feat(agent-pane): add visual verification matrix
Changelog
Added a Playwright visual verification matrix for the cmux-next agent pane.
What changed
webviews/scripts/agent-pane/visual-matrix.mjs drives the real pane against the in-page mock daemon across streaming, queue/steer, PR chip, permission cards, image replies, wallpaper, light/dark themes, and narrow/normal/wide widths. Each case records fast-clock WebM video, sampled frames, a contact sheet, and metrics.json with a CLS-style score, per-frame jumps, and sticky composer overlap findings.
The workflow fans the cases across Blacksmith Linux workers for pull requests touching webviews/src/agent-session and nightly on feat-cmux-next. The checked-in sample is in webviews/scripts/agent-pane/reviews/.
Gallery path: /live/agent-pane-visual/
First nine-case run: review. Maximum CLS-style score was 0.00363; maximum observed frame jump was 3px. Typography, themes and general spacing were stable. The spare-model contact-sheet review found a recurring bottom safe-area issue: the sticky composer obscures the bottom action row in images-light-normal, pr-chip-dark-normal, and wallpaper-dark-wide, and clips the steer panel in queue-steer-light-normal. The runner records these as explicit composerOverlaps findings so a follow-up can fix the product layout.
Behavior proof: heavy --mem 4G bun scripts/agent-pane/visual-matrix.mjs --max-frames 10
Refs: cmuxterm-hq#1969