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f8adc9f155
Two of the deferred scroll-jitter seams, on top of the integrated fix train
(T1.1 gate -> T2 writer -> T3 estimator @ 1fa4551a):
- columnWidthPx: measure the timeline row column once (useElementWidth) and
thread it into timelineRowReserveStyle so row-height reserves use the real
wrap width instead of the 64-char fallback. Pre-measure zero passes undefined
to preserve the estimator's own fallback rather than tripping its min-chars
floor. On jitter-corpus this shrinks estimate-error R from 75 -> 55 peak
(better reserves = smaller realized-vs-reserved delta) while the motion gate
stays GREEN 0.00/0.00 -- R moves only in the estimator lane, the gate only in
the writer lane, cross-lane invariant intact.
- Wren #4 anchor-contract guard: a companion perf test that reads the PRODUCTION
computed overflow-anchor on the real conversation scroller (no test override)
and asserts it resolves to none. The jitter gate forces the property for its
measurement; this proves the shipped stylesheet actually ships it, so a
regression that hands correction back to Chromium's native anchoring (masking
a WKWebView-only on-device break) fails loudly.
The onRealizedHeight seam is intentionally NOT wired: T4 ground truth
(RESEARCH/GUI_SCROLL_RECLAIM_T4.md) shows the upscroll path is append-only with
no unmount, so it needs no JS height cache; a per-event-id cache is only the
deferred, narrowly-scoped T4b for the head-refetch case. Adding an unused
callback now would be dead abstraction.
Validation:
- pnpm --dir desktop typecheck: clean
- biome check on both changed files: clean
- rowHeightEstimate.test.mjs 16/16, useAnchoredScroll.test.mjs 2/2
- perf: upscroll-jitter GREEN 0.00/0.00 (R 55), anchor-contract PASS
Co-authored-by: Tyler Longwell <tlongwell@block.xyz>
Signed-off-by: Tyler Longwell <tlongwell@block.xyz>
52 lines
2.3 KiB
TypeScript
52 lines
2.3 KiB
TypeScript
import { expect, test } from "@playwright/test";
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import { installMockBridge } from "../helpers/bridge";
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/**
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* ANCHOR-CONTRACT GUARD (Wren #4) — companion to `upscroll-jitter.perf.ts`.
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*
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* The jitter gate *forces* `overflow-anchor: none` on the scroller before it
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* measures, to reproduce shipped WKWebView (which has no `overflow-anchor` and
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* so corrects nothing) on anchoring Chromium. That force is a test convenience,
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* not a proof: it would stay green even if production ever stopped shipping the
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* property, silently handing correction back to Chromium's native anchoring and
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* masking a WKWebView-only regression on device.
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*
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* This test closes that gap by reading the PRODUCTION computed style — no test
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* override — on the real conversation scroller and asserting it resolves to
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* `none`. We run on Chromium, whose default `overflow-anchor` is `auto`, so a
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* resolved value of `none` can only have come from the shipped stylesheet
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* (`utilities.css` `[data-buzz-conversation-scroll]`). The engine-support
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* assert keeps the check honest: if it ever runs somewhere without the property
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* at all, we want the loud failure, not a vacuous pass on an empty string.
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*/
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test("CONTRACT: production ships overflow-anchor:none on the conversation scroller", async ({
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page,
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}) => {
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await installMockBridge(page);
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await page.goto("/");
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await page.waitForFunction(
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() => typeof window.__BUZZ_E2E_EMIT_MOCK_MESSAGE__ === "function",
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);
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await page.getByTestId("channel-jitter-corpus").click();
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await expect(page.getByTestId("chat-title")).toHaveText("jitter-corpus");
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const timeline = page.getByTestId("message-timeline");
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await expect(timeline.locator("[data-message-id]").first()).toBeVisible();
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// Sanity: Chromium DOES support overflow-anchor (default `auto`), so a
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// resolved `none` below is the production stylesheet's doing, not the engine
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// returning an empty/unsupported value.
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const anchorSupported = await page.evaluate(() =>
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typeof CSS !== "undefined" && typeof CSS.supports === "function"
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? CSS.supports("overflow-anchor", "auto")
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: false,
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);
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expect(anchorSupported).toBe(true);
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const resolvedOverflowAnchor = await timeline.evaluate(
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(element) => getComputedStyle(element).overflowAnchor,
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);
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expect(resolvedOverflowAnchor).toBe("none");
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});
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