fix: allow all heading depths in readme and transform them

[alexdln]

Headings were getting lost in the readme. They were getting lost because we weren't processing them. That is, if a user added h1 or h2 via HTML, they weren't processed.

I added processing to them and all other levels that weren't processed via Markdown so that the correct style would be applied.

Closes #1093

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Project	Deployment	Actions	Updated (UTC)
npmx.dev	Ready	Preview, Comment	Feb 10, 2026 1:21am

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[alexdln]

Unfortunately, the renderer will have to be rewritten, since we need to loop through both the HTML and MD from file in a single loop to ensure complete correctness. Otherwise, we can't guarantee the order in which headers are extracted and slugs are generated (especially with repeated content).

I didn't touch this here, since it would likely rewrite half the file. I'll create a new issue tomorrow

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR modifies the README sanitisation logic in server/utils/readme.ts to be more permissive with allowed heading elements. It expands ALLOWED\_TAGS to include h1 and h2, introduces a helper function to calculate semantic heading depths with constraints (README h1 maps to h3, no level skipping, cap at h6), and adds transform handlers for heading tags to map them sequentially whilst preserving depth metadata via data-level attributes.

Possibly related PRs

• fix: readme rendering result lacks anchor point jump #994: Modifies sanitisation and transform logic within the same file for heading tag handling and attributes.

Suggested reviewers

• danielroe
• trueberryless
• serhalp

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description check	✅ Passed	The PR description accurately describes the changes made: adding processing for HTML headings (h1, h2) and other heading levels that were not previously processed in README rendering.
Linked Issues check	✅ Passed	The PR addresses issue #1093 by expanding ALLOWED_TAGS to include h1 and h2 headings and implementing semantic depth transformation for all heading levels to ensure proper rendering.
Out of Scope Changes check	✅ Passed	All changes in server/utils/readme.ts are directly related to the objective of processing previously unsupported HTML headings and applying correct styles, with no out-of-scope modifications detected.

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Actionable comments posted: 1