• feat: getFixedT accepts a fourth optional fixedOpts argument carrying scopeNs — the full namespace list the bound t was created for. The selector API uses scopeNs to detect when a path's first segment is a namespace prefix, without changing resolution scope. Resolution still uses the bound ns (a single primary string in the typical react-i18next setup), so plain t('key') lookups stay isolated to the primary namespace exactly as before — only t($ => $.secondaryNs.foo) selectors now route correctly under useTranslation([nsA, nsB]). Fixes the runtime side of #2429 for the react-i18next default-nsMode case. The 4th argument is opt-in: existing 3-arg getFixedT(lng, ns, keyPrefix) callers see no behavior change.