Writing a Harness Adapter

An event-runtime adapter is an ES module with two required exports: execute() and SANDBOX_SUPPORT.

export const SANDBOX_SUPPORT = "unsupported";

export async function execute({
  spec,
  def,
  workspaceDir,
  timeoutMs,
  env,
  onTrace,
  onUsage,
  abortSignal,
}) {
  // Spawn the CLI, stream trace and usage, and write the result artifact.
  return { exitCode: 0, timedOut: false };
}

SANDBOX_SUPPORT must be "gondolin" or "unsupported". Declaring Gondolin support means the adapter owns the sandboxed execution path; unsupported adapters are refused before they run when a definition requires sandboxing.

Required Capabilities

1. Prompt ingestion: Accept instructions through the CLI’s supported input mechanism.
2. Workspace and tool policy: Honor the supplied workspace, mutability, environment, timeout, and abort signal.
3. Trace capture: Emit normalized trace events and preserve a transcript artifact.
4. Result contract: Write the declared result artifact and return a clean { exitCode, timedOut } outcome.

Built-in adapters live in event-runtime/lib/adapters/. Installable adapters can be contributed by a factory-extension.json manifest. Validate what the runtime loaded with:

factory events adapters
factory events extensions validate /path/to/extension