fix(errors,a11y): review round 1 — drop redundant onErrors, stabilize the live region

Review found my C-3.23 additions double-notified: the global error modal (api.ts req)
already surfaces 400/409/422/500 with the backend's specific message, so a caller
toast on those codes is a second, weaker surface. Only 403/404 are caller-handled and
silent — and only a YouTube WRITE action has a meaningful 403 (missing scope).

So the correct set is just the ChannelPage unsubscribe handler (a YouTube write, 403 →
"connect", matching subscribe). Reverted the redundant onErrors on block (a local DB
op, not YouTube), SettingsPanel Plex watch toggle/reimport, and the DownloadCenter job
action — the global modal already speaks for them. Removed the three now-unused keys.

Toaster: moved the polite live region onto the stable, always-mounted container (a
polite region must pre-exist to announce later insertions); error/fatal toasts keep
role="alert", which announces on insertion regardless.

frontend/src/components/ChannelPage.tsx

@@ -120,7 +120,9 @@ export default function ChannelPage({
       qc.invalidateQueries({ queryKey: ["feed"] });
       qc.invalidateQueries({ queryKey: ["blocked-channels"] });
     },
-    onError: (err) => notifyYouTubeActionError(err, t("channels.notify.blockFailed")),
+    // No onError: block/unblock is a local DB op (not a YouTube write, so no 403 "connect" case),
+    // and its 400/409/422/500 are already surfaced by the global error modal (see api.ts req) —
+    // a caller toast here would just double it.
   });
 
   const subscribe = useMutation({

frontend/src/components/DownloadCenter.tsx

@@ -681,7 +681,8 @@ export default function DownloadCenter() {
             ? api.cancelDownload(id)
             : api.deleteDownload(id),
     onSuccess: invalidate,
-    onError: () => notify({ level: "error", message: t("downloads.actionFailed") }),
+    // No onError: a failed job action returns 400/409/422/500, already surfaced by the global
+    // error modal (api.ts req) with the backend's specific message — a caller toast would double it.
   });
 
   // Remove a shared-with-me item from your list (only your grant; the owner's file is untouched).

frontend/src/components/SettingsPanel.tsx

@@ -533,14 +533,15 @@ function PlexWatchSync() {
     }
   };
 
-  const onFail = () => notify({ level: "error", message: t("settings.plexSync.failed") });
+  // No onError on these: they're Plex, not YouTube (notifyYouTubeActionError would wrongly say
+  // "connect YouTube"), and their 409/500 are already surfaced by the global error modal — a caller
+  // toast would double it. Actual import failures come back as 200 {error}, handled by announce.
   const toggle = useMutation({
     mutationFn: (next: boolean) => api.plexWatchSetLink(next),
     onSuccess: (res) => {
       qc.setQueryData(["plex-watch-link"], res);
       announce(res.import);
     },
-    onError: onFail,
   });
   const reimport = useMutation({
     mutationFn: () => api.plexWatchImport(),
@@ -548,7 +549,6 @@ function PlexWatchSync() {
       qc.setQueryData(["plex-watch-link"], res);
       announce(res.import);
     },
-    onError: onFail,
   });
 
   const busy = toggle.isPending || reimport.isPending;

frontend/src/components/Toaster.tsx

@@ -16,17 +16,23 @@ export default function Toaster() {
   const toasts = useSyncExternalStore(subscribe, getActiveToasts, getActiveToasts);
 
   return (
-    <div className="absolute bottom-4 left-4 z-overlay flex flex-col gap-2 w-80 max-w-[calc(100vw-2rem)]">
+    // Stable, always-mounted polite live region — a polite region must PRE-EXIST in the DOM for a
+    // screen reader to announce content later inserted into it (a region created together with its
+    // first message is unreliably announced). Non-error toasts render inside here and are announced
+    // politely; error/fatal toasts additionally carry role="alert", which announces assertively on
+    // insertion regardless.
+    <div
+      role="status"
+      aria-live="polite"
+      className="absolute bottom-4 left-4 z-overlay flex flex-col gap-2 w-80 max-w-[calc(100vw-2rem)]"
+    >
       {toasts.map((toast) => {
         const { icon: Icon, color, bar } = LEVEL_STYLE[toast.level];
         const urgent = toast.level === "error" || toast.level === "fatal";
         return (
           <div
             key={toast.id}
-            // Announce toasts to screen readers — the toast is the app's main feedback channel.
-            // Errors interrupt (assertive/alert); everything else waits its turn (polite/status).
-            role={urgent ? "alert" : "status"}
-            aria-live={urgent ? "assertive" : "polite"}
+            {...(urgent ? { role: "alert" } : {})}
             className="toast-card glass relative overflow-hidden rounded-xl px-3 py-3 flex items-start gap-3 animate-[popIn_0.16s_ease]"
           >
             <Icon className={`w-5 h-5 shrink-0 mt-0.5 ${color}`} />

frontend/src/i18n/locales/en/channels.json

@@ -119,7 +119,6 @@
     "syncFailed": "Subscription sync failed",
     "unsubscribed": "Unsubscribed from {{name}} on YouTube",
     "unsubscribeFailed": "Unsubscribe failed",
-    "blockFailed": "Couldn't update block state",
     "fullHistoryRequested": "Full history requested for {{count}} channels",
     "fullHistoryFailed": "Couldn't request full history",
     "needYouTube": "Connect your YouTube account to do this.",

frontend/src/i18n/locales/en/downloads.json

@@ -197,6 +197,5 @@
       "source_not_ready": "The source download isn't ready to edit.",
       "generic": "That edit couldn't be created."
     }
-  },
-  "actionFailed": "Download action failed"
+  }
 }

frontend/src/i18n/locales/en/settings.json

@@ -14,8 +14,7 @@
     "imported": "Imported from Plex: {{watched}} watched, {{in_progress}} in progress.",
     "lastSync": "Last import: {{when}}",
     "never": "Not imported yet",
-    "importing": "Importing your Plex watch history…",
-    "failed": "Plex watch sync failed"
+    "importing": "Importing your Plex watch history…"
   },
   "save": {
     "saving": "Saving…",

frontend/src/i18n/locales/hu/channels.json

@@ -119,7 +119,6 @@
     "syncFailed": "A feliratkozások szinkronizálása sikertelen",
     "unsubscribed": "Leiratkozva a(z) {{name}} csatornáról a YouTube-on",
     "unsubscribeFailed": "A leiratkozás sikertelen",
-    "blockFailed": "A tiltás állapotát nem sikerült frissíteni",
     "fullHistoryRequested": "Teljes előzmény kérve {{count}} csatornához",
     "fullHistoryFailed": "Nem sikerült teljes előzményt kérni",
     "needYouTube": "Ehhez csatlakoztasd a YouTube-fiókod.",

frontend/src/i18n/locales/hu/downloads.json

@@ -197,6 +197,5 @@
       "source_not_ready": "A forrásletöltés még nem szerkeszthető.",
       "generic": "Ezt a vágást nem sikerült létrehozni."
     }
-  },
-  "actionFailed": "A letöltési művelet sikertelen"
+  }
 }

frontend/src/i18n/locales/hu/settings.json

@@ -14,8 +14,7 @@
     "imported": "Importálva a Plexből: {{watched}} megnézve, {{in_progress}} folyamatban.",
     "lastSync": "Utolsó import: {{when}}",
     "never": "Még nincs importálva",
-    "importing": "Plex-előzmény importálása…",
-    "failed": "A Plex-megtekintés szinkron sikertelen"
+    "importing": "Plex-előzmény importálása…"
   },
   "save": {
     "saving": "Mentés…",