Zumen MCP server

日本語版は README.ja.md にあります（詳しい版）。

zumen

Let an AI draw the diagram, fix what you want by hand, ask the AI again — and your fix is still there.

AI-editable diagrams as code: a desktop editor with an MCP server for Claude Code and other agents. One YAML file is the source of truth; it renders SVG and exports Mermaid and draw.io.

Diagrams are plain text (YAML). Where you move things is stored in a pins: block the AI is not allowed to write, so however many times the AI redraws, your corrections survive.

When it helps

What you see

1. Open — the boxes a person moved are drawn with a heavier outline

2. Load the AI's proposal — the change shows as a diff, and nothing is applied until you say so

Try it in a minute

git clone https://github.com/meta-taro/zumen.git && cd zumen
corepack enable && pnpm install
pnpm dev     # the window, in a browser (http://localhost:5173)
pnpm mcp     # for an agent

Why

The hard part is not the first diagram. It is the second one, and the tenth: "the architecture changed, so the diagram has to change."

the system changes
  → updating the diagram is tedious
  → nobody updates it
  → the diagram becomes a lie
  → nobody looks at diagrams any more

Existing drawing tools are finished products for drawing the first diagram. zumen does not compete there. It competes on the diagram that has to keep up.

The one line that has to work

ask in prose → a diagram appears → a human fixes one thing
            → ask again → the human's fix is still there

That last step is the whole product. If a human's edit does not survive the next AI pass, nothing else matters.

Shortened. The full README is on GitHub.