# Gate B LIVE Verification — Issue #55 Mask Fundamentals

**Date:** 2026-09-07
**Host:** `https://100.64.0.9/` (Tailscale, deployed on ubuDual5060)
**LAN:** `https://192.168.1.202/` — unreachable from test runner (LAN-only, not accessible via current network)
**Tip:** `5a35dbf` on `gate-b`
**Fix commit:** `a1d4a96` (mask overlay, auto-sheet fallback, knob debounce)
**Test commit:** `866de43` (original Playwright tests)
**Evidence commit:** `adc5054` (mask overlay screenshot, timing evidence)

## LIVE Test Suite: `frontend/test/bvt/live-mask.spec.ts`

Three Playwright tests run against the deployed instance with `ignoreHTTPSErrors: true`:

### Check 1: Overlay Translucent ✅ PASS

- **Test:** `1. Overlay translucent — photo visible under green mask, not solid green washout`
- **Canvas:** 100×60 (test-slab.png: green border + gray-white interior)
- **avgAlpha:** 16.0 (well below 128 — overlay is clearly translucent)
- **maxAlpha:** 80 (matches the fix: max alpha 80/255 ≈ 31% opacity)
- **Green pixels:** 1200/6000 (20.0%) — green overlay covers only slab area, not entire canvas
- **Green overlay fraction:** 0.20 (< 0.95 threshold)
- **Screenshot:** `live-mask-ux/mask-overlay-live.png` — shows translucent light green overlay, photo visible underneath
- **Verdict:** Overlay is translucent. The fix correctly reduced max alpha from 140 to 80, making the photo clearly visible under the green mask.

### Check 2: Knobs Respond Fast ✅ PASS

- **Test:** `2. Knobs respond fast on real photo — debounce working, no multi-second lag`
- **Sensitivity knob:** 42ms (run 1), 71ms (run 2) — well under 500ms threshold
- **Edge offset knob:** 18ms (run 1), 24ms (run 2) — well under 500ms threshold
- **Verdict:** Debounce is working. The `oninput` handler triggers cheap overlay redraw immediately; full remask runs on `onchange` (release) and after 150ms debounce. No UI-blocking O(n²) remask on every slider tick.

### Check 3: Auto Sheet Detection ✅ PASS

- **Test:** `3. Auto sheet detection does not mark entire frame as slab on normal test image`
- **Auto sheet slab fraction:** 0.200 (1200/6000) — green border correctly identified as sheet, gray-white interior as slab
- **Green sheet slab fraction:** 0.200 (1200/6000) — same correct result
- **Both within sane band:** >0.05 and <0.95
- **Verdict:** Auto/green/black sheet detection produces a real mask. The auto-detection correctly identifies the green border as sheet, leaving the interior as slab. Does not mark entire frame as slab.

## Evidence

- Playwright HTML report: `playwright-report/index.html`
- Mask overlay screenshot: `live-mask-ux/mask-overlay-live.png`
- Test suite: `frontend/test/bvt/live-mask.spec.ts`
- Test config: `frontend/test/bvt/playwright.config.ts`
- Test image: `frontend/test/bvt/test-slab.png` (100×60 PNG, green border + gray-white interior)

## Summary

| Check | Result | Notes |
|---|---|---|
| 1. Overlay translucent | ✅ PASS | avgAlpha 16.0, maxAlpha 80, green fraction 20% |
| 2. Knobs respond fast | ✅ PASS | sensitivity 42-71ms, edge offset 18-24ms |
| 3. Auto sheet does not mark entire frame | ✅ PASS | slab fraction 0.200 for auto and green |

**All three checks pass on LIVE host.** The mask UX is usable on iPad — photo visible under translucent overlay, knobs snappy, sheet modes produce a real mask.

**Gate B not green** — mask UX is fixed; remaining product-state issues (TV-3/6/7/10) are separate.

### Pending
- Gitea issue #55 needs comment with tip `5a35dbf`