Lethe docs · Overview

Overview

Lethe is a self-hosted persistent memory platform for AI agents. It runs as a single container with an embedded SQLite store, exposes a typed HTTP API, and — through Charon — a scoped MCP surface for agents.

The problem

Agents forget. Between sessions, between restarts, between models, every conversation rebuilds context from nothing. Lethe provides two ways out of that loop, selectable per deployment (or combined):

Session memory (legacy mode) — continuity for a single agent: what happened, what was decided, what is still open, resumable after any interruption.
Versioned memory (git mode) — durable knowledge with history: project knowledge, architecture decisions, implementation notes, durable preferences, collaborative and multi-agent shared memory — written through review, never overwritten silently.

What Lethe is not

Not a chatlog store. Records are semantic — decisions, facts, tasks, flags, outcomes — with confidence scores and provenance, not raw transcripts.
Not a vector database. Retrieval is exact: by session, by ref, by head. No embeddings are required and none are tuned for you.
Not a hosted service. Lethe runs on your infrastructure, with your keys, in one non-root container. Nothing leaves your network unless you tunnel it deliberately.
Not filesystem Git. Memory Git borrows Git's semantics — refs, changesets, branching, merging, immutable history — applied to memory records. There are no .git directories involved.

Who uses it

Single-agent setups — ChatGPT, Claude, Claude Code, Cursor, a local IDE assistant, each with durable memory of their own.
Multi-agent setups — several agents writing to owned branches, one reviewed shared memory on refs/shared/main, with Charon enforcing who may write, review, and merge.
OpenClaw users — the OpenClaw plugin (legacy mode) provides automatic context injection as a first-class integration.

Design principles

Exact over approximate. Accepted memory is reconstructed at an exact changeset head. Readers get precisely what was reviewed — nothing more.
Review before acceptance. Shared memory moves only through proposal, independent review, and a signed, single-use merge authorization.
Fail closed. Missing keys, mismatched keys, malformed operations, stale bases, and replayed authorizations are all hard errors, never silent degradation.
One container, your keys. Non-root image, embedded SQLite with WAL and synchronous=FULL, operator-generated credentials, no required external services.

The ecosystem

ChatGPT / Claude / Claude Code / Cursor / IDE assistants / MCP clients
                |
                |  OAuth (S256 PKCE) or Obol
                v
             Charon        — authorization, scopes, review, protected merges
                |
                |  private typed API (bearer)
                v
              Lethe        — canonical persistent memory (legacy + Memory Git)

OpenClaw (optional) — plugin injects session memory automatically (legacy mode)

Lethe works without Charon (direct bearer-key API access) and without OpenClaw (any MCP client or plain HTTP client). Charon is the recommended gateway once memory is shared between agents or exposed beyond loopback.

Next steps

Installation →