fix: avoid task checkbox for setext heading text

[AbdelrahmanHafez]

Marked version: 18.0.2

Markdown flavor: GitHub Flavored Markdown

Description

re #3828
Setext headings inside list items that start with [x] or [ ] were parsed as task list items, so the marker was removed and a disabled checkbox was inserted.

Expectation

- [x] title
  ---

renders as a list item containing <h2>[x] title</h2>.

Result

Demo
Marked rendered the same input as a checked task list item with a heading.

What was attempted

Only finalize task-list parsing when the preserved checkbox marker belongs to a text-like first child token. Added unit coverage for the rendered HTML and lexer token shape.

Contributor

• Test(s) exist to ensure functionality and minimize regression (if no tests added, list tests covering this PR); or,
• no tests required for this PR.
• If submitting new feature, it has been documented in the appropriate places.

Committer

In most cases, this should be a different person than the contributor.

• CI is green (no forced merge required).
• Squash and Merge PR following conventional commit guidelines.

[vercel]

@AbdelrahmanHafez is attempting to deploy a commit to the MarkedJS Team on Vercel.

A member of the Team first needs to authorize it.

[gemini-code-assist]

Code Review

This pull request modifies the Tokenizer to prevent setext headings within list items from being incorrectly identified as task checkboxes. The logic now ensures that task checkbox processing only occurs if the first token of a list item is of type 'text' or 'paragraph'. Corresponding unit tests have been added to Lexer.test.js and marked.test.js to verify that these headings are rendered correctly without checkbox inputs. I have no feedback to provide.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
marked-website	Ready	Preview, Comment	Apr 30, 2026 2:48pm

[UziTech]

Thanks for improving marked! 💯