Add Payjoin Receiver Support (BIP 77) by Camillarhi · Pull Request #746 · lightningdevkit/ldk-node

Camillarhi · 2026-01-08T19:24:00Z

This PR adds support for receiving payjoin payments in LDK Node. This is currently a work in progress and implements the receiver side of the payjoin protocol.

Add session store for persisting payjoin receiver events across restarts
Implement KVStorePayjoinReceiverPersister to handle session persistence
Add Payjoin as a PaymentKind to the payment store
Add event polling mechanism for active payjoin sessions
Wire up payjoin payment request and receive flows

Note on persistence: The payjoin library currently only supports synchronous persistence, but they're working on adding async support(payjoin/rust-payjoin#1235). This PR sets up the persistence structure (KVStorePayjoinReceiverPersister), which will be updated to use async operations once the upstream PR is merged.

This PR will partially address #177

ldk-reviews-bot · 2026-01-08T19:24:03Z

👋 Thanks for assigning @tnull as a reviewer!
I'll wait for their review and will help manage the review process.
Once they submit their review, I'll check if a second reviewer would be helpful.

DanGould · 2026-01-23T03:51:53Z

We've merged the async persistence PR you mentioned. You might want to build your draft PR on the merged commit from there on until we cut you a release.

Camillarhi · 2026-01-23T12:48:54Z

We've merged the async persistence PR you mentioned. You might want to build your draft PR on the merged commit from there on until we cut you a release.

Thanks for letting me know. I'll build on the merged commit.

DanGould · 2026-02-10T07:14:04Z

Are you stuck? Did something in our library break CI @Camillarhi

Camillarhi · 2026-02-10T07:33:02Z

Are you stuck? Did something in our library break CI @Camillarhi

Not stuck at all. I was just closing out some other PRs. Still working on this one, I'll let you know when it's ready.

Camillarhi · 2026-03-12T09:50:36Z

Marking this as ready for review.

The core receiver flow is implemented, including session persistence, PSBT handling, input contribution, mempool monitoring for payjoin transactions, and node restart recovery.

Two things still pending that I'll follow up with:

Integration tests
Processing/updating confirmation state for payjoin transactions in the payment and pending payment stores

Happy to get early feedback on the overall approach in the meantime.

@tnull @DanGould

ldk-reviews-bot · 2026-03-30T10:50:59Z

🔔 3rd Reminder

Hey @zealsham @spacebear21 @bc1cindy! This PR has been waiting for your review.
Please take a look when you have a chance. If you're unable to review, please let us know so we can find another reviewer.

ldk-reviews-bot · 2026-03-30T10:52:00Z

🔔 3rd Reminder

Hey @zealsham @spacebear21 @bc1cindy! This PR has been waiting for your review.
Please take a look when you have a chance. If you're unable to review, please let us know so we can find another reviewer.

Implements the receiver side of the BIP 77 Payjoin v2 protocol, allowing LDK Node users to receive payjoin payments via a payjoin directory and OHTTP relay. - Adds a `PayjoinPayment` handler exposing a `receive()` method that returns a BIP 21 URI the sender can use to initiate the payjoin flow. The full receiver state machine is implemented covering all `ReceiveSession` states: polling the directory, validating the sender's proposal, contributing inputs, finalizing the PSBT, and monitoring the mempool. - Session state is persisted via `KVStorePayjoinReceiverPersister` and survives node restarts through event log replay. Sender inputs are tracked by `OutPoint` across polling attempts to prevent replay attacks. The sender's fallback transaction is broadcast on cancellation or failure to ensure the receiver still gets paid. - Adds `PaymentKind::Payjoin` to the payment store, `PayjoinConfig` for configuring the payjoin directory and OHTTP relay via `Builder::set_payjoin_config`, and background tasks for session resumption every 15 seconds and cleanup of terminal sessions after 24 hours.

ldk-reviews-bot · 2026-04-01T00:01:56Z

🔔 6th Reminder