Hello Mr Feynman,

> Is there any reason why continue could not take an optional file prefix for both line numbers and subs?

Just implementation.

Perldebug grew over decades since Perl 4 by little patches. (at least that's how it looks like)

The command loop alone spans hundreds of lines and is far from being generic parsing ( i.e. successive if regex and regex and regex then grep data and goto label or call sub)

AFAIS recent extensions often silently broke other features.

Adding your request might be either simple or impossible without a complete rewrite.

Good luck.