Dendro React

Dendro

Your agent is editing code it's never read.

It just scanned forty files to answer "what breaks if I change this?" It could have asked one fucking question.

Dendro is one model of your React or React Native codebase, rendered twice: semantics your agent can query, and a map you can both point at.

For your agent — the semantics

MCP tools that answer React questions in React terms: the component's contract before an edit (props, state, contexts, blast radius), rerender risk with the why, effect hygiene (leaked subscriptions, derived-state effects, fetch races that exhaustive-deps can't see), navigation graphs (Next.js, React Navigation, Remix, Expo Router), live runtime state from a running app — and whole-repo orientation in one ~300-token call.

Symbol servers tell your agent where the symbol is. Dendro tells it what rerenders, and why.

For you — the visualizer

Your app's constellation: a live dendrogram in VS Code, descended from Reactive. Your agent drives it — highlights what it's talking about, annotates, traces a prop, walks you through the architecture step by step while you click Next/Back. You watch the same map the agent reasons over.

Getting Started

1. Install Dendro React — run ext install RooneyTech.dendro-react in VS Code, or install from the Marketplace
2. Open your React or React Native project in Claude Code
3. Paste this:

Set up Dendro React for this project. The extension is already installed in VS Code. Do these steps in order:

1. Find the MCP server path: ls ~/.vscode/extensions/rooneytech.dendro-react-*/dist/mcp-server.js
2. Find the absolute node path: which node
3. Create .mcp.json in the project root using the absolute node path as "command" and the MCP server path as the first arg
4. Add a Dendro section to CLAUDE.md (create it if needed) with: the entry file path, get_usage_guide as first call, and a note to run viz commands sequentially
5. Verify by calling get_usage_guide

That's it. Your agent handles the rest.

Things to Try

Say "Dendro" in your prompts — like "Use Dendro to show me how this app is structured." It'll use the visualizer and deeper analysis instead of just reading files.

• Watch: "Open the Dendro visualizer and walk me through the app"
• Ask: "Use Dendro to check how healthy this codebase is"
• Before an edit: "Get the component contract for CheckoutForm first"
• "Where does state live? Use Dendro to trace the data flow"
• "Show me how navigation works in this app with Dendro"
• "Use Dendro to explain this repo's architecture like I've never seen it"

What It Does

• Component contracts — props, state, contexts, blast radius, complexity in one call, before your agent edits
• Health audits — A-F grade with line-anchored findings and fixes (leaked listeners, fetch races, derived-state effects)
• Complexity scoring — every component graded, refactoring candidates named
• Navigation mapping — React Navigation, Next.js, React Router, Remix, Expo Router
• Context & data flow — providers, consumers, prop drilling detection
• Visual canvas — the agent highlights, annotates, and traces flows in a live dendrogram
• Runtime inspection — connect to a running app for live state, props, and hooks (optional)

Free & local

Every tool is free — exports, snapshots, verified projection, live introspection, and batch analysis included. No account, no license key, and no code leaves your machine. The one exception is submit_feedback, which sends a debrief to the maker only when you explicitly say yes.

Configuration

Setting	Default	Description
dendro-react.autoStartRuntime	false	Auto-connect to React Native apps on activation
dendro-react.runtimePlatform	auto	Target platform: auto, ios, android, or device
dendro-react.runtimePort	8097	DevTools WebSocket port
dendro-react.runtimeHost	localhost	WebSocket host (0.0.0.0 for physical devices)
dendro-react.projectorMode	false	Larger fonts/strokes for screen sharing

Learn More

• Setup Guide — manual setup, Cursor/Windsurf config, runtime connection, troubleshooting
• Tools Reference — every MCP tool with descriptions

Feedback

Dendro is in early access. If something doesn't work, feels confusing, or you wish it did something different — I want to hear it.

• Issues & ideas: GitHub Issues
• Email: colin@rooneytech.com
• Or just tell your agent to use submit_feedback — it knows what to do.

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Built by Colin Rooney. Originally derived from Reactive, built at OSLabs with Micah Ziegler and Susana Lam. Named after the Greek word for tree and the branching dendrites of neurons.