Already installed with nucleus-mcp — just run:

nucleus-rabbithole

Claude Code .mcp.json snippet:

json { "mcpServers": { "nucleus-rabbithole": { "command": "nucleus-rabbithole", "args": [] } } }

Full documentation: docs/RABBITHOLE.md
---
Three Frontiers
The core loop that makes AI reliability compound over time:

GROUND ALIGN COMPOUND
────── ───── ────────
Machine verifies Human corrects System learns

AI writes code → You fix a mistake → Delta recorded
GROUND checks → Verdict stored → DPO pair created
Receipt logged → Event emitted → Training data grows
│ │ │
└───────────────────┴────────────────────┘
Reliability improves

GROUND — 5-tier execution verification. Syntax, imports, tests, runtime. Goes outside the formal system to check the AI's work.

ALIGN — One-call corrections. nucleus_align(action="correct", params={context, correction}). Each correction automatically records a verdict, creates a training pair, and emits an event.
COMPOUND — Deltas measure the gap between intent and reality. Recurring patterns become strategy. Negative deltas become training signal.
Every tool response shows frontier health:

[frontiers: GROUND 42 | ALIGN 12 | COMPOUND 28]

---

Quick Start
Option A — No install (ChatGPT, Claude, Perplexity):
Add https://relay.nucleusos.dev/mcp as a remote MCP server in your platform's connector settings. That's it — your AI now has persistent memory.
Option B — Local install (Cursor, Windsurf, Claude Desktop):

bash
pip install nucleus-mcp
nucleus init --recipe founder

Two commands. Nucleus is running. AI outputs are now verified. nucleus init auto-configures your MCP client — just restart it.

---
What It Does
114 MCP tools across 13 facades:
- GROUND — Execution verification (5 tiers: diff, syntax, imports, tests, runtime)

- ALIGN — Human corrections (verdict + delta + DPO + event in one call)

- Memory — Engrams that persist across sessions. Write once, recall forever.

- Sessions — Save context, resume later. Session arc shows your last 3 sessions.

- Tasks — Priority queue with escalation, HITL gates, and heartbeat monitoring.

- Governance — Kill switch, compliance configs (EU DORA, MAS TRM, SOC2), audit trails.

- Orchestration — Agent slots, multi-brain sync, task dispatch.

- Archive — Training pipeline (SFT + DPO), delta tracking, frontier health dashboard.
Benchmark: decision-retention-evals — does your AI agent remember why the code is the way it is?
---
Nucleus Pro
Everything above is free (MIT). Nucleus Pro adds verifiable governance:

bash
nucleus trial # 14-day free trial
nucleus compliance-check # Score your AI governance
nucleus audit-report --signed -o report.html # Cryptographically signed report

$19/month or $149/year — nucleusos.dev/pricing

| | Free | Pro |

|---|---|---|

| 13 tools, 10 resources, 3 prompts | Yes | Yes |

| Persistent memory | Yes | Yes |

| Governance & HITL | Yes | Yes |

| Audit trails (DSoR) | Yes | Yes |

| Signed audit reports | - | Ed25519 |

| Compliance exports | Score only | Full PDF/HTML |

| Priority issues | - | Yes |
---
Install
One-Click
| IDE | Install |

|-----|---------|

| Cursor | Add to Cursor |

| Claude Code | npx -y nucleus-mcp |

| Any IDE | pip install nucleus-mcp |
pip / npx

bash
pip install nucleus-mcp

Or use npx (zero Python setup required):

bash
npx -y nucleus-mcp

Configure Your MCP Client

Claude Desktop / Cursor / Windsurf
Add to your MCP config (claude_desktop_config.json or equivalent):

json
{
"mcpServers": {
"nucleus": {
"command": "npx",
"args": ["-y", "nucleus-mcp"]
}
}
}

<details>

<summary>Alternative: use pip install directly</summary>

json
{
"mcpServers": {
"nucleus": {
"command": "python3",
"args": ["-m", "mcp_server_nucleus"],
"env": {
"NUCLEUS_BRAIN_PATH": "/path/to/your/project/.brain"
}
}
}
}

</details>

Claude Code
Add to .mcp.json in your project root:

json
{
"mcpServers": {
"nucleus": {
"command": "npx",
"args": ["-y", "nucleus-mcp"]
}
}
}

Path Discovery

Nucleus finds your .brain automatically:

1. NUCLEUS_BRAIN_PATH environment variable (explicit)

2. Walk up from CWD looking for .brain/ directory

3. Fall back to $HOME/.nucleus/brain
---
CLI
Nucleus has a full CLI alongside the MCP tools. Auto-detects TTY (table output) vs pipe (JSON).

bash