Original title: VestigeKV: The NoPE-MLA KV Cache Carries Its Own Eviction Signal in a Vestigial Branch
WenJie Fan · September 2026
AI models use a memory called a KV cacheA memory storage in AI models that holds key and value information from previous tokens to avoid recomputation. to remember past text. Compressing this memory early is hard because the model does not know what future questions will ask. Old compression tricks fail here, scoring between 0.00 and 0.33 on memory tests because they rely on clues that have not happened yet. To fix this, researchers introduced VestigeKV for a model called Kimi Linear. The system does not discard tokens or need new training. Instead, it reads a tiny leftover 64-dimensional channel already inside the memory. This channel reveals token importance on its own. VestigeKV reads 11% of each row to keep the best rows in an active memory area while moving the rest into a bit-exact archive. This archive stays reachable whenever needed. Retrieval accuracy reaches 1.00 under 8x compression and 0.92 under 32x across 8k to 65k context lengths.
Imagine packing a suitcase for a trip, but you can only take a limited number of items. You don't know exactly what you'll need until you're there, so you might leave behind something crucial. In this paper, the system is like a suitcase that has tags on each item showing how essential it is, even before the trip starts, allowing it to pack only the most important things without losing anything vital.
This allows AI models to handle much longer texts, like entire books or lengthy conversations, without forgetting important details. It improves efficiency in applications such as document summarization or chatbots that need to maintain context over long interactions.
The method is only tested on the Kimi Linear model, so it may not work on other architectures without a matching cache layout. It exclusively applies to NoPE models and fails with RoPE-based models. The paper does not claim compatibility beyond the measured model, and extension to others is speculative.
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VestigeKV: The NoPE-MLA KV Cache Carries Its Own Eviction Signal in a Vestigial Branch — WenJie Fan
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.