No separate issue is linked.

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

Preserve the username/password and protocol-relative authority when converting URL hostnames between Unicode and Punycode. Preserve query strings and fragments equal to 0 or empty strings. Add seven bidirectional URL cases.

Testing Instructions

Run php ./libraries/vendor/bin/phpunit --configuration phpunit.xml.dist --filter PunycodeHelperTest in a configured Joomla development checkout. Verify the seven cases in both directions, including credentials, protocol-relative URLs, query/fragment 0, ordinary ASCII URLs, and relative paths. These are reproduction instructions, not a claim of a local test run in this update.

Actual result BEFORE applying this Pull Request

https://user:secret@exämple.com/feed loses user:secret@ during conversion. //exämple.com/page loses the leading //. Query or fragment 0 is discarded.

Expected result AFTER applying this Pull Request

Only the hostname encoding changes. Credentials, leading //, paths, queries, and fragments are retained.

Link to documentations

• Documentation link for guide.joomla.org:

• No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

These changes restore preservation of existing URL components rather than introduce a new public API.