[wp-block-themes]: document theme.json slug-normaliser bug class - #59
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WordPress passes every preset/custom slug through _wp_to_kebab_case() before emitting its CSS var, hyphenating at digit/letter boundaries and camelCase transitions. Handwritten references to the un-normalised form silently fall back, making the failure invisible without computed-style inspection. Adds a "Slug normalisation gotcha" section to theme-json.md (with a grep pattern for catching un-normalised references) and a cross-referenced bullet under debugging.md § "Styles not applying". Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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karmatosed
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July 6, 2026 10:59
karmatosed
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Looks good to merge from me and in checking.
We do need 2 approvals though to commit, so let's get another.
bgrgicak
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Jul 24, 2026
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Summary
Documents a silent failure in theme.json: WordPress hyphenates preset/custom slugs before emitting CSS vars, so a handwritten
var()reference to the un-normalised slug resolves to nothing and quietly falls back. No error, layout looks roughly right — invisible without computed-style inspection.Examples:
3xl→--wp--preset--font-size--3-xlcardShadow→--wp--custom--card-shadowUnder the hood,
WP_Theme_JSONruns every slug through_wp_to_kebab_case(), which splits at digit/letter boundaries, camelCase transitions, and non-alphanumeric characters.Changes
skills/wp-block-themes/references/theme-json.md— new "Slug normalisation gotcha" section with the explanation and a grep pattern for catching un-normalised references.skills/wp-block-themes/references/debugging.md— new bullet under "Styles not applying" pointing at the gotcha section.