Hexus 🧠

Postgres-Powered Vector Memory for the Agentic Age

Postgres + hexus memory substrate for hermes-agent AND a standalone Model Context Protocol (MCP) server for any client (Claude Desktop, Cursor, fleet agents, etc.).

graph TD
    classDef default fill:#1f2937,stroke:#374151,stroke-width:1px,color:#f3f4f6;
    classDef highlight fill:#3b82f6,stroke:#1d4ed8,stroke-width:2px,color:#ffffff;
    classDef db fill:#059669,stroke:#047857,stroke-width:2px,color:#ffffff;

    subgraph Clients ["Integration Clients"]
        Minions["Hermes Agent Minions<br/>(Header: X-Hermes-Session-Key)"]
        Claude["Claude Desktop<br/>(stdio MCP)"]
        Cursor["Cursor Editor<br/>(stdio MCP)"]
        Custom["Custom Agents<br/>(HTTP MCP)"]
    end

    subgraph Hexus ["Hexus (Single Process, Shared Embedder)"]
        Plugin["Hermes Plugin<br/>(hexus/__init__.py)"]
        Server["MCP Server<br/>(mcp_server)"]
        Embedder["LocalBertEmbedder<br/>(MiniLM-L6-v2)"]:::highlight
        Store["MemoryStore<br/>(psycopg pool)"]
    end

    DB[("PostgreSQL 16 + pgvector<br/>(memory_entries & conversations)")]:::db

    %% Connections
    Minions -->|X-Hermes-Session-Key| Plugin
    Claude -->|stdio| Server
    Cursor -->|stdio| Server
    Custom -->|HTTP| Server

    Plugin --> Embedder
    Server --> Embedder
    Plugin --> Store
    Server --> Store

    Store --> DB

🚨 The "Memory Crisis" (And Why Hexus Rocks 🎸)

If you've ever tried running a team of cooperating agents, you've probably hit one of these roadblocks. Here's why Hexus exists and how it changes the game:

• The Stomping Minions 🐘: Say goodbye to local markdown files that get overwritten when you run multiple agents. Hexus gives every minion a clean, scoped memory space ("themes"). Your marketing agent's notes won't contaminate your trading agent's data!
• Pure Vector Speed (No LLM in the Hot Path!) ⚡: Embedding search should be pure vector math! We use a purely local BERT model. Zero cloud calls, zero LLMs in the hot path, absolute privacy, and way faster performance.
• Ditch the Cloud Monoliths ☁️: Other memory providers require paid cloud services and route every read/write through an LLM. Not us. Hexus uses your existing Postgres + pgvector. Keep it simple, keep it fast!
• Storage Layer AND Memory Model 📦: Hexus acts as a rock-solid storage backbone and an intelligent memory model for a fleet of cooperating agents, keeping everything centralized, searchable, and clean.
• Standalone Plugin Power 🧩: Why a standalone plugin? So you can just drop it in and go! No waiting for upstream PRs in the main repositories.

🌪️ Getting Started (Installation is a breeze!)

Ready to try it out? You can get up and running in a snap.

Option 1: Hermes Plugin (via pip)

If you're integrating directly into a Hermes agent, you can grab it from pip:

pip install hexus

Note: Once installed, just point Hermes to it! You can also just drop the hexus module files straight into your ~/.hermes/plugins/hexus/ directory. Hermes's discovery system will automatically pick it up and initialize it on startup!

Configuration (hermes.yaml): When running as a Hermes plugin, configure it directly in your hermes.yaml file (not via environment variables):

plugins:
  memory:
    provider: hexus
    config:
      # The Postgres connection string (required)
      dsn: "dbname=hermes_test user=postgres password=postgres_secret host=localhost"

Option 2: Docker & MCP Server (Claude, Cursor, etc.)

The easiest way to run the standalone MCP server is via Docker (GHCR).

Note: The Docker MCP server requires a running PostgreSQL database with pgvector enabled. You can reference or use our provided docker/compose.yml file as a quick example to spin one up!

Environment Variables: When running via Docker or as a standalone MCP server, you can pass the following environment variables:

• HEXUS_DSN - The Postgres connection string (e.g., dbname=hermes_test user=postgres password=secret host=pg).
• HEXUS_DB_PASS - Used by our compose.yml to set the Postgres password (and the default DSN's password).
• HEXUS_TRANSPORT - MCP transport: "stdio" (default) or "http".
• HEXUS_AGENT_IDENTITY - Default agent identity for tool calls that don't supply one (default: "default").
• HEXUS_MEMORY_ISOLATION - Multi-agent read isolation: "shared" (default) lets any agent recall/search/read every agent's memory — a single shared knowledge base for a trusted fleet; "strict" scopes reads to the calling agent's own identity. Cross-agent mutations (confirm/reject/remove/forget/summarize by id) are always scoped to the caller in both modes. On the HTTP transport the caller's identity is taken server-side from the X-Hermes-Session-Key header and overrides any client-supplied agent_identity, so an authenticated client cannot act as another agent.
• HEXUS_EMBED_EAGER_LOAD - Set to "1" to pre-load the local embedding model at startup (saves ~1-2s on first use).
• HEXUS_EMBED_DEVICE - Torch device for the embedder (default: "cpu").
• HEXUS_WEBHOOK_URL / HEXUS_WEBHOOK_SECRET - (Optional) POST a signed webhook on memory writes.

The easiest way to bring up Postgres and the MCP server together is the mcp profile in our compose file:

# Set the DB password first (used for both Postgres and the MCP server's DSN)
export HEXUS_DB_PASS=postgres_secret

# Starts pgvector + the MCP server (HTTP streamable transport on container port 8000)
docker compose -f docker/compose.yml --profile mcp up

The MCP server port is exposed on the internal Docker network, not published to your host. To reach it from the host (e.g. on localhost:8000), uncomment the ports: mapping under the mcp service in docker/compose.yml.

Using it with Claude Code / Claude Desktop: If you want to plug Hexus straight into your Claude claude_desktop_config.json via standard stdio, add this block. It runs the server binary directly (via --entrypoint, so it talks clean JSON-RPC on stdio without the container's startup logging), pointed at your already-running Postgres:

{
  "mcpServers": {
    "hexus": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "--entrypoint",
        "hexus-mcp",
        "ghcr.io/codenamekt/hexus:latest",
        "serve",
        "--transport",
        "stdio",
        "--dsn",
        "dbname=hermes_test user=postgres password=postgres_secret host=host.docker.internal"
      ]
    }
  }
}

This expects the schema to already exist (the compose mcp/test profiles apply the migrations). It connects to a Postgres reachable at host.docker.internal — adjust the --dsn host/password for your setup.

🏎️ Look at This! Ridiculously Fast Benchmarks

We believe in speed. Check out these actual benchmarks running on a basic CPU (no GPU needed!):

• Single Embed Latency: 7.4 ms
• Batch Embed Throughput: 1,486 items/sec (batch size 32)
• Recall Latency (Top 5): 2.0 ms

Wanna run these yourself? Check out the full BENCHMARK.md to see how!

✨ Wait... There's More! (Features)

• Two Integration Paths, One Shared Store: Use it as a Hermes plugin, OR run it as a standalone Model Context Protocol (MCP) server for Claude Desktop, Cursor, and custom agents.
• Built-in Power-Ups: Hybrid search (BM25 + vector), temporal decay, TTL/memory forgetfulness, entity tagging, and conversation summaries.
• Potato-Friendly: Runs entirely local on a CPU (e.g. an old Intel NUC or mini PC).

🕳️ Digging Deeper

Looking for the nitty-gritty details? We moved the heavy technical stuff into their own docs so you can get straight to the code:

• 📖 Technical Details & Configuration - Admin DB commands, schemas, hooks, and MCP configuration.
• 🗺️ Roadmap - See where we've been and what wild features are coming next.
• 🔙 Rollback Guide - In case you change your mind (but you won't!).

License: BSD 3-Clause