fix: contain desktop board overflow

e2e/desktop-board-shell.spec.ts

@@ -0,0 +1,105 @@
+import { expect, test } from '@playwright/test';
+import { bypassAuth, cleanupRoutes, deleteTask, seedTestTask } from './helpers/auth';
+
+test.describe('Desktop board shell containment', () => {
+  const taskIds: string[] = [];
+
+  test.beforeEach(async ({ page }) => {
+    await bypassAuth(page);
+    await page.addInitScript(() => {
+      window.localStorage.setItem('veritas-kanban-theme', 'dark');
+      window.localStorage.setItem('veritas.desktop.rightRailOpen', 'true');
+      window.localStorage.setItem('veritas.workbench.dockPosition', 'right');
+      Object.defineProperty(window, 'veritasDesktop', {
+        configurable: true,
+        value: {
+          onMenuCommand: () => () => undefined,
+          toggleWindowMaximize: async () => ({ maximized: false }),
+        },
+      });
+    });
+  });
+
+  test.afterEach(async ({ page }) => {
+    await Promise.all(taskIds.splice(0).map((taskId) => deleteTask(page, taskId).catch(() => {})));
+    await cleanupRoutes(page);
+  });
+
+  test('keeps chat and a real drag inside the populated desktop viewport', async ({ page }) => {
+    for (let index = 0; index < 6; index += 1) {
+      const task = await seedTestTask(page, {
+        title: `Desktop shell source ${index + 1}`,
+        description:
+          'Representative populated-board task whose wrapped content exercises the constrained desktop workspace.',
+        type: index % 2 === 0 ? 'code' : 'content',
+      });
+      taskIds.push(task.id as string);
+    }
+    const destination = await seedTestTask(page, {
+      title: 'Desktop shell destination',
+      description: 'Visible drop target for the desktop shell containment regression.',
+      status: 'blocked',
+    });
+    taskIds.push(destination.id as string);
+
+    await page.setViewportSize({ width: 1224, height: 768 });
+    await page.goto('/');
+    await expect(page.locator('html')).toHaveAttribute('data-client', 'desktop');
+    await expect(page.getByLabel('Board right sidebar')).toBeVisible();
+    await Promise.all(
+      taskIds.map((taskId) => expect(page.locator(`[data-task-id="${taskId}"]`)).toBeAttached())
+    );
+
+    await page.getByRole('button', { name: 'Open chat dock' }).click();
+    await expect(page.getByRole('region', { name: 'Workbench right dock' })).toBeVisible();
+
+    const readViewport = () =>
+      page.evaluate(() => ({
+        innerHeight: window.innerHeight,
+        documentHeight: document.documentElement.scrollHeight,
+        scrollY: window.scrollY,
+        shellHeight: document.querySelector('.desktop-app-shell')?.getBoundingClientRect().height,
+      }));
+    const expectedViewport = {
+      innerHeight: 768,
+      documentHeight: 768,
+      scrollY: 0,
+      shellHeight: 768,
+    };
+    expect(await readViewport()).toEqual(expectedViewport);
+
+    await page.getByRole('button', { name: 'Close right dock' }).click();
+    await expect(page.getByRole('region', { name: 'Workbench right dock' })).toHaveCount(0);
+
+    const movingId = taskIds[5];
+    const destinationId = destination.id as string;
+    const source = page.locator(`[data-task-id="${movingId}"]`);
+    const destinationCard = page.locator(`[data-task-id="${destinationId}"]`);
+    const blocked = page.getByRole('region', { name: 'Blocked' });
+    await expect(source).toHaveClass(/cursor-grab/);
+    const sourceBox = await source.boundingBox();
+    const destinationBox = await destinationCard.boundingBox();
+    expect(sourceBox).not.toBeNull();
+    expect(destinationBox).not.toBeNull();
+    expect(
+      await page.evaluate(
+        ({ x, y }) =>
+          document.elementFromPoint(x, y)?.closest('[data-task-id]')?.getAttribute('data-task-id'),
+        { x: sourceBox!.x + sourceBox!.width / 2, y: sourceBox!.y + 18 }
+      )
+    ).toBe(movingId);
+
+    await page.mouse.move(sourceBox!.x + sourceBox!.width / 2, sourceBox!.y + 18);
+    await page.mouse.down();
+    await page.mouse.move(sourceBox!.x + sourceBox!.width / 2 + 30, sourceBox!.y + 48, {
+      steps: 8,
+    });
+    await expect(page.locator('[data-board-drag-overlay]')).toHaveCount(1);
+    await page.mouse.move(destinationBox!.x + destinationBox!.width / 2, destinationBox!.y + 18, {
+      steps: 8,
+    });
+    await page.mouse.up();
+    await expect(blocked.locator(`[data-task-id="${movingId}"]`)).toBeVisible();
+    expect(await readViewport()).toEqual(expectedViewport);
+  });
+});

web/src/globals.css

@@ -243,6 +243,9 @@ html[data-client='desktop'] .desktop-app-shell {
   min-height: 0;
   flex-direction: column;
   overflow: hidden;
+  /* Keep tall board and drag descendants inside the app's internal scrollers.
+     Without layout containment Chromium exposes their overflow on the document. */
+  contain: layout;
 }
 
 html[data-client='desktop'] .desktop-app-header {