diff --git a/src/App.vue b/src/App.vue
index d60ea30..d64fb01 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -12,9 +12,12 @@ import { onMounted, ref } from "vue";
 import { baseApi } from "@/api/module/base";
 import config from "@/assets/config/host.config";
 import { applyTheme, resolveTheme, type ThemeManifest } from "@/utils/theme";
+import { useSite } from "@/utils/site";
 
 const userName = ref("");
 const theme = ref<ThemeManifest>(resolveTheme(null));
+// CMS 指南页来路（T4 回跳闭环）：仅 /#/apply 深链带合法 from 参数时非空
+const { portalFrom } = useSite();
 
 onMounted(async () => {
     // 皮肤先应用（首屏观感），再拉用户信息——用户信息失败不影响办理页面使用
@@ -41,6 +44,7 @@ onMounted(async () => {
             <nav class="sh-nav">
                 <router-link to="/hall">办事大厅</router-link>
                 <router-link to="/my">我的办件</router-link>
+                <a v-if="portalFrom" :href="portalFrom" class="sh-back-portal">返回门户</a>
             </nav>
             <span class="sh-user" v-if="userName">{{ userName }}</span>
         </header>
diff --git a/src/assets/styles/theme-base.css b/src/assets/styles/theme-base.css
index aa1d262..969d745 100644
--- a/src/assets/styles/theme-base.css
+++ b/src/assets/styles/theme-base.css
@@ -80,6 +80,12 @@ body {
     background: rgba(255, 255, 255, 0.22);
     font-weight: 600;
 }
+/* 返回门户（T4 回跳闭环）：外跳文字链，与 nav 同风格白字，加分隔线区分站内导航。
+   方案原文写 var(--sh-primary)，但 nav 位于主色底 header 上会隐形，故取 nav 现有风格。 */
+.sh-header .sh-nav a.sh-back-portal {
+    border-left: 1px solid rgba(255, 255, 255, 0.35);
+    border-radius: 0;
+}
 .sh-user {
     margin-left: 16px;
     font-size: 13px;
diff --git a/src/utils/site.ts b/src/utils/site.ts
index 876ed2c..b6d4c27 100644
--- a/src/utils/site.ts
+++ b/src/utils/site.ts
@@ -13,6 +13,8 @@ import config from "@/assets/config/host.config";
  */
 const currentSiteCode = ref<string>(localStorage.getItem("svchall.public.site") || "");
 const lastItemCode = ref<string>(localStorage.getItem("svchall.public.item") || "");
+/** CMS 指南页来路（session 级内存，不落 localStorage——回跳是"这一次来的路"，不是偏好） */
+const portalFrom = ref<string>("");
 
 export function useSite() {
     /** 从 query / 运行时配置 / 本地记忆依次解析站点，命中即记住 */
@@ -29,6 +31,28 @@ export function useSite() {
         return hit;
     }
 
+    /**
+     * 解析并校验 from 参数（CMS 指南页深链带回，T4 回跳闭环）：
+     * 仅接受 http/https 且 hostname 属于本部署可信域（当前页域名或 baseHost）的 URL，否则忽略——
+     * 防 javascript: 伪协议与外域注入。
+     */
+    function resolveFrom(queryFrom?: unknown): string {
+        const raw = typeof queryFrom === "string" ? queryFrom.trim() : "";
+        if (!raw) return "";
+        try {
+            const u = new URL(raw);
+            if (u.protocol !== "http:" && u.protocol !== "https:") return "";
+            const mine = location.hostname;
+            const base = String(config.baseHost || "");
+            const baseHost = base ? new URL(base).hostname : "";
+            if (u.hostname !== mine && (!baseHost || u.hostname !== baseHost)) return "";
+            portalFrom.value = raw;
+        } catch {
+            // 非法 URL 当没有
+        }
+        return portalFrom.value;
+    }
+
     function setSite(siteCode: string) {
         currentSiteCode.value = siteCode;
         if (siteCode) {
@@ -44,5 +68,5 @@ export function useSite() {
         }
     }
 
-    return { currentSiteCode, lastItemCode, resolveSite, setSite, rememberItem };
+    return { currentSiteCode, lastItemCode, portalFrom, resolveSite, resolveFrom, setSite, rememberItem };
 }
diff --git a/src/views/Apply.vue b/src/views/Apply.vue
index ad02838..4f7662d 100644
--- a/src/views/Apply.vue
+++ b/src/views/Apply.vue
@@ -19,7 +19,7 @@ import { useSite } from "@/utils/site";
 import DynamicForm from "@/components/DynamicForm.vue";
 const route = useRoute();
 const router = useRouter();
-const { resolveSite, rememberItem } = useSite();
+const { resolveSite, resolveFrom, rememberItem } = useSite();
 
 /** 轮询参数：代发起 + 回调一般在 1s 内完成，给到 ~9s 足够，避免用户盯着"待提交"发懵 */
 const POLL_TIMES = 12;
@@ -37,6 +37,8 @@ const schemaJson = computed(() => (item.value?.schemaJson as string) || "");
 
 async function load() {
     siteCode.value = resolveSite(route.query.siteCode);
+    // CMS 指南页来路（T4）：校验通过即记入 session，App.vue 顶栏渲染"返回门户"
+    resolveFrom(route.query.from);
     const itemCode = String(route.query.itemCode || "");
     if (!siteCode.value || !itemCode) {
         loadError.value = "缺少 siteCode/itemCode 参数";