fix(W3): 预览资产代理前缀拼 request.getContextPath(/yschcms 下 CSS 404 裸 HTML),T-W3-01..04 全绿+全量 264/264

src/test/java/com/yunhai/cms/utils/PortalUrlHelperTest.java

@@ -149,6 +149,37 @@ class PortalUrlHelperTest {
         assertThat(url.rewriteUploadUrls(null)).isNull();
     }
 
+    // ===== forPreview 预览资产前缀（W3：context-path 修复，方案 §7.3）=====
+
+    @Test
+    @DisplayName("T-W3-01: forPreview 带上下文：资产前缀含 contextPath")
+    void forPreview_assetPrefixCarriesContextPath() {
+        PortalUrlHelper url = PortalUrlHelper.forPreview(
+                request("http", "base.yunhaixingtong.com", 80, "/yschcms"), "demo", "scholar-blue");
+        assertThat(url.asset("css/main.css"))
+                .isEqualTo("/yschcms/api/theme/scholar-blue/asset/css/main.css");
+    }
+
+    @Test
+    @DisplayName("T-W3-02: forPreview 空上下文退化：前缀 /api/theme/…（dev 形态不回归）")
+    void forPreview_emptyContextFallsBackToRootPrefix() {
+        PortalUrlHelper url = PortalUrlHelper.forPreview(
+                request("http", "localhost", 8072, ""), "demo", "t-demo-red");
+        assertThat(url.asset("css/main.css"))
+                .isEqualTo("/api/theme/t-demo-red/asset/css/main.css");
+    }
+
+    @Test
+    @DisplayName("T-W3-03: forPreview 站内链接不受资产前缀串味（home/category 仍指真实门户）")
+    void forPreview_homeStaysRealPortal() {
+        PortalUrlHelper url = PortalUrlHelper.forPreview(
+                request("http", "base.yunhaixingtong.com", 80, "/yschcms"), "demo", "scholar-blue");
+        assertThat(url.home()).isEqualTo("http://base.yunhaixingtong.com/yschcms/portal/demo/");
+        assertThat(url.category(3)).isEqualTo("http://base.yunhaixingtong.com/yschcms/portal/demo/c/3");
+        assertThat(url.search("x", null))
+                .isEqualTo("http://base.yunhaixingtong.com/yschcms/portal/demo/search?q=x");
+    }
+
     // ===== siteHome 分支（B-4：学校域形态下未配域子站不再退化为 "/"）=====
 
     @Test