# Zyphra's ZHA routes KV cache lookups through a summary tree

> Original title: Finding a passage in a long book? Look for the right chapter, then section, rather than rereading every sentence.

- Source: Zyphra
- Published: 2026-11-02T22:04:52.000Z
- Bad Influence: https://badinfluence.news/items/q9s009eu6s2x1hir0m90tiw8x
- Original: https://x.com/ZyphraAI/status/2117377428972847425

## Summary

Zyphra introduces ZHA, which applies a hierarchical search to the KV cache. It recursively summarizes chunks of keys into a tree and routes queries top-down. When a node is skipped, all keys beneath it go unscored.

## Post

Finding a passage in a long book? Look for the right chapter, then section, rather than rereading every sentence.

ZHA applies the same idea to the KV cache. We recursively summarize chunks into a tree and route top-down. If a node is skipped, all keys under it aren’t scored.

[Video](https://badinfluence.news/api/img-proxy?u=https%3A%2F%2Fpbs.twimg.com%2Famplify_video_thumb%2F2117373174560284672%2Fimg%2FXHJqyO_MYt1tiou4.jpg&mode=thumb&exp=1793923200&sig=8a633cfa61af35aa)