hermes-mimir

Mimir persistent memory provider for Hermes Agent.

Mimir is an encrypted, local-first memory engine for AI agents — 27 MCP tools, single Rust binary (~8 MB), embedded SQLite + FTS5 + vector search. Zero cloud dependencies.

Features

• Encrypted at rest — AES-256-GCM encryption for production deployments
• Hybrid search — BM25 (FTS5) + dense embeddings + Reciprocal Rank Fusion
• Confidence decay — memories naturally decay unless reinforced
• 27 MCP tools — full memory lifecycle: remember, recall, search, forget, summarize, decay, vault export, embed, prune
• Web dashboard — browse and manage memories at http://localhost:8080
• Single binary — no Docker, Postgres, or cloud required

Installation

# From GitHub (until published to PyPI)
pip install git+https://github.com/Perseus-Computing-LLC/hermes-mimir.git

# Or from PyPI (coming soon)
# pip install hermes-mimir

Then install the Mimir binary:

# Via cargo
cargo install mimir

# Or download from GitHub Releases
# https://github.com/Perseus-Computing-LLC/mimir/releases

Hermes Plugin Setup

Hermes discovers memory providers in $HERMES_HOME/plugins/<name>/. After installing the package, link it into your Hermes plugins directory:

HERMES_HOME="${HERMES_HOME:-$HOME/.hermes}"
mkdir -p "$HERMES_HOME/plugins/mimir"

# Copy the provider module and metadata
python3 -c "
import hermes_mimir, shutil, os
src = os.path.dirname(hermes_mimir.__file__)
shutil.copy(os.path.join(src, '__init__.py'), '$HERMES_HOME/plugins/mimir/__init__.py')
shutil.copy(os.path.join(os.path.dirname(src), 'plugin.yaml'), '$HERMES_HOME/plugins/mimir/plugin.yaml')
print('Plugin installed to $HERMES_HOME/plugins/mimir/')
"

Verify the plugin is discovered:

hermes memory setup   # should show mimir as an available provider

Configuration

Add to ~/.hermes/config.yaml:

memory:
  provider: mimir
  mimir:
    binary: /usr/local/bin/mimir     # optional — auto-detected from PATH
    db_path: ~/.hermes/mimir.db      # optional — defaults to ~/.hermes/mimir.db

Then restart Hermes:

hermes gateway restart
# or exit and re-launch the CLI

How It Works

hermes-mimir implements Hermes's MemoryProvider ABC. On startup, it:

1. Launches the Mimir binary as a subprocess
2. Performs an MCP JSON-RPC 2.0 handshake (initialize)
3. Discovers available MCP tools via tools/list
4. Exposes those tools to the Hermes agent as callable functions
5. Handles prefetch (recall before each turn) and sync_turn (persist after each turn)

The agent sees mimir_remember, mimir_recall, mimir_search_memories, and 24 other tools — all backed by the Mimir binary running alongside Hermes.

Comparison

Feature	Built-in memory	Mimir
Storage	Flat text files	Encrypted SQLite
Search	Substring grep	FTS5 + embeddings + RRF
Encryption	None	AES-256-GCM
Cross-session	Yes (same files)	Yes (structured entities)
Decay	No	Ebbinghaus decay with configurable half-life
Dashboard	No	Built-in web UI
Tools	1 (memory)	27
Dependencies	None	Single Rust binary

Development

git clone https://github.com/Perseus-Computing-LLC/hermes-mimir.git
cd hermes-mimir
pip install -e ".[dev]"
pytest

License

MIT — same as Hermes Agent and Mimir.

Related

• Mimir — the memory engine
• Hermes Agent — the agent framework
• Perseus — live context engine for AI agents