Svelte 5 migration – complete remaining components and tests

[dataCenter430]

• I have searched to see if a similar issue already exists.
  Hey @freddyaboulton 👋
  I’d really love to contribute to Gradio, I’ve been following it and it’s awesome to see how competitive and fast-moving it’s become.
  If this needs to be implemented, I’d be happy to take it on. Thanks!

Summary

Migrate the remaining Gradio frontend (Svelte) components and tests to Svelte 5 so the whole UI stack uses the new reactivity and runes APIs and we can remove temporary Python workarounds.

Context

• Most js/ components are already on Svelte 5 (e.g. Video, Audio, Upload, Textbox, Button, Gallery, Dataset, FileExplorer, JSON, Label, Markdown, Model3D, Sidebar, StatusTracker, etc.).
• Dataframe is still on the pre–Svelte 5 version. The Python gr.Dataframe component uses a temporary fix (__process_counts) for row_count/column_count until the dataframe JS component is migrated; see gradio/components/dataframe.py (TODO around lines 178–180).
• Some component tests still use the deprecated $set pattern and need to be updated for Svelte 5 (e.g. js/video/Video.test.ts, js/gallery/Gallery.test.ts, js/dropdown/dropdown.test.ts).

Scope

1. Migrate js/dataframe to Svelte 5 – update syntax (runes, $state, etc.), then remove __process_counts and the col_count fallback from gradio/components/dataframe.py.
2. Fix tests that rely on deprecated $set – update any remaining tests that use $set to the Svelte 5–compatible approach so CI stays green.
3. (Optional) Audit other js/ packages for any remaining non–Svelte 5 code or TODOs referencing the migration.

Success criteria

• All Gradio JS components run on Svelte 5.
• No temporary Python workarounds in dataframe.py for the old dataframe JS component.
• No test failures or skipped tests due to Svelte 5 / $set deprecation.