# Severian: Hermes Agent plugin

> Local-first long-term memory for Hermes agents: a canonical append-only store (SQLite or PostgreSQL+pgvector) with five-dimensional tenant/profile/collection/agent/session scope, hybrid BM25+vector retrieval…

Canonical: https://hermeswatcher.com/plugins/severian  
Tier: Community  
Official page (Nous Research): https://hermes-agent.nousresearch.com/docs/plugins/severian  
Last updated in catalog: 2026-10-28

Local-first long-term memory for Hermes agents: a canonical append-only store (SQLite or PostgreSQL+pgvector) with five-dimensional tenant/profile/collection/agent/session scope, hybrid BM25+vector retrieval with a re-ranker, memories that cite the observations they came from, per-turn user facts, real dates next to relative times, truth resolution when a newer fact replaces an older one, and a conflict note when two returned memories disagree. Fully offline by default; Qwen3-Embedding-0.6B semantic embeddings opt-in, locally or in a user-owned sidecar. On OmniMemEval's public long-term-memory leaderboard (its own models, prompts and full public sets) it scores 90.6 LongMemEval (1st), 87.3 LoCoMo (2nd) and 71.6 BEAM 100K (2nd, within noise of the lead); it re-ran LCM-X to check the board's records, and per-question results, a strict second marker and scripts are published in the repo.

## Good to know before installing

Stores every conversation turn in one SQLite database under the Hermes root (`<hermes root>/severian`) shared by all profiles with rows scoped per profile, or in the PostgreSQL database named by `SEVERIAN_DSN`; the opt-in Qwen/Granite embeddings download a model from Hugging Face on first use, and the opt-in embedding sidecar sends memory text to the URL you configure.

From the plugin's catalog listing.

## How to install

1. Install it. Hermes asks for any API keys it needs (this one needs `SEVERIAN_DSN`), then asks whether to turn it on.

```bash
hermes plugins install severian
```

2. Said no? Turn it on later:

```bash
hermes plugins enable severian
```

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, AI models & providers
- Maintained by: Sahil-SS9 (Community)
- Needs: `SEVERIAN_DSN` (API key)
- Version: 0.3.13
- In the catalog since: 2026-10-28

## Links

- [Full setup and settings (official page)](https://hermes-agent.nousresearch.com/docs/plugins/severian)
- [Source code](https://github.com/Sahil-SS9/Severian#readme)
- [All plugins](https://hermeswatcher.com/plugins.md)

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