refactor(web): playlistTrackToRef helper to dedupe TrackRef

reconstruction (#375)

PlaylistTrackRow.svelte and PlaylistCard.toTrackRefs both rebuilt
TrackRef from PlaylistTrack with the same field-by-field literal.
Server adding a new TrackRef field would have needed both sites
updated; now one helper owns the mapping.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/lib/components/PlaylistCard.svelte

@@ -4,6 +4,7 @@
   import type { Playlist, PlaylistTrack, TrackRef } from '$lib/api/types';
   import { user } from '$lib/auth/store.svelte';
   import { getPlaylist, refreshDiscover, refreshForYou } from '$lib/api/playlists';
+  import { playlistTrackToRef } from '$lib/playlists/playlistTrackToRef';
   import { errCode } from '$lib/api/errors';
   import { qk } from '$lib/api/queries';
   import { playQueue } from '$lib/player/store.svelte';
@@ -25,25 +26,12 @@
     menuOpen = !menuOpen;
   }
 
-  // Map PlaylistTrack rows to TrackRef shape and drop tracks whose upstream
-  // file has been removed (track_id is null). Mirrors PlaylistTrackRow's
-  // liveTrack derivation.
+  // Map PlaylistTrack rows to TrackRef shape and drop tracks whose
+  // upstream file has been removed (track_id null).
   function toTrackRefs(rows: PlaylistTrack[]): TrackRef[] {
-    const out: TrackRef[] = [];
-    for (const r of rows) {
-      if (!r.track_id) continue;
-      out.push({
-        id: r.track_id,
-        title: r.title,
-        album_id: r.album_id ?? '',
-        album_title: r.album_title,
-        artist_id: r.artist_id ?? '',
-        artist_name: r.artist_name,
-        duration_sec: r.duration_sec,
-        stream_url: r.stream_url ?? ''
-      });
-    }
-    return out;
+    return rows
+      .map((r) => playlistTrackToRef(r))
+      .filter((t): t is TrackRef => t !== null);
   }
 
   async function onPlayClick(e: MouseEvent) {

web/src/lib/components/PlaylistTrackRow.svelte

@@ -3,7 +3,8 @@
   import { draggable, type DragEventData } from '@neodrag/svelte';
   import LikeButton from './LikeButton.svelte';
   import TrackMenu from './TrackMenu.svelte';
-  import type { PlaylistTrack, TrackRef } from '$lib/api/types';
+  import type { PlaylistTrack } from '$lib/api/types';
+  import { playlistTrackToRef } from '$lib/playlists/playlistTrackToRef';
   import { offsetToDelta } from './queue-row-math';
 
   let {
@@ -22,22 +23,9 @@
 
   const isUnavailable = $derived(row.track_id === null);
 
-  // Construct a minimal TrackRef for the kebab menu when the upstream
-  // track still exists. When unavailable, the menu is hidden.
-  const liveTrack = $derived<TrackRef | null>(
-    row.track_id
-      ? ({
-          id: row.track_id,
-          title: row.title,
-          album_id: row.album_id ?? '',
-          album_title: row.album_title,
-          artist_id: row.artist_id ?? '',
-          artist_name: row.artist_name,
-          duration_sec: row.duration_sec,
-          stream_url: row.stream_url ?? ''
-        } as TrackRef)
-      : null
-  );
+  // Reconstruct a minimal TrackRef for the kebab menu when the
+  // upstream track still exists. When unavailable, the menu is hidden.
+  const liveTrack = $derived(playlistTrackToRef(row));
 
   let measuredRowHeight = 56; // sensible default; replaced on dragStart
 

web/src/lib/playlists/playlistTrackToRef.ts

@@ -0,0 +1,22 @@
+// Converts a PlaylistTrack row into the minimal TrackRef shape used
+// by play queues + track menus. Centralizes the mapping so server
+// additions (new TrackRef fields) only update one site.
+//
+// Returns null when the upstream track has been removed (track_id
+// is null on the playlist row); callers should filter nulls.
+
+import type { PlaylistTrack, TrackRef } from '$lib/api/types';
+
+export function playlistTrackToRef(row: PlaylistTrack): TrackRef | null {
+  if (!row.track_id) return null;
+  return {
+    id: row.track_id,
+    title: row.title,
+    album_id: row.album_id ?? '',
+    album_title: row.album_title,
+    artist_id: row.artist_id ?? '',
+    artist_name: row.artist_name,
+    duration_sec: row.duration_sec,
+    stream_url: row.stream_url ?? ''
+  };
+}