WIP: Add CSV file upload button

[markmiro]

Screen.Recording.2025-10-07.at.4.03.18.PM-for-gh.mov

[markmiro]

Getting this when running the terminal runtime:

The browser runtime works fine

[rgbkrk]

Getting this when running the terminal runtime:

The browser runtime works fine

Yeah, I don't know why the pyodide.http.open_url doesn't work in the Deno side. Worth investigating or making a new issue for it.

[rgbkrk]

Great first stab at this.

Let's think through what the protocol could work like for this instead of injecting python and runtime specific code.

Here's the steps I'd aim for

• Make a file upload button exist in the AI cell and/or this Attach File button you've created (can work beyond CSVs obviously)
• Emit an ArtifactUploaded event so that all clients can fetch it as necessary
• Runtime Agents will load the file into their runtime filesystem

[markmiro]

Closing in favor of #645