- Rich sentences (a link or button inside text) can be replaced by data: the inventory gives a rich entry `slots`, a pack value places the site's own elements with {e0}, {e1}, ... (each once, the last may be left out; no markup, plural or other parameters). The engine returns a pieces + element order template; the page inventory carries `rich` slot counts.
- Packs may carry `when: { languages }` (applies only while the site shows one of them; `en` matches `en-GB`) and `rewrite: { words }` (whole-word rewording of the site's own text, messages keep their parameters' values; no sentences of the site in the pack). The hook tells the engine the site's language; a rewording pack makes the delivery carry the whole inventory.
- Apps can ship built-in packs (BuiltInPacks) delivered before installed ones; syncStringPacks hands the tabs a delivery at start only when it changed.
- Translate mode words are a function the app supplies (asked at each draw) and gain a `plural` word; host validates `when` and `rewrite` envelopes.
- Theme doctor: every finding says where (token path or CSS rule), what and how to fix, as catalog keys wb.doctor.*; the Theme Builder shows the full report; the import hint is translated. Doctor words are in the 17 supported catalogs.
- waybetter strings check describes conditions and rewrites.
themeDoctor(theme) names the lighter mechanism for what a theme's CSS does
(radius, bevel, hiding, literal colors, fonts), its performance costs (:has,
universal selectors, blur, size) and accessibility costs (outline removed,
unguarded motion, small post text, moved navigation), plus contrast fixes.
Theme import adds the count and the first hint to its message. Tested.
