Xiaomi posts HySparse2, the sparse-attention design for MiMo-V3, which lets prefill skip every cross-decoder layer
arXiv (via r/LocalLLaMA 303 upvotes)·medium signal
arXiv 2609.26368 (submitted September 22) pairs a YOCO-style self-decoder/cross-decoder split with token-level sparse attention. The cross-decoder KV caches are built from self-decoder hidden states, so prefill stops after the self-decoder. On an 80B-A3B MoE it beats HySparse and hybrid SWA on long-context retrieval and multi-turn agent tasks while cutting prefill compute and KV storage. The r/LocalLLaMA post reached 303 upvotes.