diff --git a/docs/script/sql/update/2026-07-24-register-default-role-and-missing-menus.sql b/docs/script/sql/update/2026-07-24-register-default-role-and-missing-menus.sql
new file mode 100644
index 00000000..fcaa1fbc
--- /dev/null
+++ b/docs/script/sql/update/2026-07-24-register-default-role-and-missing-menus.sql
@@ -0,0 +1,119 @@
+-- 注册链路修复：补齐缺失的菜单权限标识 + 新建注册默认角色
+-- 关联问题：
+--   #3 注册用户无默认角色 -> 无权限访问 AI 对话界面
+--   #4 sys_menu 缺 system:session:* / system:attach:* / system:fragment:*，
+--      且 知识管理 父菜单 perms 为 knowledge:info:list，与控制器
+--      KnowledgeInfoController 用的 system:info:list 对不上，:list 无法授权。
+-- 本脚本幂等，可重复执行（INSERT IGNORE + UPDATE 天然幂等）。
+-- 新增 menu_id / role_id / config_id 统一使用 2099010100000000xxx 段，
+-- 与现有 snowflake id（2xxxxxxxxxxxxxxxxx）不冲突。
+
+-- ============================================================
+-- 1. 修正 知识管理 父菜单权限标识：knowledge:info:list -> system:info:list
+-- ============================================================
+UPDATE `sys_menu`
+SET `perms` = 'system:info:list'
+WHERE `menu_id` = 2006681261898813441 AND `perms` = 'knowledge:info:list';
+
+-- ============================================================
+-- 2. 新增 会话管理 菜单组（system:session:*）
+--    父菜单=对话管理(2000209300188356609)。
+--    管理端暂无 chat/session 页面，故 C 菜单设为隐藏(visible=1)，
+--    权限标识仍可在角色管理中授权给用户端使用。
+-- ============================================================
+INSERT IGNORE INTO `sys_menu` VALUES
+(2099010100000000001, '会话管理', 2000209300188356609, 6, 'session', NULL, NULL, 1, 0, 'C', '1', '0', 'system:session:list', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '会话管理菜单'),
+(2099010100000000002, '会话管理查询', 2099010100000000001, 1, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:session:query', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000003, '会话管理新增', 2099010100000000001, 2, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:session:add', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000004, '会话管理修改', 2099010100000000001, 3, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:session:edit', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000005, '会话管理删除', 2099010100000000001, 4, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:session:remove', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000006, '会话管理导出', 2099010100000000001, 5, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:session:export', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '');
+
+-- ============================================================
+-- 3. 新增 知识附件 菜单组（system:attach:*）
+--    父菜单=对话管理(2000209300188356609)，组件对应管理端 knowledge/attach/index。
+-- ============================================================
+INSERT IGNORE INTO `sys_menu` VALUES
+(2099010100000000010, '知识附件', 2000209300188356609, 7, 'attach', 'knowledge/attach/index', NULL, 1, 0, 'C', '0', '0', 'system:attach:list', 'ant-design:paper-clip-outlined', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '知识附件菜单'),
+(2099010100000000011, '知识附件查询', 2099010100000000010, 1, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:attach:query', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000012, '知识附件新增', 2099010100000000010, 2, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:attach:add', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000013, '知识附件修改', 2099010100000000010, 3, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:attach:edit', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000014, '知识附件删除', 2099010100000000010, 4, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:attach:remove', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000015, '知识附件导出', 2099010100000000010, 5, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:attach:export', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '');
+
+-- ============================================================
+-- 4. 新增 知识片段 菜单组（system:fragment:*）
+--    父菜单=对话管理(2000209300188356609)，组件对应管理端 knowledge/fragment/index。
+-- ============================================================
+INSERT IGNORE INTO `sys_menu` VALUES
+(2099010100000000020, '知识片段', 2000209300188356609, 8, 'fragment', 'knowledge/fragment/index', NULL, 1, 0, 'C', '0', '0', 'system:fragment:list', 'ant-design:file-text-outlined', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '知识片段菜单'),
+(2099010100000000021, '知识片段查询', 2099010100000000020, 1, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:fragment:query', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000022, '知识片段新增', 2099010100000000020, 2, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:fragment:add', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000023, '知识片段修改', 2099010100000000020, 3, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:fragment:edit', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000024, '知识片段删除', 2099010100000000020, 4, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:fragment:remove', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, ''),
+(2099010100000000025, '知识片段导出', 2099010100000000020, 5, '#', '', NULL, 1, 0, 'F', '0', '0', 'system:fragment:export', '#', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '');
+
+-- ============================================================
+-- 5. 新建 普通用户 角色（租户 000000，data_scope=5 仅本人）
+-- ============================================================
+INSERT IGNORE INTO `sys_role` VALUES
+(2099010100000000030, '000000', '普通用户', 'user', 2, '5', 1, 1, '0', '0', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '注册用户默认角色');
+
+-- ============================================================
+-- 6. 角色-菜单关联：普通用户 拥有用户端 AI 对话所需权限
+--    会话管理(001-006) + 聊天消息(2000210914680823809 及 810-814)
+--    + 知识管理(2006681261898813441 及 442-446)
+--    + 知识附件(010-015) + 知识片段(020-025)
+-- ============================================================
+INSERT IGNORE INTO `sys_role_menu` (`role_id`, `menu_id`) VALUES
+-- 会话管理
+(2099010100000000030, 2099010100000000001),
+(2099010100000000030, 2099010100000000002),
+(2099010100000000030, 2099010100000000003),
+(2099010100000000030, 2099010100000000004),
+(2099010100000000030, 2099010100000000005),
+(2099010100000000030, 2099010100000000006),
+-- 聊天消息
+(2099010100000000030, 2000210914680823809),
+(2099010100000000030, 2000210914680823810),
+(2099010100000000030, 2000210914680823811),
+(2099010100000000030, 2000210914680823812),
+(2099010100000000030, 2000210914680823813),
+(2099010100000000030, 2000210914680823814),
+-- 知识管理
+(2099010100000000030, 2006681261898813441),
+(2099010100000000030, 2006681261898813442),
+(2099010100000000030, 2006681261898813443),
+(2099010100000000030, 2006681261898813444),
+(2099010100000000030, 2006681261898813445),
+(2099010100000000030, 2006681261898813446),
+-- 知识附件
+(2099010100000000030, 2099010100000000010),
+(2099010100000000030, 2099010100000000011),
+(2099010100000000030, 2099010100000000012),
+(2099010100000000030, 2099010100000000013),
+(2099010100000000030, 2099010100000000014),
+(2099010100000000030, 2099010100000000015),
+-- 知识片段
+(2099010100000000030, 2099010100000000020),
+(2099010100000000030, 2099010100000000021),
+(2099010100000000030, 2099010100000000022),
+(2099010100000000030, 2099010100000000023),
+(2099010100000000030, 2099010100000000024),
+(2099010100000000030, 2099010100000000025);
+
+-- ============================================================
+-- 7. 注册默认角色配置项 sys.register.defaultRoleId
+--    后端 SysRegisterService 注册成功后读取此配置为新用户绑定角色；
+--    值为空字符串时不绑定（保留旧行为）。
+-- ============================================================
+INSERT IGNORE INTO `sys_config` VALUES
+(2099010100000000031, '000000', '注册-默认角色ID', 'sys.register.defaultRoleId', '2099010100000000030', 'Y', 103, 1, '2026-07-24 00:00:00', NULL, NULL, '新注册用户绑定的默认角色ID，留空则不绑定');
+
+-- ============================================================
+-- 8. 前置条件（运营项，默认不执行）：开启用户注册
+--    sys.account.registerUser 默认 false，后端 AuthController.register
+--    会据此返回「当前系统没有开启注册功能」。若要开放注册，取消注释执行。
+-- ============================================================
+-- UPDATE `sys_config` SET `config_value` = 'true'
+-- WHERE `config_key` = 'sys.account.registerUser' AND `tenant_id` = '000000';
diff --git a/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/SysRegisterService.java b/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/SysRegisterService.java
index c2912fb7..0a65ce14 100644
--- a/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/SysRegisterService.java
+++ b/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/SysRegisterService.java
@@ -1,5 +1,6 @@
 package org.ruoyi.system.service;
 
+import cn.hutool.core.convert.Convert;
 import cn.hutool.crypto.digest.BCrypt;
 import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
 import lombok.RequiredArgsConstructor;
@@ -35,6 +36,12 @@ public class SysRegisterService {
     private final ISysUserService userService;
     private final SysUserMapper userMapper;
     private final CaptchaProperties captchaProperties;
+    private final ISysConfigService configService;
+
+    /**
+     * 注册默认角色配置 key，值为角色 ID；未配置或为空则不绑定角色。
+     */
+    private static final String DEFAULT_ROLE_CONFIG_KEY = "sys.register.defaultRoleId";
 
     /**
      * 注册
@@ -68,9 +75,27 @@ public class SysRegisterService {
         if (!regFlag) {
             throw new UserException("user.register.error");
         }
+        // 绑定默认角色（未配置则跳过，不影响注册流程）
+        bindDefaultRole(tenantId, sysUser.getUserId());
         recordLogininfor(tenantId, username, Constants.REGISTER, MessageUtils.message("user.register.success"));
     }
 
+    /**
+     * 读取配置 sys.register.defaultRoleId 并为新用户绑定默认角色。
+     * 配置为空或角色 ID 无效时静默跳过。
+     */
+    private void bindDefaultRole(String tenantId, Long userId) {
+        if (userId == null) {
+            return;
+        }
+        Long defaultRoleId = TenantHelper.dynamic(tenantId, () ->
+            Convert.toLong(configService.selectConfigByKey(DEFAULT_ROLE_CONFIG_KEY), null));
+        if (defaultRoleId == null) {
+            return;
+        }
+        userService.insertUserAuth(userId, new Long[]{defaultRoleId});
+    }
+
     /**
      * 校验验证码
      *
diff --git a/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/impl/SysUserServiceImpl.java b/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/impl/SysUserServiceImpl.java
index df494d61..a71a30a9 100644
--- a/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/impl/SysUserServiceImpl.java
+++ b/ruoyi-modules/ruoyi-system/src/main/java/org/ruoyi/system/service/impl/SysUserServiceImpl.java
@@ -333,7 +333,10 @@ public class SysUserServiceImpl implements ISysUserService, UserService {
         user.setUpdateBy(0L);
         SysUser sysUser = MapstructUtils.convert(user, SysUser.class);
         sysUser.setTenantId(tenantId);
-        return baseMapper.insert(sysUser) > 0;
+        boolean rows = baseMapper.insert(sysUser) > 0;
+        // 回写主键，调用方（注册服务、mpLogin）需要用 userId 绑定默认角色或登录
+        user.setUserId(sysUser.getUserId());
+        return rows;
     }
 
     /**