Reference-frame upload, the mp4 download and OpenAsset (/content) streaming now egress on the local IP; only the generate submit uses proxy.url. Verified live: submit egress 98.97.26.37 (proxy) vs upload/download 76.209.9.65 (local), 3.47MB video generated OK.
Derive the 49-byte header seed and the salt F per-session from the grok homepage (browser-free tls-client GET), instead of hardcoding constants that go stale on every grok web rebuild (403 anti-bot). F is reproduced natively in Go (curve keyframe sampling: cubic-bezier easing, color lerp, rotation matrix, JS-exact number->hex). Static constants remain as env-overridable fallback. Adds offline regression test against server-verified ground-truth triples.