Coywolf Code Block Enhancer

Coywolf Code Block Enhancer extends the built-in core/code block. In the editor
it adds a “Code language” dropdown to the block sidebar; on the front end
it highlights the code with Prism.js using a custom token palette, prints
the language name as a small label on the block, and pins a
copy-to-clipboard button to the top-right corner.

• Adds a “Code language” dropdown to the core Code block’s sidebar. A
  baseline of 9 languages (Bash, CSS, HTML/Markup, JavaScript, JSON,
  PHP, Python, SQL, YAML) is always loaded; an additional 40 grammars
  can be toggled on via Language packs in Tools → Code Blocks
  (Web/App dev — TypeScript, JSX/TSX, SCSS, Sass, Less, GraphQL — is
  enabled by default).
• Highlights code on the front end with Prism.js. Pick from 45 bundled
  themes — the 8 stock Prism themes (Prism Default, Coy, Dark, Funky,
  Okaidia, Solarized Light, Tomorrow Night, Twilight) plus 37 community
  themes from PrismJS/prism-themes (a11y Dark, Atom Dark, Dracula,
  Nord, One Dark, Night Owl, Synthwave ’84, Gruvbox, Material, VS Code
  Dark+, and more) — or the bundled Default palette (selected on
  first install).
• Adds a small language label in the top-left of each highlighted block
  (only when a language is set).
• Adds an accessible copy-to-clipboard button — aria-label, a polite
  status region that announces “Copied to clipboard,” and a visible “✓”
  state for two seconds after a successful copy. Falls back to
  document.execCommand(‘copy’) on non-HTTPS or older browsers.
• Assets load only on singular posts/pages that contain a code block;
  Prism core and grammars are loaded with the defer strategy so they
  never block rendering.
• Dark-mode aware out of the box — with the bundled Default — Auto
  theme (selected on first install), code blocks follow each visitor’s
  prefers-color-scheme automatically. Override from
  Tools → Code Blocks by switching to Default — Always light /
  Always dark, or by picking any of the static Prism themes.

How it works

The chosen language is stored as a language block attribute on
core/code, which lives in the block delimiter comment rather than the
saved markup. That means blocks without a language stay valid and
existing content is never migrated.

On render, the plugin uses WP_HTML_Tag_Processor to add data-language
to the <pre> and language-xxx to the <code> server-side — so KSES
won’t strip data-* attributes for non-admin authors, and there is no
block-validation churn.

Prism core and the per-language grammars are bundled under
assets/prism/ at v1.30.0 (MIT — see assets/prism/LICENSE.txt). They
register as deferred scripts with explicit dependency ordering (e.g.
markup-templating before php, clike before languages that extend
it). The copy-button script depends on the last grammar in the chain,
so all of Prism is present before the copy UI is wired up. Reading
code.textContent returns the original source even after Prism wraps
tokens in spans, so the copied text is unaffected by highlighting.

Self-hosting Prism (rather than loading from a public CDN) keeps the
third-party-script supply chain off the plugin’s surface and means the
plugin works on sites with strict CSPs or no external egress.

Privacy

Privacy-first: this plugin includes no analytics, no tracking, and no data gathering. Nothing about you, your site, or your visitors is ever collected or sent anywhere.