fix(markdown): comprehensive improvements to markdown block/inline parsing and UI rendering

[Yashh56]

PR Description

Summary

This PR introduces a series of robust fixes to the Markdown parser and UI rendering engine. It addresses multiple edge cases in both block- and inline-Markdown parsing, ensuring that complex combinations—such as nested lists, blockquotes containing lists, and nested inline elements—are formatted precisely to specification.

It also resolves a UI styling conflict with spoiler elements.

Key Changes

1. Block-Level Parsing

• Nested Lists: Refactored indentation tracking (buildList stack) to accurately map indentation depths, ensuring nested lists are generated with the correct hierarchy rather than being flattened.

• Ordered Lists:

  • Updated the regex to support multi-digit markers (e.g., 10., 100.), which were previously failing to parse.
  • Restricted alphabetical lists to valid types (a, A, i, I), preventing arbitrary letters (e.g., Q.) from erroneously triggering list creation.
  • Fixed an editor fallback bug where malformed ordered lists would default to a - metadata attribute, accidentally converting them to unordered lists.

• Unordered Lists: Fixed getListType to properly recognize hyphens (-) alongside asterisks (*) as valid unordered list markers.

• Blockquotes: Enabled recursive parsing inside BlockQuoteRule, allowing internal block elements (such as lists or headings) to be formatted correctly within a quote rather than rendering as raw text.

2. Inline-Level Parsing

• Rule Precedence: Moved CodeRule into LeveledRules to fix regex precedence issues. This prevents inline code blocks from prematurely splitting strings, which previously broke outer syntax such as links or spoilers containing code.

• Escaped Characters: Added \[ and \] to INLINE_SEQUENCE_SET so that escaped square brackets are correctly unescaped and ignored by the link parser.

3. UI & Styling

• Spoiler Visibility: Fixed a styling conflict where child elements inside an unrevealed spoiler (such as <code /> blocks with distinct backgrounds/colors) remained visible.

  Used Vanilla Extract's globalStyle to apply opacity: 0 to all descendants of an unrevealed spoiler, ensuring everything is completely hidden until clicked.

Testing

• Verified blockquote recursive rendering.
• Verified nested unordered/ordered lists mapping to Slate editor states.
• Verified lists starting with double digits (e.g., 10. Foo).
• Verified invalid lists (e.g., Q. Foo) are gracefully parsed as regular paragraphs.
• Verified escaped brackets (\[bracket\]) render as raw text.
• Verified spoiler tags (||) properly mask inline <code /> blocks.

Close: #2845

[Yashh56]

Tested the changes with the following Markdown cases to verify nested lists, escaped brackets in links, inline code within links, blockquotes, and spoilers containing inline code:

- Foo
  - Bar
- Baz

[This is a link with a \[bracket\]](https://example.com)

[This is a link with `code`](https://example.com)

> #### The story of markdown
>
> Markdown is a thing.

||`hidden code`||

All of the above cases are rendering as expected. I’ve also attached a screenshot of the resulting output below.

[Yashh56]

Hey @kfiven, can you please review this PR and share your feedback

[wigmarbled]

https://github.com/cinnyapp/cinny/blob/dev/CONTRIBUTING.md#ai-usage

As per their contribution policy, no AI code is allowed.

[Yashh56]

I reviewed the AI generated Code by myself. I don't think this might generate any problem in future.

[kfiven]

Hi @Yashh56
Since we review all the code by ourselves, we expect same from contributors as per new policy. There is also licensing concern regarding the AI generated code. We are happy to help you out on any issues but please follow the policy.

[Yashh56]

Hey @kfiven, thanks for clarifying. I understand the concern regarding the new policy and the licensing aspects of AI-generated code.

I’ll make sure to review and understand the code myself before submitting any further contributions and follow the project’s contribution guidelines going forward.

[Yashh56]

Hey @kfiven, Should I close this PR now and recreate a new one or make changes in it?

[kfiven]

Hi, A new one will be better.