The Local-First Agentic Stack: Syncing Cursor, Claude, and Windsurf with Nucleus MCP

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The Local-First Agentic Stack: Syncing Cursor, Claude, and Windsurf with Nucleus MCP

The AHA Moment: Context Amnesia

The "AHA" moment for me wasn't when I first used an AI coder. It was when I realized I was fragmented.

I’d do a deep architectural brainstorm in Claude, switch to Cursor to implement, and then jump into Windsurf to use its agentic flow. But Claude didn't know what Cursor did, and Cursor had no idea about the architectural epiphany I just had in Claude.

I was manually copy-pasting my own "brain" across tabs. Then I built Nucleus.

🏗️ The Architecture of Sovereignty

Nucleus is an MCP (Model Context Protocol) Recursive Aggregator. Instead of treating MCP servers as individual plugins, Nucleus treats them as a Unified Control Plane.

It creates a local-first memory layer (we call them Engrams) that stays on your hardware.

One Brain, All Tools

When I teach Claude something, it writes to the Nucleus ledger. When I open Cursor, Cursor reads that same ledger. The context is no longer session-bound; it's persistent and sovereign.

The Technical Stack:

Core: Python-driven MCP interface with fastmcp for robust tool registration.
Sync: fcntl.flock for cross-process synchronization + Watchdog for real-time auto-sync between IDEs.
Engrams: Git-native context storage inside your project's .brain/ folder.

🛡️ Hypervisor: Security in the Agentic Age

Giving agents full filesystem access is terrifying. Nucleus solves this with a multi-layer Hypervisor:

Layer 1 (Watchdog): Real-time monitoring of sensitive files (like .env).
Layer 4 (Immutable Locking): Uses OS-level chflags uchg (macOS/BSD) to lock files. Even a root-access agent cannot modify a hypervisor-locked resource.
DSoR (Decision System of Record): Every sync event and decision is SHA-256 hashed and logged. Full forensic auditability.

⚡ Quick Start: 2 Minutes to Sovereignty

I wanted to make setup as painless as possible:

pip install nucleus-mcp
nucleus-init --scan

This auto-configures Claude Desktop, Cursor, and Windsurf, and auto-ingests your README.md to seed the brain with your project's core context.

🚀 Join the Sovereign Movement

We just hit the registries (MCP.so, Glama, and the official Anthropic list). The response has been humbling. If you're tired of being a "context-courier" between agents, come check it out.

👉 Nucleus on GitHub (Help us hit 50 stars! ⭐)
👉 Join the Nucleus Vanguard (Discord)

See it in action (Forensic Proof):