test: approve automated portfolio visual quality

docs/accessibility/flash-analysis.md

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+# Flash analysis evidence
+
+Status date: 2026-09-02
+
+## Shipped surfaces in scope
+
+- Procedural journey scene in its default and scroll-accelerated states.
+- Static and `prefers-reduced-motion` poster states.
+- Project media: **not applicable yet**. The public asset manifest is intentionally empty while final derivatives and imagery rights await Luca's approval. This record must be extended before any video or animated project asset is published.
+
+## Automated method
+
+`tests/browser/visual-regression.spec.ts` captures the real `.journey-world` at 10 frames per second. The accelerated sequence receives two production wheel inputs before a two-second capture. Static and reduced-motion sequences are captured separately.
+
+Each frame is downsampled to 160×90 RGB pixels. Between adjacent frames, a pixel is classed as a general-flash luminance change when:
+
+1. relative luminance changes by at least 0.1; and
+2. the darker state is below 0.8.
+
+A transition is conservatively treated as large-area when one direction affects at least 25% of the sampled viewport. Within every rolling one-second window, opposing large-area transitions are paired into flashes. The test fails above three flashes per second. JSON event evidence is attached to the Playwright result for the live, Static, and reduced-motion sequences.
+
+This deliberately conservative area rule does not use the WCAG small-area exemption. It checks luminance flash, not red-flash chromaticity in isolation; the shipped scene contains no full-field saturated-red strobe, and the manual review below remains required.
+
+## Automated result
+
+| Engine/state                                             | Result                                                         | Evidence                                                   |
+| -------------------------------------------------------- | -------------------------------------------------------------- | ---------------------------------------------------------- |
+| Chrome for Testing 151.0.7922.34, accelerated live scene | **PASS — no rolling one-second window exceeded three flashes** | `live-scene-flash-analysis.json` Playwright attachment     |
+| Chrome for Testing 151.0.7922.34, Static                 | **PASS — zero qualifying flashes**                             | `static-flash-analysis.json` Playwright attachment         |
+| Chrome for Testing 151.0.7922.34, reduced motion         | **PASS — zero qualifying flashes**                             | `reduced-motion-flash-analysis.json` Playwright attachment |
+
+These results came from Playwright 1.62.1 and were reconfirmed in the final successful complete browser run (157 passed, 41 deliberate skips):
+
+```text
+npm run test:browser -- tests/browser/visual-regression.spec.ts
+```
+
+## Required human/platform evidence — pending, not passed
+
+- [ ] Review the accelerated scene at normal speed and during repeated direction changes; record reviewer, date, display refresh rate, and result.
+- [ ] Review every final encoded project video/animation after its exact approved bytes are bound into the public manifest.
+- [ ] Run the automated capture in current Firefox and WebKit/Safari-capable infrastructure and attach the corresponding JSON.
+- [ ] Run the automated capture in current Edge and the previous stable desktop majors named by the release matrix.
+- [ ] Review on the physical iPhone 13 and Pixel 6 during `physical-drive.v1`.
+
+No unsupported engine, physical device, or unpublished project-media result is represented as passed.