WpOptionSchemaVersionStore
Corex\Database\Schema\WpOptionSchemaVersionStore · class · Core layer
WordPress options are site-scoped by construction: under switch_to_blog(), every call targets that site’s options table (spec 100 FR-029, FR-034). The versions are stored with autoload off and stay so. No front-end request reads them, and an admin or cron request reads them in one statement however many components there are, so autoloading them would save that one statement by loading them everywhere else. And WordPress leaves the autoload of a stored option alone when the value written is the one it has, so a site that holds them today would need a migration of its own to move them (DECISIONS #360).