Hooks Reference

// Register
$events->addAction(string $hook, callable $callback, int $priority = 10, int $acceptedArgs = 1): void;

// Fire (core only)
$events->doAction(string $hook, mixed ...$args): void;

// Register
$events->addFilter(string $hook, callable $callback, int $priority = 10, int $acceptedArgs = 2): void;

// Apply (core only)
$result = $events->applyFilter(string $hook, mixed $value, mixed ...$args): mixed;

public function register(EventManager $events, Container $container): void
{
    $events->addAction('payment.transaction.completed', function (array $txn) use ($container): void {
        $service = $container->get(NotificationService::class);
        $service->notify($txn);
    }, priority: 15);

    $events->addFilter('payment.fee.calculate', function (string $fee, array $ctx): string {
        return bcadd($fee, '0.50', 2); // flat $0.50 fee add-on
    }, priority: 20);
}