add use_scroll_spy() hook + TableOfContents comp

component.json

@@ -35,6 +35,7 @@
     "preview/src/components/aspect_ratio",
     "preview/src/components/scroll_area",
     "preview/src/components/date_picker",
+    "preview/src/components/time_picker",
     "preview/src/components/textarea",
     "preview/src/components/skeleton",
     "preview/src/components/card",

playwright/combobox.spec.ts

@@ -3,6 +3,8 @@ import { test, expect, devices, type Page } from "@playwright/test";
 const URL = "http://127.0.0.1:8080/component/?name=combobox&";
 const variantUrl = (variant: string) =>
     `http://127.0.0.1:8080/component/?name=combobox&variant=${variant}&`;
+const blockVariantUrl = (variant: string) =>
+    `http://127.0.0.1:8080/component/block/?name=combobox&variant=${variant}&`;
 
 const input = (page: Page) =>
     page.getByRole("combobox", { name: "Select framework" });
@@ -230,6 +232,7 @@ test("dynamic option removal updates filtering and keyboard selection", async ({
     await page.waitForLoadState('networkidle');
 
     const trigger = page.getByRole("combobox", { name: "Dynamic framework" });
+    const toggleSvelte = page.getByRole("button", { name: "Toggle SvelteKit" });
     await trigger.click();
     await page.keyboard.type("s");
 
@@ -246,12 +249,13 @@ test("dynamic option removal updates filtering and keyboard selection", async ({
         "true",
     );
 
-    await page.getByRole("button", { name: "Toggle SvelteKit" }).click();
+    await expect(trigger).toBeFocused();
+    await toggleSvelte.click();
     await expect(list(page).getByRole("option", { name: "SvelteKit" })).toHaveCount(0);
     await expect(list(page).getByRole("option", { name: "SolidStart" })).toBeVisible();
-
-    await trigger.click();
+    await expect(content(page)).toBeVisible();
     await expect(trigger).toBeFocused();
+
     await page.keyboard.press("ArrowDown");
     const next = list(page).getByRole("option", { name: "Next.js" });
     await expect(next).toHaveAttribute("data-highlighted", "true");
@@ -261,6 +265,119 @@ test("dynamic option removal updates filtering and keyboard selection", async ({
     await expect(trigger).toHaveValue("Next.js");
 });
 
+test("virtualized variant shows visible options when opened", async ({ page }) => {
+    await page.goto(blockVariantUrl("virtualized"), { timeout: 20 * 60 * 1000 });
+    await page.waitForLoadState('networkidle');
+
+    const trigger = page.getByRole("combobox", { name: "Virtualized option picker" });
+    await trigger.click();
+
+    const menu = list(page);
+    await expect(menu).toBeVisible();
+    await expect(menu.getByRole("option", { name: "Option 0", exact: true })).toBeVisible();
+    await expect(menu.getByRole("option", { name: "Option 1", exact: true })).toBeVisible();
+});
+
+test("virtualized variant keeps scrollHeight stable while scrolling", async ({ page }) => {
+    await page.goto(blockVariantUrl("virtualized"), { timeout: 20 * 60 * 1000 });
+    await page.waitForLoadState('networkidle');
+
+    const trigger = page.getByRole("combobox", { name: "Virtualized option picker" });
+    await trigger.click();
+
+    const menu = list(page);
+    await expect(menu).toBeVisible();
+    await page.waitForTimeout(500);
+
+    const initialState = await menu.evaluate((el) => ({
+        scrollHeight: el.scrollHeight,
+        clientHeight: el.clientHeight,
+        ratio: el.scrollHeight / el.clientHeight,
+    }));
+
+    const maxScroll = initialState.scrollHeight - initialState.clientHeight;
+    const steps = 20;
+    const stepSize = maxScroll / steps;
+    const measurements: Array<{
+        scrollTop: number;
+        scrollHeight: number;
+        clientHeight: number;
+        ratio: number;
+    }> = [];
+
+    for (let i = 1; i <= steps; i++) {
+        const targetScroll = Math.round(stepSize * i);
+
+        await menu.evaluate((el, scroll) => {
+            el.scrollTop = scroll;
+        }, targetScroll);
+        await page.waitForTimeout(100);
+
+        measurements.push(await menu.evaluate((el) => ({
+            scrollTop: el.scrollTop,
+            scrollHeight: el.scrollHeight,
+            clientHeight: el.clientHeight,
+            ratio: el.scrollHeight / el.clientHeight,
+        })));
+    }
+
+    const duringScrollMeasurements = measurements.slice(0, -1);
+    const scrollHeights = duringScrollMeasurements.map((m) => m.scrollHeight);
+    const clientHeights = duringScrollMeasurements.map((m) => m.clientHeight);
+    const ratios = duringScrollMeasurements.map((m) => m.ratio);
+    const minHeight = Math.min(...scrollHeights);
+    const maxHeight = Math.max(...scrollHeights);
+    const heightVariance = maxHeight - minHeight;
+    const minClientHeight = Math.min(...clientHeights);
+    const maxClientHeight = Math.max(...clientHeights);
+    const clientHeightVariance = maxClientHeight - minClientHeight;
+    const minRatio = Math.min(...ratios);
+    const maxRatio = Math.max(...ratios);
+    const ratioVariance = maxRatio - minRatio;
+
+    expect(
+        heightVariance,
+        `combobox scrollHeight changed by ${heightVariance}px during scroll`
+    ).toBeLessThan(100);
+    expect(
+        clientHeightVariance,
+        `combobox clientHeight changed by ${clientHeightVariance}px during scroll`
+    ).toBeLessThanOrEqual(1);
+    expect(
+        ratioVariance,
+        `combobox scrollHeight/clientHeight ratio changed by ${ratioVariance} during scroll`
+    ).toBeLessThan(0.5);
+
+    const lastMeasurement = measurements.at(-1);
+    expect(lastMeasurement).toBeDefined();
+
+    await page.waitForTimeout(650);
+
+    const settledState = await menu.evaluate((el) => ({
+        scrollTop: el.scrollTop,
+        scrollHeight: el.scrollHeight,
+        clientHeight: el.clientHeight,
+        ratio: el.scrollHeight / el.clientHeight,
+    }));
+
+    expect(
+        Math.abs(settledState.scrollHeight - lastMeasurement!.scrollHeight),
+        "combobox scrollHeight shifted after the 600ms scroll debounce settled"
+    ).toBeLessThan(100);
+    expect(
+        Math.abs(settledState.clientHeight - lastMeasurement!.clientHeight),
+        "combobox clientHeight changed after the 600ms scroll debounce settled"
+    ).toBeLessThanOrEqual(1);
+    expect(
+        Math.abs(settledState.ratio - lastMeasurement!.ratio),
+        "combobox scrollHeight/clientHeight ratio shifted after the 600ms scroll debounce settled"
+    ).toBeLessThan(0.5);
+    expect(
+        Math.abs(settledState.scrollTop - lastMeasurement!.scrollTop),
+        "combobox scrollTop drifted after the 600ms scroll debounce settled"
+    ).toBeLessThanOrEqual(1);
+});
+
 test("touch selection commits and closes", async ({ browser, browserName }) => {
     test.skip(browserName === "firefox", "Firefox does not support mobile contexts");