Running astral/ty on marimo

[Noobzik]

Hello, I have some trouble running ty from astral for marimo.

• Installed ty with uv add ty,
• Installed marimo with uv add "marimo[lsp]",
• Run uv run ty server,
• Opened a notebook uv run marimo edit,
• User setting and checked the ty setting,

Notice the error on the terminal

╰─ uv run ty server                                                          ─╯
WARNING: the ty LSP server should not be run interactively
See https://docs.astral.sh/ty/editors/ for how to configure your editor

╰─ uv run marimo edit                                                        ─╯

        Create or edit notebooks in your browser :pencil:

        ➜  URL: http://localhost:2718?access_token=uQklpHWUc7JxaP-1XFo8GA

[E 260222 12:51:24 middleware:496] Failed to connect to ws://localhost:3121/lsp/ty?file=notebooks/12. Tracking et Model Registry.py after 3 attempts. Final error: server rejected WebSocket connection: HTTP 400
[E 260222 12:51:24 middleware:575] WebSocket proxy error for ws://localhost:3121/lsp/ty?file=notebooks/12. Tracking et Model Registry.py: server rejected WebSocket connection: HTTP 400
[E 260222 12:51:24 middleware:415] Error proxying websocket: Cannot call "send" once a close message has been sent.

Has anyone ever succeeded running ty on marimo ?

Also asked kapa-ai on discord

The knowledge sources don’t describe how to use ty as a language server with marimo, so I can’t give a confirmed, step‑by‑step setup. They only mention ty in passing (as an optional tool marimo can’t currently auto‑detect from PATH) and focus on python-lsp-server as the supported LSP backend.[Optional deps]

[manzt]

Hi there, you shouldn't need to start the ty server on your own (e.g., uv run ty) marimo manages starting the ty server internally.

midir test-ty && cd test-ty
uv init --bare
uv add ty
uv add "marimo[lsp]"
uv run marimo edit foo.py

Then in the UI you can select the ty under: Settings > User Settings > Editor > Language Servers.

[Noobzik]

uv add "marimo[lsp]" --upgrade
Resolved 197 packages in 536ms
Audited 191 packages in 37ms
uv add ruff --upgrade
Resolved 197 packages in 505ms
Audited 191 packages in 28ms
uv add ty --upgrade
Resolved 197 packages in 598ms
Audited 191 packages in 9ms
uv run marimo edit

        Create or edit notebooks in your browser 📝

        ➜  URL: http://localhost:2718?access_token=0RRznIc2sJbN0IIBLWKfBw

[E 260301 16:22:40 middleware:496] Failed to connect to ws://localhost:3121/lsp/ty?file=notebooks/11. MLflow.py after 3 attempts. Final error: server rejected WebSocket connection: HTTP 400
[E 260301 16:22:40 middleware:575] WebSocket proxy error for ws://localhost:3121/lsp/ty?file=notebooks/11. MLflow.py: server rejected WebSocket connection: HTTP 400
[E 260301 16:22:40 middleware:415] Error proxying websocket: Cannot call "send" once a close message has been sent.