What it records
PHP errors and fatals grouped by message and attributed to the plugin or theme that raised them. Every plugin, theme and core update with version before and after. Cron and Action Scheduler runs, slow hooks, slow database queries and external HTTP requests. All of it stays on your site until you decide to connect it.
What it never does
Detective never auto-updates, never deactivates plugins on its own, never cleans your database and never optimises anything. Investigation mode (Pro) lets you test a hypothesis – "is it plugin X?" – in an isolated session that only you see; visitors are never affected.
Overhead budget
At most 5 ms and 2 MB on an ordinary uncached front-end request. That budget is enforced by an automated benchmark in our build pipeline; if it fails, the release does not ship.