> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hystersis.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Persistent memory infrastructure for AI agents

# Hystersis

Hystersis is an open-source long-term memory layer for AI agents. It provides persistent memory, semantic search, knowledge graphs, and real-time multi-agent sync.

## Why Hystersis?

AI agents forget everything between sessions. Hystersis gives them persistent memory that adapts, compresses, and improves over time.

### Key Capabilities

* **Semantic Memory** -- Store and retrieve by meaning, not keywords
* **Knowledge Graph** -- Neo4j-powered entity relationships with 30+ edge types
* **Spreading Activation** -- Multi-hop reasoning with +23% accuracy
* **ProMem Compression** -- 80-85% token reduction at 97% accuracy
* **Temporal Reasoning** -- Phase rotation preserves history
* **Memory Worth Scoring** -- Outcome-linked importance
* **Safety Classifier** -- Blocks prompt injection and PII

## Quick Start

```bash theme={null}
docker compose up -d
curl -X POST http://localhost:8080/memories \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-key" \
  -d '{"content": "User prefers dark mode", "type": "user", "user_id": "alice"}'
```