Gemini 4 Hydrogen: Default Is High, $1.50/$7.50 Is 2x Flash's Promo, and Sync Caps at 64K

Google launched gemini-4-hydrogen on Nov 12 at a flat $1.50/$7.50 — 2x 3.8 Flash's promo through Dec 31. The API default thinking level is high, AA's default page is xhigh (54, not the API's 51), and sync output still caps at 64K. No API call on this box.