Type hints not recognized by language server

[Antyos]

Describe the bug

Marimo's language server does not detect manually specified type hints. This can be important, as functions which lack return typing or have wrapped return typing, e.g., alt.Chart().encode(), will become typed as Unknown and lose the benefits of the language server.

Environment

Details

marimo VS Code Extension Diagnostics
=====================================

Language Server (LSP):
	UV Bin: Discovered (C:\Users\andrew\.local\bin\uv.exe)
	UV: uv 0.9.9 (4fac4cb7e 2025-11-12) ✓
	Using bundled marimo-lsp via uvx

Python Extension:
	Interpreter: c:\Users\andrew\Code\project\code\.venv\Scripts\python.exe
	Version: 3.13.9.final.0
	Environment: VirtualEnvironment (biaxtic)

Python Language Server (ty):
	Status: running ✓
	Version: 0.0.8 (aa7559db8 2025-12-29)
	Python: c:\Users\andrew\Code\project\code\.venv\Scripts\python.exe (3.13.9.final.0)

Extension Configuration:
	Version: 0.8.10 
	UV integration disabled: false 

System Information:
	Host: desktop 
	IDE: Visual Studio Code 
	IDE version: 1.108.0 
	Platform: win32 
	Architecture: x64 
	Node version: v22.21.1 

Common Issues:
	1. If notebooks won't open:
		- Check Python interpreter is selected
		- Ensure marimo and pyzmq are installed
		- Check 'marimo-lsp' output channel for errors
	2. If features are missing:
		- Ensure marimo version is >= 0.17.0
		- Try reloading the window

Steps to reproduce

Code snippet:

import altair as alt
import polars as pl

chart: alt.Chart = alt.Chart(pl.DataFrame({
        "x": [0, 1, 0, 1], "y": [0, 0, 1, 1], "c": [0, 1, 2, 3]
    })).mark_rect().encode(
    x="x:O",
    y="y:O",
    color="c:O"
)

[manzt]

Thanks for reporting the issue. I believe this is a limitation of the upstream ty language server at the moment. We are on v0.0.11. I just tried in a regular Jupyter notebook: