Long-form notes on the parts of Drupal you only meet when something is slow, broken, or newly possible, in chronological order.
Entity Adapter attaches domain-specific behaviour to entities, and to any other object, with a PHP attribute and an interface of your own. No bundle class, no entity class override, no helper functions in a .module file.
Drupal spends a request filling static caches and then throws the whole process away. Keep the process alive, in a Symfony Messenger worker or a FrankenPHP worker, and every one of those caches becomes a lie that outlives the work it was computed for.
WebProfiler now collects every call the AI module makes to a provider, with timings, tokens, guardrail verdicts and tool exchanges. Here is what it records and how it stays out of the AI module's way.