Verify mobile geometry and themed media icons across browsers

perf/README.md

@@ -335,3 +335,15 @@ No product behavior changes are involved in these measurement corrections.
 Keep browser/build/test processes idle during full timing measurements. WebKit's
 zero long-task field means unavailable, not zero work. Autoplay-blocked/media-ready
 null results do not establish playback performance or iPhone audio continuity.
+
+## UI geometry and media icons
+
+```sh
+node perf/ui-geometry.mjs
+node perf/ui-icons.mjs
+node --test frontend/media-icons.test.js
+```
+
+Both harnesses run Chromium and WebKit at mobile dimensions with stubbed SpeechRecognition and local Saved/Queue metadata. They serve only the frontend, block service workers and external requests, and never download media. Geometry tests cold and switched layouts, six widths (320–430), mic visible/hidden and update icon visible/hidden: center spread ≤1px, touch targets ≥40px, Saved image/text gap ≥8px, no horizontal overflow or clipped car control. `--quick` limits widths and speech cases; `--browser` selects an engine; `--frontend` selects historical fixtures. `--measure-only --label before` records known broken geometry without exiting nonzero.
+
+Icon checks switch the same page through four layouts × dark/light/contrast, assert SVG definitions, inherited colour, stroke family and save/progress/offline state, and save Queue/Now Playing/navigation shots. Glass Stage intentionally hides bottom navigation, so its full page is recorded instead. Any assertion failure exits nonzero. Shots and raw measurements live in git-ignored plans/ui-shots/. Full production inventory: plans/ui-icon-inventory.md. Native speech recognition, installed-PWA safe-area insets and iPhone rendering still need device verification.