# Gallery CDP probes

Behavioral verification for docs/prototypes/panel-widget-gallery.html — headless Chrome
driven over the DevTools protocol (Node global WebSocket/fetch, no playwright).

- probe.mjs — full regression: card count, size toggle, drag + click behavior under zoom,
  zero-exception gate. Run: `node probe.mjs [--shot out.png]`. Update the card-count
  assertion when cards are added.
- probe-fams.mjs — screen-color families: default fallbacks pixel-identical, chip clicks
  recolor ink/face/trace, dynamic fills stay var-based.

Both exit nonzero on failure. The gallery's componentization work (widgets.js extraction)
uses a green run of these as its no-regression gate per batch.

## Traps when writing new checks

- Dispatch clicks on the element that owns the listener, not an ancestor; drive drags
  with in-page synthetic PointerEvents (setPointerCapture stubbed).
- A `find()` by textContent that matches nothing returns undefined, and the dispatch
  no-ops silently — the check then fails looking like a widget bug. Match glyphs
  exactly against the builder source (e.g. the transport stop button is '⏹' U+23F9,
  not '■' U+25A0), and prefer asserting the find() hit before dispatching.
- Reduced-motion emulation must be set before Page.navigate (launch on about:blank,
  Emulation.setEmulatedMedia, then navigate) or the page's matchMedia snapshot misses it.
- Kill stale headless Chromes after a crashed run; bracket the pkill pattern
  (`pkill -f 'remote-debugging-port=934[5]'`) so it can't match its own command line.