Charon

Lethe — Persistent Memory for AI Agents

Lethe is a self-hosted persistent memory platform for AI agents. It gives agents durable, reviewable memory that survives sessions, restarts, and model changes — without surrendering that memory to a third party.

Any agent can use Lethe: ChatGPT, Claude, Claude Code, Cursor, VS Code agents, OpenClaw, custom MCP clients, local IDE assistants, or backend services. Lethe is a general-purpose memory platform; the OpenClaw plugin is one excellent integration, not a requirement.

Why it exists

Every agent session starts from zero. The same question, the same reasoning, the same dead ends — every time. Lethe breaks that loop with two complementary memory systems:

• Session memory — events, summaries, checkpoints, and interruption recovery so an agent resumes exactly where it stopped.
• Versioned memory — durable, shared, review-gated knowledge with immutable history, provenance, branching, and merging (see Memory Git).

Who it is for

• Individuals giving a single agent (ChatGPT, Claude, Cursor, an IDE assistant) a long memory.
• Teams running several agents against one shared, reviewed memory backend.
• Operators who need memory to stay on their own infrastructure, in one container, with their keys.

Three runtime modes

Mode	Purpose	Choose it when
Legacy	Session-oriented memory: events, summaries, checkpoints, interruption recovery, task tracking	You use OpenClaw, or want session continuity only
Git	Versioned persistent memory for any agent: durable knowledge, decisions, shared multi-agent memory, reviewable history	You want persistent, shared, or governed memory — with or without OpenClaw
Hybrid	Both memory systems in one instance	Migration, development, or when you want session and versioned memory together

Details and decision guidance: docs/runtime-modes.md.

Install

# legacy session memory, port 18483
docker run -d --name lethe \
  -p 127.0.0.1:18483:18483 \
  -v ./lethe-data:/data \
  ghcr.io/openlethe/lethe:latest

Memory Git (git mode) runs from docker-compose.git.yml; hybrid mode is one instance with both surfaces. Full instructions, all compose variations, and source builds: docs/installation.md · docs/docker-compose.md

Documentation

Read in order:

1. Overview — what Lethe is and isn't, principles, ecosystem
2. Installation — Docker, git mode, hybrid, source build
3. Runtime modes — legacy vs git vs hybrid, how to choose
4. Memory Git — versioned memory, refs, changesets, proposals, merges
5. Legacy mode — session memory and the OpenClaw experience
6. Architecture — components, boundary, data model, security
7. Configuration — every environment variable
8. Deployment & operations — production checklist, upgrades, backup
9. Compose variations — legacy, git, hybrid, governed stack
10. HTTP API reference — every route, both surfaces
11. OpenClaw — the plugin integration
12. Integrations — ChatGPT, Claude Code, Cursor, MCP, multi-agent
13. Migration & upgrading — version migrations, legacy ↔ Memory Git
14. FAQ

Protocol and deep-dive references: memory-git-v1.md (the memory_git/v1 contract) · memory-context-bridge.md (projection & manifests) · observability.md (metrics, SLOs, alerts)

Related projects

• Charon — the MCP authorization and governance gateway for Lethe: scoped principals, independent review, replay-proof protected merges, and a fail-closed audit ledger. Recommended for shared or multi-agent deployments.
• OpenClaw plugin — optional context engine for OpenClaw, published on ClawHub as lethe. Optional; everything works without it.

Compatibility

Component	Release
Lethe	v0.4.0
Charon	v0.1.0-beta.1
Memory Git schema	memory_git/v1
Merge authorization	memory-git-merge/v2
Lethe OpenClaw plugin	matching Lethe release

License

See LICENSE. Issues and contributions: CONTRIBUTING.md · Security reports: SECURITY.md