Transient messages

Transient messages belong to the current request. They are kept in runtime configuration rather than the session, so they do not survive a redirect.

In a controller:

$this->Flash->transientSuccess('Preview generated.');
$this->Flash->transientWarning('This preview has not been saved.');
$this->Flash->transientMessage('Review pending.', ['type' => 'info']);

In a view, the same typed methods are available through the helper:

$this->Flash->transientInfo('Showing a preview.');

Add these messages before the layout calls render(). The helper combines transient and session messages, orders them by type, and removes the rendered entries from their stores.

For a message at a specific point in a template, render it directly:

<?= $this->Flash->message('This section is read only.', 'info') ?>

Direct rendering returns HTML immediately and does not add a message to either stack. The helper's transient methods accept their options, including key, params and escape; its configured limit applies per transient key.

The TransientFlash configuration namespace is runtime storage. Do not pre-populate it in config/app.php. Use the shared Flash key or individual load options for configuration.