# OSCAR — Open Source CAD Automation Claude Code and Autodesk Fusion 360

A secure MCP (Model Context Protocol) server that gives Claude Code the ability to build parametric, time-line based models in Autodesk Fusion 360 on your computer.

## What Is This?

OSCAR is a build package that creates a two-process bridge between Claude Code and Fusion 360 on your local computer. Feed the master prompt to Claude Code, and it builds the entire system for you — a Fusion add-in and an MCP server that lets Claude design, model, and manipulate 3D geometry through natural conversation.
The goals are:
1. AI Assisted Fully Parametric Design
2. Automatic Parameter Naming

## What This Is Not?
OSCAR, out of the box, is not an expert CAD designer.  You will be able to watch it learn.   It will be slow at first, while it learns(!) how to do things.   When finishing a session or any time during a session, asked OSCAR if it needs to make any notes on things it has learned.   It will give you the option of saving it privately or publicly.  It makes notes of its learnings, so it's faster and better each time you run it.
This is NOT for someone that does not know Fusion.


```
Claude Code ──stdio──> MCP Server (FastMCP, Python)
                              │
                         HTTP POST (localhost:45876)
                         Bearer token auth
                              │
                              ▼
                       Fusion Add-in (runs inside Fusion 360)
```

## Quick Start

1. **Feed** `prompt/MASTER-PROMPT.md` to Claude Code (create a directory on your C drive "OSCAR_Public", open that directory in terminal, add the repo there, type 'Claude' first, then give it the master-prompt)
2. **Reference** `build-guide/BUILD-GUIDE.md` for the full architecture spec
3. **Install and test** — follow the steps in the build guide

```bash
# Option 1: Feed the master prompt directly
claude "$(cat prompt/MASTER-PROMPT.md)"

# Option 2: Paste the contents of prompt/MASTER-PROMPT.md into a Claude Code session
```

## Prerequisites

- Autodesk Fusion 360 installed
- Python 3.10+ (system Python, separate from Fusion's bundled Python)
- `pip install mcp` (for the MCP server component)
- Claude Code (claude.ai/code)
- (run this from the terminal window vs of Claude Code Desktop. Use file explorer(PC), navigate to C:\\Oscar_Public (or where ever you copied the files), right click, "open in terminal" click, type "Claude", and then tell it want you want to build.)

## What's Inside

```
OSCAR/
├── prompt/MASTER-PROMPT.md           # Feed this to Claude Code to build the system
├── build-guide/BUILD-GUIDE.md        # Full architecture spec + implementation details
├── docs/       
│   ├── fusion-api/                   # 17 Fusion 360 API reference files
│   ├── mcp-protocol/                 # 7 MCP protocol reference files
│   ├── FUSION-BEST-PRACTICES.md      # 72-rule modeling guide
│   └── TESTING-GUIDE.md              # Testing instructions
├── fusion-api/                       # 36 extended API reference files
├── fusion_bridge/                    # Fusion add-in source code
├── fusion_mcp_server/                # MCP server source code
└── experience/                       # Your learnings go here (see below)
```

## The Experience Layer

As you use OSCAR, you'll discover API quirks, develop modeling recipes, and learn what works. These hard-won lessons — your **experience** — make OSCAR dramatically better over time.

The `experience/` folder is where you store these learnings. They're yours to keep private or share.

### Sharing Your Experience

We'd love to build a shared knowledge base. If you've discovered something useful, submit a PR with your experience files. Over time, the community's collective expertise will make OSCAR smarter for everyone.

See `experience/README.md` for the format.

## Security

- **Localhost-only** — binds to `127.0.0.1`, never `0.0.0.0`
- **Token auth** — random Bearer token generated on each startup
- **No binaries** — you own every line of code
- **No auto-updater** — no phone-home, no bundled bloat
- **Stdlib only** in the Fusion add-in — no pip dependencies inside Fusion

## Architecture

The system uses two processes bridged by HTTP:

**Fusion Add-in** (`fusion_bridge/`) — runs inside Fusion 360's Python interpreter. Uses Fusion's CustomEvent system to safely marshal API calls from a background HTTP server thread to the main thread.

**MCP Server** (`fusion_mcp_server/`) — runs as a separate Python process using FastMCP with stdio transport. Receives tool calls from Claude Code and forwards them as HTTP requests to the add-in.

## License

Apache 2.0