Planu

The high-performance SDD stack for AI coding agents.

Documentation · Docs in Spanish · Docs in Portuguese

What is Planu?

Planu is the complete Spec Driven Development stack for AI coding agents — an MCP server that enforces a structured workflow from brainstorm to validation. Powered by a native Rust core, Planu provides the performance and reliability needed for large-scale AI development.

Spec first, always. No approved spec means no code. This eliminates vibe-coding debt at scale.

• Native Rust Engine — 10x faster project scanning, parallel hashing, and regex extraction.
• Instant Drift Detection — OS-level file watcher reacts to changes with 0% CPU overhead.
• Unified Spec Format — Requirements and technical details in a single, context-efficient spec.md.
• Atomic Integrity — Indestructible writes and Freeze-on-done immutability (P0).
• 550+ MCP tools across spec lifecycle, Figma, analysis, documentation, git, and autopilot.
• Multi-agent compatible — Optimized for Claude Code, Cursor, Windsurf, and Gemini CLI.

Installation

Add to your MCP client config (Claude Desktop: ~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "planu": {
      "command": "npx",
      "args": ["-y", "@planu/cli@latest"]
    }
  }
}

Requirements: Node.js >= 22. The native Rust core is bundled and auto-detected for macOS (Intel/M1), Linux, and Windows.

The SDD Lifecycle

init_project → create_spec → challenge_spec → check_readiness → implement → validate → done

Every transition is gated by Definition of Ready (DoR) and Definition of Done (DoD) checks. Specs are the single source of truth — implementation is validated against them.

Autopilot: tools cascade automatically

Planu runs follow-up actions automatically after each step:

• create_spec automatically runs challenge_spec + check_readiness.
• update_status(done) automatically runs validate + scans crash risks + freezes the spec.
• update_status(approved) automatically snapshots the spec version.

Unified Spec Format (v3.0)

Specs are context-efficient: 1 single file per spec containing both functional requirements and technical implementation details.

planu/specs/SPEC-001-auth/
└── spec.md       # Requirements + Technical + Criteria + Status

Criteria use zero-ambiguity GIVEN/WHEN/THEN format — ensuring your AI never misinterprets the goal.

Native Performance (v3.0)

Planu v3.0 introduces The Rust Revolution:

| Feature | Node.js (Legacy) | Planu-RS (v3.0) | Benefit | |---------|:----------------:|:-------------------:|:-------:| | Project Scanning | Sequential (Slow) | Parallel (Rayon) | 10x Speedup | | File Watching | Polling/Event Loop | OS-level (Notify) | 0% CPU Idle | | Spec Hashing | JS Crypto | Native SHA-256 | Instant Sync | | Drift Monitor | Memory Heavy | Streaming Scan | Monorepo Ready |

Architecture

src/
├── engine/           # Hybrid Core: TS Business Logic + Rust Native Engine
│   └── planu-core.node # High-performance native module
├── tools/            # 550+ MCP tool handlers
├── storage/          # Atomic persistence layer
└── types/            # Strict TypeScript contracts

data/                 # Local storage (gitignored)
├── projects/{hash}/  # Per-project: specs, metrics, patterns, knowledge
└── global/           # Shared: templates, pricing

Development

pnpm install       # Install dependencies
pnpm build         # Compile TS + Build Rust bridge
pnpm dev           # Watch mode
pnpm test          # Run 31,000+ tests

License

MIT