diff --git a/dashboard/tests/e2e/security/security.spec.ts b/dashboard/tests/e2e/security/security.spec.ts
new file mode 100644
index 0000000..55a3d09
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+++ b/dashboard/tests/e2e/security/security.spec.ts
@@ -0,0 +1,81 @@
+import { expect, test } from '@playwright/test';
+
+// Phase B8 — Cross-cutting security. Things that aren't tied to a
+// single page: session handling, secret leakage, error states for
+// missing resources, and a sanity check that no XSS sink fires
+// anywhere in the dashboard's main authed routes.
+
+const VALID_USERNAME = process.env.E2E_ADMIN_USERNAME ?? 'admin';
+const VALID_PASSWORD = process.env.E2E_ADMIN_PASSWORD ?? 'admin';
+
+test.describe('B8 cross-cutting security', () => {
+	test('expired/stale token: any authed call redirects to /login', async ({ page }) => {
+		// Replace the storageState token with an obvious garbage
+		// value; the fetch wrapper treats 401 as "go to /login".
+		await page.goto('/admin/login');
+		await page.evaluate(() => {
+			localStorage.setItem('picloud.admin.token', 'expired-or-bogus-token');
+		});
+		await page.goto('/admin/apps');
+		await expect(page).toHaveURL(/\/admin\/login$/);
+	});
+
+	test('login response cookie is HttpOnly', async ({ request }) => {
+		const res = await request.post('/api/v1/admin/auth/login', {
+			data: { username: VALID_USERNAME, password: VALID_PASSWORD },
+			headers: { 'content-type': 'application/json' }
+		});
+		expect(res.ok()).toBe(true);
+		const headers = res.headers();
+		const setCookie = headers['set-cookie'];
+		// Backend may or may not set a cookie (the dashboard primarily
+		// uses bearer-in-localStorage). If it does, it must be
+		// HttpOnly so XSS can't exfiltrate it.
+		if (setCookie) {
+			expect(setCookie.toLowerCase()).toContain('httponly');
+		}
+	});
+
+	test('bootstrap password is not present in the DOM after login', async ({ page }) => {
+		await page.goto('/admin/apps');
+		const body = await page.locator('body').innerText();
+		expect(body).not.toContain(VALID_PASSWORD);
+	});
+
+	test('non-existent app slug shows a recoverable error, not a crash', async ({ page }) => {
+		await page.goto('/admin/apps/does-not-exist-e2e-9999');
+		// Page must render *something* and the layout must remain
+		// intact (header link to Apps still works).
+		await expect(page.getByRole('link', { name: 'Apps' })).toBeVisible();
+		// And surface the failure to the user — either a "couldn't
+		// load" message or a "back to apps" link.
+		const errorOrBack = page.locator('.error, a[href$="/admin/apps"]');
+		await expect(errorOrBack.first()).toBeVisible();
+	});
+
+	test('xss probe across major surfaces never fires a dialog', async ({ page }) => {
+		page.on('dialog', async (dialog) => {
+			await dialog.dismiss();
+			throw new Error(
+				`XSS sink fired — got a ${dialog.type()} dialog: "${dialog.message()}"`
+			);
+		});
+
+		// Cover each main authed route. None should evaluate any
+		// payload that earlier tests may have stored, and none should
+		// inject inline <script> tags from server responses.
+		for (const path of ['/admin/apps', '/admin/profile', '/admin/users']) {
+			await page.goto(path);
+			await page.waitForLoadState('domcontentloaded');
+			const inlineScripts = await page.locator('script[src=""], script:not([src])').count();
+			// Svelte itself injects no inline <script> in the
+			// production bundle; vite dev does, but never with
+			// onerror/alert payload text in them.
+			const evilInline = await page
+				.locator('script:has-text("alert"), script:has-text("__xss")')
+				.count();
+			expect(evilInline, `evil inline script tag on ${path}`).toBe(0);
+			expect(inlineScripts).toBeGreaterThanOrEqual(0); // sanity assertion, no crash
+		}
+	});
+});