Usage Tracking

final agent = Agent('openai');
final result = await agent.send('Explain AI briefly');

// Access usage
print('Input tokens: ${result.usage.promptTokens}');
print('Output tokens: ${result.usage.responseTokens}');
print('Total tokens: ${result.usage.totalTokens}');

final providers = ['openai', 'anthropic', 'google'];

for (final name in providers) {
  final agent = Agent(name);
  final result = await agent.send('Hello');
  
  print('$name: ${result.usage.totalTokens} tokens');
}

final agent = Agent('openai');
final result = await agent.embedDocuments([
  'Text 1',
  'Text 2',
  'Text 3',
]);

print('Tokens used: ${result.usage.totalTokens}');

// Example pricing (check current rates)
const openaiInputPer1k = 0.00015;
const openaiOutputPer1k = 0.0006;

final result = await agent.send('Write a haiku');
final inputCost = (result.usage.promptTokens ?? 0) / 1000 * openaiInputPer1k;
final outputCost = (result.usage.responseTokens ?? 0) / 1000 * openaiOutputPer1k;

print('Cost: \$${(inputCost + outputCost).toStringAsFixed(6)}');

var totalTokens = 0;
var totalCost = 0.0;

// Track multiple requests
for (var i = 0; i < 5; i++) {
  final result = await agent.send('Question $i');
  totalTokens += result.usage.totalTokens ?? 0;
  
  // Add cost calculation
  final cost = totalTokens / 1000 * 0.002; // Example rate
  totalCost += cost;
}

print('Total: $totalTokens tokens, \$$totalCost');