feat: Support URL extraction from markdown link syntax

[LexioJ]

Summary

Fixes #55849

This PR updates the URL_REGEX pattern to support URL extraction from markdown link syntax [label](url), while maintaining backward compatibility with plain URL extraction.

Problem

The current URL_REGEX pattern requires whitespace or newlines before and after URLs:

'(\s|\n|^)(https?:\/\/)...*(\s|\n|$)'

This pattern fails to match URLs embedded in markdown link syntax where URLs are preceded by ]( and followed by ), preventing Reference Providers (GitHub, GitLab, Jira, etc.) from generating rich previews for markdown-formatted links.

Examples of affected use cases:

• [GH #55845](https://github.com/nextcloud/server/issues/55845) - GitHub issues
• [Ticket #12345](https://support.example.com/#ticket/zoom/12345) - Zammad Support tickets
• [PROJ-123](https://jira.example.com/browse/PROJ-123) - JIRA issues
• Any markdown link in Text app, Talk, or Comments

Solution

Updated the regex pattern to also accept markdown link syntax:

Before:

'(\s|\n|^)(https?:\/\/)([-A-Z0-9+_.]+...)(\s|\n|$)'

After:

'(\s|\n|^|\]\()(https?:\/\/)([-A-Z0-9+_.]+...)(\s|\n|$|\))'
//        ^^^^ added markdown start                  ^^^ added closing paren

Changes

• lib/public/IURLGenerator.php: Updated URL_REGEX_NO_MODIFIERS constant to match markdown syntax
• core/src/OCP/comments.js: Updated frontend regex to match backend changes (as per comment requirement)
• Added @since 31.0.0 version tag documenting the change

Backward Compatibility

✅ Existing plain URL extraction continues to work
✅ New: Markdown links now also extracted
✅ No breaking changes for reference providers
✅ No API changes - only regex pattern enhancement

Testing

Before this fix:

Plain URL: "Check https://github.com/nextcloud/server/issues/55845"
✅ Extracted successfully

Markdown: "Check [GH #55845](https://github.com/nextcloud/server/issues/55845)"  
❌ Not extracted

After this fix:

Plain URL: "Check https://github.com/nextcloud/server/issues/55845"
✅ Still works

Markdown: "Check [GH #55845](https://github.com/nextcloud/server/issues/55845)"
✅ Now extracted

Impact

• Users: Can now use more readable markdown-formatted links while still getting rich reference previews
• Reference Providers: Will automatically work with markdown links without any code changes
• Affected components: Text app, Talk, Comments, any component using ReferenceManager::extractReferences()

Related Code

The regex is used primarily in:

• lib/private/Collaboration/Reference/ReferenceManager.php line 53: extractReferences() method
• All registered Reference Providers that rely on URL extraction

---

Nextcloud Version: Targets v31+
Type: Bug fix / Enhancement

[susnux]

cc @nickvergessen is this relevant for Talk?

[nickvergessen]

Since LexioJ I maintaining a bot, I assume it does :P

[nickvergessen]

since line also needs to be on URL_REGEX to reflect the change of the value there

[nickvergessen]

Should also add that those are now part of the match and therefor regex group 2+3 are the actual link going forward and the full match in itself does not have to be a full valid link anymore.

[nickvergessen]

Checking with mobile app devs if the regex changes anything in clients

[nickvergessen]

Should definitely add tests for this method, are you able to do that, or should someone assist/take over?

[nickvergessen]

I removed the dist/ from the diff for now, so the code page loads and allows leaving comments

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[nickvergessen]

We'll discuss this and make the final call for it in the week of 17-21. November in our Talk Team week, as we have other related topics on our list.

[LexioJ]

We'll discuss this and make the final call for it in the week of 17-21. November in our Talk Team week, as we have other related topics on our list.

This PR does not primary address Talk - it would allow generally usage like in Notes, Collectives, Deck, etc. Smart-Picker Providers (like integration_github) can then generate Links to be more compact and „meaningful“ without sacrificing functionality like picking an element and put the link this way:
Check GH #xyz

For Talk it would be great if you could discuss/decide on nextcloud/spreed#16114 as well 😉

[nickvergessen]

This PR does not primary address Talk - it would allow generally usage like in Notes, Collectives, Deck, etc. Smart-Picker Providers (like integration_github) can then generate Links to be more compact

Totally aware, but there is more to it and as mentioned before, the current change breaks existing clients. So we will have a look if we can incorporate it somehow in a backwards compatible manner or we need to add a new constant.
At the same time there is more related things in parallel that impact the same code point that are more important to address.