// No valid path exists
if (!plan) {
  // Analyze which preconditions cannot be satisfied
  const unsatisfiable = findUnsatisfiablePreconditions(goalState);
  console.error(`Cannot reach goal: missing ${unsatisfiable}`);

  // Suggest partial goals that ARE achievable
  const partialGoals = suggestAchievableSubsets(goalState);
}

// Action failed during execution
if (actionResult.failed) {
  // Check if alternative action available
  if (action.fallback) {
    await executeAction(action.fallback);
  } else {
    // Replan from current state
    const newPlan = await replan(currentState, goalState);
  }
}