Two live probes that run the built GUI against a real relay (port-forward
+ Host rewrite) and walk real scrollback in a real channel:
- upscroll-1px-live.perf.ts: settled steps (BUZZ_PERF_STEP_PX), scores
per-step row movement through real fetchOlder loads, measures the felt
jump at each prepend commit.
- upscroll-trackpad-live.perf.ts: macOS trackpad replica — wheel events at
~8ms spacing in finger-ramp + momentum-decay swipe profiles, no settling,
with a per-RAF sampler scoring tracked-row motion vs applied scroll.
Plus playwright.perf-webkit.config.ts: the same probes on Playwright
WebKit. This is the config that exposed the T2 compensation being
near-ineffective on WebKit-family engines under momentum input while
Chromium scored clean — Chromium-only probing cannot see the defect class
the shipped WKWebView app exhibits.
Co-authored-by: Tyler Longwell <tlongwell@block.xyz>
Signed-off-by: Tyler Longwell <tlongwell@block.xyz>
