refactor(plex): extract shared PlexLibraryPicker (F6)

AddItemPanel (Collection page) and NewCollectionPanel (browse) had near-
duplicate debounced library-search + result-list rendering. Extract it into
one PlexLibraryPicker that owns the query, the loading/error/empty states and
the row markup; callers keep their own chrome and pass term + renderAction.
No behaviour change.

frontend/src/components/PlexCollectionView.tsx

@@ -6,10 +6,10 @@ import { qk } from "../lib/queryKeys";
 import { api, isIntrinsicReadOnly, type PlexCard, type PlexCollectionDetail } from "../lib/api";
 import { formatRuntime } from "../lib/format";
 import { notifyActionError } from "../lib/actionErrors";
-import { useDebounced } from "../lib/useDebounced";
 import { useConfirm } from "./ConfirmProvider";
 import { BackBtn, ActionBtn, DetailHero } from "../lib/plexDetailUi";
 import { PlexPosterCard } from "./plexCards";
+import PlexLibraryPicker from "./PlexLibraryPicker";
 import { toggleWatchState } from "../lib/plexWatch";
 import { LoadingState, StateMessage } from "./QueryState";
 
@@ -342,14 +342,7 @@ function AddItemPanel({
 }) {
   const { t } = useTranslation();
   const [term, setTerm] = useState("");
-  const debounced = useDebounced(term.trim(), 300);
   const [added, setAdded] = useState<Set<string>>(new Set());
-  const q = useQuery({
-    queryKey: qk.plexLibrary("collection-add", scope, debounced),
-    queryFn: () => api.plexLibrary({ scope, q: debounced, limit: 12 }),
-    enabled: debounced.length > 0,
-  });
-  const results = q.data?.items ?? [];
 
   async function add(card: PlexCard) {
     try {
@@ -381,30 +374,13 @@ function AddItemPanel({
           <X className="h-4 w-4" />
         </button>
       </div>
-      {debounced.length === 0 ? (
-        <p className="text-muted text-sm">{t("plex.collection.addHint")}</p>
-      ) : q.isLoading ? (
-        <LoadingState label={t("plex.loading")} />
-      ) : q.isError ? (
-        <p className="text-muted text-sm">{t("common.loadError")}</p>
-      ) : results.length === 0 ? (
-        <p className="text-muted text-sm">{t("plex.collection.addNoResults")}</p>
-      ) : (
-        <ul className="flex flex-col gap-1">
-          {results.map((c) => {
+      <PlexLibraryPicker
+        scope={scope}
+        term={term}
+        emptyHint={<p className="text-muted text-sm">{t("plex.collection.addHint")}</p>}
+        renderAction={(c) => {
           const inColl = existing.has(c.id) || added.has(c.id);
           return (
-              <li key={c.id} className="flex items-center gap-3">
-                <img
-                  src={c.thumb}
-                  alt=""
-                  className="h-12 w-8 shrink-0 rounded object-cover"
-                  loading="lazy"
-                />
-                <span className="min-w-0 flex-1 truncate text-sm">
-                  {c.title}
-                  {c.year != null && <span className="text-muted"> · {c.year}</span>}
-                </span>
             <button
               onClick={() => add(c)}
               disabled={inColl}
@@ -413,11 +389,9 @@ function AddItemPanel({
               {inColl ? <Check className="h-3.5 w-3.5" /> : <Plus className="h-3.5 w-3.5" />}
               {inColl ? t("plex.collection.added") : t("plex.collection.add")}
             </button>
-              </li>
           );
-          })}
-        </ul>
-      )}
+        }}
+      />
     </div>
   );
 }

frontend/src/components/PlexLibraryPicker.tsx

@@ -0,0 +1,60 @@
+import { type ReactNode } from "react";
+import { useTranslation } from "react-i18next";
+import { useQuery } from "@tanstack/react-query";
+import { qk } from "../lib/queryKeys";
+import { api, type PlexCard } from "../lib/api";
+import { useDebounced } from "../lib/useDebounced";
+import { LoadingState } from "./QueryState";
+
+// A debounced library search-and-pick list, shared by the "Add title" panel (PlexCollectionView) and
+// the "New collection" first-title panel (plexBrowseLists) — both search the library the same way and
+// render the same result rows, differing only in the per-row action. Callers keep their own chrome
+// (search input, name field, close button) and supply `term` + `renderAction`; this owns the query,
+// the loading/error/empty states, and the row markup so those can't drift between the two surfaces.
+export default function PlexLibraryPicker({
+  scope,
+  term,
+  enabled = true,
+  emptyHint = null,
+  renderAction,
+}: {
+  scope: string;
+  /** The raw search term; debounced internally. */
+  term: string;
+  /** Gate the query off (e.g. until a collection name is valid). When false, renders nothing. */
+  enabled?: boolean;
+  /** Shown while the (debounced) term is empty — a hint, or nothing. */
+  emptyHint?: ReactNode;
+  /** The trailing control for each result row (Add / Create-with / …). */
+  renderAction: (card: PlexCard) => ReactNode;
+}) {
+  const { t } = useTranslation();
+  const debounced = useDebounced(term.trim(), 300);
+  const q = useQuery({
+    queryKey: qk.plexLibrary("collection-pick", scope, debounced),
+    queryFn: () => api.plexLibrary({ scope, q: debounced, limit: 12 }),
+    enabled: enabled && debounced.length > 0,
+  });
+  const results = q.data?.items ?? [];
+
+  if (!enabled) return null;
+  if (debounced.length === 0) return <>{emptyHint}</>;
+  if (q.isLoading) return <LoadingState label={t("plex.loading")} />;
+  if (q.isError) return <p className="text-muted text-sm">{t("common.loadError")}</p>;
+  if (results.length === 0) return <p className="text-muted text-sm">{t("plex.collection.addNoResults")}</p>;
+
+  return (
+    <ul className="flex flex-col gap-1">
+      {results.map((c) => (
+        <li key={c.id} className="flex items-center gap-3">
+          <img src={c.thumb} alt="" className="h-12 w-8 shrink-0 rounded object-cover" loading="lazy" />
+          <span className="min-w-0 flex-1 truncate text-sm">
+            {c.title}
+            {c.year != null && <span className="text-muted"> · {c.year}</span>}
+          </span>
+          {renderAction(c)}
+        </li>
+      ))}
+    </ul>
+  );
+}

frontend/src/components/plexBrowseLists.tsx

@@ -17,6 +17,7 @@ import { notify } from "../lib/notifications";
 import { useDebounced } from "../lib/useDebounced";
 import { LoadingState, StateMessage } from "./QueryState";
 import PosterTile from "./PosterTile";
+import PlexLibraryPicker from "./PlexLibraryPicker";
 
 // A collection tile's sub-line: item count · total runtime (each dropped when unknown, e.g. show-only
 // collections have no movie runtime).
@@ -86,7 +87,6 @@ function NewCollectionPanel({
   const [name, setName] = useState("");
   const [term, setTerm] = useState("");
   const [busy, setBusy] = useState(false);
-  const debounced = useDebounced(term.trim(), 300);
   const trimmed = name.trim();
   // Advisory only: `existingNames` is the search-scoped, all-library collection union, whereas the
   // backend enforces uniqueness PER library (Plex only conflates same-named collections within one
@@ -94,12 +94,6 @@ function NewCollectionPanel({
   // same-name collection in another library would be un-creatable. The backend's 409 is authoritative.
   const dupHint = trimmed.length > 0 && existingNames.has(trimmed.toLowerCase());
   const nameOk = trimmed.length > 0;
-  const q = useQuery({
-    queryKey: qk.plexLibrary("collection-new", debounced),
-    queryFn: () => api.plexLibrary({ scope: "both", q: debounced, limit: 12 }),
-    enabled: nameOk && debounced.length > 0,
-  });
-  const results = q.data?.items ?? [];
 
   async function create(card: PlexCard) {
     if (!nameOk || busy) return;
@@ -155,26 +149,11 @@ function NewCollectionPanel({
           className="glass-card flex-1 rounded-lg px-3 py-1.5 text-sm focus:outline-hidden focus:ring-2 focus:ring-accent/40 disabled:opacity-50"
         />
       </div>
-      {!nameOk || debounced.length === 0 ? null : q.isLoading ? (
-        <LoadingState label={t("plex.loading")} />
-      ) : q.isError ? (
-        <p className="text-muted text-sm">{t("common.loadError")}</p>
-      ) : results.length === 0 ? (
-        <p className="text-muted text-sm">{t("plex.collection.addNoResults")}</p>
-      ) : (
-        <ul className="flex flex-col gap-1">
-          {results.map((c) => (
-            <li key={c.id} className="flex items-center gap-3">
-              <img
-                src={c.thumb}
-                alt=""
-                className="h-12 w-8 shrink-0 rounded object-cover"
-                loading="lazy"
-              />
-              <span className="min-w-0 flex-1 truncate text-sm">
-                {c.title}
-                {c.year != null && <span className="text-muted"> · {c.year}</span>}
-              </span>
+      <PlexLibraryPicker
+        scope="both"
+        term={term}
+        enabled={nameOk}
+        renderAction={(c) => (
           <button
             onClick={() => create(c)}
             disabled={busy}
@@ -183,10 +162,8 @@ function NewCollectionPanel({
             <Check className="h-3.5 w-3.5" />
             {t("plex.collection.createWith")}
           </button>
-            </li>
-          ))}
-        </ul>
         )}
+      />
     </div>
   );
 }