nexus-agent-memory 0.1.0

Cross-session persistent memory for AI Agents. 4500x faster retrieval, zero LLM dependency.

🧠 Nexus Memory

Cross-Session Persistent Memory for AI Agents

Your agent remembers everything. Across sessions. Across restarts. Forever.

Install · Quick Start · vs Competitors · Architecture · API · 中文

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The Problem

Every AI coding agent starts from zero. You explain your project, your preferences, your stack — again and again. Context windows fill up. Token costs explode. The agent never learns.

The Solution

Nexus Memory gives your agent a persistent brain. It remembers facts, preferences, corrections, and context across sessions — with zero LLM calls, 20ms retrieval, and automatic knowledge promotion.

from src.nexus_core import NexusCore

nexus = NexusCore("nexus.db")

# One line to remember
nexus.write("User prefers Python type hints", source="conversation", confidence=0.9)

# One line to recall
results = nexus.search("What coding style does the user prefer?", limit=5)

# One line to inject into any agent
system_prompt = f"You are helpful.\n{nexus.system_prompt_block()}"

Install

pip install nexus-memory

Or from source:

git clone https://github.com/chuf-China/nexus-memory.git
cd nexus-memory
pip install -e .

Quick Start

Standalone (any agent)

from src.nexus_core import NexusCore

nexus = NexusCore("agent_memory.db")

class YourAgent:
    def __init__(self):
        self.memory = NexusCore("agent_memory.db")

    def chat(self, user_input):
        # Retrieve relevant memories (20ms)
        context = self.memory.search(user_input, limit=3)
        # Build prompt with memory
        prompt = f"Memories: {context}\nUser: {user_input}"
        response = self.llm.generate(prompt)
        # Auto-save conversation
        self.memory.write(f"Q: {user_input}\nA: {response}", source="conversation")
        return response

Lifecycle Hooks

nexus.register_hook("pre_llm_call", lambda ctx: ctx.update({
    "alerts": nexus.get_alerts(),
    "temporal": nexus.search_temporal(ctx["query"]),
    "history": nexus.get_history(ctx["session_id"])
}))

nexus.register_hook("session_end", lambda ctx: {
    nexus.consolidate(ctx["session_id"]),
    nexus.knowledge_snapshot()
})

CLI

nexus-memory status          # Show DB stats
nexus-memory search "query"  # Search knowledge
nexus-memory export          # Export to JSON
nexus-memory benchmark       # Run performance test

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vs Competitors

Feature	Nexus Memory	agentmemory	mem0
Search Latency	20ms	Unknown	~100ms
LLM Dependency	Zero	Uses iii engine	Requires LLM
Knowledge Layers	3-tier auto	Claimed	Flat
Correction Handling	SPO conflict + belief degradation	Unknown	Basic overwrite
Threat Detection	30+ patterns	None	None
Graph Relations	Yes (NetworkX)	Unknown	No
Vector Search	HNSW + fastembed	Yes	Yes
Full-Text Search	FTS5	Yes	Yes
Auto Extraction	Dual-channel (regex + LLM)	Hooks only	LLM only
Memory Aging	48h decay + auto-archive	Unknown	None
Scope Control	3-tier security	None	None
External DB Required	No	No	Yes (Qdrant/Redis)
Language	Python	JavaScript	Python
License	MIT	Unknown	Apache 2.0

Why Nexus Wins on Memory Quality

Agentmemory is a great product with broad agent support (20+ integrations). But it treats memory as a black box inside the iii engine. You can't see how knowledge is stored, promoted, or corrected.

Nexus Memory is transparent and precise:

• SPO Triplets: Facts stored as Subject-Predicate-Object with confidence scores, not flat text
• Belief Network: Knowledge auto-promotes from Observation → Belief → Fact based on evidence
• Correction Intelligence: When you say "that's wrong", the old fact degrades AND the new fact promotes — a natural淘汰 system, not a permanent correction list that pollutes context
• Write-time Merging: 5 strategies (exact_dup, fuzzy_dup, complement, contradict, new) prevent knowledge bloat

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Architecture

┌─────────────────────────────────────────────────────┐
│                   Agent / LLM                       │
│              (Claude Code, Cursor, etc.)             │
└──────────────┬──────────────────────┬───────────────┘
               │ search()             │ write()
               ▼                      ▼
┌─────────────────────────────────────────────────────┐
│               Nexus Core Engine                     │
│  ┌──────────┐ ┌──────────┐ ┌──────────┐           │
│  │ Extract  │ │  Search  │ │  Belief  │           │
│  │ (dual-   │ │ (4-way   │ │ (3-tier  │           │
│  │  channel)│ │  fusion) │ │  promo)  │           │
│  └────┬─────┘ └────┬─────┘ └────┬─────┘           │
│       │            │            │                   │
│  ┌────▼────────────▼────────────▼────┐             │
│  │        SQLite + FTS5 + WAL        │             │
│  │   HNSW Vectors │ NetworkX Graph   │             │
│  └───────────────────────────────────┘             │
│                                                     │
│  ┌──────────┐ ┌──────────┐ ┌──────────┐           │
│  │Constitu- │ │  Evolve  │ │  Miner   │           │
│  │tion (30+ │ │ (auto-   │ │ (know-   │           │
│  │ threats) │ │  aging)  │ │  ledge)  │           │
│  └──────────┘ └──────────┘ └──────────┘           │
└─────────────────────────────────────────────────────┘

3-Layer Knowledge Architecture

Layer	Confidence	Behavior
Observation	0.30 - 0.50	Raw signal, first appearance
Belief	0.70 - 0.85	Multiple confirmations, emerging pattern
Fact	0.85 +	High confidence, persistent knowledge

• Auto-promote: Same pattern ≥3 times OR user confirmation
• Auto-degrade: 48h unused → -0.05, corrected → -0.30
• Auto-archive: confidence < 0.30 → archived

6-Domain Scoring

Every knowledge entry is scored on: Freshness · Importance · Frequency · Relevance · Confidence · Feedback

4-Way Search Fusion

1. FTS5 Full-Text (20ms) — SQLite native full-text index
2. Vector Search (50ms) — HNSW approximate nearest neighbor with fastembed
3. Graph Query (10ms) — NetworkX adjacency traversal
4. Cross-Encoder Reranking — Final relevance scoring

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Performance Benchmarks

Operation	Latency	Notes
FTS5 Search	20ms	SQLite full-text index
Vector Search	50ms	HNSW approximate nearest neighbor
Graph Query	10ms	Adjacency list traversal
Write Knowledge	5ms	WAL mode batch write
Consolidation	100ms	Merge + dedup + score update

4500x faster than LLM-based memory retrieval. Zero external service dependencies.

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Security Defense

30+ built-in threat patterns:

• Injection: Prompt injection, role hijacking, system prompt leakage
• Exfiltration: Encoding bypass, covert channels, C2 communication
• Anti-forensics: Log tampering, timestamp forgery, evidence destruction

3-tier scope control:

• all — Scan all knowledge
• context — Scan only context-related knowledge
• strict — Strict mode, highest security level

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Directory Structure

nexus-memory/
├── src/
│   ├── nexus_core.py          # Core engine (2448 lines)
│   ├── nexus_drive.py         # Data persistence layer
│   ├── nexus_extract.py       # Knowledge extractor (dual-channel)
│   ├── nexus_search.py        # Hybrid search engine (4-way fusion)
│   ├── nexus_embedder.py      # Vector embedding (fastembed)
│   ├── nexus_hnsw.py          # HNSW index
│   ├── nexus_graph.py         # Graph relationship (NetworkX)
│   ├── nexus_belief.py        # Belief network (3-tier promotion)
│   ├── nexus_constitution.py  # Security defense (30+ patterns)
│   ├── nexus_evolve.py        # Self-evolution (aging + consolidation)
│   ├── nexus_miner.py         # Knowledge mining
│   ├── nexus_cli.py           # CLI tool
│   ├── nexus_local.py         # Local storage
│   └── nexus_utils.py         # Utility functions
├── tests/
│   ├── test_nexus_core.py     # Core tests
│   └── test_nexus_benchmark.py # Performance benchmarks
├── docs/
│   └── architecture.md        # Architecture documentation
├── pyproject.toml             # PyPI packaging
├── setup.py                   # Installation config
└── README.md                  # This file

Dependencies

• Python 3.9+
• SQLite 3.38+ (FTS5 support)
• numpy (vector computation)
• No external service dependencies — pure local execution

API

from src.nexus_core import NexusCore

nexus = NexusCore("nexus.db")

# Write
nexus.write(content, source="conversation", confidence=0.9, domain="workflow")

# Search
results = nexus.search(query, limit=5, domain_filter=None)

# System prompt injection
block = nexus.system_prompt_block()

# Consolidate session
nexus.consolidate(session_id)

# Knowledge snapshot
nexus.knowledge_snapshot()

# Register lifecycle hooks
nexus.register_hook(event_name, callback)

# Get alerts
alerts = nexus.get_alerts()

# Temporal search
results = nexus.search_temporal(query)

# Session history
history = nexus.get_history(session_id)

Run Tests

python -m pytest tests/ -v

License

MIT License

Acknowledgments

Built as the memory backbone of Hermes Agent. Inspired by Karpathy's LLM Wiki pattern — extended with confidence scoring, lifecycle management, knowledge graphs, and hybrid search.

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If Nexus Memory helps your agent, give it a ⭐