claude-task-master/scripts/modules/task-manager.js (lines 3036-3084)

async function updateSubtaskById(tasksPath, subtaskId, prompt, useResearch = false) {
  let loadingIndicator = null;
  try {
    log('info', `Updating subtask ${subtaskId} with prompt: "${prompt}"`);

    // Validate subtask ID format
    if (!subtaskId || typeof subtaskId !== 'string' || !subtaskId.includes('.')) {
      throw new Error(`Invalid subtask ID format: ${subtaskId}. Subtask ID must be in format "parentId.subtaskId"`);
    }

    // Validate prompt
    if (!prompt || typeof prompt !== 'string' || prompt.trim() === '') {
      throw new Error('Prompt cannot be empty. Please provide context for the subtask update.');
    }

    // Prepare for fallback handling
    let claudeOverloaded = false;

    // Validate tasks file exists
    if (!fs.existsSync(tasksPath)) {
      throw new Error(`Tasks file not found at path: ${tasksPath}`);
    }

    // Read the tasks file
    const data = readJSON(tasksPath);
    // ... rest of the function
  } catch (error) {
    // Handle errors
    console.error(`Error updating subtask: ${error.message}`);
    throw error;
  }
}