fix: apply both solo bonuses to FUWAMOCO songs

src/lib/engine/board-effects.test.ts

@@ -27,6 +27,38 @@ const cards = [
   { id: 'card-b', characterId: 'b', type: '퓨어', generation: '1기생' }
 ];
 
+test('FUWAMOCO 악곡은 두 멤버의 솔로 보너스를 합산하고 단체 보너스를 제외한다', () => {
+  const sisters = ['chr-04016', 'chr-04017'];
+  const songSummary: BoardSummarySource = {
+    nodeGroups: Object.fromEntries(['solo', 'solo-fuwamoko', 'group'].map((mode) => [
+      `Y-${mode}`,
+      [{ characterIds: [], effect: {
+        id: `music_singer_type-${mode}`,
+        type: 'live_score_bonus_add_permil_up_by_music_skill_tree_character_and_music_singer_type',
+        value: 5
+      } }]
+    ]))
+  };
+  const bonus = (singerCharacterIds: string[], singerType: string, mode: string, owners = sisters) =>
+    calculateBoardEffects(songSummary, Object.fromEntries(owners.map((id) => [id, [`Y-${mode}`]])),
+      [], '', { singerType, singerCharacterIds }).directSongScoreBonusPercent;
+
+  for (const singerType of ['solo', 'group']) {
+    for (const mode of ['solo', 'solo-fuwamoko']) {
+      assert.equal(bonus(sisters, singerType, mode), 1);
+      for (const sister of sisters) assert.equal(bonus(sisters, singerType, mode, [sister]), 0.5);
+      assert.equal(bonus([...sisters, 'other'], 'group', mode), 0);
+      assert.equal(bonus(sisters, singerType, mode, ['other']), 0);
+    }
+    assert.equal(bonus(sisters, singerType, 'group'), 0);
+  }
+  for (const sister of sisters) {
+    assert.equal(bonus([sister], 'solo', 'solo'), 0.5);
+    assert.equal(bonus([sister], 'solo', 'solo-fuwamoko'), 0);
+  }
+  assert.equal(bonus([...sisters, 'other'], 'group', 'group'), 1);
+});
+
 test('JP 3기생 보너스가 코보의 ID 3기생 보너스 상한을 소모하지 않는다', () => {
   const summary: BoardSummarySource = {
     nodeGroups: {

src/lib/engine/board-effects.ts

@@ -75,10 +75,14 @@ function songBonusApplies(effect: BoardEffect, ownerId: string, song?: BoardEffe
   if (!effect.id) return false;
   const expectedType = effect.id.match(/music_singer_type-(all|group|solo)/)?.[1];
   if (expectedType === 'all') return true;
-  if (!song || expectedType !== song.singerType) return false;
+  if (!song) return false;
   const singers = song.singerCharacterIds ?? [];
+  // FUWAMOCO-only songs count as solo songs for both sisters.
+  const isFuwamoco = singers.length === 2 && singers.includes('chr-04016') && singers.includes('chr-04017');
+  const singerType = isFuwamoco ? 'solo' : song.singerType;
+  if (expectedType !== singerType) return false;
   if (effect.id.endsWith('-fuwamoko')) {
-    return singers.length === 2 && singers.includes('chr-04016') && singers.includes('chr-04017');
+    return isFuwamoco && singers.includes(ownerId);
   }
   return singers.includes(ownerId);
 }