> Judging from my own frustrating attempts to use Gemini for vibe-coding, it seems like Google is badly over-sold (i.e., under-provisioned).

Based on my experience lately with Codex, it seems the opposite. Gemini 3.6 Flash (high) in Antigravity CLI feels a LOT faster than GPT 5.6 Luna (high) in codex. In the order of 10-50x.