git:20260921.b731809 to git:20260922.b0d7494

2 added, 1 removed. Audit A to A.

# Arc (LLM Guide)

Arc is a visual editor for building architecture diagrams that stay in code.

Dense reference: docs/llm.txt · Contributor guide: CLAUDE.md

## Quickstart

```bash

bun install && bun run dev # → http://localhost:5188/editor

```

## Packages

| Need | Package |

|------|---------|

| Render 2D diagram | `@arach/arc` or `@arach/arc-viewer` |

| Mermaid sequences | `@arach/arc-viewer` |

| Isometric | `@arach/arc-iso` |

| Full studio | This repo |

## Diagram schema (canonical)

`src/types/diagram.ts` — sizes are `xs` | `s` | `m` | `l` (not large/normal/small)

```json

{

"layout": { "width": 700, "height": 300 },

"nodes": { "api": { "x": 100, "y": 100, "size": "m" } },

- "nodeData": { "api": { "icon": "Server", "name": "API", "color": "emerald" } },

+ "nodeData": { "api": { "name": "API", "kind": "backend" } },

"connectors": [{ "from": "a", "to": "b", "fromAnchor": "right", "toAnchor": "left", "style": "http" }],

"connectorStyles": { "http": { "color": "amber", "strokeWidth": 2, "label": "HTTP" } }

}

```

## Agent docs

- docs/llm.txt — full briefing

- docs/agent/*.agent.md — packages, actions, MCP, verification

- skills/arc-diagrams/SKILL.md — diagram generation

- CLAUDE.md — editor contributor guide

## CLI + MCP

`arc` on `@arach/arc` — `arc check`, `arc diff`, `arc render`, `arc bench`, `arc schema` (`bun run build:cli` for the published bin).

`arc-mcp` on `@arach/arc` — `bun run mcp` locally, `bun run build:mcp` for the published bin.

+ Tools include validate/diff/layout plus ASCII, SVG, component/iframe/HTML, and optional Chrome-backed PNG rendering.

See docs/agent/mcp.agent.md.