[pengfeixx]

Root Cause Analysis

remark-parse parses inline HTML tags like <br> as type: "html" mdast nodes. In Milkdown's read-only preview mode, htmlSchema.toDOM renders html nodes via span.textContent, which outputs the raw tag as literal text instead of a line break. The preview pipeline had no transformation step to convert <br> html nodes into proper break nodes.

Fix Approach

Added a self-implemented remark plugin remarkTransformBrToHardbreak that walks the mdast tree and replaces html nodes matching /^<br\s*\/?>$/i with type: "break" nodes. Break nodes are rendered by Milkdown's hardbreakSchema as <br> HTML elements, producing the expected line break. No third-party remark plugins were introduced. The fix is applied in both main.js (source) and main.bundle.js (committed build artifact).

Change Safety Assessment

Code Safety

• Risk Level: Low
• New self-contained plugin function; no existing function signatures modified, no public APIs changed
• Plugin registered as independent .use() in boot chain, does not alter existing plugin ordering or behavior

Business Impact Scope

Only affects <br> tag rendering in Markdown preview: previously displayed as literal text <br>, now displays as a line break. [[...]] wiki links remain as literal text (out of scope). Standard Markdown syntax (headings, code blocks, tables, bold, links) rendering is unaffected.

Verification Suggestion

1. Open a Markdown file containing <br> tags and verify they render as line breaks in preview
2. Test <br/>, <br />, <BR> variants all render as line breaks
3. Verify <br> text inside code blocks is not converted
4. Verify standard Markdown syntax renders correctly

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根因分析

remark-parse 将内联 HTML 标签（如 <br>）解析为 type: "html" 的 mdast 节点。在 Milkdown 只读预览模式下，htmlSchema.toDOM 通过 span.textContent 渲染 html 节点，将原始标签作为字面文本输出而非换行。预览管线中缺少将 <br> html 节点转换为 break 节点的转换步骤。

修复方案

新增自实现的 remark 插件 remarkTransformBrToHardbreak，遍历 mdast 树，将匹配 /^<br\s*\/?>$/i 的 html 节点替换为 type: "break" 节点。break 节点由 Milkdown 的 hardbreakSchema 渲染为 <br> HTML 元素，实现换行效果。未引入任何第三方 remark 插件。修复同时应用于 main.js（源码）和 main.bundle.js（已提交的构建产物）。

改动安全评估

代码安全评估

• 风险等级: 低风险
• 新增自包含插件函数，不修改任何已有函数签名，不改变公开 API
• 插件作为独立的 .use() 注册在 boot 链中，不改变已有插件的注册顺序或行为

业务影响范围

仅影响 Markdown 预览中 <br> 标签的渲染行为：之前显示为字面文本 <br>，修复后显示为换行。[[...]] wiki 链接保持字面文本显示（不在修复范围）。标准 Markdown 语法（标题、代码块、表格、加粗、链接等）渲染行为不受影响。

验证建议

1. 打开包含 <br> 标签的 Markdown 文件，确认预览中显示为换行
2. 测试 <br/>、<br />、<BR> 等变体均正确渲染为换行
3. 确认代码块内的 <br> 文本不被转换
4. 确认标准 Markdown 语法渲染正常

Summary by Sourcery

Convert standalone <br> HTML nodes into Markdown hard breaks so previews display line breaks instead of literal tags.

Bug Fixes:

• Render <br> HTML tags as line breaks in the Markdown read-only preview, including common casing and spacing variants.

Build:

• Update the committed preview bundle to include the <br> rendering fix.

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: pengfeixx

The full list of commands accepted by this bot can be found here.

Details

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• debian/deepin/OWNERS

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[sourcery-ai]

Reviewer's Guide

The preview Markdown pipeline now transforms standalone <br> HTML nodes into Milkdown hardbreak nodes, so supported tag variants render as line breaks instead of literal text while code-block content and other Markdown behavior remain unchanged.

Flow diagram for converting br HTML to preview hardbreaks

flowchart LR
    A[Markdown source] --> B[remark-parse]
    B --> C{html node matches br variant}
    C -->|yes| D[remarkTransformBrToHardbreak]
    D --> E[mdast break node]
    E --> F[Milkdown hardbreakSchema]
    F --> G[Rendered line break]
    C -->|no| H[Existing Markdown pipeline]
    H --> I[Existing preview rendering]

Loading

File-Level Changes

Change	Details	Files
Convert standalone HTML <br> nodes into mdast hardbreak nodes during Markdown parsing.	Traverse the mdast tree recursively, including nested containers. Match case-insensitive <br>, <br/>, and <br /> forms and replace matching html nodes with { type: "break" }. Register the custom remark plugin in Milkdown's preview boot chain after code-block trailing-line trimming. Mirror the source change in the committed bundle artifact.	src/editor/markdown/web/main.js src/editor/markdown/web/build/main.bundle.js

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