Weekly Check-in: Week of 2026-04-20

[payjoin-bot]

Weekly standup — each contributor has a thread below with auto-gathered activity.

Reply to your thread by end-of-day Monday (your timezone). Copy the template below and fill it in:

### Shipped
<!-- Add anything the bot missed: design work, specs, conversations, off-GitHub contributions. Correct any mistakes. Skip if the bot covered everything. -->

### Focus
What are you working on this week?

### Bottleneck
What is the single biggest bottleneck in progress toward your greater goal?
Name your goal. Name the constraint. Name who or what can unblock it.

Participated: @DanGould, @spacebear21, @arminsabouri, @chavic, @Mshehu5, @0xZaddyy

[payjoin-bot]

DanGould

@DanGould

Shipped

PRs reviewed:

• Use internal Url struct in favor of url::Url to minimize the url dep in payjoin
• Receive cancel()
• Properly format history timestamp

Last Week

Review your previous thread: Last week's thread

[DanGould]

Shipped

Last week I made really significant progress internally so I have a lot more freedom to come back to code world. Feels like a weight off my shoulders.

Focus

• I want to enable people to call on @payjoin-bot because right now not everyone has the ability to take advantage even if they're contributing a ton
• I want to test some payjoins. Bull Bitcoin/Cake/BTCPayServer/Boltz/Liana are all in an almost-there limbo and I think we can get Bull Bitcoin working.
• If our reference implementation doesn't inform what we actually do with the Bull Bitcoin Mobile it should reflect that.

Bottleneck

I think my bottleneck is information on what I can review to unblock or what my eyes specifically would help make a decision where otherwise there's a lack of clarity.

[payjoin-bot]

spacebear21

@spacebear21

Shipped

PRs merged:

• Expose standard Rust traits on FFI error types

PRs reviewed:

• Handle Retry-After header for 429 and 503 in gateway prober
• Remove amount assert in pjuri fuzzer
• Expose Receiver Error Kinds
• Expose V2 Transport Error Kinds
• Unify mailbox TTL to a single value
• Disable reqwest dep when _manual-tls is enabled in the payjoin crate

Last Week

Review your previous thread: Last week's thread

[spacebear21]

Shipped

• Receive cancel() #1470

Focus

• Wrangling BBM upgrade and fixing dart bindings issues as they come up, e.g. Expose standard Rust traits on FFI error types #1485 and Implement native http.fetchOhttpKeys in dart #1495. Also stumbled upon

  rust-payjoin/payjoin-ffi/src/receive/mod.rs

  Line 483 in b39d0b4

  .assume_checked();

  which I'm not sure is safe, we probably need to pass and validate a network parameter for receiver address.

Bottleneck

• Reviewing lots of LLM slop, I probably need to revise my workflow to minimize this burden

[DanGould]

state transition upgrade review by @xstoicunicornx also in here this week

[payjoin-bot]

arminsabouri

@arminsabouri

Shipped

PRs merged:

• Clean up
• Decompose unilateral actions
• Tip to depth
• Migrate partitions code and tests

PRs reviewed:

• Return output type from abstract types and handles
• Demonstrate failure handling with fallback TX broadcast
• Add RoundNumberHeuristics for change identification
• Implement JoinMarket n_locktime Coinjoin detection
• Properly format history timestamp
• Implement script type matching change heuristic
• Fix all clippy warnings across the codebase
• Remove unneeded http feature via the bhttp dep in payjoin-mailroom
• Split resume session relays

Issues opened:

• actions use both walletview and mut wallet handle
• Migrate parts of https://github.com/0xB10C/rawtx-rs to this repo
• input/output handle/abstract types should return output type
• Return non-conclusive change in output type checks

Last Week

Review your previous thread: Last week's thread

Auto-detected signals:

• PR awaiting review: Exclude miner coins from graphviz
• PR awaiting review: Remove WalletView infavor of individual methods
• PR awaiting review: Dense storage improvments
• PR has requested changes: Add semi-honest overview

[arminsabouri]

Focus:

• interface design for privacy metrics that will plug into the meta cost function. The interface is the tricky part. One the interface looks good enough (works at least with a intra-tx measure e.g subset sum bruteforce) we can start experimenting with other metrics. This work has involved refactoring lots actions and strategy internals. Pr for this is coming soon
• Add honest overview multiparty-protocol-docs#4 <- ressurecting this document and getting it into a reviewable state
• Refactored the dense indexing interface a bit (covered above). This API was half-hazardly put together and confusing other contributors.

Blockers:

• I've become a review bottle neck. Getting others comfortable with reviewing each others PRs
• Still doing too much at the same time. Hoping to wrap up the the interface design work soon -> get it into others hands for review -> then write!

[payjoin-bot]

benalleng

@benalleng

Shipped

PRs merged:

• Disable reqwest dep when _manual-tls is enabled in the payjoin crate
• Remove unneeded http feature via the bhttp dep in payjoin-mailroom
• Remove amount assert in pjuri fuzzer

PRs reviewed:

• Expose standard Rust traits on FFI error types
• docs: clarify bech32 uppercase assertion TODO

Issues opened:

• Should we expose a sync version of fetch_ohttp_keys?
• Should the _manual-tls feature include enabling reqwest?
• Should we be opinionated about the actual amount value
• bip21 with amount greater than MAX_MONEY does not produce a parse error

Last Week

Review your previous thread: Last week's thread

[benalleng]

Shipped

• Finished Use internal Url struct in favor of url::Url to minimize the url dep in payjoin #1377

Focus

• Pushing forward the liana receiver Pr [WIP] Payjoin receiver wizardsardine/liana#2011 with some great feedback from @xstoicunicornx
  • With Receive cancel() #1470 merged I can add this to the delete function in the PSBT page

Bottleneck

• Just classic code throughput on the Liana PR. Though I think early this week it would be helpful to walk through a Payjoin flow at a high level to get some better architecture plans for what else is needed

[DanGould]

regarding the fuzzer this discussion might be useful rust-bitcoin/rust-bitcoin#5315

[payjoin-bot]

chavic

@chavic

Shipped

No activity found.

Last Week

Review your previous thread: Last week's thread

[chavic]

Shipped:

• Opened the BTC checkout model seam PR for the BTCPay Payjoin Plugin — moves Payjoin BTC checkout ownership into BTCPay's payment-method checkout seam instead of patching Vue state post-render. Adds
  PayjoinBitcoinCheckoutModelExtension, routes URL generation through the existing Payjoin payment URL service, removes the old mutation view, and adds unit + Docker-backed integration coverage for the checkout controller
  path. (Add PayJoin checkout model support and payment toggle chavic/btcpayserver-payjoin-plugin#3)
• Continued pushing the session-persistence PR upstream with follow-up updates. (Persist payjoin receiver sessions across restarts ValeraFinebits/btcpayserver-payjoin-plugin#6, Persist payjoin receiver sessions across restarts chavic/btcpayserver-payjoin-plugin#1)
• Feedback on closed PRs from the error-surface stack (Expose Receiver Error Kinds #1428, Expose V2 Transport Error Kinds #1431, Expose Sender Input Index #1432, Expose Receiver Modification Errors #1433) — closed due to exposing too much information that implementers may not need. Three remain open.
  (Expose JSON reply accessors #1427, Preserve Persisted Error Classification #1429, Expose Retryability Metadata #1430)
• Reviewed and approved CodeQL analysis workflow configuration for the BTCPay plugin (merged). (Add CodeQL analysis workflow configuration ValeraFinebits/btcpayserver-payjoin-plugin#7)
• Reviewed payjoin-cli integration test utilities for the BTCPay plugin (merged). (test: Add payjoin-cli integration test utilities ValeraFinebits/btcpayserver-payjoin-plugin#5)
• Made a branch to unblock the Cake Wallet issue to upgrade payjoin bindings from payjoin_flutter to payjoin_ffi — tracking the migration to the stabilized 0.25/1.0-rc API. (Upgrade payjoin bindings to use payjoin_ffi cake-tech/cake_wallet#3173), still need to consider implications of version switching and ensure no one depends on newer Dart versions for an important reason before creating PR.

Focus:

• Finish live restart/replay validation proving a real negotiation survives a restart — the code for session persistence is in place but the end-to-end proof is still missing.
  (Persist payjoin receiver sessions across restarts ValeraFinebits/btcpayserver-payjoin-plugin#6)
• Land the BTC checkout model seam through review and testing. (Add PayJoin checkout model support and payment toggle chavic/btcpayserver-payjoin-plugin#3)
• Clear or close the remaining three error-surface PRs. (Expose JSON reply accessors #1427, Preserve Persisted Error Classification #1429, Expose Retryability Metadata #1430)
• Considering the C++ integrations setup, as this was due to this month

Blockers:

• Review bandwidth on the rust-payjoin error-surface PRs — three still open with no movement.

[payjoin-bot]

zealsham

@zealsham

Shipped

No activity found.

Last Week

Review your previous thread: Last week's thread

Auto-detected signals:

• PR has requested changes: OHTTP keys should be rotated
• PR has requested changes: Request size limiter
• PR has requested changes: Demonstrate failure handling with fallback TX broadcast
• PR has requested changes: Add config saving to payjoin-cli

[DanGould]

Zealsham's computer got hosed last week fyi for anyone tuning in. Gonna be a minute til he's back online

[payjoin-bot]

Mshehu5

@Mshehu5

Shipped

PRs merged:

• Return output type from abstract types and handles
• Implement script type matching change heuristic

PRs reviewed:

• Remove WalletView infavor of individual methods
• Exclude miner coins from graphviz
• Dense storage improvments
• Tip to depth
• Clean up
• Fix all clippy warnings across the codebase

Issues opened:

• mark change as inconclusive using the variant from #48

Last Week

Review your previous thread: Last week's thread

[Mshehu5]

Shippped :
on bdk-cli made some requested changes from maintainer .
got comments from maintainer that changes have been addressed just require some final testing and PR is ready to go : bitcoindevkit/bdk-cli#242 (review)

Focus:
Finding out why signet indexing in tx-indexer is failing
Make plans with armin for priority changes for Demo talk on tx-indexer and implement

[payjoin-bot]

0xZaddyy

@0xZaddyy

Shipped

PRs merged:

• Fix all clippy warnings across the codebase

PRs reviewed:

• Remove WalletView infavor of individual methods
• Decompose unilateral actions
• Tip to depth

Issues opened:

• Resolve Clippy warnings in preparation for tx-indexer migration

Last Week

Review your previous thread: Last week's thread

Auto-detected signals:

• PR has requested changes: Add RoundNumberHeuristics for change identification

[0xZaddyy]

Focus

• Review PRs
• continue more work around multiparty
• sync with the team

[xstoicunicornx]

Shipped

PRs Reviewed:

• Use internal Url struct in favor of url::Url to minimize the url dep in payjoin #1377 (x2)
• Remove amount assert in pjuri fuzzer #1480
• Remove unneeded http feature via the bhttp dep in payjoin-mailroom #1481

Focus

• Re-review [WIP] Payjoin receiver wizardsardine/liana#2011
• Completing BOSS grant info form
• Continue delving into multiparty topics

Bottleneck

• Traveling until April 22

[ValeraFinebits]

Shipped

PRs opened:

• test: prepare payjoin-cli integration test harness (skipped for CI) ValeraFinebits/btcpayserver-payjoin-plugin#8

PRs reviewed:

• Persist payjoin receiver sessions across restarts ValeraFinebits/btcpayserver-payjoin-plugin#6
• Add Payjoin artifact freshness tooling chavic/btcpayserver-payjoin-plugin#2
• Add PayJoin checkout model support and payment toggle chavic/btcpayserver-payjoin-plugin#3

Focus

• Continue adding payjoin-cli-based tests to the integration test suite.
• Investigate C++ bindings for payjoin_ffi.
• Continue reviewing PRs.

[DanGould]

I Imagine the tests will take inspiration from the work @benalleng did with Bull Bitcoin, is that the plan or something else?

[ValeraFinebits]

I Imagine the tests will take inspiration from the work @benalleng did with Bull Bitcoin, is that the plan or something else?

I haven't looked at the Bull Bitcoin work.

My goal here was to make the plugin tests more reliable and closer to real usage, so I integrated payjoin-cli as an external payer, with the plugin under test acting as the receiver.

[bc1cindy]

Shipped

I've been hyper focusing on this project ( https://github.com/bc1cindy/dense-subset-sum ) to find necessary answers to the cost function, with @nothingmuch

this week I'll also focus on reviews and on this open PR payjoin/tx-indexer#26

[caarloshenriq]

Shipped

PRs opened:

• fix(test): remove payjoin-ffi from root CRATES and update ffi test script #1492

PRs reviewed:

• Expose standard Rust traits on FFI error types #1485
• Remove unneeded http feature via the bhttp dep in payjoin-mailroom #1481
• Fix clippy::question_mark warnings in FFI load() impls #1491

Focus

• Continue reviewing PRs