---
name: preview
description: Renders a ChatKit widget JSON file to a PNG image or a self-contained HTML file locally. Use when the user wants to see a saved widget JSON, needs a shareable/openable HTML version of a widget, or wants a dark-mode PNG.
---

# Preview a widget file

Renders saved widget JSON (a bare tree, or any JSON with a `widget` field —
`generate_widget`/`widget-generate --out` output works as-is) without calling
any API.

The CLI is `widget-render`, on PATH in plugin sessions (bare checkout:
`node scripts/render-widget.mjs` from the repo).

```bash
widget-render --in widget.json --png widget.png                # light PNG, 2x scale
widget-render --in widget.json --png widget-dark.png --theme dark
widget-render --in widget.json --html preview.html             # self-contained HTML, opens anywhere
```

- `--in -` reads stdin, so you can pipe edited JSON without a temp file.
- `--theme` affects PNGs only. The HTML output has no baked-in theme — it
  follows the viewer's system light/dark preference when opened.
- Both outputs are dependency-free (PNG rendering is bundled — no browser
  needed). If rendering errors, run `/widget-studio:doctor`.
- Show the result: attach the PNG, or point the user at the HTML file.