Your agent reasons, decides, acts — then forgets. Lethe keeps the reasoning alive. Persistent memory across sessions, crash recovery, and a human review layer for every decision your agent makes.
In Greek mythology, the underworld was crossed by five rivers. The darkest of these was Λήθη — Lethe, the river of oblivion. Every soul that drank from it lost all memory of their former life. Identity, knowledge, everything — dissolved into the current.
Souls were not supposed to drink from Lethe. The Orphic gold tablets — buried with the dead for two thousand years — contained a single instruction: avoid the river on the left. Drink instead from Mnemosyne, the spring of memory.
We named this project for the river — not to honour forgetting, but to build its opposite.The founding idea
Your Docker container is the vessel floating on Lethe. The water flows around it. Nothing is lost.
Souls drank from Lethe to forget their past lives entirely. We named our project for the thing it defeats — the forgetting your agents experience between every session.
The Orphic tablets told souls to seek Mnemosyne instead — the spring whose waters preserved all memory. Lethe's session summary is your agent's draught from Mnemosyne.
Charon carried souls across the river for an obol. Your Docker container is the vessel he carries — floating on Lethe, passing through it untouched, memory intact.
Meet the ferryman →At Cape Tainaron the Greeks placed an entrance to the underworld — watched in both directions. Matapan is that gate for agents: isolated workspaces in, sealed and verified proposals out.
Approach the gate →One command adds the Lethe skill to OpenClaw. It registers as a context engine — no config, no code changes to your agent.
Every session start runs two-stage retrieval: previous session summary first, then recent events. The agent has context before it processes a single message.
The system prompt preamble conditions the agent to call memory.record(), memory.log(), and memory.flag(). No explicit tagging needed.
A background process writes a snapshot every 60 seconds. If the container crashes, the next session resumes from the last checkpoint automatically.
Every uncertainty your agent surfaced appears in the review board. Mark it resolved — the next session knows what was approved.
{
"session_summary": {
"decisions": [
"Docker Compose v2 — profiles needed",
"Traefik over nginx — service discovery"
],
"open_threads": [
"healthcheck interval unverified"
]
},
"resume_flag": true,
"interrupted_at": "2026-03-24T05:10:00Z"
}
Stores what the agent decided and why — not just facts. The full reasoning chain survives session boundaries.
Heartbeat checkpoints every 60 seconds. If the container goes down, the next session resumes automatically from the last snapshot.
Agents self-report uncertainty with confidence scores. Humans review and resolve before the next session continues.
Session summary first for continuity, then recent events fill the token budget. Precise, never overflowing context.
Installs as a ClawHub skill. Full bootstrap, assemble, compact context engine hooks wired out of the box.
Every event is append-only, threaded by parent_event_id. Reconstruct exactly what the agent was thinking at any point.
The five rivers of Hades each carried a different fate. Lethe — the river of forgetting — was the most powerful. Your agent's memory floats above them all, untouched.
One environment variable separates the two tiers.
One container. No account. No configuration.
$ docker run -p 18483:18483 -v ./data:/data ghcr.io/openlethe/lethe$ openclaw skills install lethe-memory→ docs.html — the full guide