lethe

Node.js bindings to the Rust core of lethe, a self-improving memory store for LLM agents. Built with napi-rs and distributed as prebuilt platform binaries, so no Rust toolchain is needed at install time.

Install

npm install @lethe-memory/lethe
# or
bun add @lethe-memory/lethe

Use

import { MemoryStore } from "@lethe-memory/lethe";

const store = await MemoryStore.open("./my_memories");
await store.add("I prefer window seats on flights");
await store.add("My wife needs aisle seats");
await store.add("I work at Google as a software engineer");

const hits = await store.retrieve("What are my travel preferences?", 5);
for (const h of hits) {
  console.log(`  [${h.score.toFixed(1)}] ${h.content}`);
}

await store.save();

add / retrieve / save are async. napi-rs runs them via tokio::spawn_blocking so the Node event loop never stalls on the ONNX inference or DuckDB I/O.

Open options

MemoryStore.open(path, {
  biEncoder?:    string,   // default "Xenova/all-MiniLM-L6-v2"
  crossEncoder?: string,   // default "Xenova/ms-marco-MiniLM-L-6-v2"
  nClusters?:    number,   // RIF clusters; 0 disables clustering
  useRankGap?:   boolean,
  kShallow?:     number,   // default 30
  kDeep?:        number,   // default 100
});

See also

• Project landing page: architecture, benchmarks, research journey
• lethe-cli (Homebrew: lethe): the standalone CLI

License: MIT.