You were mentioning that developer A produces version 1.0 of some C::A subclass for application Foo. Then, developer B comes along and upgrades that same C::A subclass to version 1.1 for application Bar. All of a sudden, application Foo doesn't work the same.

To me, each application should have its own subclass, even if that class is nothing more than

package Our::Web::Apps::Foo;

use base 'Our::Web::Apps';

1;
[download]

If only to avoid the problem that you're discussing.