diff --git a/src/main/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImpl.java b/src/main/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImpl.java
index b508c08..a22b882 100644
--- a/src/main/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImpl.java
+++ b/src/main/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImpl.java
@@ -65,7 +65,7 @@ public class CmsSiteDirectoryImpl implements SiteDirectory {
                 // 由 CmsSiteDirectoryImplTest 冻结）。仅用于 siteCode 反解，权限判定仍走 requireSchoolMember。
                 sites = fetchSites(null);
             } catch (Exception e) {
-                log.warn("[svc-hall] CMS 站点目录不可达：{}", e.getMessage());
+                log.warn("[svc-hall] CMS 站点目录不可达：{}{}", e.getMessage(), rootCauseBrief(e));
                 return null;
             }
             if (sites != null) {
@@ -93,7 +93,8 @@ public class CmsSiteDirectoryImpl implements SiteDirectory {
             try {
                 return fetchSites(schId);
             } catch (Exception e) {
-                log.warn("[svc-hall] CMS 站点列表获取失败(schId={})：{}", schId, e.getMessage());
+                log.warn("[svc-hall] CMS 站点列表获取失败(schId={})：{}{}",
+                        schId, e.getMessage(), rootCauseBrief(e));
                 throw new BizException(ErrorCode.PARAM_ERROR, "站点服务不可达，请稍后重试");
             }
         });
@@ -124,6 +125,20 @@ public class CmsSiteDirectoryImpl implements SiteDirectory {
         return s;
     }
 
+    /**
+     * 最内层原因摘要。SDK 的 "OpenAPI request failed: ioError" 只说明请求没拿到响应，
+     * 真正的原因是 cause 链末端的 ConnectException/SocketTimeoutException/SSLException；
+     * 不补这一段，日志里永远分不清"对端没起"和"读超时"。
+     * 包可见：契约测试直接断言摘要形态。
+     */
+    static String rootCauseBrief(Throwable e) {
+        Throwable cur = e;
+        while (cur.getCause() != null && cur.getCause() != cur) {
+            cur = cur.getCause();
+        }
+        return cur == e ? "" : "（根因 " + cur.getClass().getSimpleName() + ": " + cur.getMessage() + "）";
+    }
+
     /** resolveSite 的全量缓存键（与真实 schId 不冲突的哨兵） */
     private static final String ALL_SITES_KEY = "-1";
 }
diff --git a/src/test/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImplTest.java b/src/test/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImplTest.java
index c58df60..c0caab8 100644
--- a/src/test/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImplTest.java
+++ b/src/test/java/com/yunhai/svchall/service/impl/CmsSiteDirectoryImplTest.java
@@ -123,4 +123,20 @@ class CmsSiteDirectoryImplTest {
     void listSites_rejectsNullSchId() {
         assertThrows(BizException.class, () -> directory.listSites(null));
     }
+
+    @Test
+    @DisplayName("rootCauseBrief：ioError 包装层要透出最内层原因（区分\"对端没起\"与\"读超时\"）")
+    void rootCauseBrief_exposesInnermostCause() {
+        // 无 cause：不追加，避免与 e.getMessage() 重复
+        assertEquals("", CmsSiteDirectoryImpl.rootCauseBrief(
+                new RuntimeException("OpenAPI request failed: ioError")));
+
+        // 实际形态：OpenApiException(ioError) ← ResourceAccessException ← ConnectException
+        java.net.ConnectException refused = new java.net.ConnectException("Connection refused: connect");
+        Exception wrapped = new RuntimeException("OpenAPI request failed: ioError",
+                new RuntimeException("I/O error on GET request", refused));
+        String brief = CmsSiteDirectoryImpl.rootCauseBrief(wrapped);
+        assertTrue(brief.contains("ConnectException"), brief);
+        assertTrue(brief.contains("Connection refused: connect"), brief);
+    }
 }