marimo

Tier 2 — documented best-effort, verified manually before each release.

Render idiom

• mo.ui.anywidget(MyIO(...).add_layer(...).render())

Reactive surface

• widget.value returns a dict of all synced traitlets.
• widget.brushed and related fields are reactive.

Known gotchas

• marimo's static HTML export preserves client-side interactivity for anywidgets.