[Julia Roldi (juliaroldi)]

Summary

Fix Markdown paste conversion to preserve heading tags and sizes, bold, italic, and strikethrough while inheriting target formatting such as font family and text color. Add an opt-in preserveParagraphDecorator merge option and include target paragraph decorator and segment formatting in mergeModel's inherited defaults. Enable Markdown paste auto-conversion in the demo and add regression coverage for all six heading levels, rendered heading sizes and colors, emphasis, and existing content.

How to test

1. Run yarn eslint, yarn test:fast, and yarn b. All passed locally, including 6,523 tests. For focused coverage, run yarn test:fast --testPathPattern="mergeModelTest|MarkdownPastePluginTest".
2. In the demo, set the insertion-point font to Arial, 20px, and red, then paste plain-text Markdown containing # Heading, ## Subheading, and plain **bold** *italic* ~~strike~~. Auto-conversion is enabled by default. Before this fix, target formatting could override Markdown emphasis and heading sizes; after this fix, headings retain their tags and relative sizes, Markdown emphasis is preserved, and the content inherits the target font family and color.
3. Repeat with target strikethrough enabled. Plain text should inherit strikethrough, and Markdown bold and italic should remain intact.

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-10-26 22:02 UTC