📝 Add sniffio dependency to project requirements

[jujumilk3]

It fails to import with anyio>=4.12.0 due to missing sniffio dependency.

• asyncer/_main.py directly imports sniffio (line 27)
• Previously, sniffio was installed as a transitive dependency of anyio
• As of anyio 4.12.0 (released 2025-11-28), sniffio was dropped as a dependency
  (https://anyio.readthedocs.io/en/stable/versionhistory.html)
• Since sniffio is not listed in asyncer's pyproject.toml, it is no longer installed

The most critical issue is that many projects depending on asyncer (without pinning anyio<4.12 or sniffio) are broken. You can easily verify this by pip install asyncer and import asyncer.

[github-actions]

📝 Docs preview

Last commit 1876898 at: https://1e7c617c.asyncer.pages.dev

[owenlamont]

I just ran into this too, it'd also be good to set up some lint tooling to confirm all referenced dependencies are added as explicit first order dependencies.

Maybe too much scope creep but adding https://github.com/fpgmaas/deptry as a pre-commit lint to check it flags this as a problem then fix it would be good for preventing this sort of issue reoccurring.

[jujumilk3]

@svlandeg Sorry to tag you but you guys' package is broken. Could you please check it?

[tiangolo]

Thank you! 🙌

This will be available in Asyncer 0.0.11 released in the next hours. 🚀

[aaronsteers]

Thanks, @tiangolo and @jujumilk3 and team for the fast work on this. 🚀

I have had very good experiences with deptry and I use it in all my projects now. I can probably create a PR to your repo if helpful. Tag me if so and I'll send you something from a personal fork.