fix: enhance link title parsing with hyphens and underscores in URL's

[Vaishali021103]

Proposed changes (including videos or screenshots)

This PR fixes URL and markdown-link parsing for cases where the URL or query string contains underscores and hyphenated values, without breaking valid host parsing or treating underscores as invalid emphasis boundaries.

The fix updates the parser rules in the message-parser grammar to allow valid URL paths and query parameters containing underscores while still rejecting malformed underscore-prefixed domains. It also adds regression coverage for real-world link cases such as:

• [testwithatextcontainingan_here](http://example.com?a_param)
• [test-with-a-text-containing-an_here](http://example.com?param=my_value)
• http://te_st.com
• https://developer.rocket.chat?query=query_with_underscore
• https://developer.rocket.chat/path_with_underscore

This ensures markdown links remain parsed correctly in messages containing mixed hyphen/underscore URL content.

Issue(s)

Fixes #41725 URL parsing bug for markdown links and autolinks containing underscores in the path/query string and mixed hyphen/underscore link titles.

Steps to test or reproduce

1. Parse a markdown link with a query string containing an underscore:
   • [testwithatextcontainingan_here](http://example.com?a_param)
2. Parse a markdown link with a path/query parameter using mixed hyphen/underscore values:
   • [test-with-a-text-containing-an_here](http://example.com?param=my_value)
3. Parse a plain autolink URL containing underscores:
   • https://developer.rocket.chat/path_with_underscore
   • https://developer.rocket.chat?query=query_with_underscore
4. Confirm the parser still handles valid links and does not incorrectly parse malformed underscore-prefixed domains.

Further comments

This is a targeted parser fix in the message parser grammar and is covered by regression tests in the package’s link and URL test suites. The change is intentionally narrow: it preserves existing parsing behavior for valid URLs while avoiding false positives caused by underscores in host/path contexts.

[dionisio-bot]

Looks like this PR is not ready to merge, because of the following issues:

• This PR is missing the 'stat: QA assured' label
• This PR is missing the required milestone or project

Please fix the issues and try again

If you have any trouble, please check the PR guidelines

[changeset-bot]

⚠️ No Changeset found

Latest commit: 7302b6a

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[CLAassistant]

All committers have signed the CLA.

[coderabbitai]

Walkthrough

The parser now uses link-title-specific emphasis rules that preserve ]( terminators. Tests cover link titles and URLs containing hyphens and underscores.

Changes

Link Title Parsing

Layer / File(s)	Summary
Link-title emphasis rules and validation packages/message-parser/src/grammar.pegjs, packages/message-parser/tests/link.test.ts	The grammar adds guarded italic and plain-run rules that exclude ] from link-title content. Tests cover hyphenated text, underscored text, and URLs with underscore-containing query parameters.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested labels: type: bug

Suggested reviewers: ggazzo, ricardogarim

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: improved Markdown link-title parsing for hyphens and underscores in URLs.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[cubic-dev-ai]

All reported issues were addressed across 2 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>