feat(pc): 详情页增加吸顶返回列表按钮，首页按筛选签名恢复滚动位置

frontend/src/features/listings/views/HomeView.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
 import { computed, ref, watch } from 'vue'
-import { RouterLink, useRoute, useRouter } from 'vue-router'
+import { RouterLink, onBeforeRouteLeave, useRoute, useRouter } from 'vue-router'
 import {
   defaultAWRecycleConfig,
   defaultHomeAnnouncements,
@@ -164,6 +164,7 @@ async function loadHome() {
     publishOptions.value = emptyListingPublishOptions
   } finally {
     loading.value = false
+    restorePcHomeScroll()
   }
 }
 
@@ -268,6 +269,63 @@ function buildDesktopHomeQueryValues(): Record<string, HomeQueryValue> {
   }
 }
 
+// ========== PC 首页滚动位置持久化 ==========
+// 详情页返回/浏览器后退时，首页列表异步加载导致页面高度不足，
+// vue-router 的 savedPosition 恢复会被浏览器钳制到错误位置，
+// 因此按「筛选签名」显式保存/恢复滚动位置，确保回到上次筛选的位置。
+const pcHomeScrollStorageKey = 'hfb.home.scroll.desktop'
+
+function savePcHomeScroll() {
+  try {
+    window.sessionStorage.setItem(
+      pcHomeScrollStorageKey,
+      JSON.stringify({ signature: desktopHomeStateSignature(), top: window.scrollY })
+    )
+  } catch {
+    // sessionStorage 不可用时忽略，仅损失滚动恢复
+  }
+}
+
+function restorePcHomeScroll() {
+  let savedTop = 0
+  let savedSignature = ''
+  try {
+    const raw = window.sessionStorage.getItem(pcHomeScrollStorageKey)
+    if (raw) {
+      const parsed = JSON.parse(raw) as { signature?: string; top?: number }
+      if (typeof parsed.signature === 'string' && typeof parsed.top === 'number') {
+        savedSignature = parsed.signature
+        savedTop = parsed.top
+      }
+    }
+  } catch {
+    return
+  }
+  // 仅当返回时的筛选条件与离开时一致才恢复，避免把滚动带到别的筛选结果上
+  if (savedTop <= 0 || savedSignature !== desktopHomeStateSignature()) return
+
+  let attempts = 0
+  const apply = () => {
+    const maxTop = Math.max(0, document.documentElement.scrollHeight - window.innerHeight)
+    if (savedTop <= maxTop) {
+      window.scrollTo({ top: savedTop })
+      return
+    }
+    // 首页无限滚动分页：已渲染高度不足时继续加载一页后重试，尽量恢复到位
+    if (attempts < 5 && hasMoreListings.value && !loadingMore.value) {
+      attempts += 1
+      void loadListingsPage(false).then(() => requestAnimationFrame(apply))
+    } else {
+      window.scrollTo({ top: maxTop })
+    }
+  }
+  requestAnimationFrame(apply)
+}
+
+onBeforeRouteLeave(() => {
+  savePcHomeScroll()
+})
+
 syncHomeQuery()
 loadHome()
 </script>