Pasting rich text inserts unwanted formatting

Phenomenon

When pasting content from external sources (like Word documents or web pages) into a contenteditable region, unwanted formatting is often included. There is no simple way to paste as plain text without manually stripping the formatting.

Reproduction example

1. Copy formatted text from a Word document or web page (with bold, colors, fonts, etc.).
2. Paste it into a contenteditable div.
3. Observe that all the formatting is included.

Observed behavior

• Safari pastes rich text with all formatting by default.
• There is no built-in “Paste as plain text” option.
• Manual intervention is required to strip formatting.

Expected behavior

• There should be a way to paste as plain text (e.g., Cmd+Shift+V or a context menu option).
• The paste behavior should be controllable by the application.
• The beforeinput event should allow intercepting and modifying paste operations.