CLAUDE WATERMARK REMOVER · MARKDOWN TEST
Can a hidden space stop Markdown from decoding a named entity?
A hidden U+200B before the semicolon stopped this named reference from becoming ©. Removing that character restored the reference.
What changed in the preview
The raw preview escaped the ampersand and displayed the entity spelling. The cleaned preview emitted the copyright character. If the spelling is intentional, write an escaped ampersand or put the example in a code span.
What this test covers
The test isolates one named reference and does not establish how numeric references behave. Compare the two rendered outputs below with the original and cleaned source.
Measured source and preview
Original Markdown
Tea ©\u200B;
Cleaned Markdown
Tea ©
The original source and its preview contain a literal U+200B, displayed below as \u200B. The HTML is shown as text.
Before cleanup
<p>Tea &copy\u200B;</p>
After cleanup
<p>Tea ©</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.