grammars: Highlight inline HTML comments in Markdown

[qrkks]

Summary

• highlight inline HTML comments in Markdown with the theme's comment style
• leave other inline HTML tags unaffected
• add regression coverage for the Markdown-inline highlight query

Root cause

The Markdown-inline grammar exposes comments and ordinary inline HTML as the same html_tag node. The existing highlight query did not distinguish comments by their source text, so <!-- ... --> received no comment capture inside paragraphs.

This change adds a query predicate that applies @comment only when an html_tag starts with <!--.

Validation

• rustup run stable rustfmt --edition 2024 --check crates/grammars/src/grammars.rs
• git diff --check
• parsed inline Markdown containing both <!-- hidden note --> and <span>after</span> with the updated query and verified that only the comment received the comment capture

Release Notes:

• Improved Markdown syntax highlighting for inline HTML comments.

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[qrkks]

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[qrkks]

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[qrkks]

Hi! Just checking in on this small Markdown grammar fix. Is this approach still aligned with the current direction for Markdown highlighting in Zed? Happy to adjust anything if needed. Thanks!

[MrSubidubi]

Mind sharing a before-after, please? I had a look now and highlighting worked as I'd expect it for me, so would like to be sure to not just see the test (thanks for adding that upfront) but also a visual before-after

[qrkks]

Thanks for checking, and good catch! I took another look and found that #61212, which was merged after this PR was opened, now handles inline HTML tags through HTML grammar injection and includes coverage for inline and multiline HTML comments. I also noticed that it initially used the same direct @comment capture as this PR before switching to the more general injection-based approach.

That explains why highlighting already works on the current main. This PR has therefore been superseded, so I’ll close it. Thanks for the review!

[MrSubidubi]

No problem, appreciate you checking in on this!