openisd-mcp

MCP server (stdio) for the OpenISD Thiele/Small loudspeaker physics engine.

An agent (Claude, opencode, etc.) can:

• search_drivers("dayton 10") → match from 1065+ curated .wdr drivers

• get_driver → full T/S parameters with upstream validation issues (errors block, warns only omit a reference line)

• design_box → sealed (target Qtc) or vented (QB3/Thiele alignment) with Vb, Fb, port dimensions, EBP suitability advice

• simulate → SPL curve (≈60 points), F3, Qtc/Fc or Fb, max SPL & limiter (Xmax vs power), excursion & impedance peaks; degenerate designs (NaN curves) are rejected before returning

All physics comes from the vendored @openisd/engine + @openisd/winisd (pinned to a commit SHA) — zero reimplementation. The server is stateless: the design lives in the agent's conversation.

Quick start (opencode)

npm install -g @opencode-ai/cli
git clone https://github.com/OddieDank/openisd-mcp
cd openisd-mcp
opencode mcp add openisd-mcp -- node /path/to/openisd-mcp/dist/index.js
opencode run "Design a closed box with Qtc 0.707 for the Dayton driver ND105-8 of the library"

Related MCP server: LTspice MCP Server

Quick start (Claude Desktop)

// ~/Library/Application Support/Claude/claude_desktop_config.json (macOS)
// %APPDATA%\Claude\claude_desktop_config.json (Windows)
{
  "mcpServers": {
    "openisd-mcp": {
      "command": "node",
      "args": ["/absolute/path/to/openisd-mcp/dist/index.js"]
    }
  }
}

Then in Claude: "Design a closed box with Qtc 0.707 for the Dayton driver ND105-8 of the library".

Updating the vendored engine

# Edit OPENISD_SHA to a newer commit from Johnlon/openisd
npm run vendor   # downloads, compiles, indexes
npm test         # golden regression + flow + self-test

The scripts/vendor.sh script documents the SHA, applies one documented patch (winisd's workspace import @openisd/engine → relative), compiles with tsc, and builds the driver search index using upstream's own Driver.fromWdr.

Architecture notes

• Vendor commit pinned in OPENISD_SHA — reproducible, diffable.

• Engine source is TypeScript with zero deps; compiled to plain JS for runtime stability.

• All tools validate at the boundary (zod) before touching the engine.

• Engine Result<T> issues propagate as-is: agent sees {level:'error'} vs {level:'warn'}.

• classifyFinite runs on every sweep — a NaN curve never reaches the agent.

• Self-test at startup mirrors OpenISD's AD-5: golden SPL match (<0.1 dB), vented sweep finite, validation alive.

License

MIT — same as OpenISD.