Weekly Check-in: Week of 2026-03-30

[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, @benalleng, @chavic, @zealsham, @Mshehu5

[payjoin-bot]

DanGould

@DanGould

Shipped

PRs merged:

• Fix apostrophe

PRs reviewed:

• Add db entry metrics
• Add basic readme to setup a nix flake for standalone payjoin-mailroom
• Add semi-honest overview
  Some items hidden for brevity see the last comment

• Payjoin-cli should cache ohttp-keys for re-use
• directory: limit V1 requests to 7168 bytes

[DanGould]

Shipped

• Grant report drafts / submitting today
• not me but worth noting that @mehmetefeumit shippied payjoin in https://github.com/bitcoindevkit/bdk-cli/releases/tag/v3.0.0

Focus

• PF Finance/Ops bottleneck removal
• Prep board meeting next week
• Draft new Lugano proposal

Bottleneck

• I'm moving from medium-term housing to long-term housing, moving takes energy
• Our manual finance/ops issues are piling up. This is the thing I have to clear before closing the quarter and moving on to integrations/review focus

[payjoin-bot]

spacebear21

@spacebear21

Shipped

PRs merged:

• Bump payjoin version to 0.25.0

PRs reviewed:

• Async Compatible Interface for Payjoin State Machine
• Add uniffi-dart to standup activity search
• Pin unicode-segmentation in payjoin-mailroom
• Fingerprinting edits
• Make corepc-node optional in payjoin-test-utils
• Unpin the nix crane dip from a specific commit
• Use contrib/test.sh in all language bindings
• Add db entry metrics
• Request size limiter
  Some items hidden for brevity see the last comment

Issues opened:

• Release payjoin-0.25

[spacebear21]

Focus:

• Non-blocking Interface for Payjoin State Machine  #1446 review and testing with BBM
• Session cancel() API

Bottleneck:

• I was pretty burned out last week and couldn't focus for long periods of time.

[payjoin-bot]

arminsabouri

@arminsabouri

Shipped

PRs merged:

• Migrate fingerprint binary
• Create HasInputWithPrevoutFingerprints trait
• Clippy job + Fix clippy warnings
• Clean up legacy fingerprint code
• FMD notes
• Fingerprinting edits
• Invert utility max to cost minimization

PRs reviewed:

• Implement JoinMarket n_locktime Coinjoin detection
• Add locktime default to payjoin-cli
• Add uniffi-dart to standup activity search
• Split TxOutDataIndex to use separate methods
• Enrich DummyTxOutData with script_pubkey bytes field
• Add InputCount trait and input_len to AbstractTransaction
• Use official bitcoind-async-client release with support for mainnet and testnet
• Expose script_pubkey_bytes on TxOutHandle
• Bump payjoin version to 0.25.0
• Add abstract cost function framework
• Async client bitcoind network parsing
• Make corepc-node optional in payjoin-test-utils
• lock inputs via strategies and unlock early due to payment anxiety
  Some items hidden for brevity see the last comment

• Demonstrate failure handling with fallback TX broadcast
• Expose fail() and cancel() on Receiver session
• Payjoin-cli should cache ohttp-keys for re-use

Auto-detected signals:

• PR awaiting review: Propose co spends
• PR has requested changes: Add semi-honest overview
• PR has requested changes: Look up RK instead of looping

[arminsabouri]

Focus:

• Getting others onboarded on the privacy metrics project and revewing Prs
• Finished up the remaining stragling items of the fingerprinting migration
• Published the fingerprinting blog -> reposted on delving. Thanks to all those who suggested edits and reviewed. There is alot of follow up work to do here. The larger scale analysis / attack. Creating better standards for wallets that want to integrate -- how do I know i am fingerprinting my self. A survey of how bad the problem is. Lots of rabbit holes that our tools can help serve.
• Mob programming went well. We came out of with actionable items on Expose fail() and cancel() on Receiver session #1134 and Demonstrate failure handling with fallback TX broadcast #1164
• First piece to the larger cost function story Propose co spends  btsim#12. Need to follow up with the remaining todos.

Bottleneck:

• taxes and other logistics slowly doing damage on my productivity

[payjoin-bot]

benalleng

@benalleng

Shipped

PRs merged:

• Add locktime default to payjoin-cli
• Use official bitcoind-async-client release with support for mainnet and testnet
• Pin unicode-segmentation in payjoin-mailroom

PRs reviewed:

• Bump payjoin version to 0.25.0
• Expose Receiver Error Kinds

Auto-detected signals:

• PR awaiting review: Adds a recommended pre-commit hook that ensures lock files are updated
• PR awaiting review: Possible Lint fixes

[benalleng]

• Successfully demonstrated V2 send <-> receive with payjoin cli and bull bitcoin via Create automated script for testing bull bitcoin mobile against payjoin-cli SatoshiPortal/bullbitcoin-mobile#1978

Focus:

• Get a V2 send <-> receive working in cake wallet starting with some UI fixes like Fix support for sats amount input on send screen cake-tech/cake_wallet#3138
• Gauge both bull bitcoin and cake on their openness for easier paths to automate the testing, i.e. Regtest ideally.

Bottleneck:

• Cake wallet takes like 30 min to compile each individual change.

[DanGould]

• Ben will bring up regtest CI with @kumulynja

• And smoke test w/ testnet3/testnet4 upgrade

• Big problem is with Cake, issue to be opened to make test-passing changes. Cake takes forever to compile. No hot reload? Ask Konsti ASAP

[payjoin-bot]

chavic

@chavic

Shipped

PRs merged:

• Fix Dart error object renaming
• Add uniffi-dart to standup activity search

Issues opened:

• Track release readiness for the real Payjoin C# NuGet package

Auto-detected signals:

• PR has requested changes: Expose Receiver Error Kinds

[chavic]

Focus:

• Resolving issues with last weeks draft PR and addressing change requests
• Working through the NuGet readiness tracking issue Track release readiness for the real Payjoin C# NuGet package #1448
• Documenting the final BTCPay Plugin specs, and implementation and testing

Blockers

• I may need some input (just a few questions answered) before commiting to the final spec for the BTCPay Plugin

[DanGould]

I'm a bit concerned uniffi-dart has no review requirement but hey it's beta and we're chugging along. @spacebear21 says we need a third maintainer to make that requirement work.

[payjoin-bot]

zealsham

@zealsham

Shipped

PRs reviewed:

• Guard concurrent sends with exclusive DB lock and URI/RK checks
• feat: implement ohttp gateway middleware

Auto-detected signals:

• PR awaiting review: 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: Payjoin-cli should cache ohttp-keys for re-use
• PR has requested changes: Add config saving to payjoin-cli

[zealsham]

Focus

• Implement the changes based on review for OHTTP keys should be rotated #1449
• implement the hyperloglog cardinality , was waiting for Add db entry metrics #1412 to go in since i'll use the same db adapter
• Likely continue Payjoin-cli should cache ohttp-keys for re-use #1035 if OHTTP keys should be rotated #1449 goes in before the week elapse

Blocked

• @nothingmuch suggested a Kdf based solution which i partially understand right now

[DanGould]

• https://github.com/orgs/payjoin/discussions/1450

[payjoin-bot]

Mshehu5

@Mshehu5

Shipped

PRs merged:

• Use contrib/test.sh in all language bindings

Auto-detected signals:

• PR has requested changes: Guard concurrent sends with exclusive DB lock and URI/RK checks
• PR has requested changes: lock inputs via strategies and unlock early due to payment anxiety

[Mshehu5]

Focus :
Waiting for feedback on bdk cli review/questions will resume immediatelty thats addressed
For now will help out on btsim and tx-indexer issues/reviews

[DanGould]

Shehu stepped up to help fix the bot. These are the concerns from last week: https://github.com/orgs/payjoin/discussions/1435#discussioncomment-16272877 And the new ones relate to Ben's comment. Better if changes to the process can be small, easy to review, and independent so that we can just get some subset of them merged ASAP, hopefully for next week.

[DanGould]

One thing I would REALLY like the bot to do is relate last week to this week. We're losing the main acocuntability function without manual intervention otherwise

[payjoin-bot]

0xZaddyy

@0xZaddyy

Shipped

PRs reviewed:

• lock inputs via strategies and unlock early due to payment anxiety
• Add semi-honest overview

Auto-detected signals:

• PR has requested changes: Implement fee savings and privacy metrics for payjoin outcomes

[DanGould]

Looks blocked by @arminsabouri and @nothingmuch's review but it's also not on our mainline path. Might take some time to get a review. @arminsabouri suggests that payjoin/btsim#2 is a rabbit hole that might be worth coming out of. Need to have a convo about what sort of category you're the most interested in running with on a longer term trajectory. Please define your own area of accountability by Apr 3 on a conversation w/ @arminsabouri

[benalleng]

I cleared out stale branches on my fork this past week and the AI thought that activity was an indicator of relevance for this week's discussion. I simply commented them out where I saw them. I may have missed some or caught actually relevant items but they can be seen on any comment with an edit history.

[ValeraFinebits]

Shipped

• Added a lot of tests for the Payjoin plugin.
• Did some small refactoring to improve testability.
• Improved test stability.

Focus

Continue adding tests for the plugin.

[bc1cindy]

hi there! my first sharing here.

Shipped

I've been contributing to tx-indexer, mostly on blockers to implement Joinmarket Coinjoin detection

• Actual CoinJoin Detection tx-indexer#5
• Remove --lib flag from CI test command tx-indexer#17
• Expose script_pubkey_bytes on TxOutHandle tx-indexer#18
• Add InputCount trait and input_len to AbstractTransaction tx-indexer#19
• Enrich DummyTxOutData with script_pubkey bytes field tx-indexer#23
• Split TxOutDataIndex to use separate methods tx-indexer#24
• Encapsulate DummyTxData fields behind constructors tx-indexer#28

Also delivered a draft of the PoC to use Asmap for relay selection

• PoC: Asmap for relay selection #1452

Reviewed

lightningdevkit/ldk-node#746
payjoin/tx-indexer#12
payjoin/tx-indexer#25

Focus

Joinmarket Coinjoin detection

Blockers

I do have blockers

• reviewing integrations without having clear patterns to follow its a bit hard, I felt that with triggering fallback broadcast in create_poll_request, try_preserving_privacy, contribute_inputs, and create_post_request in the LDK-node integration
• I'm still learning the about payjoin and tx-indexer codebases, so coding/reviewing takes me longer then if I already had a bigger understanding and also makes me insecure
• at the same time I want to check 300 times what I did before sending, I want send too see what you guys have to say
• contributing to BOSS is new for me, but I'll improve with more practice and spec knowledge

[bc1cindy]

i understand that changes has to be very well thought, like in #1380 , #1385

so I feel its normal and don't see it as a blocker

[bc1cindy]

if you have any specific PRs that you want me to review it will be great, for now I have #1164 in mind to take a look

[DanGould]

Yes Cindy that's great it takes a bunch off of Armin's plate and gives him deeper context to review from

[DanGould]

If you are able to document any of the missing context that would have unblocked you a week or two prior, that might help the next generation stay less blocked too. Just an idea.

[bc1cindy]

it was when #1422 was created, because maybe we need re-thinking, and for the same reason, I also felt that with ohttp-relay, as commented in #1385 (comment)

[xstoicunicornx]

Shipped

• Opened Non-blocking Interface for Payjoin State Machine  #1446
• Revised PR 1446 based on feedback and additional constraints
• Merged Fix invalid discord link #1455

Focus

Finish up implementation revision for PR 1446 and move onto tests.

Bottleneck

None.

[DanGould]

Just fyi if you dump the github link in an unordered list you'll automatically get a nicely formatted line with PR status, title, and number like this:

• Non-blocking Interface for Payjoin State Machine  #1446

By no bottleneck you mean you're not waiting for anyone's review and you're just limited by the time you can spend on the implementation and testing of your own change?

[xstoicunicornx]

Derp... thats great to know thanks.

Correct about the no bottleneck - I've put some tentative stuff out there that would nice to have some feedback on but as far as getting the PR to more "ready for review" state I think I've gotten enough feedback to proceed and the only blockers are my time.

[arminsabouri]

PDK Dev Call Updates - March 31st, 2026

Ben

• Built an automated script to test Bull Bitcoin Mobile against payjoin-cli.

• Investigating whether Bull Bitcoin Mobile can support a regtest configuration.

• Aligning transaction locktime behavior with Bitcoin Core Add locktime default to payjoin-cli #1445

• Debugging Cake Payjoin failures:

  • UI flow works, but Payjoin execution fails.
  • Next step: open detailed GitHub issues.

• Plans to coordinate with Cake developers to improve DX, including hot reloading support (?)

Chavic

• Reviewed Valera’s BTCPay integration work.

  • Noted that changes are pushed directly to master without PRs, which complicates review.

• UniFFI-Dart PRs lack review; Ben and Spacebear are now reviewing.

• Will help refactor and upgrade the standup bot.

Shehu

• Focused on following up on open PRs.
• Responding to review comments on the BDK CLI persistence PR.
• Reviewing ASMAP PR (Unify mailbox TTL to a single value #1457); unclear whether it is a proof of concept or production-ready. Expecting to take it over or help devleoper and review it. Cindy will follow up

Zealsham

• Requested review from Armin on Demonstrate failure handling with fallback TX broadcast #1164.

• Working on key rotation PR (OHTTP keys should be rotated #1449).

  • Received initial feedback from Nothingmuch.
  • Proposed key rotation approach needs further discussion; will bring to mob programming.

• Blocking payjoin-cli caching PR (feat: expose PsbtInputsError index in FFI #1305).

  • Not a hard blocker, but both PRs modify the same code paths.
  • Merging one now would require reworking the same code later.