Weekly Check-in: Week of 2026-04-27

[payjoin-bot]

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

🆕 type /check-in as a comment to have the @payjoin-bot auto-discover your contributions to the best of its ability as a response.

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: @spacebear21, @chavic, @zealsham, @Mshehu5

[payjoin-bot]

DanGould

@DanGould

Shipped

PRs reviewed:

• Expose JSON reply accessors
• Add safe catch-all for secp256k1::Error conversion in HpkeError
• Receive cancel()
• Use internal Url struct in favor of url::Url to minimize the url dep in payjoin

Issues opened:

• Nix flake installs dart 3.9.4, but uniffi-dart requires 3.10 minimum

Last Week

Review your previous thread: Last week's thread

Auto-detected signals:

• PR awaiting review: Add comment-triggered activity collection to payjoin-bot

[DanGould]

Shipped

• Add comment-triggered activity collection to payjoin-bot #1503 shipped now, woo hoo. @xstoicunicornx mentioned links could be posted raw and then github'd render them more nicely. Noting here
• Got an environment with Upgrade payjoin SatoshiPortal/bullbitcoin-mobile#2041 running

Focus

• get Upgrade payjoin SatoshiPortal/bullbitcoin-mobile#2041 in a shippable state. I think we've got hand off sorted
• Write a monthly letter

Bottleneck

Dart environment was not reproducible. I think it's close now. Hoping @benalleng might be able to step in a bit while @spacebear21 is out of office

[payjoin-bot]

spacebear21

@spacebear21

Shipped

PRs merged:

• Sync main readme
• Prepare v0.2.0+v0.31.1 release
• Prepare v0.1.1+v0.30.0 release
• Update release process
• Fix HTTP error handling in payjoin-cli
• Send cancel()

PRs reviewed:

• fix(test): remove payjoin-ffi from root CRATES and update ffi test script
• feat: uniffi 0.31
• Update use of deprecated from_sat_per_vb_unchecked
• Fix send success log error and order
• Add safe catch-all for secp256k1::Error conversion in HpkeError
• Use internal Url struct in favor of url::Url to minimize the url dep in payjoin

Issues opened:

• Release v0.2.0+v0.31.0
• Release v0.1.1+v0.30.0

Last Week

Review your previous thread: Last week's thread

Auto-detected signals:

• PR awaiting review: Update Dart fetchOhttpKeys to support https

[spacebear21]

PR opened:

• Upgrade payjoin SatoshiPortal/bullbitcoin-mobile#2041
  • status: it compiles but tests are failing. Update Dart fetchOhttpKeys to support https #1500 is a working fix for fetchOhttpKeys errors (tls-in-tls is not supported in native dart io libraries). another set of errors are caused by uniffi-dart callback methods not supporting cross-isolate calls (this limitation appears to be a uniffi-rs one). i think this is fixable by removing the isolates architecture entirely from the bbm payjoin integration, they should not longer be needed now that we dropped flutter-rust-bridge.

Focus/Blocker:

• BTC conf this week, will be afk most of the time

[payjoin-bot]

arminsabouri

@arminsabouri

Shipped

PRs merged:

• Remove WalletView infavor of individual methods
• Dense storage improvments

PRs reviewed:

• Add RoundNumberChangeHeuristics for change identification
• Add decimal_hamming_weight utility with test coverage
• Fix HTTP error handling in payjoin-cli
• Fix signet indexing

Issues opened:

• Keep graph traversal indecies (tx_out_end / tx_in_end) in memory during build
• Mapping bitcoin::txid to dense::txid is a bottleneck
• Eliminate random seek-writes to out_spent.bin during index build
• Caching AST node results
• Change Clustering Bundle

Last Week

Review your previous thread: Last week's thread

Auto-detected signals:

• PR awaiting review: Return txids as an iterator
• PR awaiting review: Mmap index files
• PR awaiting review: Privacy bundle interface
• PR has requested changes: Add semi-honest overview

[arminsabouri]

Focus:

• Split semi-honest concrete overview into honest + semi-honest. Next step is to pair review with nothingmuch -> create tracking issue and POC semi-honest (at first with no cost function. Once we are happy with the txstructures in the simulations then we will introduce privacy metrics which can be thought of as a generalization of the 2p coinselection algo).
• Privacy bundle interface  btsim#27 has taken a backseat while I worked on writing.
• Ressurected psbt-lattice library last week in preperation for a mp pj POCs. Nothingmuch is working on some further refactors and getting us feature complete
• Refining Shehue + Damola 's talk proposal at BTC++ Kenya. Focused on clustering, intersection attacks and the work we are doing around privacy metrics and txindexer.
• Ticketing analysis pass and indexing optimizations before I forget them.
• Reviewing pdk prs where I can Guard concurrent sends with exclusive DB lock and URI/RK checks #1376 Add comment-triggered activity collection to payjoin-bot #1503 Demonstrate failure handling with fallback TX broadcast #1164

Blockers:

• Follow up on last week: contributors are reviewing each others work. I am less of a review burden. That is going well.
• Its always been difficult to know what the stopping condition of the cost function work is. i.e how do we know its good enough in terms of the interface or output. My new strategy is to build / ticket out the protocol work first and iterate on the cost function when it is needed.

[payjoin-bot]

benalleng

@benalleng

Shipped

PRs merged:

• Update use of deprecated from_sat_per_vb_unchecked
• Use internal Url struct in favor of url::Url to minimize the url dep in payjoin

PRs reviewed:

• Non-blocking Interface for Payjoin State Machine
• Send cancel()

Issues opened:

• cancel() should probably return an Option(Transaction)

Last Week

Review your previous thread: Last week's thread

[benalleng]

Focus

• More cycles on [WIP] Payjoin receiver wizardsardine/liana#2011 I think it is getting very close though, there are a few primary things left but it is close
  • integration tests and the associated test utils
  • Some QA on the current error handling
• I need to sit down and write the press release announcing my grant renewal. I received this request "We want a really high quality and detailed press release this time of possible."

Bottleneck

• Just some pure how quickly can I type/prompt/code what I want in the PR. @xstoicunicornx has been super helpful with review unblocking me on that front now its up to me to get it coded.

[benalleng]

With Spacebear away this week once I resolve most of the comments from the current review cycle in liana I will shift some focus to getting the dart PR SatoshiPortal/bullbitcoin-mobile#2041 moving along

[payjoin-bot]

chavic

@chavic

Shipped

No activity found.

Last Week

Review your previous thread: Last week's thread

[chavic]

Shipped:

Reviewed and merged PRs in the BTCPay Payjoin plugin:

• RunTestPaymentService and self-pay checks . (refactor: Add RunTestPaymentService and self-pay checks ValeraFinebits/btcpayserver-payjoin-plugin#4)
• payjoin-cli integration test harness, skipped for CI. (test: prepare payjoin-cli integration test harness (skipped for CI) ValeraFinebits/btcpayserver-payjoin-plugin#8)
• todo.md documentation update. (doc: update todo ValeraFinebits/btcpayserver-payjoin-plugin#11)
• Alpha Release Checklist added to `todo.md. (Add Alpha Release Checklist to todo.md ValeraFinebits/btcpayserver-payjoin-plugin#12)
• Close-requested session lifecycle handling — under review. (feat: handle close-requested sessions ValeraFinebits/btcpayserver-payjoin-plugin#9)
• Merged the contributor-facing todo.md into the shared upstream repo — repo-local Milestone 1/2/3 tracker that any contributor can read without private planning context. (Add contributor-facing plugin TODO ValeraFinebits/btcpayserver-payjoin-plugin#10)

Filed Issue and progress with PRs in BTCPay Payjoin plugin:

• Filed a bug on PayjoinReceiverPoller that logs ordinary OHTTP long-poll timeouts as warning-level "polling failed" entries while a receiver session is still in Initialized state. Proposes treating initialized poll timeouts separately from real relay failures so live validation logs become readable. (PayjoinReceiverPoller logs initialized OHTTP long-poll timeouts as repeated failures ValeraFinebits/btcpayserver-payjoin-plugin#17)
• BTC checkout model seam — added greenfield payjoin API endpoints, a checkout payjoin toggle, and made checkout URI parameters preserve through the seam; fixed checkout tests after a helper split. (Add PayJoin checkout model support and payment toggle chavic/btcpayserver-payjoin-plugin#3)
• Session persistence — covered receiver replay with persisted input, made the receiver session store database-authoritative while removing the _sync locking issue, (Persist payjoin receiver sessions across restarts chavic/btcpayserver-payjoin-plugin#1)

Updates from discussions:

• The rust-payjoin error-surface / FFI PR stack was wound down the three remaining open PRs (Expose JSON reply accessors #1427, Preserve Persisted Error Classification #1429, Expose Retryability Metadata #1430) were closed. The direction is that proper fallback handling should be demonstrated in the core library first (PR Demonstrate failure handling with fallback TX broadcast #1164) before deciding what needs to surface through FFI. (Expose JSON reply accessors #1427, Preserve Persisted Error Classification #1429, Expose Retryability Metadata #1430)
• Closed long-standing uniffi-dart PR Support all rust-bitcoin networks #83 (int-primitive BigInt refactor) after confirming the specific bound-checking fix had shipped via PR ci: remove workspace and fix to test lib with MSRV 1.57.0 #95 — kept the queue honest.
  (Refactored int primitives with BigInt support and bounds checking Uniffi-Dart/uniffi-dart#83)
• Engaged on the unifi-dart WASM target PR — encouraged the contributor and suggested splitting one commit into its own PR to keep review scope tight. (Add WASM web target support to uniffi-dart bindings Uniffi-Dart/uniffi-dart#126)

Focus:

• Drive session-persistence and BTC checkout seam to merge upstream, then have a demonstration of progress so far in a demo video (Persist payjoin receiver sessions across restarts ValeraFinebits/btcpayserver-payjoin-plugin#6), (Add PayJoin checkout model support and payment toggle chavic/btcpayserver-payjoin-plugin#3)
• Address the PayjoinReceiverPoller logging issue so live validation stops looking broken when the receiver is just waiting.
  (PayjoinReceiverPoller logs initialized OHTTP long-poll timeouts as repeated failures ValeraFinebits/btcpayserver-payjoin-plugin#17)
• Open the Cake Wallet payjoin bindings upgrade PR Dart version implications for bdk are settled. (Upgrade payjoin bindings to use payjoin_ffi cake-tech/cake_wallet#3173)
• Revisit the error-surface effort behind core-library fallback-handling (PR Demonstrate failure handling with fallback TX broadcast #1164), before thinking of the FFI surface
• Set up C++, currently low priority, but if time allows, would like to get this done this week

[DanGould]

@arminsabouri's gonna handle #1164 because he already has the context

[DanGould]

Open the Cake Wallet payjoin bindings upgrade PR Dart version implications for bdk are settled.

Issue wasn't made right away because of split between having/not having native assets. Need to make sure downgrade doesn't cause problems for bdk-dart and can otherwise be done in tandem with that team. It's ok to ship a hack for both payjoin AND bdk as specific commits/forks that cake runs. We can give them advice / working version without getting ourselves too far off the beaten path.

[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

[zealsham]

Finally setup my new PC

Focus

• OHTTP keys should be rotated #1449 . In the course of working on this a couple of privacy consigns has been raised by @nothingmuch, I think the compromises involve in letting this feature live are something the rest of the team needs to be aware of and debate on.

• Demonstrate failure handling with fallback TX broadcast #1164. almost complete and since Send cancel() #1496 is in already, i'll remove cancel here to prevent double fallback broadcast.

• Track unique shortids seen #1459.

• Request size limiter #1410. i'll like to know the verdict on this PR,

[zealsham]

@arminsabouri took over #1164 since #1449 has been my primary focus recently

[payjoin-bot]

Mshehu5

@Mshehu5

Shipped

PRs merged:

• Fix signet indexing

PRs reviewed:

• Return txids as an iterator
• Add decimal_hamming_weight utility with test coverage
• Dense storage improvments
• Remove WalletView infavor of individual methods

Issues opened:

• Improve memory usage with blk files streaming
• Fix signet indexing

Last Week

Review your previous thread: Last week's thread

[Mshehu5]

Focus

• picked backed up on the asmap relay selection issue need to get it in a PR ready state seems to have alot of moving parts, I'm trying to decide whats necessary and what's not
• continue with reviews and picking up issues on tx-indexer

[arminsabouri]

continue with reviews and picking up issues on tx-indexer

Do you have specific issues you are working on?

[Mshehu5]

for reviews I need to review payjoin/tx-indexer#36 and payjoin/tx-indexer#69

For issues : https://github.com/payjoin/tx-indexer/issues/72will probably pick up something else if I am done with this and the asmap PR

[payjoin-bot]

0xZaddyy

@0xZaddyy

Shipped

PRs merged:

• Add decimal_hamming_weight utility with test coverage

PRs reviewed:

• Return txids as an iterator
• Mmap index files

Issues opened:

• Exclude OP_RETURN outputs from change heuristics

Last Week

Review your previous thread: Last week's thread

Auto-detected signals:

• PR awaiting review: Exclude OP_RETURN outputs from change identification heuristics
• PR awaiting review: Add RoundNumberChangeHeuristics for change identification

[0xZaddyy]

Focus

1. Finish up

• Exclude OP_RETURN outputs from change identification heuristics tx-indexer#73
• Add RoundNumberChangeHeuristics for change identification tx-indexer#67

2. Review PRs
3. Sync with the team
4. Do more research work

[arminsabouri]

Any update on the sim migration?

Do more research work

Do you have specific items your working on?

[0xZaddyy]

Any update on the sim migration?

we have one more open PR, when that goes in.

Do you have specific items your working on?

i have some notes(also discussions like https://github.com/orgs/payjoin/discussions/411 and #365) that i have been spending my time on

[caarloshenriq]

/check-in

[payjoin-bot]

Shipped

No activity found.

Auto-detected signals:

• PR awaiting review: parallelize FFI language binding tests in contrib/test.sh

[caarloshenriq]

PRs merged:

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

PRs reviewed:

• Add max_fee_rate() method to Config to encapsulate default #1490
• Fix clippy::question_mark warnings in FFI load() impls #1491
• Add comment-triggered activity collection to payjoin-bot #1503

Focus

• Continue working on no_std implemention
• Continue reviewing PRs

[ValeraFinebits]

Shipped

PRs opened:

• feat: handle close-requested sessions ValeraFinebits/btcpayserver-payjoin-plugin#9
• fix: Add CheatModeRoute to RunTestPayment ValeraFinebits/btcpayserver-payjoin-plugin#13
• test: Add same-wallet payjoin integration test ValeraFinebits/btcpayserver-payjoin-plugin#14
• test: Enable integration tests for CI ValeraFinebits/btcpayserver-payjoin-plugin#15
• feat: use external payer for run test payment flow ValeraFinebits/btcpayserver-payjoin-plugin#16

PRs reviewed:

• Persist payjoin receiver sessions across restarts ValeraFinebits/btcpayserver-payjoin-plugin#6

Focus

• Continue working on the plugin.
• Continue reviewing PRs.

[bc1cindy]

@bc1cindy

Shipped

PRs merged:

• multiparty side project: Bootstrap crate with Transaction type bc1cindy/dense-subset-sum#8
• multiparty side project: Add Pearson, Spearman, median helpers bc1cindy/dense-subset-sum#9

PRs reviewed:

• Add decimal_hamming_weight utility with test coverage tx-indexer#48
• Fix signet indexing  tx-indexer#63
• Dense storage improvments tx-indexer#61
• Mmap index files tx-indexer#69
• Exclude OP_RETURN outputs from change identification heuristics tx-indexer#73
• Return txids as an iterator tx-indexer#74

PR awaiting review:

• Add HasBlockHeight and HasInputPrevOuts traits tx-indexer#75

Focus

• multiparty side project (dense-subset-sum)
• reviews
• coinjoin detection (tx-indexer)

[xstoicunicornx]

Shipped

• Reviewed [WIP] Payjoin receiver wizardsardine/liana#2011

Focus

• Investigating JsonSenderSessionPersister[Async] crashes WASM heap in real browsers #1508
• Finalizing Non-blocking Interface for Payjoin State Machine  #1446 (after ensuring this PR won't introduce issues similar to the issue being investigated above)

Bottleneck

None