow
.create_async_receive_offer_builder(entropy_source, blinded_paths_to_always_online_node)
.create_async_receive_offer_builder(
entropy_source,
&NullCurrencyConversion,
blinded_paths_to_always_online_node,
)
.unwrap();
let offer = offer_builder.build().unwrap();
let static_invoice_unknown_req_features =
Expand Down Expand Up @@ -1677,7 +1686,11 @@ fn invalid_async_receive_with_retry<F1, F2>(
let (offer_builder, offer_nonce) = nodes[2]
.node
.flow
.create_async_receive_offer_builder(entropy_source, blinded_paths_to_always_online_node)
.create_async_receive_offer_builder(
entropy_source,
&NullCurrencyConversion,
blinded_paths_to_always_online_node,
)
.unwrap();
let offer = offer_builder.build().unwrap();
let amt_msat = 5000;
Expand Down
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