Function buildStepMessages

src/session/parallel_executor.js:44–51

* Build an isolated messages array for a single parallel step. * The step sees the system prompt and its task description, but NOT * the full conversation history (which would include sibling results). * * IMPORTANT: sharedSystemMessages must contain ONLY {role:'system'} entries — * not user/as

(sharedSystemMessages, stepInstruction)

 * @returns {object[]}
 */
function buildStepMessages(sharedSystemMessages, stepInstruction) {
  // Safety: only allow system messages to prevent history bleed
  const systemOnly = (sharedSystemMessages || []).filter(m => m.role === 'system');
  return [
    ...systemOnly,
    { role: 'user', content: stepInstruction },
  ];
}

/**
 * Execute a single batch of steps concurrently.