fix(now-playing): episode as title, podcast as artist on both paths

The card put the podcast name in the title slot ('Podcast — Episode'
prefix truncating on long names) with an empty artist slot for local
playback — the downloaded files carry no artist tag. Now:
- mediaTitle is the episode title only (UI + CLI); streams keep their
  artist from stream tags, matching Apple Podcasts' title/artist layout.
- downloads are tagged at completion (ffmpeg -c copy, atomic rename):
  title=episode, artist=podcast — verified on a real 72MB file in 1.5s.

src/hooks/useAudio.ts

@@ -348,7 +348,7 @@ async function play(episode: Episode): Promise<void> {
 			volume: vol,
 			speed: spd,
 			startPosition: startPos > 0 ? startPos : undefined,
-			mediaTitle: podcastTitle ? `${podcastTitle} — ${episode.title}` : episode.title,
+			mediaTitle: episode.title,
 			coverArtPath: coverArtPath ?? undefined,
 		});
 
@@ -444,9 +444,7 @@ async function load(episode: Episode): Promise<void> {
 				volume: volume(),
 				speed: storeSpeed || speed(),
 				startPosition: pos > 0 ? pos : undefined,
-				mediaTitle: podcastTitle
+mediaTitle: episode.title,
-					? `${podcastTitle} — ${episode.title}`
-					: episode.title,
 				coverArtPath: coverArtPath ?? undefined,
 			})
 			.catch(() => {});
@@ -620,9 +618,7 @@ async function switchBackend(name: BackendName): Promise<void> {
 				startPosition: pos,
 				volume: vol,
 				speed: spd,
-				mediaTitle: podcastTitle
+mediaTitle: ep.title,
-					? `${podcastTitle} — ${ep.title}`
-					: ep.title,
 				coverArtPath: coverArtPath ?? undefined,
 			});
 			setIsPlaying(true);

src/index.tsx

@@ -195,7 +195,7 @@ async function handlePlay(feeds: Feed[], arg: string): Promise<void> {
 				? await fetchCoverArt(coverUrl)
 				: null
 			await backend.play(episodeResult.audioUrl, {
-				mediaTitle: `${feedResult.podcast.title} — ${episodeResult.title}`,
+				mediaTitle: episodeResult.title,
 				coverArtPath: coverArtPath ?? undefined,
 			})
 			console.log("Playback started (use the UI to control)")

src/stores/download.ts

@@ -269,6 +269,39 @@ function createDownloadStore() {
 						.exited.catch(() => {});
 				}
 			}
+
+			// Tag the local file (codec-copy, no re-encode) so mpv's Now
+			// Playing metadata for local playback is title=episode,
+			// artist=podcast — the source streams carry no usable tags and
+			// macOS composes "title - artist" from exactly these fields.
+			// Atomic: ffmpeg writes a temp file, then renames into place.
+			if (result.filePath && episode) {
+				const podcastTitle =
+					feedStore.feeds().find((f) => f.id === item.feedId)?.podcast.title ??
+					downloads().get(item.episodeId)?.podcastTitle;
+				if (podcastTitle) {
+					const tmp = `${result.filePath}.tag`;
+					Bun.spawn([
+						"ffmpeg",
+						"-y",
+						"-i",
+						result.filePath,
+						"-c",
+						"copy",
+						"-metadata",
+						`title=${episode.title}`,
+						"-metadata",
+						`artist=${podcastTitle}`,
+						tmp,
+					])
+						.exited.then(async (code) => {
+							if (code !== 0) return;
+							const { renameSync } = await import("node:fs");
+							renameSync(tmp, result.filePath);
+						})
+						.catch(() => {});
+				}
+			}
 		} else {
 			updateDownload(item.episodeId, {
 				status: DownloadStatus.FAILED,