Function buildMessage

src/engine.ts:321–347

Build a user-facing failure message. Deliberately does NOT inline the * prompt — see EngineInvocationError for why.

(
  engineName: string,
  reason: 'timeout' | 'maxbuffer' | 'exit' | 'spawn',
  stderr: string,
  code: number | null,
  signal: NodeJS.Signals | null,
  timeoutMs: number,
)

/** Build a user-facing failure message. Deliberately does NOT inline the
 *  prompt — see EngineInvocationError for why. */
function buildMessage(
  engineName: string,
  reason: 'timeout' | 'maxbuffer' | 'exit' | 'spawn',
  stderr: string,
  code: number | null,
  signal: NodeJS.Signals | null,
  timeoutMs: number,
): string {
  const stderrSnippet = stderr.trim().slice(-500);
  const detail = stderrSnippet ? ` \u2014 ${stderrSnippet}` : '';
  switch (reason) {
    case 'timeout': {
      const duration = timeoutMs < 1000 ? `${timeoutMs}ms` : `${Math.round(timeoutMs / 1000)}s`;
      return `${engineName} timed out after ${duration}${detail}`;
    }
    case 'maxbuffer':
      return `${engineName} output exceeded buffer cap${detail}`;
    case 'spawn':
      return `${engineName} failed to start${detail}`;
    case 'exit':
    default: {
      const signalPart = signal ? ` (signal ${signal})` : '';
      const codePart   = code !== null ? ` exit ${code}` : '';
      return `${engineName} failed${codePart}${signalPart}${detail}`;
    }
  }
}

/**
 * Synchronous engine call — uses `spawnSync` with `input: ''` so the child's