Robohopper

01 / requirements

What you need

• Rhino 8 with Grasshopper, on Windows (the Mac build is not yet validated).
• An AI coding agent to drive Robohopper.

02 / how it works

Your agent does the Grasshopper work

You do not click through dialogs and you do not place anything on the canvas. The "brain" is your own AI agent; Robohopper is the bridge it drives - its eyes and hands inside Grasshopper. You ask in plain language, the agent sends commands to Robohopper's two local servers (http://127.0.0.1:5200 for authoring and wiring C# components, http://127.0.0.1:9999 for general canvas operations and running code), and Robohopper acts directly inside Grasshopper and reads the result back.

03 / setup (once)

Download once, then onboard your agent

1. Download the installer. Get RobohopperInstaller.rhp, drag it into Rhino 8 and approve the download from Rhino's official package server.
2. Complete the setup window. Choose the workspace your AI coding agent will use. The installer places the bridge, kit and Robohopper skills together in that workspace.
3. Hand over to your agent. Open the selected workspace with your agent and paste the starter prompt from the Robohopper page. The agent verifies the delivered skill and kit before asking you to open Grasshopper.
4. Open Grasshopper - your job, not the agent's. Start Rhino 8 yourself, then open Grasshopper. The bridge starts automatically the moment Grasshopper opens - nothing to place on the canvas, no command to type. Then tell your agent it is open.
5. The agent verifies and builds. Once Grasshopper is open, the agent checks both local servers respond and runs a smoke test that confirms the connection, then it is ready to build.

04 / everyday use

Describe the result; it builds it

1. Ask your agent, in plain language, to read the canvas, create and edit C# script components, wire them together, run them, or build a small reusable definition. Give precise instructions; vague prompts produce literal, minimal results.
2. The agent sends the request to Robohopper's local servers; Robohopper executes inside Grasshopper and reads the produced values back, instead of blind scripting.
3. Verify a result by reading the value the component actually produced, not by a status flag. A C# script component has two outputs: out (the text log) and a (the value) - check a.
4. Review the result on screen and iterate by asking the agent to refine.

05 / beta notes

What to expect

This is an early Windows beta. The bridge listens on loopback (127.0.0.1), and requests to the authoring bridge without its per-session token are rejected before dispatch. It makes no outbound network calls of its own. Transient localhost socket hiccups can occur (just retry). If you keep old separate bridge components in your libraries folder, remove them first to avoid duplicate-component conflicts. Package Manager removal does not yet delete files deposited by the setup wizard; contact support for the cleanup steps.