Transform blocks

In case you want something globally available on all transformed urls then transform block is a good way to go.

The regions and transform blocks can be configured in a tab in the core block layout administration interface and works much the same, except the regions are from config and not your theme.

The blocks are divided into regions that can be queries independently of eachother on an url and a block can be added to multiple regions with multiple configurations. For instance a menu block could be added to the header region with the main menu and another menu block could be added to the footer region with footer links.

Alter hook

The output of a transform block can be altered through it’s transform array alter hook, however the configration of transform blocks can be altered through:

hook_blocks_transform_config_alter()

This allows you to alter or add any transform blocks you need to.