add-block

name	add-block
description	Create a new Gutenberg block with scaffolding
argument-hint	["block-name"]
allowed-tools	Read, Write, Edit, Glob, Grep, Bash(mkdir *), Bash(npm run *)

Create a new Gutenberg block following WordPress best practices.

Pre-flight: Variation check

Before scaffolding a new block, run this check:

1. Search existing blocks (src/blocks/*) for anything conceptually similar.
2. Ask: would the new block differ from an existing one only by 1–3 attributes and share the same save() output structure?
3. If yes → register a variation via registerBlockVariation, not a new block. Variations have no migration cost and no deprecation debt.
4. If the save markup or inner-block structure actually differs → a new block is justified. Proceed.

See the "Variations vs. new blocks" section in .claude/claude.md for rationale and the consolidation pattern for sibling blocks.

Ask the User For

• Block name (e.g., "accordion", "testimonial-slider")
• Block category (e.g., "design", "widgets", "text", "media")
• Needs frontend JavaScript? (Yes/No)
• Needs dynamic rendering (PHP)? (Yes/No)

What Gets Created

1. Block directory: src/blocks/[block-name]/
2. block.json with proper metadata and attributes
3. index.js to register the block
4. edit.js with editor controls
5. save.js with frontend markup
6. style.scss for frontend styles
7. editor.scss for editor-only styles
8. frontend.js (if needed for interactivity)
9. render.php (if dynamic rendering needed)

Before Scaffolding — Check Shared Primitives

Before generating any block code, check src/hooks/ and src/components/shared/ for primitives that already cover the patterns you're about to write. The plugin maintains shared building blocks specifically to keep new blocks consistent with the rest of the codebase. See the Shared Primitives First and Variation vs New Block sections of .claude/claude.md for the full list and the variation-vs-block decision rule.

If a new block differs from an existing one only by 1–3 attributes and shares the same save() output, register a variation in the existing block's block.json instead of creating a new block.

Critical Patterns to Follow

ALWAYS use these in edit.js:

• useBlockProps() for block wrapper
• useInnerBlocksProps() for nested blocks (NOT plain <InnerBlocks />)
• Declarative styling (NO useEffect for styles)

ALWAYS include in block.json:

• Comprehensive supports for FSE compatibility
• example property for pattern library
• WordPress presets (no hardcoded colors/spacing)

Color controls:

• Use ColorGradientSettingsDropdown (NOT PanelColorSettings)
• Place in <InspectorControls group="color">
• Require clientId parameter in edit function

After Creation

Block will be auto-detected by webpack - no need to modify src/index.js.

If dynamic rendering is used, add PHP registration in includes/class-plugin.php.

Build and Test

npm run build

Test in both editor and frontend.

Reference

See BEST-PRACTICES-SUMMARY.md for complete patterns.