"HySparse2: Hybrid Sparse Attention with Two-Level KV Sharing" Xiaomi dropped their new attention mechanism for their upcoming V3 model. Their new HySparse2 makes long-context agents much cheaper by sharing KV caches across layers instead of repeatedly processing and storing the entire context. With two-level KV sharing and token-level sparse attention, HySparse2 can stop prefill halfway through the model while still retrieving the right tokens from long contexts. At 1M context, it cuts…