Feature request: Python: Support for ruff server

[Daggerfall-is-the-best-TES-game]

I think ruff server is a more modern LSP implementation than ruff-lsp. Helix supports it, for example
And ruff is very useful as a linter and autoformatter.

[neurocyte]

What does Flow Control need to do to support ruff? Did you try just adding it to you python file type config?

[Daggerfall-is-the-best-TES-game]

I'm not sure what it needs. I just noticed it didn't show up in flow --list-languages.
I will try adding it to that file later today. It might work.
And if there's some kind of permanent change I need to make to get it to show up in flow --list-languages, I can make a PR

[neurocyte]

You can edit the language server for python with the Edit file type configuration command. The changed language server will show up in --list-languages too.

[Daggerfall-is-the-best-TES-game]

Ok I made the edit (I got tripped up for a bit because I wrote language_server ["ruff server"] instead of language_server ["ruff", "server"]). Now it does show up in the list with a checkmark, so that part at least is working. And when I open a python file and check the log, it says lsp: initialized LSP: ruff server. So that's a good sign. But I don't get any diagnostics inline diagnostics like I do with zls. So It's possible it does need something else (although I'm not sure what)

[Daggerfall-is-the-best-TES-game]

However, I can say that the ruff formatter (with ruff format -) does work out of the box

[neurocyte]

But I don't get any diagnostics inline diagnostics like I do with zls. So It's possible it does need something else (although I'm not sure what)

Please upload the lsp log file here and I'll have a look at it. It should be ~/.local/state/flow/lsp-ruff.log

[razcore-rad]

I was just looking at this and I can confirm that seems like ruff isn't working. Here's the log file:

lsp-ruff.log

[neurocyte]

That log file looks fine to me. ruff just isn't sending any textDocument/publishDiagnostics messages, so there is nothing for flow to display. I'm not sure what flow can fix to make ruff work properly. Flow requests diagnostics, so ruff should be sending them.

[Daggerfall-is-the-best-TES-game]

astral-sh/ruff#11059
Seems like there is a pull diagnostics request that the editor can make to the server. It seems to be newer than publish diagnostics.
But also according to this issue/11059 ruff is supposed to fall-back to textDocument/publishDiagnostics when pull diagnostics isn't supported.
this pr implements that feature astral-sh/ruff#11092
so maybe flow is not communicating to ruff server that it doesn't support pull diagnostics?

[razcore-rad]

That log file looks fine to me. ruff just isn't sending any textDocument/publishDiagnostics messages, so there is nothing for flow to display. I'm not sure what flow can fix to make ruff work properly. Flow requests diagnostics, so ruff should be sending them.

Yea, you're actually right... I forgot I had multiple LSes configured in helix and ruff only reports diagnostic/lint. That said, I switched the flow Python LS to basedpyright-langserver like in helix and I still can't get hover info.

Here's the two log files for comparison:

lsp-basedpyright-langserver.log

helix.log

For completeness, here's a screenshot of the two side-by-side. I have no idea how flow is supposed to show the diagnostics, but I did try the command palette for hover & diagnostics, but they didn't do anything. So in this setup, they both are supposed to use basedpyright-langserver:

[neurocyte]

so maybe flow is not communicating to ruff server that it doesn't support pull diagnostics?

You are completely correct. Flow was falsely claiming to support pull diagnostics. I simply misunderstood that part of the client capabilities request. Fix incomming.

[Daggerfall-is-the-best-TES-game]

ok good! Now that ruff server works, should I make a pr to make it the default lsp server, and make ruff format the default formatter?

[neurocyte]

Please check if the latest nightly build (or a build from current master branch) now works with ruff. I am not able to test it myself.

If ruff is the preferred LSP in the python ecosystem you are welcome to make a PR to make it the default. I've no way to judge that though because I don't to much serious python at the moment, so I'll just take your word for it.