diff --git a/backend/app/routes/channels.py b/backend/app/routes/channels.py
index adfa4b8..bdb5230 100644
--- a/backend/app/routes/channels.py
+++ b/backend/app/routes/channels.py
@@ -101,12 +101,7 @@ def list_channels(
 
     return [
         {
-            "id": ch.id,
-            "title": ch.title,
-            "handle": ch.handle,
-            "thumbnail_url": ch.thumbnail_url,
-            "subscriber_count": ch.subscriber_count,
-            "video_count": ch.video_count,
+            **_channel_summary(ch),
             "stored_videos": (agg.get(ch.id) or {}).get("stored", 0),
             "last_video_at": (agg.get(ch.id) or {}).get("last_video_at"),
             "total_duration_seconds": (agg.get(ch.id) or {}).get("total_duration_seconds", 0),
@@ -195,12 +190,7 @@ def discover_channels(
 
     return [
         {
-            "id": ch.id,
-            "title": ch.title,
-            "handle": ch.handle,
-            "thumbnail_url": ch.thumbnail_url,
-            "subscriber_count": ch.subscriber_count,
-            "video_count": ch.video_count,
+            **_channel_summary(ch),
             "playlist_video_count": int(vid_count),
             "playlist_count": int(pl_count),
             "details_synced": ch.details_synced_at is not None,
@@ -209,6 +199,18 @@ def discover_channels(
     ]
 
 
+def _channel_summary(ch: Channel) -> dict:
+    """The channel fields common to the list and discovery projections."""
+    return {
+        "id": ch.id,
+        "title": ch.title,
+        "handle": ch.handle,
+        "thumbnail_url": ch.thumbnail_url,
+        "subscriber_count": ch.subscriber_count,
+        "video_count": ch.video_count,
+    }
+
+
 def _channel_detail_dict(
     channel: Channel, *, subscribed: bool, explored: bool, blocked: bool, stored: int
 ) -> dict:
@@ -268,11 +270,7 @@ def channel_detail(
             ExploredChannel.user_id == user.id, ExploredChannel.channel_id == channel_id
         )
     ).first() is not None
-    blocked = db.execute(
-        select(BlockedChannel.id).where(
-            BlockedChannel.user_id == user.id, BlockedChannel.channel_id == channel_id
-        )
-    ).first() is not None
+    blocked = _is_blocked(db, user, channel_id)
     stored = db.scalar(select(func.count(Video.id)).where(Video.channel_id == channel_id)) or 0
     return _channel_detail_dict(
         channel, subscribed=subscribed, explored=explored, blocked=blocked, stored=int(stored)
@@ -295,11 +293,7 @@ def explore_channel(
     channel = db.get(Channel, channel_id)
     if channel is None:
         raise HTTPException(status_code=404, detail="Unknown channel")
-    if db.execute(
-        select(BlockedChannel.id).where(
-            BlockedChannel.user_id == user.id, BlockedChannel.channel_id == channel_id
-        )
-    ).first() is not None:
+    if _is_blocked(db, user, channel_id):
         raise HTTPException(status_code=403, detail="You've blocked this channel.")
     if quota.remaining_today(db) <= sysconfig.get_int(db, "backfill_quota_reserve"):
         raise HTTPException(
@@ -359,6 +353,19 @@ def _user_subscription(db: Session, user: User, channel_id: str) -> Subscription
     return sub
 
 
+def _is_blocked(db: Session, user: User, channel_id: str) -> bool:
+    """Whether this user has blocked this channel."""
+    return (
+        db.execute(
+            select(BlockedChannel.id).where(
+                BlockedChannel.user_id == user.id,
+                BlockedChannel.channel_id == channel_id,
+            )
+        ).first()
+        is not None
+    )
+
+
 @router.patch("/{channel_id}")
 def update_channel(
     channel_id: str,
@@ -546,12 +553,7 @@ def block_channel(
     un-kept search/explore videos are reclaimed by the discovery-cleanup job in due course."""
     if db.get(Channel, channel_id) is None:
         raise HTTPException(status_code=404, detail="Unknown channel")
-    exists = db.execute(
-        select(BlockedChannel.id).where(
-            BlockedChannel.user_id == user.id, BlockedChannel.channel_id == channel_id
-        )
-    ).first()
-    if exists is None:
+    if not _is_blocked(db, user, channel_id):
         db.add(BlockedChannel(user_id=user.id, channel_id=channel_id))
         # Stop any active exploration of it so it can be cleaned up.
         db.execute(
diff --git a/frontend/src/components/ChannelDiscovery.tsx b/frontend/src/components/ChannelDiscovery.tsx
index f51a7fe..f4ddb7b 100644
--- a/frontend/src/components/ChannelDiscovery.tsx
+++ b/frontend/src/components/ChannelDiscovery.tsx
@@ -1,10 +1,11 @@
 import { useTranslation } from "react-i18next";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { UserPlus } from "lucide-react";
-import { api, HttpError, type DiscoveredChannel } from "../lib/api";
-import { accountKey } from "../lib/storage";
-import { formatViews } from "../lib/format";
+import { api, type DiscoveredChannel } from "../lib/api";
+import { accountKey, LS } from "../lib/storage";
+import { formatCountOrDash } from "../lib/format";
 import { notify } from "../lib/notifications";
+import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import Tooltip from "./Tooltip";
 import ChannelLink from "./ChannelLink";
 import DataTable, { type Column } from "./DataTable";
@@ -48,19 +49,8 @@ export default function ChannelDiscovery({
         meta: { kind: "channel-subscribed", channelId: c.id, channelName: name },
       });
     },
-    onError: (err: unknown) => {
-      // A 403 means the user hasn't granted the write scope — offer to connect instead of
-      // a vague failure (mirrors the subscriptions tab).
-      if (err instanceof HttpError && err.status === 403) {
-        notify({
-          level: "error",
-          message: t("channels.notify.needYouTube"),
-          action: { label: t("channels.notify.connect"), onClick: onOpenWizard },
-        });
-      } else {
-        notify({ level: "error", message: t("channels.discovery.subscribeFailed") });
-      }
-    },
+    onError: (err: unknown) =>
+      notifyYouTubeActionError(err, t("channels.discovery.subscribeFailed"), onOpenWizard),
   });
 
   // Subscribing changes the user's real YouTube account and spends a little quota — confirm
@@ -96,9 +86,7 @@ export default function ChannelDiscovery({
       sortable: true,
       sortValue: (c) => c.subscriber_count ?? -1,
       render: (c) => (
-        <span className="text-muted tabular-nums">
-          {c.subscriber_count != null ? formatViews(c.subscriber_count) : "—"}
-        </span>
+        <span className="text-muted tabular-nums">{formatCountOrDash(c.subscriber_count)}</span>
       ),
     },
     {
@@ -109,9 +97,7 @@ export default function ChannelDiscovery({
       sortable: true,
       sortValue: (c) => c.video_count ?? -1,
       render: (c) => (
-        <span className="text-muted tabular-nums">
-          {c.video_count != null ? formatViews(c.video_count) : "—"}
-        </span>
+        <span className="text-muted tabular-nums">{formatCountOrDash(c.video_count)}</span>
       ),
     },
     {
@@ -174,7 +160,7 @@ export default function ChannelDiscovery({
           rows={rows}
           columns={columns}
           rowKey={(c) => c.id}
-          persistKey={accountKey("siftlode.channelDiscoveryTable") ?? undefined}
+          persistKey={accountKey(LS.channelDiscoveryTable) ?? undefined}
           controlsPosition="top"
           emptyText={t("channels.discovery.empty")}
         />
diff --git a/frontend/src/components/ChannelPage.tsx b/frontend/src/components/ChannelPage.tsx
index 2c81407..08e259b 100644
--- a/frontend/src/components/ChannelPage.tsx
+++ b/frontend/src/components/ChannelPage.tsx
@@ -6,6 +6,7 @@ import Avatar from "./Avatar";
 import Feed from "./Feed";
 import { useConfirm } from "./ConfirmProvider";
 import { notify } from "../lib/notifications";
+import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import { api, type FeedFilters, type Me } from "../lib/api";
 import { channelYouTubeUrl, formatViews } from "../lib/format";
 
@@ -89,8 +90,14 @@ export default function ChannelPage({
       qc.invalidateQueries({ queryKey: ["channel", channelId] });
       qc.invalidateQueries({ queryKey: ["feed"] });
       qc.invalidateQueries({ queryKey: ["channels"] });
+      // Match ChannelDiscovery: the channel leaves discovery and the manager's stats move.
+      qc.invalidateQueries({ queryKey: ["my-status"] });
+      qc.invalidateQueries({ queryKey: ["discovered-channels"] });
       notify({ level: "info", message: t("channel.subscribed", { name: ch?.title ?? "" }) });
     },
+    // A 403 (missing write scope) otherwise fails silently on the channel page (no wizard handle
+    // here, so no Connect button — but the user at least sees why it didn't work).
+    onError: (err) => notifyYouTubeActionError(err, t("channels.discovery.subscribeFailed")),
   });
   const unsubscribe = useMutation({
     mutationFn: () => api.unsubscribeChannel(channelId),
diff --git a/frontend/src/components/Channels.tsx b/frontend/src/components/Channels.tsx
index 0729a4d..4b08b08 100644
--- a/frontend/src/components/Channels.tsx
+++ b/frontend/src/components/Channels.tsx
@@ -16,10 +16,11 @@ import {
   UserMinus,
   X,
 } from "lucide-react";
-import { api, HttpError, type ManagedChannel, type Tag } from "../lib/api";
-import { accountKey } from "../lib/storage";
+import { api, type ManagedChannel, type Tag } from "../lib/api";
+import { notifyYouTubeActionError } from "../lib/youtubeErrors";
+import { accountKey, LS } from "../lib/storage";
 import { useDismiss } from "../lib/useDismiss";
-import { formatEta, formatTotalHours, formatViews, relativeTime } from "../lib/format";
+import { formatCountOrDash, formatEta, formatTotalHours, relativeTime } from "../lib/format";
 import { notify } from "../lib/notifications";
 import Tooltip from "./Tooltip";
 import DataTable, { type Column } from "./DataTable";
@@ -73,19 +74,6 @@ export default function Channels({
   const qc = useQueryClient();
   const confirm = useConfirm();
 
-  // A YouTube-gated action (sync, backfill, unsubscribe) that 403s means the user hasn't
-  // granted the needed scope — surface that with a "Connect" action instead of a vague fail.
-  const notifyActionError = (err: unknown, fallbackKey: string) => {
-    if (err instanceof HttpError && err.status === 403) {
-      notify({
-        level: "error",
-        message: t("channels.notify.needYouTube"),
-        action: { label: t("channels.notify.connect"), onClick: onOpenWizard },
-      });
-    } else {
-      notify({ level: "error", message: t(fallbackKey) });
-    }
-  };
   const channelsQuery = useQuery({ queryKey: ["channels"], queryFn: api.channels });
   const tagsQuery = useQuery({ queryKey: ["tags"], queryFn: api.tags });
   const statusQuery = useQuery({ queryKey: ["my-status"], queryFn: api.myStatus });
@@ -160,7 +148,7 @@ export default function Channels({
       invalidate();
       notify({ level: "success", message: t("channels.notify.synced", { count: r.subscriptions ?? 0 }) });
     },
-    onError: (e) => notifyActionError(e, "channels.notify.syncFailed"),
+    onError: (e) => notifyYouTubeActionError(e, t("channels.notify.syncFailed"), onOpenWizard),
   });
   const unsubscribe = useMutation({
     mutationFn: (v: { id: string; name: string }) => api.unsubscribeChannel(v.id),
@@ -169,7 +157,7 @@ export default function Channels({
       qc.invalidateQueries({ queryKey: ["my-status"] });
       notify({ level: "success", message: t("channels.notify.unsubscribed", { name: v.name }) });
     },
-    onError: (e) => notifyActionError(e, "channels.notify.unsubscribeFailed"),
+    onError: (e) => notifyYouTubeActionError(e, t("channels.notify.unsubscribeFailed"), onOpenWizard),
   });
   const resetBackfill = useMutation({
     mutationFn: (v: { id: string; name: string }) => api.resetChannelBackfill(v.id),
@@ -178,7 +166,7 @@ export default function Channels({
       qc.invalidateQueries({ queryKey: ["my-status"] });
       notify({ level: "success", message: t("channels.notify.resetDone", { name: v.name }) });
     },
-    onError: (e) => notifyActionError(e, "channels.notify.resetFailed"),
+    onError: (e) => notifyYouTubeActionError(e, t("channels.notify.resetFailed"), onOpenWizard),
   });
   const deepAll = useMutation({
     mutationFn: () => api.deepAll(true),
@@ -190,7 +178,7 @@ export default function Channels({
         message: t("channels.notify.fullHistoryRequested", { count: r.updated ?? 0 }),
       });
     },
-    onError: (e) => notifyActionError(e, "channels.notify.fullHistoryFailed"),
+    onError: (e) => notifyYouTubeActionError(e, t("channels.notify.fullHistoryFailed"), onOpenWizard),
   });
 
   // Channel-name search + tag-chip filtering, applied client-side over the status-filtered list
@@ -294,9 +282,7 @@ export default function Channels({
       sortable: true,
       sortValue: (c) => c.subscriber_count ?? -1,
       render: (c) => (
-        <span className="text-muted tabular-nums">
-          {c.subscriber_count != null ? formatViews(c.subscriber_count) : "—"}
-        </span>
+        <span className="text-muted tabular-nums">{formatCountOrDash(c.subscriber_count)}</span>
       ),
     },
     {
@@ -570,7 +556,7 @@ export default function Channels({
           rows={visibleChannels}
           columns={columns}
           rowKey={(c) => c.id}
-          persistKey={accountKey("siftlode.channelsTable") ?? undefined}
+          persistKey={accountKey(LS.channelsTable) ?? undefined}
           controlsPosition="top"
           controlsLeading={statusChips}
           rowClassName={(c) => (c.hidden ? "opacity-60" : "")}
diff --git a/frontend/src/i18n/locales/de/channels.json b/frontend/src/i18n/locales/de/channels.json
index d653eef..a1cc7fc 100644
--- a/frontend/src/i18n/locales/de/channels.json
+++ b/frontend/src/i18n/locales/de/channels.json
@@ -1,6 +1,5 @@
 {
   "intro": "Lege die <0>Priorität</0> eines Kanals fest, um seine Videos nach oben zu schieben, wenn du nach „Kanalpriorität“ sortierst, hänge eigene <1>Tags</1> an, um den Feed zu filtern, oder <2>blende</2> einen Kanal <2>aus</2>, um ihn ohne Abbestellung aus dem Feed zu entfernen.",
-  "filterPlaceholder": "Kanäle filtern…",
   "syncSubscriptions": "Abos von YouTube lesen",
   "syncSubscriptionsHint": "Importiert deine Abo-Liste erneut von YouTube — fügt neu abonnierte Kanäle hinzu und entfernt abbestellte. Die Videos selbst werden weiterhin automatisch im Hintergrund synchronisiert; sie werden hierbei nicht neu geladen.",
   "backfillEverything": "Alles nachladen",
@@ -35,9 +34,7 @@
   "tags": {
     "yourTags": "Deine Tags",
     "manage": "Tags verwalten",
-    "yourTagsHint": "Deine persönlichen Labels. Hänge sie unten an Kanäle an und filtere den Feed dann über die Seitenleiste nach Tag. (Getrennt von den automatischen Sprach-/Themen-Tags.)",
-    "newTag": "neuer Tag",
-    "createTag": "Tag erstellen"
+    "yourTagsHint": "Deine persönlichen Labels. Hänge sie unten an Kanäle an und filtere den Feed dann über die Seitenleiste nach Tag. (Getrennt von den automatischen Sprach-/Themen-Tags.)"
   },
   "loading": "Kanäle werden geladen…",
   "empty": "Keine Kanäle.",
@@ -74,8 +71,6 @@
     "quotaLeftHint": "Heute noch verbleibendes gemeinsames YouTube-API-Budget (wird um Mitternacht US-Pazifikzeit zurückgesetzt)."
   },
   "row": {
-    "stored": "{{formatted}} gespeichert",
-    "subs": "{{formatted}} Abonnenten",
     "openOnYouTube": "Auf YouTube öffnen",
     "editTags": "Tags bearbeiten",
     "filterFeedByTag": "Feed nach „{{name}}“ filtern",
@@ -98,8 +93,6 @@
     "fullHistoryComing": "vollständiger Verlauf unterwegs",
     "queuedRequestedHint": "Vollständiger Verlauf angefordert — der gesamte Katalog dieses Kanals wird nachgeladen, soweit das gemeinsame Kontingent es zulässt. Klicke, um deine Anforderung abzubrechen.",
     "queuedByOtherHint": "Ein anderer Abonnent hat den vollständigen Verlauf dieses Kanals bereits angefordert, sein gesamter Katalog ist also für alle unterwegs — hier gibt es nichts zu tun.",
-    "getFullHistory": "vollständigen Verlauf laden",
-    "getFullHistoryHint": "Bisher nur neueste Uploads. Klicke, um den gesamten Katalog dieses Kanals anzufordern (ältere Videos + vollständige Suche).",
     "hiddenHint": "Ausgeblendet — die Videos dieses Kanals bleiben aus deinem Feed heraus. Klicke, um sie wieder anzuzeigen.",
     "hideHint": "Blendet die Videos dieses Kanals aus deinem Feed aus. Er bleibt abonniert; dies bestellt nicht bei YouTube ab.",
     "unhide": "Einblenden",
diff --git a/frontend/src/i18n/locales/en/channels.json b/frontend/src/i18n/locales/en/channels.json
index 5bd7c45..faf4ea0 100644
--- a/frontend/src/i18n/locales/en/channels.json
+++ b/frontend/src/i18n/locales/en/channels.json
@@ -1,6 +1,5 @@
 {
   "intro": "Set a channel's <0>priority</0> to push its videos up when you sort by “Channel priority”, attach your own <1>tags</1> to filter the feed, or <2>hide</2> a channel to drop it from the feed without unsubscribing.",
-  "filterPlaceholder": "Filter channels…",
   "syncSubscriptions": "Read subscriptions from YouTube",
   "syncSubscriptionsHint": "Re-import your subscription list from YouTube — adds channels you've newly followed and drops ones you've unfollowed. The videos themselves keep syncing automatically in the background; this does not re-fetch them.",
   "backfillEverything": "Backfill everything",
@@ -35,9 +34,7 @@
   "tags": {
     "yourTags": "Your tags",
     "manage": "Manage tags",
-    "yourTagsHint": "Your personal labels. Attach them to channels below, then filter the feed by tag from the sidebar. (Separate from the automatic language/topic tags.)",
-    "newTag": "new tag",
-    "createTag": "Create tag"
+    "yourTagsHint": "Your personal labels. Attach them to channels below, then filter the feed by tag from the sidebar. (Separate from the automatic language/topic tags.)"
   },
   "loading": "Loading channels…",
   "empty": "No channels.",
@@ -74,8 +71,6 @@
     "quotaLeftHint": "Shared YouTube API budget left today (resets midnight US Pacific)."
   },
   "row": {
-    "stored": "{{formatted}} stored",
-    "subs": "{{formatted}} subs",
     "openOnYouTube": "Open on YouTube",
     "editTags": "Edit tags",
     "filterFeedByTag": "Filter the feed by “{{name}}”",
@@ -98,8 +93,6 @@
     "fullHistoryComing": "full history coming",
     "queuedRequestedHint": "Full history requested — this channel's whole back-catalog will backfill as the shared quota allows. Click to cancel your request.",
     "queuedByOtherHint": "Another subscriber already requested this channel's full history, so its whole back-catalog is on its way to everyone — nothing to do here.",
-    "getFullHistory": "get full history",
-    "getFullHistoryHint": "Only recent uploads so far. Click to request this channel's full back-catalog (older videos + complete search).",
     "hiddenHint": "Hidden — this channel's videos are kept out of your feed. Click to show them again.",
     "hideHint": "Hide this channel's videos from your feed. It stays subscribed; this doesn't unsubscribe on YouTube.",
     "unhide": "Unhide",
diff --git a/frontend/src/i18n/locales/hu/channels.json b/frontend/src/i18n/locales/hu/channels.json
index 5ff911f..f533397 100644
--- a/frontend/src/i18n/locales/hu/channels.json
+++ b/frontend/src/i18n/locales/hu/channels.json
@@ -1,6 +1,5 @@
 {
   "intro": "Állíts be egy csatornának <0>prioritást</0>, hogy a videói előrébb kerüljenek, amikor „Csatorna prioritás” szerint rendezel, csatolj saját <1>címkéket</1> a hírfolyam szűréséhez, vagy <2>rejts el</2> egy csatornát, hogy leiratkozás nélkül kivedd a hírfolyamból.",
-  "filterPlaceholder": "Csatornák szűrése…",
   "syncSubscriptions": "Feliratkozások beolvasása a YouTube-ról",
   "syncSubscriptionsHint": "Újraimportálja a feliratkozási listádat a YouTube-ról — hozzáadja az újonnan követett csatornákat, és eltávolítja azokat, amelyekről leiratkoztál. Maguk a videók a háttérben automatikusan tovább szinkronizálódnak; ez nem tölti le őket újra.",
   "backfillEverything": "Minden letöltése",
@@ -35,9 +34,7 @@
   "tags": {
     "yourTags": "Címkéid",
     "manage": "Címkék kezelése",
-    "yourTagsHint": "Saját személyes címkéid. Csatold őket az alábbi csatornákhoz, majd szűrd a hírfolyamot címke szerint az oldalsávból. (Az automatikus nyelvi/téma címkéktől függetlenül.)",
-    "newTag": "új címke",
-    "createTag": "Címke létrehozása"
+    "yourTagsHint": "Saját személyes címkéid. Csatold őket az alábbi csatornákhoz, majd szűrd a hírfolyamot címke szerint az oldalsávból. (Az automatikus nyelvi/téma címkéktől függetlenül.)"
   },
   "loading": "Csatornák betöltése…",
   "empty": "Nincsenek csatornák.",
@@ -74,8 +71,6 @@
     "quotaLeftHint": "A ma még hátralévő megosztott YouTube API-keret (csendes-óceáni idő szerint éjfélkor nullázódik)."
   },
   "row": {
-    "stored": "{{formatted}} tárolt",
-    "subs": "{{formatted}} feliratkozó",
     "openOnYouTube": "Megnyitás a YouTube-on",
     "editTags": "Címkék szerkesztése",
     "filterFeedByTag": "Hírfolyam szűrése: „{{name}}”",
@@ -98,8 +93,6 @@
     "fullHistoryComing": "teljes előzmény úton",
     "queuedRequestedHint": "Teljes előzmény kérve — a csatorna teljes archívuma letöltődik, ahogy a megosztott kvóta engedi. Kattints a kérés visszavonásához.",
     "queuedByOtherHint": "Egy másik feliratkozó már kérte ennek a csatornának a teljes előzményét, így a teljes archívuma már úton van mindenkihez — itt nincs teendőd.",
-    "getFullHistory": "teljes előzmény lekérése",
-    "getFullHistoryHint": "Egyelőre csak a legutóbbi feltöltések. Kattints a csatorna teljes archívumának lekéréséhez (régebbi videók + teljes keresés).",
     "hiddenHint": "Elrejtve — a csatorna videói nem jelennek meg a hírfolyamodban. Kattints, hogy újra láthatóak legyenek.",
     "hideHint": "A csatorna videóinak elrejtése a hírfolyamodból. Feliratkozva marad; ez nem iratkoztat le a YouTube-on.",
     "unhide": "Megjelenítés",
diff --git a/frontend/src/lib/format.ts b/frontend/src/lib/format.ts
index 04b7700..84afec6 100644
--- a/frontend/src/lib/format.ts
+++ b/frontend/src/lib/format.ts
@@ -101,3 +101,8 @@ export function formatViews(n: number | null): string {
   if (n >= 1e3) return `${(n / 1e3).toFixed(1).replace(/\.0$/, "")}K`;
   return String(n);
 }
+
+// A count for a right-aligned table cell: the humanized number, or an em-dash when unknown (null).
+export function formatCountOrDash(n: number | null | undefined): string {
+  return n != null ? formatViews(n) : "—";
+}
diff --git a/frontend/src/lib/storage.ts b/frontend/src/lib/storage.ts
index b7babae..7a3aa2d 100644
--- a/frontend/src/lib/storage.ts
+++ b/frontend/src/lib/storage.ts
@@ -16,6 +16,8 @@ export const LS = {
   perfMode: "siftlode.perfMode",
   channelFilter: "siftlode.channelFilter",
   channelsView: "siftlode.channelsView",
+  channelsTable: "siftlode.channelsTable",
+  channelDiscoveryTable: "siftlode.channelDiscoveryTable",
   settingsTab: "siftlode.settingsTab",
   statsTab: "siftlode.statsTab",
   adminUsersTab: "siftlode.adminUsersTab",
diff --git a/frontend/src/lib/youtubeErrors.ts b/frontend/src/lib/youtubeErrors.ts
new file mode 100644
index 0000000..5d8440e
--- /dev/null
+++ b/frontend/src/lib/youtubeErrors.ts
@@ -0,0 +1,25 @@
+import { HttpError } from "./api";
+import { notify } from "./notifications";
+import i18n from "../i18n";
+
+// A YouTube-gated action (subscribe, sync, backfill, unsubscribe) that 403s means the user hasn't
+// granted the write scope — surface a "Connect" affordance instead of a vague failure. Pass
+// `onConnect` to offer the connect-wizard button (callers that have no wizard handle, e.g. the
+// channel page, just get the message). `fallbackMessage` is the already-translated non-403 error.
+export function notifyYouTubeActionError(
+  err: unknown,
+  fallbackMessage: string,
+  onConnect?: () => void,
+): void {
+  if (err instanceof HttpError && err.status === 403) {
+    notify({
+      level: "error",
+      message: i18n.t("channels.notify.needYouTube"),
+      action: onConnect
+        ? { label: i18n.t("channels.notify.connect"), onClick: onConnect }
+        : undefined,
+    });
+  } else {
+    notify({ level: "error", message: fallbackMessage });
+  }
+}