Digest cycle synchronization for third-party event callbacks

AngularJS State Synchronization

In AngularJS 1.x, the framework utilizes a digest cycle to synchronize the model and view via dirty checking. While internal services like $http and $timeout automatically trigger this cycle, updates originating from external third-party libraries or asynchronous callbacks occur outside the Angular context.

The primary constraint is maintaining UI synchronization without triggering the $apply "already in progress" error, which occurs if a manual digest is requested while the framework is already processing a cycle.

What is the recommended configuration for ensuring external state changes are reflected in the view when the callback execution timing relative to the digest loop is unpredictable? Which mechanism provides the safest boundary to prevent recursive digest errors?