What?

Enhances the block removal warning modal specifically for the Post Content block with a clearer, more informative design that requires explicit user confirmation before removal.

Why?

Addresses #58136 - Users frequently accidentally remove the Post Content block from templates, causing their content to not display. The existing warning modal was not effective at preventing this.

How?

BlockRemovalWarningModal (packages/block-editor/src/components/block-removal-warning-modal/index.js):

• Added support for structured message objects (in addition to simple strings for backward compatibility)
• Added confirmation checkbox that must be checked before the Remove button is enabled
• Support for custom title, description, warning text, and button labels

BlockRemovalWarnings (packages/editor/src/components/block-removal-warnings/index.js):

• Post Content block now returns a structured message object with:
  • Title: "Remove content block?"
  • Clear description of what the block does
  • Bold warning about consequences
  • Subtext about visitor impact
  • Required confirmation checkbox
• Other template blocks (Query, Post Template) continue using the existing string-based warning

Design

Based on design from @jasmussen in #58136:

Testing Instructions

1. Open Site Editor > Templates > Pages
2. Select the Post Content block
3. Delete it (press Delete or use block toolbar)
4. Verify the new modal appears with:
   • Title: "Remove content block?"
   • Description, bold warning, and subtext
   • Checkbox: "I understand the consequences"
   • "Remove" button disabled until checkbox is checked
5. Verify Cancel closes modal without removing block
6. Verify Remove (after checkbox) removes the block
7. Test backward compatibility: remove a Query block - should show old-style "Be careful!" modal

Video

Here's what the new experience looks like:

🤖 Generated with Claude Code