From Agent Skills for WordPress. Copyright (C) 2026 WordPress Contributors, licensed under GPL-2.0-or-later. Changed from upstream: the compatibility: frontmatter line was dropped when this copy was made in March 2026, and license frontmatter plus this notice were added on 2026-10-24. See NOTICE.md.

WP Block Themes

When to use

Use this skill for block theme work such as:

• editing theme.json (presets, settings, styles, per-block styles)
• adding or changing templates (templates/*.html) and template parts (parts/*.html)
• adding patterns (patterns/*.php) and controlling what appears in the inserter
• adding style variations (styles/*.json)
• debugging “styles not applying” / “editor doesn’t reflect theme.json”

Inputs required

• Repo root and which theme is targeted (theme directory if multiple exist).
• Target WordPress version range (theme.json version and features vary by core version).
• Where the issue manifests: Site Editor, post editor, frontend, or all.

Procedure

0) Triage and locate block theme roots

1. Run triage:
   • node skills/wp-project-triage/scripts/detect_wp_project.mjs
2. Detect theme roots + key folders:
   • node skills/wp-block-themes/scripts/detect_block_themes.mjs

If multiple themes exist, pick one and scope all changes to that theme root.

1) Create a new block theme (if needed)

If you are creating a new block theme from scratch (or converting a classic theme):

• Prefer starting from a known-good scaffold (or exporting from a WP environment) rather than guessing file layout.
• Be explicit about the minimum supported WordPress version because theme.json schema versions differ.

Read:

• references/creating-new-block-theme.md

After creating the theme root, re-run detect_block_themes and continue below.

2) Confirm theme type and override expectations

• Block theme indicators:
  • theme.json present
  • templates/ and/or parts/ present
• Remember the style hierarchy:
  • core defaults → theme.json → child theme → user customizations
  • user customizations can make theme.json edits appear “ignored”

Read:

• references/debugging.md (style hierarchy + fastest checks)

3) Make theme.json changes safely

Decide whether you are changing:

• settings (what the UI allows): presets, typography scale, colors, layout, spacing
• styles (how it looks by default): CSS-like rules for elements/blocks

Read:

• references/theme-json.md

4) Templates and template parts

• Templates live under templates/ and are HTML.
• Template parts live under parts/ and must not be nested in subdirectories.

Read:

• references/templates-and-parts.md

5) Patterns

Prefer filesystem patterns under patterns/ when you want theme-owned patterns.

Read:

• references/patterns.md

6) Style variations

Style variations are JSON files under styles/. Note: once a user picks a style variation, that selection is stored in the DB, so changing the file may not “update what the user sees” automatically.

Read:

• references/style-variations.md

Verification

• Site Editor reflects changes where expected (Styles UI, templates, patterns).
• Frontend renders with expected styles.
• If styles aren’t changing, confirm whether user customizations override theme defaults.
• Run the repo’s build/lint scripts if assets are involved (fonts, custom JS/CSS build).

Failure modes / debugging

Start with:

• references/debugging.md

Common issues:

• wrong theme root (editing an inactive theme)
• user customizations override your defaults
• invalid theme.json shape/typos prevent application
• templates/parts in wrong folders (or nested parts)

Escalation

If upstream behavior is unclear, consult canonical docs:

• Theme Handbook and Block Editor Handbook for theme.json, templates, patterns, and style variations.