People migrating Rails apps from classic to zeitwerk told me they needed an estimation.

The task zeitwerk:check eager loads. Name mismatches trigger built-in error logic, and you cannot continue because doing so would be unpredictable.

But you can get some sense of "progress": 1) In classic mode, eager load the application by setting config.eager_load = true in config/environments/development.rb.

Then, iterate over ActiveSupport::Dependencies.autoloaded_constants, and print their const_source_location.