int8_per_token_head keeps a separate fp32 scale tensor per (token,
head); Gemma4's hybrid head dims (SWA 256 / full 512) make the
per-token page bytes 4160 vs 8256, not an integer ratio, so
unify_kv_cache_spec_page_size raises NotImplementedError — nine
crash-loop restarts measured. TurboQuant k8v4 packs its block scales
inside the tensor, keeps the 2:1 page ratio, and has a dedicated
backend with an explicit Ampere path. 289,647 -> ~772k-token pool.
Frank
5e581666f2