export function buildErrandPrompt(description: string): string {
  return `You are working on a small, focused change in an isolated worktree.

Description: ${description}

Work interactively with the user. Make only the changes needed to fulfill the description.
When you are done, write .cw/output/signal.json:

{ "status": "done", "result": { "message": "<one-sentence summary of what you changed>" } }

If you cannot complete the change:

{ "status": "error", "error": "<explanation>" }

Do not create any other output files.`;
}