AI Patch Builder

The extension bundles an AI Patch Builder — a Model Context Protocol (MCP) server that gives AI coding agents full knowledge of the FV-1 block library and the block-diagram compiler. With it, an agent such as GitHub Copilot (agent mode) or Claude Code can build and validate .spndiagram block-diagram programs for you from a plain-language description or a screenshot of an existing patch.

Because the agent can compile every draft against the real FV-1 compiler as it works, the patches it produces are checked for correct wiring and for fitting within the FV-1’s limits (128 instructions, 32 registers, 32768 words of delay memory) — not just guessed at.

How it works

The server is launched automatically by your AI agent and exposes a small set of tools the agent calls on demand:

Discover blocks

Browse the full catalog of built-in blocks and read the exact ports and parameters of any block, so the agent wires things up correctly.

Learn from examples

Fetch curated, ready-made example diagrams (echo, hall reverb, chorus, LFO-swept filter, parallel dry/wet mix) to adapt rather than starting from a blank canvas.

Validate

Compile a candidate diagram and report any errors, warnings, and resource usage. This is the heart of the loop: the agent drafts, validates, fixes what the compiler reports, and repeats until the patch is correct.

Author new blocks

When no existing block does the job, the agent can read the Audiofab Template Language (ATL) reference, study a similar block’s source, and write a brand-new custom .atl block on the fly — then use it immediately in your diagram.

Requirements

  • VS Code 1.101 or newer (required for the Copilot MCP integration).

  • An AI agent:

    • GitHub Copilot with agent mode, or

    • Claude Code (the VS Code integrated extension, or the CLI).

Set up with GitHub Copilot

The server is contributed to VS Code’s built-in MCP host, so Copilot discovers it automatically once the extension is installed.

  1. Open the Copilot Chat view and switch the mode selector to Agent.

  2. Confirm the server is available: run MCP: List Servers from the Command Palette (Ctrl+Shift+P) and look for Audiofab FV-1 Patch Builder. Start it if it is not already running.

  3. Ask Copilot to build something (see Example prompts below).

Note

Copilot may ask you to trust or enable the server the first time. This is a one-time confirmation.

Set up with Claude Code

Claude Code uses its own configuration file, so the extension writes one for you.

  1. Run FV-1: Enable AI Patch Builder for Claude Code from the Command Palette. This creates (or updates) a .mcp.json file at the root of your workspace folder.

  2. Restart VS Code (or reload the window).

  3. When Claude Code starts, approve the project’s MCP server when prompted, then verify with the /mcp command that audiofab-fv1 is connected.

Important

Claude Code reads .mcp.json only at startup. A freshly generated file will not be picked up until you restart VS Code (or reload the window). If /mcp shows the server as not connected right after enabling it, a restart is almost always the fix.

Where custom blocks are saved

Any block the agent authors is written to your custom-block directory so it survives future sessions and appears in the block palette:

  • the first path in your fv1.customBlockPaths setting, if that setting is set; or

  • a managed .fv1/blocks folder inside your workspace, if it is not.

Newly written blocks are loaded live — you do not need to run Refresh Custom Blocks manually. See FV-1 Block Developer Guide for the ATL block format the agent uses.

Example prompts

Create a new .spndiagram for a stereo hall reverb with a short pre-delay.
Validate it, then save it as reverb.spndiagram.

Here's a screenshot of a SpinCAD patch — recreate it as a block diagram.

Build a lo-fi vibrato. If no block does what you need, author a custom one.
Validate before saving.

After the agent saves a .spndiagram file, open it to see it in the Visual Block Diagram Editor, tweak parameters, and audition it in the Simulator & Debugger.

Troubleshooting

Claude Code sees the server but it is “not running.”

Restart VS Code so .mcp.json is re-read (see the note above). If it still fails, open a terminal and run claude mcp list to see the actual startup error.

The server path looks wrong after a VS Code update.

The extension rewrites the launch path in .mcp.json automatically each time it activates, so reloading the window once after an update corrects a stale path.

Copilot doesn’t show the server.

Make sure you are on VS Code 1.101+ and that Copilot agent mode is enabled for your account, then re-check MCP: List Servers.