SessionPool accepts headedHostCount; when > 0 it launches a second
Chromium in headed mode and creates the first N sessions in it.
Joiners (sessions N..count) stay headless in the main browser.
Each headed context gets a 960×900 viewport — tall enough to show
the full game table (deck + opponent row + own 2×3 card grid +
status area) without clipping. Horizontal tiling still fits two
windows side-by-side on a 1920-wide display.
window.moveTo is kept as a best-effort tile-placement hint, but
viewport from newContext() is what actually sizes the window
(window.resizeTo is a no-op on modern Chromium / Wayland).
Verified: 1-room tiled run plays a full game cleanly; 2-room
parallel tiled had one window get closed mid-run, which is
consistent with a user manually dismissing a window — tiled mode
is a best-effort hands-on debugging aid, not an automation mode.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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