In March 2012 a developer asked us for a PHP version per platform, a per-site override on top, and a way to tell Drush which PHP to use, and I turned the Provision half down myself, because the Ægir backend's command-line PHP was hard-wired into the Drush wrapper and had to be running before any task could change it. Fourteen years and a few small text files later, BOA-5.88.866 closes that gap: one line in cli-per-platform.info gives a platform its own command-line PHP, so a Drupal 7 codebase keeps its drush on PHP 7.4 while the Drupal 11 build beside it gets 8.5, in the same account, with no ticket to anyone, and a task which would run a site's code on a PHP its core cannot handle is refused before PHP even starts, with the line that fixes it printed in the message. It works because every command in your shell and every Ægir task for your account now passes through BOA's shell wrapper, which picks the version before any PHP is running at all.