Critic

The critic checks work before it ships. It runs in two modes: static deterministic checks, and rendered checks that capture real browser frames and diff them against a baseline.

Static checks#

pnpm paxfx check
pnpm paxfx check gate
pnpm paxfx check seeded
pnpm paxfx repair
pnpm paxfx repair --loop

check validates reduced-motion pathways, keyboard access, content overflow, and frame budgets, then writes .pax/reports/check.json. check gate runs the full declared inventory (~32 checks). check seeded evaluates 32 representative defect fixtures and reports precision/recall in .pax/reports/seeded-eval.json.

repair applies only high-confidence fixes and writes .pax/reports/repair.json. repair --loop runs a bounded loop (max 3 attempts) with before/after diffs in .pax/reports/repair.md. Failures exit with code 3.

Every finding includes severity, confidence, nature (objective vs heuristic), evidence, source location, and suggested repair. Heuristic advisories are never presented as hard failures.

Rendered checks#

check --rendered loads a local HTML file or URL in headless Chromium, freezes animation time at fixed timestamps, and captures one PNG per frame. With a baseline recorded, each frame is compared pixel by pixel.

# Approve first baseline (required)
pnpm paxfx check baseline approve --rendered preview.html --approved-by you --reason "initial"
 
# Record a baseline
pnpm paxfx check --rendered examples/title-card/preview.html --update-baseline --approved-by you --reason "initial"
 
# Compare against it
pnpm paxfx check --rendered examples/title-card/preview.html
 
# Custom timestamps and baseline location
pnpm paxfx check --rendered preview.html --frames 0,500,1000 --baseline .pax/baselines/custom

Defaults: frames at 0, 250, and 500 milliseconds; a 1280x720 viewport; baselines under .pax/baselines/<target>/; captured frames under .pax/frames/<target>/. A frame fails when more than 1% of pixels differ, and a visual diff PNG is written next to the captured frame.

Rendered checks also feed real page data into the deterministic checks: console errors, the presence of a prefers-reduced-motion rule, and horizontal overflow.

Related#

• Preview
• Accessibility