refactor(player): E.31 — extract Last.fm love actions as factory (#595)

Four Last.fm-related actions move out of the playerStore create()
body into `src/store/lastfmActions.ts` as a `createLastfmActions(set, get)`
factory:

  - `toggleLastfmLove` — flip love + write through to the cache map
  - `setLastfmLoved` — force-set (used by external events)
  - `setLastfmLovedForSong` — write cache for an arbitrary title/artist
  - `syncLastfmLovedTracks` — startup bulk fetch + merge

The store body uses `...createLastfmActions(set, get)` to inline them
back into the actions map. First action-factory cut — sets the
pattern for follow-up Phase E extractions of larger action groups
(playback transport, queue mutators, etc.).

Side-cleanup: 3 last.fm imports drop from playerStore
(`lastfmLoveTrack`, `lastfmUnloveTrack`, `lastfmGetAllLovedTracks`)
since they only fed the moved actions.

playerStore 1550 → 1504 LOC.

src/store/lastfmActions.ts

@@ -0,0 +1,87 @@
+import {
+  lastfmGetAllLovedTracks,
+  lastfmLoveTrack,
+  lastfmUnloveTrack,
+} from '../api/lastfm';
+import { useAuthStore } from './authStore';
+import type { PlayerState } from './playerStoreTypes';
+
+type SetState = (
+  partial: Partial<PlayerState> | ((state: PlayerState) => Partial<PlayerState>),
+) => void;
+type GetState = () => PlayerState;
+
+/**
+ * Four Last.fm love-related actions, factored out of the playerStore
+ * `create()` body so the action set can be tested + reasoned about
+ * separately:
+ *
+ *  - `toggleLastfmLove` — flip the current track's love state on the
+ *    server, write through to the local cache map keyed by
+ *    `${title}::${artist}` so other queue rows showing the same song
+ *    update too.
+ *  - `setLastfmLoved` — force-set the boolean (used by the
+ *    `track:lastfm-loved` SSE-style event). Updates the cache when a
+ *    current track exists.
+ *  - `setLastfmLovedForSong` — write the cache for an arbitrary
+ *    title/artist pair (used by the QueuePanel love button on
+ *    not-yet-current tracks).
+ *  - `syncLastfmLovedTracks` — startup-time bulk fetch of the user's
+ *    loved-tracks list, merged into the local cache (local likes win
+ *    on conflict) plus a recompute of the current track's flag.
+ */
+export function createLastfmActions(set: SetState, get: GetState): Pick<
+  PlayerState,
+  'toggleLastfmLove' | 'setLastfmLoved' | 'setLastfmLovedForSong' | 'syncLastfmLovedTracks'
+> {
+  return {
+    toggleLastfmLove: () => {
+      const { currentTrack, lastfmLoved } = get();
+      const { lastfmSessionKey } = useAuthStore.getState();
+      if (!currentTrack || !lastfmSessionKey) return;
+      const newLoved = !lastfmLoved;
+      const cacheKey = `${currentTrack.title}::${currentTrack.artist}`;
+      set(s => ({ lastfmLoved: newLoved, lastfmLovedCache: { ...s.lastfmLovedCache, [cacheKey]: newLoved } }));
+      if (newLoved) {
+        lastfmLoveTrack(currentTrack, lastfmSessionKey);
+      } else {
+        lastfmUnloveTrack(currentTrack, lastfmSessionKey);
+      }
+    },
+
+    setLastfmLoved: (v) => {
+      const { currentTrack } = get();
+      if (currentTrack) {
+        const cacheKey = `${currentTrack.title}::${currentTrack.artist}`;
+        set(s => ({ lastfmLoved: v, lastfmLovedCache: { ...s.lastfmLovedCache, [cacheKey]: v } }));
+      } else {
+        set({ lastfmLoved: v });
+      }
+    },
+
+    syncLastfmLovedTracks: async () => {
+      const { lastfmSessionKey, lastfmUsername } = useAuthStore.getState();
+      if (!lastfmSessionKey || !lastfmUsername) return;
+      const tracks = await lastfmGetAllLovedTracks(lastfmUsername, lastfmSessionKey);
+      const newCache: Record<string, boolean> = {};
+      for (const t of tracks) newCache[`${t.title}::${t.artist}`] = true;
+      // Merge with existing cache (local likes take precedence)
+      set(s => ({ lastfmLovedCache: { ...newCache, ...s.lastfmLovedCache } }));
+      // Update current track's loved state if it's in the new cache
+      const { currentTrack } = get();
+      if (currentTrack) {
+        const loved = newCache[`${currentTrack.title}::${currentTrack.artist}`] ?? false;
+        set({ lastfmLoved: loved });
+      }
+    },
+
+    setLastfmLovedForSong: (title, artist, v) => {
+      const cacheKey = `${title}::${artist}`;
+      const isCurrentTrack = get().currentTrack?.title === title && get().currentTrack?.artist === artist;
+      set(s => ({
+        lastfmLovedCache: { ...s.lastfmLovedCache, [cacheKey]: v },
+        ...(isCurrentTrack ? { lastfmLoved: v } : {}),
+      }));
+    },
+  };
+}

src/store/playerStore.ts

@@ -6,7 +6,7 @@ import i18n from '../i18n';
 import { buildStreamUrl, getPlayQueue, savePlayQueue, reportNowPlaying, getSong, getSimilarSongs2, getTopSongs, setRating } from '../api/subsonic';
 import { resolvePlaybackUrl } from '../utils/resolvePlaybackUrl';
 import { setDeferHotCachePrefetch } from '../utils/hotCacheGate';
-import { lastfmUpdateNowPlaying, lastfmLoveTrack, lastfmUnloveTrack, lastfmGetTrackLoved, lastfmGetAllLovedTracks } from '../api/lastfm';
+import { lastfmUpdateNowPlaying, lastfmGetTrackLoved } from '../api/lastfm';
 import { useAuthStore } from './authStore';
 import { useOfflineStore } from './offlineStore';
 import { useHotCacheStore } from './hotCacheStore';
@@ -174,6 +174,7 @@ export {
 import type { PlayerState, Track } from './playerStoreTypes';
 export type { PlayerState, Track };
 import { applyQueueHistorySnapshot } from './applyQueueHistorySnapshot';
+import { createLastfmActions } from './lastfmActions';
 
 
 // ─── Module-level playback primitives ─────────────────────────────────────────
@@ -257,54 +258,7 @@ export const usePlayerStore = create<PlayerState>()(
       },
       toggleFullscreen: () => set(state => ({ isFullscreenOpen: !state.isFullscreenOpen })),
 
-      toggleLastfmLove: () => {
-        const { currentTrack, lastfmLoved } = get();
-        const { lastfmSessionKey } = useAuthStore.getState();
-        if (!currentTrack || !lastfmSessionKey) return;
-        const newLoved = !lastfmLoved;
-        const cacheKey = `${currentTrack.title}::${currentTrack.artist}`;
-        set(s => ({ lastfmLoved: newLoved, lastfmLovedCache: { ...s.lastfmLovedCache, [cacheKey]: newLoved } }));
-        if (newLoved) {
-          lastfmLoveTrack(currentTrack, lastfmSessionKey);
-        } else {
-          lastfmUnloveTrack(currentTrack, lastfmSessionKey);
-        }
-      },
-
-      setLastfmLoved: (v) => {
-        const { currentTrack } = get();
-        if (currentTrack) {
-          const cacheKey = `${currentTrack.title}::${currentTrack.artist}`;
-          set(s => ({ lastfmLoved: v, lastfmLovedCache: { ...s.lastfmLovedCache, [cacheKey]: v } }));
-        } else {
-          set({ lastfmLoved: v });
-        }
-      },
-
-      syncLastfmLovedTracks: async () => {
-        const { lastfmSessionKey, lastfmUsername } = useAuthStore.getState();
-        if (!lastfmSessionKey || !lastfmUsername) return;
-        const tracks = await lastfmGetAllLovedTracks(lastfmUsername, lastfmSessionKey);
-        const newCache: Record<string, boolean> = {};
-        for (const t of tracks) newCache[`${t.title}::${t.artist}`] = true;
-        // Merge with existing cache (local likes take precedence)
-        set(s => ({ lastfmLovedCache: { ...newCache, ...s.lastfmLovedCache } }));
-        // Update current track's loved state if it's in the new cache
-        const { currentTrack } = get();
-        if (currentTrack) {
-          const loved = newCache[`${currentTrack.title}::${currentTrack.artist}`] ?? false;
-          set({ lastfmLoved: loved });
-        }
-      },
-
-      setLastfmLovedForSong: (title, artist, v) => {
-        const cacheKey = `${title}::${artist}`;
-        const isCurrentTrack = get().currentTrack?.title === title && get().currentTrack?.artist === artist;
-        set(s => ({
-          lastfmLovedCache: { ...s.lastfmLovedCache, [cacheKey]: v },
-          ...(isCurrentTrack ? { lastfmLoved: v } : {}),
-        }));
-      },
+      ...createLastfmActions(set, get),
 
       toggleRepeat: () => set(state => {
         const modes = ['off', 'all', 'one'] as const;