Served with isolation headers; start-screen capability notices; tests on the real GPU (t88 phase 1)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/firefox_smoke.py

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+"""An isolated Firefox title screen and three seconds of a new pixel world."""
+import json
+from pathlib import Path
+import sys
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent / 'tools'))
+from use_venv import ensure_playwright
+ensure_playwright()
+from browser import capabilities, consume_gpu_option, installed, launch
+
+consume_gpu_option()
+if not installed('firefox'):
+    print('SKIP firefox_smoke.py: Playwright Firefox is not installed')
+    sys.exit(0)
+
+with launch(browser_name='firefox') as (_, page, url):
+    errors = []
+    page.on('pageerror', lambda e: errors.append(str(e)))
+    page.add_init_script("localStorage.setItem('deepgrain.settings', JSON.stringify({look:'pixel', sv:2}));")
+    page.goto(url)
+    caps = capabilities(page)
+    print('Firefox: ' + json.dumps(caps))
+    assert caps['isolated']
+    if not caps['webgpu']:
+        assert page.locator('#cap-notice').is_visible()
+        text = page.inner_text('#cap-notice')
+        assert 'about:config' in text and 'dom.webgpu.enabled' in text and 'Firefox Nightly' in text
+    print('PASS Firefox isolation and capability notice')
+    page.click('#btn-new')
+    page.fill('#nw-seed', '424242')
+    page.select_option('#nw-size', '2048x1024')
+    page.click('#btn-generate')
+    page.wait_for_function('GAME.running && !GAME.loading', timeout=60000)
+    before = page.evaluate('tick')
+    page.wait_for_timeout(3000)
+    assert page.evaluate('tick') > before
+    assert not errors, errors
+    print('PASS Firefox new world runs for three seconds without page errors')