fix(public): unify family representative selection with detail endpoint

List/home endpoints picked the family representative row via goods[0],
which drifted with the list sort parameter (cheapest under PRICE_ASC,
lowest id under DEFAULT ties), causing goodName and other
representative-derived fields to differ from the detail endpoint.
Extract pickFamilyRepresentative (goodPriority desc -> createdAt desc
-> id asc, same as getGoodByFamilyId) and use it in getGoods and
getHomeGoods grouping. Group ordering and API contracts unchanged.

apps/api/src/public/public.service.spec.ts

@@ -728,4 +728,118 @@ describe('PublicService', () => {
       expect(idx.indexOf(orderedFamilyIds[2])).toBeLessThan(idx.indexOf(orderedFamilyIds[3]));
     });
   });
+
+  describe('family representative row consistency (列表/首页代表行对齐详情)', () => {
+    // 同族两条 Good：同 priority=10，Low 的 id 更小/createdAt 更早/价格更低/位置更好，
+    // High 的 createdAt 更新。详情代表行规则 = priority desc → createdAt desc → id asc
+    // → 详情永远取 High；列表/首页必须与详情一致，而不是随排序参数漂移到 Low。
+    const stamp3 = `${stamp}-rep`;
+    let repFamilyId: bigint;
+    let trash = {
+      goodIds: [] as bigint[],
+      positionIds: [] as bigint[],
+      originGoodIds: [] as bigint[],
+    };
+    const repLowName = `Rep Low ${stamp3}`;
+    const repHighName = `Rep High ${stamp3}`;
+
+    beforeAll(async () => {
+      const posLow = await prisma.position.create({
+        data: { indexVal: 1, countryId, categoryId },
+      });
+      const posHigh = await prisma.position.create({
+        data: { indexVal: 5, countryId, categoryId },
+      });
+      trash.positionIds = [posLow.id, posHigh.id];
+
+      const ogLow = await prisma.originGood.create({
+        data: { sdsGoodId: `rep-low-${stamp3}`, goodName: repLowName, goodPrice: 10 },
+      });
+      const ogHigh = await prisma.originGood.create({
+        data: { sdsGoodId: `rep-high-${stamp3}`, goodName: repHighName, goodPrice: 20 },
+      });
+      trash.originGoodIds = [ogLow.id, ogHigh.id];
+
+      const family = await prisma.productFamily.create({
+        data: { familyName: `rep-fam-${stamp3}`, primaryOriginGoodId: ogLow.id },
+      });
+      repFamilyId = family.id;
+      await prisma.originGood.updateMany({
+        where: { id: { in: [ogLow.id, ogHigh.id] } },
+        data: { familyId: family.id },
+      });
+
+      const gLow = await prisma.good.create({
+        data: {
+          goodName: repLowName,
+          originGoodId: ogLow.id,
+          familyId: family.id,
+          countryId,
+          categoryId,
+          goodPriority: 10,
+          positionId: posLow.id,
+          createdAt: new Date(stamp),
+        },
+      });
+      const gHigh = await prisma.good.create({
+        data: {
+          goodName: repHighName,
+          originGoodId: ogHigh.id,
+          familyId: family.id,
+          countryId,
+          categoryId,
+          goodPriority: 10,
+          positionId: posHigh.id,
+          createdAt: new Date(stamp + 60_000),
+        },
+      });
+      trash.goodIds = [gLow.id, gHigh.id];
+    });
+
+    afterAll(async () => {
+      await prisma.good.deleteMany({ where: { id: { in: trash.goodIds } } }).catch(() => undefined);
+      await prisma.position
+        .deleteMany({ where: { id: { in: trash.positionIds } } })
+        .catch(() => undefined);
+      await prisma.productFamily.delete({ where: { id: repFamilyId } }).catch(() => undefined);
+      await prisma.originGood
+        .deleteMany({ where: { id: { in: trash.originGoodIds } } })
+        .catch(() => undefined);
+    });
+
+    it('DEFAULT 列表代表行与详情一致（priority 并列时取 createdAt 最新，而非 id 最小）', async () => {
+      const detail = await service.getGood(repFamilyId.toString());
+      expect(detail.goodName).toBe(repHighName);
+
+      const list = await service.getGoods({
+        page: 1,
+        pageSize: 50,
+        keyword: 'Rep ', // 本文件夹具唯一前缀，圈定本族（goodName: Rep Low/High）
+      });
+      const ours = list.items.filter((i) => i.goodId === repFamilyId.toString());
+      expect(ours).toHaveLength(1);
+      expect(ours[0].goodName).toBe(detail.goodName);
+    });
+
+    it('PRICE_ASC 列表代表行不漂移到价格更低的成员', async () => {
+      const detail = await service.getGood(repFamilyId.toString());
+      const list = await service.getGoods({
+        page: 1,
+        pageSize: 50,
+        keyword: 'Rep ',
+        sort: 'PRICE_ASC',
+      });
+      const ours = list.items.filter((i) => i.goodId === repFamilyId.toString());
+      expect(ours).toHaveLength(1);
+      expect(ours[0].goodName).toBe(detail.goodName);
+    });
+
+    it('home-goods 代表行与详情一致（不取位置更好的成员）', async () => {
+      const detail = await service.getGood(repFamilyId.toString());
+      const home = await service.getHomeGoods({ limit: 50, countryId: countryId.toString() });
+      const ours = home.filter((h) => h.goodId === repFamilyId.toString());
+      expect(ours).toHaveLength(1);
+      expect(ours[0].goodName).toBe(detail.goodName);
+    });
+  });
 });

apps/api/src/public/public.service.ts

@@ -254,7 +254,7 @@ export class PublicService {
       else grouped.set(key, [good]);
     }
     let items = [...grouped.values()].map((goods) => {
-      const rep = goods[0];
+      const rep = this.pickFamilyRepresentative(goods);
       const dto = this.toPublicGood(rep);
       // 列表价 = 族矩阵最低价（"这个款之下有哪些价格"的起价）；无矩阵回退链接价
       const familyMin = rep.familyId
@@ -421,16 +421,20 @@ export class PublicService {
       take: query.limit,
     });
     const familyMinPrices = await this.loadFamilyMinPrices();
-    // 首页同样按族去重（同族多条位置配置只保留排序最前一条），再截取 limit
-    const seen = new Set<string>();
-    const items: PublicGoodDto[] = [];
+    // 首页同样按族去重（一族只出一条），代表行选取与详情/列表一致
+    const grouped = new Map<string, PublicGoodListRow[]>();
     for (const good of rows) {
       const key = good.familyId ? `f:${good.familyId}` : `g:${good.id}`;
-      if (seen.has(key)) continue;
-      seen.add(key);
-      const dto = this.toPublicGood(good);
-      const familyMin = good.familyId
-        ? familyMinPrices.get(good.familyId.toString())
+      const bucket = grouped.get(key);
+      if (bucket) bucket.push(good);
+      else grouped.set(key, [good]);
+    }
+    const items: PublicGoodDto[] = [];
+    for (const goods of grouped.values()) {
+      const rep = this.pickFamilyRepresentative(goods);
+      const dto = this.toPublicGood(rep);
+      const familyMin = rep.familyId
+        ? familyMinPrices.get(rep.familyId.toString())
         : undefined;
       if (familyMin !== undefined) dto.price = familyMin;
       items.push(dto);
@@ -438,6 +442,22 @@ export class PublicService {
     return items.slice(0, query.limit);
   }
 
+  /**
+   * 族代表行选取：与详情 getGoodByFamilyId 的 orderBy 保持一致
+   * （goodPriority desc → createdAt desc → id asc），
+   * 保证列表/首页与详情返回的 goodName、主图、分类等代表行字段一致。
+   */
+  private pickFamilyRepresentative<T extends { goodPriority: number | null; createdAt: Date; id: bigint }>(
+    goods: T[],
+  ): T {
+    return [...goods].sort(
+      (a, b) =>
+        (b.goodPriority ?? 0) - (a.goodPriority ?? 0) ||
+        b.createdAt.getTime() - a.createdAt.getTime() ||
+        (a.id < b.id ? -1 : a.id > b.id ? 1 : 0),
+    )[0];
+  }
+
   /** 入参用精简行类型：列表（PublicGoodListRow）与详情（PublicGoodRow，字段超集）都能传 */
   private toPublicGood(good: PublicGoodListRow): PublicGoodDto {
     const formatGroup = (group: { id: bigint; groupName: string; sortOrder: number } | null) =>