UDS tpt backend breaks windows on import..

[goodboy]

Apparently us linux heads totally forgot (specifically in #375)
that windows doesn't have (obvious) support for unix-domain-sockets,
though TIL apparently there is/has-been support ?? (for a long
time)

To start we likely just want to fix the immediate crash-on-import

Bp

So for that we should prolly do all of,

• make sure we aren't always importing the .ipc._uds module
  by guarding the current ip._types sub-import
  with a platform check so that by default we're only loading it for supported OSes..
• maybe log.warning()-explain when we're unable to use that backend
  and/or require further special dependencies/sys-config to do so (see below) ??
• write a test which checks if we're running on windows that can at least run in CI
  • presuming we get it running again per Disable win tests in CI #327 and any @no_windows skip-mark
    usage throughout.

---

On the topic of UDS support in the windows kernel, this blog post claims support was added "Beginning in Insider Build 17063"..

That build page further states,

Unix style sockets (AF_UNIX) are available on Windows AF_UNIX is an
address family which has enabled inter-process communication on
Unix for countless years. The windows equivalent is named pipes,
which offers similar facilities. Based on user feedback, we heard
that you’d like an easier path when porting tools relying on
AF_UNIX to Windows. As a result, two Win32 processes can now use
the AF_UNIX address family over Winsock API to communicate with
each other. Read this blog for more details.

and the blog post claims and/or links these further resources:

• only TCP-like "reliable" use is supported per,

  Currently, the support only exists for the stream (SOCK_STREAM)
  socket type, which is a connection-oriented protocol for one-to-one
  communication. Support for the datagram (SOCK_DGRAM) can be
  considered in future depending on the adoption, feedback and
  scenarios.

  • we [are already using this type] afaik, so we-should-be-gud?

• cpython has for a long while talked support, but it's been super
  slow moving..
  • longstanding feat-req: Enable AF_UNIX support in Windows python/cpython#77589
    • 2024 summary comment is Enable AF_UNIX support in Windows python/cpython#77589 (comment)
    • latest necro-bump from 2025 is Enable AF_UNIX support in Windows python/cpython#77589 (comment)
  • recent WIP patch => gh-77589: Add unix domain socket for Windows python/cpython#137420
    • latest request for review: gh-77589: Add unix domain socket for Windows python/cpython#137420 (comment)

• the specific section/steps (from that post) on how-to write an AF_UNIX app
• the winsock API docs
• some winsock GH exs (but it doesn't seem to have any examples for AF_UNIX in
  particular ??)