Simplify CC dropdown: downloaded langs at top, YouTube langs below

Single CC chip shows downloaded langs inline. One click opens a dropdown
with optgroups — already-on-disk at top, YouTube-available below loading
async. No re-download needed to select an already-downloaded lang.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/Watch.jsx

@@ -671,8 +671,8 @@ export default function Watch() {
   const { data: subtitleFiles = [] } = useQuery({
     queryKey: ["subtitle-files", youtubeVideoId],
     queryFn: () => getSubtitleFiles(youtubeVideoId).then(r => r.data),
-    enabled: fileReady,
+    enabled: !!youtubeVideoId,
-    staleTime: Infinity,
+    staleTime: 60_000,
   });
 
   const { data: dlStatus } = useQuery({
@@ -995,41 +995,22 @@ export default function Watch() {
               )}
 
               {(() => {
-                // Subs already on disk → show langs + "+" to add more
+                const onDisk = subtitleFiles.map(s => s.lang);
-                if (subtitleFiles.length > 0 && !subsRequested) return (
+                const onDiskSet = new Set(onDisk);
-                  <div className="flex items-center gap-1">
+
-                    <span className="px-3 py-1.5 rounded-full bg-zinc-800 text-zinc-400 text-xs font-mono">
-                      CC: {subtitleFiles.map(s => s.lang).join(", ")}
-                    </span>
-                    <button
-                      onClick={() => setSubsRequested(true)}
-                      className="px-2.5 py-1.5 rounded-full text-xs bg-zinc-800 text-zinc-500 hover:bg-zinc-700 transition-colors"
-                      title="Add subtitle language"
-                    >+</button>
-                  </div>
-                );
-                // Not yet asked → show CC chip
                 if (!subsRequested) return (
                   <button
                     onClick={() => setSubsRequested(true)}
                     className="flex items-center gap-1 px-3 py-1.5 rounded-full text-xs font-medium bg-zinc-800 text-zinc-400 hover:bg-zinc-700 transition-colors"
-                    title="Check available subtitles on YouTube"
                   >
-                    CC
+                    CC{onDisk.length > 0 ? ` · ${onDisk.join(", ")}` : ""}
                   </button>
                 );
-                // Loading YouTube subtitle list
+
-                if (subsLoading) return (
+                const ytManual = (availableSubs?.manual ?? []).filter(l => !onDiskSet.has(l));
-                  <span className="flex items-center gap-1.5 px-3 py-1.5 rounded-full bg-zinc-800 text-zinc-500 text-xs">
+                const ytAuto   = (availableSubs?.auto   ?? []).filter(l => !onDiskSet.has(l) && !ytManual.includes(l));
-                    <span className="w-3 h-3 border border-zinc-600 border-t-transparent rounded-full animate-spin inline-block" />
+                const needsDownload = selectedSubLang && !onDiskSet.has(selectedSubLang);
-                    CC
+
-                  </span>
-                );
-                const manual = new Set(availableSubs?.manual ?? []);
-                const auto   = (availableSubs?.auto ?? []).filter(l => !manual.has(l));
-                if (!manual.size && !auto.length) return (
-                  <span className="px-3 py-1.5 rounded-full bg-zinc-800 text-zinc-600 text-xs">No CC</span>
-                );
                 return (
                   <>
                     <select
@@ -1038,18 +1019,25 @@ export default function Watch() {
                       className="bg-zinc-800 text-zinc-300 text-xs rounded-full px-3 py-2 border border-zinc-700 focus:outline-none focus:border-accent"
                     >
                       <option value="">No subtitles</option>
-                      {[...manual].map(l => <option key={l} value={l}>{l}</option>)}
+                      {onDisk.length > 0 && (
-                      {auto.map(l => <option key={l} value={l}>{l} (auto)</option>)}
+                        <optgroup label="— Downloaded —">
+                          {onDisk.map(l => <option key={l} value={l}>{l}</option>)}
+                        </optgroup>
+                      )}
+                      {(subsLoading || ytManual.length > 0 || ytAuto.length > 0) && (
+                        <optgroup label={subsLoading ? "— Loading YouTube… —" : "— Available on YouTube —"}>
+                          {ytManual.map(l => <option key={l} value={l}>{l}</option>)}
+                          {ytAuto.map(l => <option key={l} value={l}>{l} (auto)</option>)}
+                        </optgroup>
+                      )}
                     </select>
-                    {dlComplete && selectedSubLang && (
+                    {dlComplete && needsDownload && (
                       <button
                         onClick={() => addSubsMut.mutate()}
                         disabled={addSubsMut.isPending}
                         className="flex items-center gap-1 px-3 py-1.5 rounded-full text-xs font-medium bg-accent text-black hover:bg-yellow-300 transition-colors disabled:opacity-50"
                       >
-                        {addSubsMut.isPending ? (
+                        {addSubsMut.isPending && <span className="w-3 h-3 border-2 border-black/40 border-t-transparent rounded-full animate-spin inline-block" />}
-                          <span className="w-3 h-3 border-2 border-black/40 border-t-transparent rounded-full animate-spin inline-block" />
-                        ) : null}
                         {addSubsMut.isPending ? "Fetching…" : "Add subtitles"}
                       </button>
                     )}