Bolt PHP Core
This PHP package is for the Bolt Design System.
This package gets deployed as a read-only git repo bolt-design-system/core-php, however it's source is at bolt-design-system/bolt in packages/core-php, so don't send PRs to the first repo link, send them to the second repo link!!
Categories of Twig Extension
BoltCore
These are the set of custom Twig extensions globally used within the Bolt Design System + automatically wired up to other systems (ex. within Drupal via the bolt_connect module).
BoltCoreCompat
These are additional Twig extensions for Twig functions / filters used within the Bolt Design System's components that are specifically for cross-platform compatibility. For example, all of these extensions should already exist in Drupal enviroments by default with the exception of the pattern_template Twig function (which ships with the UI Patterns module).
BoltExtras
These are extra Twig extensions used primarily for internal testing within the Bolt Design System and are used to help build and maintain the documentation site and demos.