Lethe docs · Legacy Mode

Legacy Mode

Legacy mode is Lethe's session-oriented memory: the original OpenLethe service. It gives one agent continuity across sessions — what happened, what was decided, what remains open — resumable after any interruption. It is the required mode for the OpenClaw plugin and the right choice when session continuity is all you need.

What it records

Type Use case
record A decision made, a direction chosen, a conclusion reached
log An observation, a discovery, something worth noting
flag Uncertainty that needs human review before proceeding
task A work unit with a status chain: todo → in_progress → done

Records carry confidence scores (0.0–1.0). Flags persist across sessions until explicitly reviewed. Task events chain so you can trace the history of any piece of work.

How it works

  1. Sessions — each agent session gets a stable key. State: active, interrupted, or completed.
  2. Events — every meaningful action is logged: decisions, observations, flags, tasks. Events are append-only and threaded by parent_event_id.
  3. Checkpoints — periodic snapshots; an interrupted session resumes from the last checkpoint, not from zero.
  4. Compaction — long sessions synthesize events into a narrative summary while the full history stays in the database.
  5. Threads — flags and open questions group into named threads tracked across sessions.
  6. Assemblies — bounded context packs built at read time (summary first, then recent events to the token budget), with optional quality feedback (good, stale_included, missing_memory, too_large, irrelevant, other).

Deploying it

docker run -d --name lethe \
  -p 127.0.0.1:18483:18483 \
  -v "$PWD/lethe-data:/data" \
  ghcr.io/openlethe/lethe:latest

Loopback needs no key. For anything beyond loopback, set LETHE_API_KEY (see configuration.md). The dashboard is at http://127.0.0.1:18483/ui/dashboard.

For OpenClaw users, the plugin automates the whole loop: it registers as a context engine, loads the previous session summary and recent events at startup, conditions the agent to record as it works, checkpoints every 60 seconds in the background, and surfaces flags in the review board.

openclaw skills install lethe-memory

The plugin is optional and OpenClaw-specific — see openclaw.md. Any other client can drive the same API directly (see api.md).

When not to choose it

← Memory GitArchitecture →