End-of-line attributes fail to apply to block tokens in the presence of inline Markdown

[kentrpg]

Describe the bug

The current logic for applying block-level attributes is too strict, as it assumes the children array will contain exactly two elements: a text node and the props token.

if (
  token.type === 'inline'
  && token.children?.length === 2
  && token.children[0].type === 'text'
  && token.children[1].type === 'mdc_inline_props'
) {
 // ... logic to apply props
}

However, when the line also contains other inline Markdown syntax like bold or code, markdown-it parses these into additional inline-level tokens, causing the children array to have more than two elements.

For example, after calling state.push('mdc_inline_props', 'span', 0), the state.tokens array may look like:

// For "**markdown bold**{.text-red}"
state.tokens = [
  { type: 'strong_open', markup: '**', ... },
  { type: 'text', content: 'markdown bold', ... },
  { type: 'strong_close', markup: '**', ... },
  { type: 'mdc_inline_props', ... }
]

// For "markdown syntax `inline block`{.text-red}"
state.tokens = [
  { type: 'text', content: 'markdown syntax', ... },
  { type: 'code_inline', content: 'inline block', ... },
  { type: 'mdc_inline_props', ... }
]

As a result, the attributes intended for the parent block element are incorrectly applied to the immediately preceding inline element.

Markdown content

**markdown bold**{.text-red}

markdown syntax `inline block`{.text-red}

Actual HTML Rendered

<p><strong class="text-red">markdown bold</strong></p>
<p>markdown syntax <code class="text-red">inline block</code></p>

Expected HTML Rendered

<p class="text-red"><strong>markdown bold</strong></p>
<p class="text-red">markdown syntax <code>inline block</code></p>

Reproduction

PR #16

System Info

System:
    OS: macOS 15.1.1
    CPU: (8) arm64 Apple M2
    Memory: 65.80 MB / 16.00 GB
    Shell: 5.9 - /opt/homebrew/bin/zsh
  Binaries:
    Node: 22.5.1 - ~/.nvm/versions/node/v22.5.1/bin/node
    npm: 10.8.2 - ~/.nvm/versions/node/v22.5.1/bin/npm
    pnpm: 9.1.3 - ~/Documents/Slidev/markdown-it-mdc/node_modules/.bin/pnpm
    bun: 1.2.6 - ~/.bun/bin/bun
  Browsers:
    Chrome: 137.0.7151.120
    Safari: 18.1.1

Used Package Manager

pnpm

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Contributions

• I am willing to submit a PR to fix this issue
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