Lisp

OpenCode plugin that runs a persistent SBCL (Steel Bank Common Lisp) sidecar for evaluating Common Lisp expressions.

State, packages, and defvars persist across evaluations for the lifetime of the sidecar process.

Prerequisites

You need SBCL installed on your system:

# macOS
brew install sbcl

# Ubuntu / Debian
sudo apt install sbcl

# Fedora
sudo dnf install sbcl

# Windows — download from https://www.sbcl.org

Installation

Add the plugin to your opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-plugin-lisp"]
}

OpenCode will automatically install the plugin via Bun on startup.

Usage

The plugin provides two tools:

lisp_eval

Evaluate a Common Lisp expression in the persistent SBCL sidecar. The expression must be a single line.

lisp_eval code="(let ((x 40)) (+ x 2))"

Returns the printed value, its type, and any output the expression wrote.

lisp_reset

Clear the sidecar's observation history.

lisp_reset

Configuration

Environment Variable	Default	Description
OPL_SBCL	sbcl	Path to the SBCL binary
OPL_DEBUG	0	Set to 1 to enable debug logging

How It Works

The plugin spawns a persistent SBCL subprocess that communicates over stdin/stdout using a simple line-based, tab-separated protocol. The sidecar maintains state between evaluations — variables, packages, and definitions persist until the process is restarted.

The plugin also observes chat messages and tool calls via OpenCode hooks, feeding context to the sidecar's history buffer.

License

MIT