Qwen3.8 125B (6B active) Flash-Next

User reports Qwen3.8 Flash-Next at 38.3 t/s decode and 937 t/s prefill on a Ryzen AI Max+ 395 with 128 GB, at 1,004,581 tokens of context. Setup is the halogen server (0.12.0) with HALOGEN_ROPE_YARN=4 and HALOGEN_CTX=1048576, greedy, 64 tokens, using the default speculative drafter; the 1M row is a single cold request. At 258,794 tokens the same setup gives 45.0 t/s decode and 1,114 t/s prefill; a follow-up turn over the prompt cache at 1M reaches first token in about 0.55 s.