# LCM-X: Hermes Agent plugin

> Lossless memory for long sessions: LCM-X keeps every turn in a local store instead of compacting it away, and the agent can search and expand it.

Canonical: https://hermeswatcher.com/plugins/hermes-lcm-x  
Tier: Community  
Official page (Nous Research): https://hermes-agent.nousresearch.com/docs/plugins/hermes-lcm-x  
Last updated in catalog: 2026-10-25

Lossless memory for long sessions: LCM-X keeps every turn in a local store instead of compacting it away, and the agent can search and expand it. The store is local SQLite (lcm.db) with a recoverable DAG of summaries over it and 15 lcm_* tools for search, recall and expansion. Select it with context.engine: lcm-x. Upgrading from hermes-lcm (breaking in v0.24.0): stop Hermes, then in plugins.enabled replace hermes-lcm with hermes-lcm-x and run exactly one LCM copy (the install script prints the steps; the old engine name lcm still resolves with a deprecation warning); lcm.db and the lcm: config block are unchanged. Summaries use the model Hermes is configured with.

## Good to know before installing

Optional semantic recall (embeddings_enabled, off by default) sends message text to the embedding provider you configure (Voyage via VOYAGE_API_KEY, an OpenAI-compatible endpoint, or a local Ollama), and once enabled new summaries are embedded automatically in the background; in-process FastEmbed keeps it on the machine after a one-time model download. For known cloud providers the provider-bound copy is privacy-transformed by default (LCM_EMBEDDING_PRIVACY_ENABLED=false opts out), while lcm.db keeps the raw text. Every turn (user, assistant and tool output) is stored in plaintext in lcm.db (secret redaction at rest is opt-in), and oversized tool outputs are by default written as plaintext files under HERMES_HOME/lcm-large-outputs and replaced in the model's context by recoverable references. The engine also reads Hermes' state.db read-only for session lineage, reads private AIAgent attributes via the call stack on Hermes builds without subagent hooks, and runs git on its own install directory for lcm_status/lcm_doctor; tiktoken may fetch its BPE file on first use.

From the plugin's catalog listing.

## How to install

1. Install it. Hermes asks for any API keys it needs, then asks whether to turn it on.

```bash
hermes plugins install hermes-lcm-x
```

2. Said no? Turn it on later:

```bash
hermes plugins enable hermes-lcm-x
```

3. Restart Hermes so it loads the plugin.

Some plugins also need a sign-in or settings: see the official page. Memory plugins ask whether to become your memory provider instead. Steps follow the official plugins guide: https://hermes-agent.nousresearch.com/docs/user-guide/features/plugins

## Facts

- Category: Memory & notes
- Maintained by: 100yenadmin (Community)
- Needs: No API keys declared
- Adds tools: `lcm_grep`, `lcm_recall`, `lcm_query_state`, `lcm_compute`, `lcm_compile_evidence`, `lcm_evidence_pack`, `lcm_retrieve`, `lcm_recent`, `lcm_load_session`, `lcm_describe`, `lcm_expand`, `lcm_expand_query`, `lcm_status`, `lcm_inspect`, `lcm_doctor`
- Requires Hermes: `>=0.21.3`
- Version: 0.28.1
- In the catalog since: 2026-09-26, updated 2026-10-25

## Links

- [Full setup and settings (official page)](https://hermes-agent.nousresearch.com/docs/plugins/hermes-lcm-x)
- [Source code](https://github.com/electricsheephq/lcm-x#readme)
- [All plugins](https://hermeswatcher.com/plugins.md)

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