DeepSeek cuts long-context cache costs to 890 bytes per token
DeepSeek-V4.1-Flash targets cheaper long-horizon agents by cutting the always-in-memory KV cache to 890 bytes per token, roughly one quarter of DeepSeek-V4-Flash's footprint. Its Causal Encoder-Decoder activates 8B parameters during prompt processing and 16B during decoding, while CSA2 reuses KV data across layers and FP4 stores it at lower precision. A separate replay method cuts persistent cache needs to roughly one eighth of the earlier model's.