Propagate Jupyter client errors

[lionel-]

Closes #40884

• Make IOPub task return a Result
• Create a monitoring task that watches over IOPub, Control, Routing and Shell tasks.
• If any of these tasks fail, report the error with kernel_errored() (which is already used to report process crashes)

Screen.Recording.2025-10-22.at.13.28.36.mov

This is not perfect. I did not have time to look into this but:

• When such errors happen, the kernel should be shut down.
• The kernel should no longer appear as online in the UI

But at least the user is getting feedback on what went wrong.

Release Notes:

• Jupyter client errors are now surfaced in the UI (Jupyter client errors are not propagated to the UI #40884)

[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have @lionel- on file. You can sign our CLA at https://zed.dev/cla. Once you've signed, post a comment here that says '@cla-bot check'.

[lionel-]

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[rgbkrk]

Hey thanks for coming in to make this better.

[rgbkrk]

It looks like you need to run cargo fmt as well

Diff in /home/runner/work/zed/zed/crates/repl/src/kernels/native_kernel.rs:3:
     AsyncBufReadExt as _, SinkExt as _,
     channel::mpsc::{self},
     io::BufReader,
-    stream::{SelectAll, StreamExt, FuturesUnordered},
+    stream::{FuturesUnordered, SelectAll, StreamExt},
 };

[lionel-]

It looks like you need to run cargo fmt as well

oops sorry about that, for some reason format-on-save wasn't working. Now fixed!

[ConradIrwin]

Thanks! Nice to see someone using this stuff :D

[lionel-]

Nice to see someone using this stuff :D

yep there are some R users in Zed!

What the R community would really like though is a console-based workflow, e.g. https://fosstodon.org/@josi/115448105735120564

I'm hoping that one day users will be able to opt into their preferred workflow for Zed's Jupyter client, either inline output in editors or console/terminal output.

Thanks for merging!