The regex '/([a-z0-9])([A-Z])/' does not split on underscores, so
Interface_Spam_Source, Settings_Page, Dashboard_Widget stayed as
'interface_spam_source', 'settings_page', 'dashboard_widget' after
strtolower — no file matched. Added str_replace('_', '-', ...).
Then Interface_Spam_Source's slug became 'interface-spam-source',
and the candidate 'includes/sources/interface-' . \$slug doubled
the prefix into 'interface-interface-spam-source.php'. Replaced
that candidate family with a slug-as-filename fallback that maps
interface-* slugs directly to their files.
Sanity check on plugin bootstrap: 17/17 classes/interfaces resolve.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Vladimir Bryzgalov