diff --git a/src/main/java/com/imutil/service/impl/SyncServiceImpl.java b/src/main/java/com/imutil/service/impl/SyncServiceImpl.java
index 82d2f11..1797a9a 100644
--- a/src/main/java/com/imutil/service/impl/SyncServiceImpl.java
+++ b/src/main/java/com/imutil/service/impl/SyncServiceImpl.java
@@ -85,6 +85,10 @@ public class SyncServiceImpl implements SyncService {
     @Inject("${imutil.sync.groupMsgMaxPages:500}")
     private int groupMsgMaxPages;
 
+    /** 单次同步群组数量上限（同步阻塞 HTTP，避免海量群卡死；如需全量调大） */
+    @Inject("${imutil.sync.maxGroups:500}")
+    private int maxGroups;
+
     /** 数据源密钥解析结果 */
     private static class SyncCtx {
         long sdkAppId;
@@ -158,7 +162,9 @@ public class SyncServiceImpl implements SyncService {
                 ONode groupIds = root.get("GroupIdList");
                 int n = groupIds.size();
                 for (int i = 0; i < n; i++) {
-                    String groupId = groupIds.get(i).getString();
+                    // 实测 GroupIdList 元素为对象 {GroupId:"..."}，兼容字符串形态
+                    ONode gidNode = groupIds.get(i);
+                    String groupId = gidNode.isObject() ? gidNode.get("GroupId").getString() : gidNode.getString();
                     if (groupId == null || groupId.isEmpty()) {
                         continue;
                     }
@@ -168,7 +174,12 @@ public class SyncServiceImpl implements SyncService {
                             upserted++;
                         }
                     } catch (Exception ge) {
-                        log.warn("同步单群失败 {} : {}", groupId, ge.getMessage());
+                        log.warn("同步单群失败 {} : {}", groupId, ge.toString());
+                    }
+                    // 达上限停止（for 内精确限制，避免单页海量群卡死同步 HTTP）
+                    if (total >= maxGroups) {
+                        log.warn("群组同步达上限 {}，停止（调大 imutil.sync.maxGroups 可继续）", maxGroups);
+                        break;
                     }
                 }
                 task.setTotalCount((long) total);
@@ -176,10 +187,16 @@ public class SyncServiceImpl implements SyncService {
                 task.setPosCursor("page:" + guard);
                 migrateTaskMapper.updateById(task);
 
-                next = root.get("Next").getString();
-                if (next == null || next.isEmpty()) {
+                // 达上限停止（由 for 内触发并告警，此处仅跳出 while）
+                if (total >= maxGroups) {
                     break;
                 }
+                // Next 游标推进；为空或未变化则结束（防死循环）
+                String respNext = root.get("Next").getString();
+                if (respNext == null || respNext.isEmpty() || respNext.equals(next)) {
+                    break;
+                }
+                next = respNext;
             }
             task.setStatus(3);
             task.setFinishedAt(OffsetDateTime.now());
@@ -363,11 +380,11 @@ public class SyncServiceImpl implements SyncService {
                         }
                         ONode rspList = root.get("RspMsgList");
                         int n = rspList.size();
-                        long oldestSeq = 0;
+                        long oldestSeq = Long.MAX_VALUE; // 本页最小 seq（最旧）
                         for (int i = 0; i < n; i++) {
                             ONode m = rspList.get(i);
                             long seq = m.get("MsgSeq").getLong();
-                            if (seq > oldestSeq) {
+                            if (seq > 0 && seq < oldestSeq) {
                                 oldestSeq = seq;
                             }
                             ImMessage msg = parseGroupMsgForSync(m, ctx.tenantId, groupId);
@@ -384,7 +401,12 @@ public class SyncServiceImpl implements SyncService {
                             imported++;
                         }
                         boolean finished = root.get("IsFinished").getLong() == 1;
-                        if (finished || n == 0 || oldestSeq <= 0) {
+                        // 终止：已拉完 / 空页 / 本页无有效 seq
+                        if (finished || n == 0 || oldestSeq == Long.MAX_VALUE) {
+                            break;
+                        }
+                        // 游标未向更旧方向推进则停（占位消息群 IsFinished 恒为 2，靠此兜底防死循环）
+                        if (reqSeq > 0 && oldestSeq >= reqSeq) {
                             break;
                         }
                         reqSeq = oldestSeq;
@@ -413,6 +435,10 @@ public class SyncServiceImpl implements SyncService {
      * 解析腾讯群消息节点为 ImMessage（source=SYNC，dist_status=1 不进分发）
      */
     private ImMessage parseGroupMsgForSync(ONode m, String tenantId, String groupId) {
+        // 过滤占位/系统消息（IsPlaceMsg=1：From_Account 与 MsgBody 均空，非真实消息，不入库）
+        if (m.get("IsPlaceMsg").getLong() == 1) {
+            return null;
+        }
         long msgSeq = m.get("MsgSeq").getLong();
         long msgRandom = m.get("MsgRandom").getLong();
         long msgTs = m.get("MsgTimeStamp").getLong();
diff --git a/src/main/java/com/imutil/task/SchemaUpgradeBootstrap.java b/src/main/java/com/imutil/task/SchemaUpgradeBootstrap.java
new file mode 100644
index 0000000..048ddfc
--- /dev/null
+++ b/src/main/java/com/imutil/task/SchemaUpgradeBootstrap.java
@@ -0,0 +1,47 @@
+package com.imutil.task;
+
+import com.imutil.mapper.PartitionMapper;
+import lombok.extern.slf4j.Slf4j;
+import org.noear.solon.annotation.Component;
+import org.noear.solon.annotation.Init;
+import org.noear.solon.annotation.Inject;
+
+/**
+ * 数据库 Schema 启动自动升级（幂等）
+ * <p>
+ * 解决"实体加字段但运行库未 ALTER"问题：init.sql 仅新建库时执行，老库不会自动加列，
+ * 导致 MyBatis insert/update 到新列时报 column 不存在。启动时对增量列执行
+ * ADD COLUMN IF NOT EXISTS，老库自动补列，新库重复执行也无副作用。
+ *
+ * @author imutil
+ */
+@Slf4j
+@Component
+public class SchemaUpgradeBootstrap {
+
+    @Inject
+    private PartitionMapper partitionMapper;
+
+    @Init
+    public void init() {
+        // T17: group_mapping/user_mapping 同步资料列
+        String[] ddls = {
+                "ALTER TABLE group_mapping ADD COLUMN IF NOT EXISTS name varchar(256)",
+                "ALTER TABLE group_mapping ADD COLUMN IF NOT EXISTS owner_account varchar(128)",
+                "ALTER TABLE group_mapping ADD COLUMN IF NOT EXISTS member_count int",
+                "ALTER TABLE group_mapping ADD COLUMN IF NOT EXISTS last_synced_at timestamptz",
+                "ALTER TABLE user_mapping ADD COLUMN IF NOT EXISTS nick varchar(128)",
+                "ALTER TABLE user_mapping ADD COLUMN IF NOT EXISTS last_synced_at timestamptz",
+        };
+        int ok = 0;
+        for (String sql : ddls) {
+            try {
+                partitionMapper.execute(sql);
+                ok++;
+            } catch (Exception e) {
+                log.warn("schema升级跳过 [{}] : {}", sql, e.getMessage());
+            }
+        }
+        log.info("启动 schema 升级完成（{}/{} 条 DDL）", ok, ddls.length);
+    }
+}
diff --git a/src/main/java/com/imutil/tencent/TencentImClient.java b/src/main/java/com/imutil/tencent/TencentImClient.java
index d389bcd..1cd11e0 100644
--- a/src/main/java/com/imutil/tencent/TencentImClient.java
+++ b/src/main/java/com/imutil/tencent/TencentImClient.java
@@ -379,8 +379,9 @@ public class TencentImClient {
      * @return 腾讯响应原始 JSON，由调用方解析
      */
     public String getGroupInfo(String groupId, long srcSdkAppId, String srcSecretKey) {
+        // 腾讯 get_group_info 要求 GroupIdList: ["groupId"]（字符串数组，元素须为 string）
         Map<String, Object> body = new HashMap<>();
-        body.put("GroupId", List.of(groupId));
+        body.put("GroupIdList", List.of(groupId));
         return callApiAs("group_open_http_svc/get_group_info", Jsons.stringify(body), srcSdkAppId, srcSecretKey);
     }