font-loading-and-performancelisted

# Font loading and performance Webfonts are render-blocking-adjacent resources that change text metrics when they arrive. Two separate problems: **when text becomes visible**, and **whether the page moves when the font swaps**. ⚠️ **Part of the corpus is obsolete here — but not all of it.** Rutter (2017) calls `font-display` "a nascent CSS property under development," supported only behind experimental flags at the time; that support status is obsolete — `font-display` now has universal support and is the standard mechanism. His five-value taxonomy and their descriptions (`auto`/`block`/`swap`/`fallback`/ `optional`), however, match the current spec closely and are still accurate — don't discard the substance along with the outdated adoption note. What's genuinely dead is the workaround the books reach for instead: the Font Loading API + `wf-loading`/`wf-active`/`wf-inactive` classes (Rutter) and Web Font Loader (both Rutter and Santa Maria) exist specifically to fake `font-display` behavior in browsers that don't support it. No browser needs that workaround now. Source-hierarchy rule 1 (browser behavior) outranks rules 4 and 8. Verify against MDN before emitting code. ## 1. When to invoke - Adding, replacing, or auditing webfonts. - FOIT (invisible text) or FOUT (unstyled flash) reported. - CLS regression traced to text. - Font payload is large, or you're choosing between static and variable files. - Self-hosting vs. a font CDN. ## 2. Required context - Which **familie