Classic Block: Copy/paste broken for empty Classic Block

[BugReportOnWeb]

What?

Closes #75798

Copy/paste from the block options menu does nothing for an empty Classic Block because it is invisible in the code editor when empty, unlike other block types (Image, Audio, Custom HTML, etc.).

Why?

An empty Classic Block serializes to empty HTML instead of a block comment delimiter. As a result, the clipboard receives no data when the block is copied or cut, so pasting produces no output.

By emitting a block comment when the Classic Block is empty and ensuring it is properly parsed (without being ignored), we allow empty Classic Blocks to be copied/cut and pasted correctly, while preserving the existing HTML parsing behavior when the block contains content.

How?

• Emit <!-- wp:freeform /--> when the Classic Block’s saveContent is empty.
• Only ignore implicit freeform blocks during parsing (rawBlock.blockName !== getFreeformContentHandlerName())
• Use attributes?.content in the paste handler to distinguish and empty Classic Blocks from the legacy freeform blocks containing raw HTML

Testing Instructions

1. Insert an empty Classic Block
2. Copy or cut it using the block options menu, then paste
   • An empty Classic Block should be inserted
3. Switch to the code editor and confirm <!-- wp:freeform /--> is present
4. Repeat with a non-empty Classic Block
   • Content should copy and paste correctly
5. (Optional) Paste raw HTML directly into the code editor
   • Legacy content handling should continue to work as before

Screenshots or screencast

Screen.Recording.2026-04-27.at.11.31.52.PM.mov

Use of AI Tools

Code assistance with GitHub Copilot and ChatGPT for rephrasing PR description.

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Co-authored-by: BugReportOnWeb <devasheeshkaul@git.wordpress.org>
Co-authored-by: hiroshisatoy <hiroshisato@git.wordpress.org>

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