# NEXO Brain

> Open-source cognitive memory system for AI agents

NEXO Brain gives AI agents persistent memory using the Atkinson-Shiffrin cognitive architecture. It provides 77+ MCP tools across 16 categories including semantic RAG, trust scoring, episodic memory, metacognitive error prevention, and natural memory decay.

## Key Features

- Three-store memory: Sensory Register, Short-Term Memory, Long-Term Memory
- Semantic vector search with fastembed (BAAI/bge-small-en-v1.5, 384 dimensions)
- Ebbinghaus forgetting curve for natural memory pruning
- Discriminative sister memory fusion
- Cognitive dissonance detection
- Trust score (0-100) for internal rigor calibration
- Metacognitive Guard: pre-edit checks with learnings and blocking rules
- Episodic memory: change logs, decisions, session diaries
- Plugin system with hot-reload
- 100% local: SQLite + ONNX Runtime, zero cloud dependencies

## Installation

```
npx nexo-brain init
```

## Documentation

- Website: https://nexo-brain.com
- GitHub: https://github.com/wazionapps/nexo
- Wiki: https://github.com/wazionapps/nexo/wiki
- npm: https://www.npmjs.com/package/nexo-brain

## Architecture

Based on the Atkinson-Shiffrin model from cognitive psychology:
1. Sensory Register captures raw input (30s TTL, attention filter)
2. Short-Term Memory holds working context (rehearsal resets decay)
3. Long-Term Memory consolidates via semantic similarity (permanent)

## API

NEXO Brain exposes all functionality as MCP (Model Context Protocol) tools. Compatible with Claude Code and any MCP client.

Tool categories: Cognitive (8), Episodic Memory (8), Learnings (5), Entities (5), Reminders (4), Followups (4), Credentials (5), Preferences (4), Guard (3), Messaging (4), Sessions (4), Plugins (3), Backup (3), and more.

## License

MIT License. Built by WAzion (https://www.wazion.com).