Use when developing WordPress (Gutenberg) blocks: block.json metadata, register_block_type(_from_metadata), attributes/serialization, supports, dynamic rendering (render.php/render_callback), deprecations/migrations, viewScript vs viewScriptModule, and @wordpress/scripts/@wordpress/create-block buil

WP Block Development When to use Use this skill for block work such as: creating a new block, or updating an existing one changing block.json (scripts/styles/supports/attributes/render/viewScriptModule) fixing “block invalid / not saving / attributes not persisting” adding dynamic rendering ( render.php / render callback ) block deprecations and migrations ( deprecated versions) build tooling for blocks ( @wordpress/scripts , @wordpress/create block , wp env ) Inputs required Repo root and target (plugin vs theme vs full site). The block name/namespace and where it lives (path to block.json if known). Target WordPress version range (especially if using modules / viewScriptModule ). Procedure 0) Triage and locate blocks 1. Run triage: node skills/wp project triage/scripts/detect wp project.mjs 2. List blocks (deterministic scan): node skills/wp block development/scripts/list blocks.mjs 3. Identify the block root (directory containing block.json ) you’re changing. If this repo is a full site ( wp content/ present), be explicit about which plugin/theme contains the block. 1) Create a new block (if needed) If you are creating a new block, prefer scaffolding rather than hand rolling structure: Use @wordpress/create block to scaffold a modern block/plugin setup. If you need Interactivity API from day 1, use the interactive template. Read: references/creating new blocks.md After scaffolding: 1. Re run the block list script and confirm the new block root. 2. Continue with the remaining steps (model choice, metadata, registration, serialization). 2) Ensure apiVersion 3 (WordPress 6.9+) WordPress 6.9 enforces apiVersion: 3 in the block.json schema. Blocks with apiVersion 2 or lower trigger console warnings when SCRIPT DEBUG is enabled. Why this matters: WordPress 7.0 will run the post editor in an iframe regardless of block apiVersion. apiVersion 3 ensures your block works correctly inside the iframed editor (style isolation, viewport units, media queries). Migration: Changing from version 2 to 3 is usually as simple as updating the apiVersion field in block.json . However: Test in a local environment with the iframe editor enabled. Ensure any style handles are included in block.json (styles missing from the iframe won't apply). Third party scripts attached to a specific window may have scoping issues. Read: references/block json.md (apiVersion and schema details) 3) Pick the right block model Static block (markup saved into post content): implement save() ; keep attributes serialization stable. Dynamic block (server rendered): use render in block.json (or render callback in PHP) and keep save() minimal or null . Interactive frontend behavior : Prefer viewScriptModule for modern module based view scripts where supported. If you're working primarily on data wp directives or stores, also use wp interactivity api . 4) Update block.json safely Make changes in the block’s block.json , then confirm registration matches metadata. For field by field guidance, read: references/block json.md Common pitfalls: changing name breaks compatibility (treat it as stable API) changing saved markup without adding deprecated causes “Invalid block” adding attributes without defining source/serialization correctly causes “attribute not saving” 5) Register the block (server side preferred) Prefer PHP registration using metadata, especially when: you need dynamic rendering you need translations ( wp set script translations ) you need conditional asset loading Read and apply: references/registration.md 6) Implement edit/save/render patterns Follow wrapper attribute best practices: Editor: useBlockProps() Static save: useBlockProps.save() Dynamic render (PHP): get block wrapper attributes() Read: references/supports and wrappers.md references/dynamic rendering.md (if dynamic) 7) Inner blocks (block composition) If your block is a “container” that nests other blocks, treat Inner Blocks as a first class feature: Use useInnerBlocksProps() to integrate inner blocks with wrapper props. Keep migrations in mind if you change inner markup. Read: references/inner blocks.md 8) Attributes and serialization Before changing attributes: confirm where the attribute value lives (comment delimiter vs HTML vs context) avoid the deprecated meta attribute source Read: references/attributes and serialization.md 9) Migrations and deprecations (avoid "Invalid block") If you change saved markup or attributes: 1. Add a deprecated entry (newest → oldest). 2. Provide save for old versions and an optional migrate to normalize attributes. Read: references/deprecations.md 10) Tooling and verification commands Prefer whatever the repo already uses: @wordpress/scripts (common) → run existing npm scripts wp env (common) → use for local WP + E2E Read: references/tooling and testing.md Verification Block appears in inserter and inserts successfully. Saving + reloading does not create “Invalid block”. Frontend output matches expectations (static: saved markup; dynamic: server output). Assets load where expected (editor vs frontend). Run the repo’s lint/build/tests that triage recommends. Failure modes / debugging If something fails, start here: references/debugging.md (common failures + fastest checks) references/attributes and serialization.md (attributes not saving) references/deprecations.md (invalid block after change) Escalation If you’re uncertain about upstream behavior/version support, consult canonical docs first: WordPress Developer Resources (Block Editor Handbook, Theme Handbook, Plugin Handbook) Gutenberg repo docs for bleeding edge behaviors

wp-block-development