CLAUDE WATERMARK REMOVER · MARKDOWN TEST
Why did a Markdown backslash stop showing and start a line break?
In CommonMark a backslash directly before a newline makes a hard break. The invisible point stopped them from touching.
What changed in the preview
The original line ends with a backslash, U+200B and then a line feed. There is no br element and the backslash is still visible in the serialized paragraph. The cleaned source retains the backslash and line feed. The renderer consumes the backslash as syntax and inserts br. Look for that distinction if you want a visible backslash at the end of a line: a source diff can show that it survived while the preview shows it was interpreted.
What this test covers
This fixture uses the backslash marker inside a paragraph. The separate trailing spaces guide covers the alternate hard break syntax.
Measured source and preview
Original Markdown
Keep this line\\u200B Then this one
Cleaned Markdown
Keep this line\ Then this one
The original source and its preview contain a literal U+200B, displayed below as \u200B. The HTML is shown as text.
Before cleanup
<p>Keep this line\\u200B Then this one</p>
After cleanup
<p>Keep this line<br /> Then this one</p>
Reproduce locally
Save reproduce.cjs and tested-app.js together. Run npm install --no-save commonmark@0.31.2, then node reproduce.cjs. Compare with the recorded input, output and HTML. The test uses the homepage callback with a minimal DOM. It does not use Claude output or test statistical watermark detection.
See the CommonMark specification and another measured Markdown case.