fix(ui,i18n): E30 review round 3 — the stored language follows the screen, a fresh text starts collapsed, Retry waits again

frontend/src/components/BootGate.tsx

@@ -1,7 +1,9 @@
 import { useLayoutEffect, useRef, useState, type ReactNode } from "react";
-import { useQuery } from "@tanstack/react-query";
+import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { useTranslation } from "react-i18next";
 import { api, getActiveAccount, setActiveAccount } from "../lib/api";
+import { log } from "../lib/log";
+import { saveLanguage } from "../lib/saveLanguage";
 import { qk } from "../lib/queryKeys";
 import i18n, { isSupported, setLanguage } from "../i18n";
 import { LoadingState, StateMessage } from "./ui/QueryState";
@@ -38,6 +40,7 @@ export function BootScreen() {
 
 export default function BootGate({ children }: { children: ReactNode }) {
   const { t } = useTranslation();
+  const qc = useQueryClient();
   // First-run install gate: a fresh instance reports configured=false and runs in setup mode, where
   // every other route is locked — so `me` is held back until the instance is known to be set up
   // (otherwise it would 503 against the setup-mode lock).
@@ -81,7 +84,10 @@ export default function BootGate({ children }: { children: ReactNode }) {
   //     not is corrected here — otherwise the tab would run as the default account on the server while
   //     reading and writing the gone account's local state.
   //   • Adopt the account's language, which follows the account across devices — the local copy only
-  //     knows what this browser last showed.
+  //     knows what this browser last showed. An account with none stored yet (the setup wizard's admin,
+  //     an account older than the stamp sign-up gives) stores the language it is shown in: the server
+  //     orders its lists and writes its mail in the stored one, else English, and a Hungarian screen
+  //     over English-ordered lists breaks "A→Z in the UI language's alphabet".
   const [readyFor, setReadyFor] = useState<number | null | undefined>(undefined);
   // `me` is read for the identity it produced, so it rides a ref: a background refetch of the same
   // account must not re-run the adoption over a language the user has just changed. That rule used
@@ -104,11 +110,21 @@ export default function BootGate({ children }: { children: ReactNode }) {
     const account = meRef.current;
     if (account && getActiveAccount() !== account.id) setActiveAccount(account.id);
     const lang = account?.preferences?.language;
-    // eslint-disable-next-line local/locale-format -- a one-shot read in an effect, compared before adopting the account's language; nothing renders it, so there is no memoized value to go stale.
-    if (typeof lang === "string" && isSupported(lang) && lang !== i18n.language) setLanguage(lang);
+    if (typeof lang === "string" && isSupported(lang)) {
+      // eslint-disable-next-line local/locale-format -- a one-shot read in an effect, compared before adopting the account's language; nothing renders it, so there is no memoized value to go stale.
+      if (lang !== i18n.language) setLanguage(lang);
+    } else if (account) {
+      // eslint-disable-next-line local/locale-format -- a one-shot read of the language the app is about to be shown in, stored once; nothing renders it.
+      const shown = i18n.language;
+      saveLanguage(qc, shown).catch((e: unknown) =>
+        log.warn("boot.language_store_failed", "the shown language could not be stored", {
+          error: String(e),
+        }),
+      );
+    }
     // eslint-disable-next-line react-hooks/set-state-in-effect -- the adoption latch. It cannot be derived: the whole point is that the tree mounts only AFTER the pin and the language have been applied, and both are writes to things outside React (sessionStorage, i18n). A layout effect so the frame that first shows the app already has them.
     setReadyFor(identity);
-  }, [identity, readyFor]);
+  }, [identity, readyFor, qc]);
 
   // No answer at all (a network or 5xx failure on the very first setup or account probe — past the
   // one retry `req` already makes): say so, with a retry. An unanswered setup probe is NOT "signed