feat: polish nightdrive road sun and signage

tests/browser/journey-integration.spec.ts

@@ -1,4 +1,4 @@
-import { expect, test } from '../helpers/serve-dist';
+import { clickNavigationLink, expect, test } from '../helpers/serve-dist';
 import {
   installSceneInstrumentation,
   readSceneInstrumentation,
@@ -104,6 +104,65 @@ test('draws only the independently eligible next roadside sign during passive fo
   expect([...new Set(labels)]).toEqual([oracle.expectedLabel]);
 });
 
+test('keeps a readable sign immutable through reversal, resize, and a multi-section jump', async ({
+  page,
+  distUrl,
+}) => {
+  await page.setViewportSize({ width: 1440, height: 900 });
+  await page.goto(distUrl, { waitUntil: 'domcontentloaded' });
+  await expect(page.locator('.journey-world')).toHaveAttribute('data-scene-state', 'running');
+
+  const oracle = await page.evaluate(() => {
+    const profile = document.getElementById('profile-heading');
+    if (!(profile instanceof HTMLElement)) throw new Error('Missing profile heading');
+    const viewportHeight = window.visualViewport?.height ?? window.innerHeight;
+    const headingTop = profile.getBoundingClientRect().top + window.scrollY;
+    return {
+      destination: Math.max(1, headingTop - viewportHeight * (0.35 + 0.8)),
+      viewportHeight,
+    };
+  });
+  await page.mouse.wheel(0, 1);
+  for (let y = 1; y < oracle.destination; y += oracle.viewportHeight * 0.5) {
+    await page.evaluate((nextY) => window.scrollTo(0, nextY), y);
+    await waitForOneAnimationFrame(page);
+  }
+  await page.evaluate((destination) => window.scrollTo(0, destination), oracle.destination);
+  await expect.poll(async () => (await readSceneInstrumentation(page)).routeLabelsDrawn)
+    .toContain('Profile');
+  await page.waitForTimeout(1_250);
+
+  await page.mouse.wheel(0, -120);
+  await page.setViewportSize({ width: 844, height: 390 });
+  await page.evaluate(() => {
+    const target = document.getElementById('selected-builds-heading');
+    if (!(target instanceof HTMLElement)) throw new Error('Missing selected builds heading');
+    window.scrollTo(0, target.getBoundingClientRect().top + window.scrollY);
+  });
+  await page.waitForTimeout(450);
+
+  const labels = (await readSceneInstrumentation(page)).routeLabelsDrawn;
+  expect([...new Set(labels)]).toEqual(['Profile']);
+  expect((await readSceneInstrumentation(page)).maximumCanvasCount).toBeLessThanOrEqual(1);
+});
+
+test('suppresses roadside signs for explicit navigation and history restoration', async ({
+  page,
+  distUrl,
+}) => {
+  await page.goto(distUrl, { waitUntil: 'domcontentloaded' });
+  await expect(page.locator('.journey-world')).toHaveAttribute('data-scene-state', 'running');
+
+  await clickNavigationLink(page, '#selected-builds');
+  await expect(page.locator('#selected-builds-heading')).toBeFocused();
+  await page.waitForTimeout(400);
+  expect((await readSceneInstrumentation(page)).routeLabelsDrawn).toEqual([]);
+
+  await page.goBack({ waitUntil: 'domcontentloaded' });
+  await page.waitForTimeout(400);
+  expect((await readSceneInstrumentation(page)).routeLabelsDrawn).toEqual([]);
+});
+
 function colorEnergy(color: string): number {
   const value = Number.parseInt(color.slice(1), 16);
   return ((value >> 16) & 0xff) + ((value >> 8) & 0xff) + (value & 0xff);