Merge chore/code-hygiene: Phase 3 — jscpd clones to zero

Extract the last 3 duplicated blocks: shared CollapsedFilterRail (both sidebars),
VideoCard textBlock (list+card layouts), subsColumn factory (Channels +
ChannelDiscovery). jscpd 8→0 clones. Behavior-neutral; E2E-verified (feed cards,
collapsed rail); tsc/knip green.

frontend/src/components/ChannelDiscovery.tsx

@@ -4,6 +4,7 @@ import { UserPlus } from "lucide-react";
 import { api, type DiscoveredChannel } from "../lib/api";
 import { accountKey, LS } from "../lib/storage";
 import { formatCountOrDash } from "../lib/format";
+import { subsColumn } from "./channelColumns";
 import { notify } from "../lib/notifications";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import Tooltip from "./Tooltip";
@@ -78,17 +79,7 @@ export default function ChannelDiscovery({
         <ChannelLink id={c.id} title={c.title} handle={c.handle} thumbnailUrl={c.thumbnail_url} />
       ),
     },
-    {
-      key: "subs",
-      header: t("channels.cols.subs"),
-      align: "right",
-      nowrap: true,
-      sortable: true,
-      sortValue: (c) => c.subscriber_count ?? -1,
-      render: (c) => (
-        <span className="text-muted tabular-nums">{formatCountOrDash(c.subscriber_count)}</span>
-      ),
-    },
+    subsColumn<DiscoveredChannel>(t),
     {
       key: "videos",
       header: t("channels.discovery.cols.totalVideos"),

frontend/src/components/Channels.tsx

@@ -20,7 +20,8 @@ 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 { formatCountOrDash, formatEta, formatTotalHours, relativeTime } from "../lib/format";
+import { formatEta, formatTotalHours, relativeTime } from "../lib/format";
+import { subsColumn } from "./channelColumns";
 import { notify } from "../lib/notifications";
 import Tooltip from "./Tooltip";
 import DataTable, { type Column } from "./DataTable";
@@ -274,17 +275,7 @@ export default function Channels({
       sortValue: (c) => c.stored_videos,
       render: (c) => <span className="text-muted tabular-nums">{c.stored_videos.toLocaleString()}</span>,
     },
-    {
-      key: "subs",
-      header: t("channels.cols.subs"),
-      align: "right",
-      nowrap: true,
-      sortable: true,
-      sortValue: (c) => c.subscriber_count ?? -1,
-      render: (c) => (
-        <span className="text-muted tabular-nums">{formatCountOrDash(c.subscriber_count)}</span>
-      ),
-    },
+    subsColumn<ManagedChannel>(t),
     {
       key: "lastUpload",
       header: t("channels.cols.lastUpload"),

frontend/src/components/CollapsedFilterRail.tsx

@@ -0,0 +1,39 @@
+import { ChevronRight, SlidersHorizontal } from "lucide-react";
+import { useTranslation } from "react-i18next";
+
+// The thin 46px rail shown when a filter sidebar is collapsed (both the feed Sidebar and the Plex
+// PlexSidebar rendered byte-identical copies): an expand control + a filter icon carrying the
+// active-filter count so you can tell filters are on without opening the panel.
+export default function CollapsedFilterRail({
+  activeCount,
+  onToggleCollapse,
+}: {
+  activeCount: number;
+  onToggleCollapse: () => void;
+}) {
+  const { t } = useTranslation();
+  return (
+    <aside className="hidden md:flex w-[46px] shrink-0 flex-col items-center gap-2 border-r border-border bg-surface/40 py-3">
+      <button
+        onClick={onToggleCollapse}
+        title={t("sidebar.expandPanel")}
+        aria-label={t("sidebar.expandPanel")}
+        className="p-1 rounded-md text-muted hover:text-fg hover:bg-card transition"
+      >
+        <ChevronRight className="w-4 h-4" />
+      </button>
+      <button
+        onClick={onToggleCollapse}
+        title={t("sidebar.filters")}
+        className="relative p-2 rounded-lg text-muted hover:text-fg hover:bg-card transition"
+      >
+        <SlidersHorizontal className="w-5 h-5" />
+        {activeCount > 0 && (
+          <span className="absolute -top-1 -right-1 min-w-[16px] h-4 px-1 rounded-full bg-accent text-accent-fg text-[10px] font-bold leading-none grid place-items-center ring-2 ring-bg">
+            {activeCount > 9 ? "9+" : activeCount}
+          </span>
+        )}
+      </button>
+    </aside>
+  );
+}

frontend/src/components/PlexSidebar.tsx

@@ -1,7 +1,8 @@
 import { useState, type ReactNode } from "react";
 import { useTranslation } from "react-i18next";
 import { useQuery, useQueryClient } from "@tanstack/react-query";
-import { ChevronRight, Film, Layers, ListMusic, Plus, SlidersHorizontal, Tv2, X } from "lucide-react";
+import { Film, Layers, ListMusic, Plus, Tv2, X } from "lucide-react";
+import CollapsedFilterRail from "./CollapsedFilterRail";
 import { api, EMPTY_PLEX_FILTERS, plexFilterCount, type PlexFilters } from "../lib/api";
 import { useDebounced } from "../lib/useDebounced";
 
@@ -115,30 +116,7 @@ export default function PlexSidebar({
   )?.key;
 
   if (collapsed) {
-    return (
-      <aside className="hidden md:flex w-[46px] shrink-0 flex-col items-center gap-2 border-r border-border bg-surface/40 py-3">
-        <button
-          onClick={onToggleCollapse}
-          title={t("sidebar.expandPanel")}
-          aria-label={t("sidebar.expandPanel")}
-          className="p-1 rounded-md text-muted hover:text-fg hover:bg-card transition"
-        >
-          <ChevronRight className="w-4 h-4" />
-        </button>
-        <button
-          onClick={onToggleCollapse}
-          title={t("sidebar.filters")}
-          className="relative p-2 rounded-lg text-muted hover:text-fg hover:bg-card transition"
-        >
-          <SlidersHorizontal className="w-5 h-5" />
-          {activeCount > 0 && (
-            <span className="absolute -top-1 -right-1 min-w-[16px] h-4 px-1 rounded-full bg-accent text-accent-fg text-[10px] font-bold leading-none grid place-items-center ring-2 ring-bg">
-              {activeCount > 9 ? "9+" : activeCount}
-            </span>
-          )}
-        </button>
-      </aside>
-    );
+    return <CollapsedFilterRail activeCount={activeCount} onToggleCollapse={onToggleCollapse} />;
   }
 
   return (

frontend/src/components/Sidebar.tsx

@@ -5,7 +5,6 @@ import {
   Check,
   ChevronDown,
   ChevronLeft,
-  ChevronRight,
   Eye,
   EyeOff,
   GripVertical,
@@ -13,7 +12,6 @@ import {
   Pencil,
   RotateCcw,
   Share2,
-  SlidersHorizontal,
   User,
   X,
 } from "lucide-react";
@@ -44,6 +42,7 @@ import { useDebounced } from "../lib/useDebounced";
 import { Switch } from "./ui/form";
 import TagManager from "./TagManager";
 import SavedViewsWidget from "./SavedViewsWidget";
+import CollapsedFilterRail from "./CollapsedFilterRail";
 
 // Filter ids; display labels resolved at render time via t("sidebar.sort.<id>") etc.
 const SORT_IDS = [
@@ -477,30 +476,7 @@ export default function Sidebar({
   // Collapsed: a thin rail (mirroring the nav) — an expand control plus a filter icon that
   // carries the active-filter count so you can tell filters are on without opening it.
   if (collapsed) {
-    return (
-      <aside className="hidden md:flex w-[46px] shrink-0 flex-col items-center gap-2 border-r border-border bg-surface/40 py-3">
-        <button
-          onClick={onToggleCollapse}
-          title={t("sidebar.expandPanel")}
-          aria-label={t("sidebar.expandPanel")}
-          className="p-1 rounded-md text-muted hover:text-fg hover:bg-card transition"
-        >
-          <ChevronRight className="w-4 h-4" />
-        </button>
-        <button
-          onClick={onToggleCollapse}
-          title={t("sidebar.filters")}
-          className="relative p-2 rounded-lg text-muted hover:text-fg hover:bg-card transition"
-        >
-          <SlidersHorizontal className="w-5 h-5" />
-          {activeCount > 0 && (
-            <span className="absolute -top-1 -right-1 min-w-[16px] h-4 px-1 rounded-full bg-accent text-accent-fg text-[10px] font-bold leading-none grid place-items-center ring-2 ring-bg">
-              {activeCount > 9 ? "9+" : activeCount}
-            </span>
-          )}
-        </button>
-      </aside>
-    );
+    return <CollapsedFilterRail activeCount={activeCount} onToggleCollapse={onToggleCollapse} />;
   }
 
   return (

frontend/src/components/VideoCard.tsx

@@ -285,6 +285,23 @@ function VideoCard({
       {video.title}
     </a>
   );
+  // Title + channel button + meta — identical in both layouts (only their wrapper / Actions placement
+  // differs). Safe to reuse the same element: exactly one of the two branches below renders.
+  const textBlock = (
+    <>
+      {title}
+      <button
+        onClick={(e) => {
+          e.stopPropagation();
+          onOpenChannel?.(video.channel_id, video.channel_title ?? t("card.thisChannel"));
+        }}
+        className="text-sm text-muted truncate mt-0.5 block w-fit max-w-full text-left hover:text-fg"
+      >
+        {video.channel_title}
+      </button>
+      <div className="text-xs text-muted mt-0.5">{meta}</div>
+    </>
+  );
 
   if (view === "list") {
     return (
@@ -295,19 +312,7 @@ function VideoCard({
         )}
       >
         <Thumb video={video} className="w-44 aspect-video shrink-0" onOpen={onOpen} />
-        <div className="min-w-0 flex-1">
-          {title}
-          <button
-            onClick={(e) => {
-              e.stopPropagation();
-              onOpenChannel?.(video.channel_id, video.channel_title ?? t("card.thisChannel"));
-            }}
-            className="text-sm text-muted truncate mt-0.5 block w-fit max-w-full text-left hover:text-fg"
-          >
-            {video.channel_title}
-          </button>
-          <div className="text-xs text-muted mt-0.5">{meta}</div>
-        </div>
+        <div className="min-w-0 flex-1">{textBlock}</div>
         <Actions video={video} onState={onState} onResetState={onResetState} onToggleSave={onToggleSave} />
       </div>
     );
@@ -328,17 +333,7 @@ function VideoCard({
           className="w-9 h-9 rounded-full shrink-0 mt-0.5"
         />
         <div className="min-w-0 flex-1">
-          {title}
-          <button
-            onClick={(e) => {
-              e.stopPropagation();
-              onOpenChannel?.(video.channel_id, video.channel_title ?? t("card.thisChannel"));
-            }}
-            className="text-sm text-muted truncate mt-0.5 block w-fit max-w-full text-left hover:text-fg"
-          >
-            {video.channel_title}
-          </button>
-          <div className="text-xs text-muted mt-0.5">{meta}</div>
+          {textBlock}
           <Actions video={video} onState={onState} onResetState={onResetState} onToggleSave={onToggleSave} />
         </div>
       </div>

frontend/src/components/channelColumns.tsx

@@ -0,0 +1,18 @@
+import type { TFunction } from "i18next";
+import { formatCountOrDash } from "../lib/format";
+import type { Column } from "./DataTable";
+
+/** The shared "subscribers" DataTable column (right-aligned, sortable, em-dash for null) — identical
+ * in the Channels manager and the ChannelDiscovery table, which show subscriber counts on different
+ * channel row shapes. */
+export function subsColumn<T extends { subscriber_count: number | null }>(t: TFunction): Column<T> {
+  return {
+    key: "subs",
+    header: t("channels.cols.subs"),
+    align: "right",
+    nowrap: true,
+    sortable: true,
+    sortValue: (c) => c.subscriber_count ?? -1,
+    render: (c) => <span className="text-muted tabular-nums">{formatCountOrDash(c.subscriber_count)}</span>,
+  };
+}