the most recent 6.3 development snapshot (Release swift-wasm-6.3-SNAPSHOT-2026-03-05-a · swiftwasm/swift · GitHub) had a wasm32-unknown-wasip1-threads bundle. but there is no corresponding swift-6.3-RELEASE bundle on that page, nor does it appear on swift.org.
what happened to wasm32-unknown-wasip1-threads?
As you've mentioned, wasm32-unknown-wasip1-threads is currently not supported by Swift SDKs distributed from swift.org. Swift CI doesn't run the full test suite for this target triple (blocked by `wasip1-threads` proposal support · Issue #332 · swiftwasm/WasmKit · GitHub), which means in the current state it's untested and not supported officially.
understood. are there any plans to distribute a 6.3 wasm32-unknown-wasip1-threads outside of swift.org, from the swiftwasm/swift repository, as was done for Swift 6.1 and 6.2? we are in the very awkward situation where Swift WebAssembly users are stuck on Swift 6.1, which had wasm32-unknown-wasip1-threads, and cannot upgrade to keep pace with the rest of the library ecosystem.
I cannot speak for what's going to be done in that repository as I don't maintain it, but I'm also not sure what exactly you mean here. Latest 6.3 snapshot in swiftwasm/swift releases does include a Swift SDK for wasip1-threads: Release swift-wasm-6.3-SNAPSHOT-2026-03-05-a · swiftwasm/swift · GitHub
nightlies just aren’t a viable substrate to build on, at any organization i’ve ever worked at.
if you say “we’re going to use 6.3-SNAPSHOT-2026-03-05-a”, then you either have to make that the global substrate for everything your org builds, or you have to create a second infrastructural universe just for your webassembly projects, which must not cross wires with the rest of your stuff that’s using 6.3-RELEASE.
it doesn’t really help if the compiler is 99% identical, because the version string printed by swift --version is different, and the version string is what the CD system cares about. we could teach the CD system to treat 6.x-SNAPSHOT-XXX-XX-XX-a as interchangeable with 6.x-RELEASE, but that wouldn’t really be correct in the general case.
I just shipped p1-threads SDK on swiftwasm/swift for you 
Release swift-wasm-6.3-RELEASE · swiftwasm/swift · GitHub
you’re too kind, thank you!! 