diff --git a/src/main/java/com/yunhai/userbase/controller/oapi/ChannelBindController.java b/src/main/java/com/yunhai/userbase/controller/oapi/ChannelBindController.java
new file mode 100644
index 0000000..9ec3d27
--- /dev/null
+++ b/src/main/java/com/yunhai/userbase/controller/oapi/ChannelBindController.java
@@ -0,0 +1,71 @@
+package com.yunhai.userbase.controller.oapi;
+
+import com.yunhai.platform.utils.model.BoaUser;
+import com.yunhai.userbase.common.annotation.OapiLog;
+import com.yunhai.userbase.config.Config;
+import com.yunhai.userbase.model.channel.ChannelBindByPhoneRequest;
+import com.yunhai.userbase.model.channel.ChannelBindRequest;
+import com.yunhai.userbase.model.channel.ChannelUnbindRequest;
+import com.yunhai.userbase.service.impl.ChannelBindService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.validation.annotation.Validated;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * 移动端渠道绑定开放接口（sys_user_channel_rel，移动端接入 步 3，方案 §3.13）。<br>
+ * <br>
+ * 供 SDK 登录端点（门户 / 各子应用）经 yh-app-auth 签名调用（{@code /oapi/channel/...}）；
+ * 签名由 {@code OpenApiAuthEnforceConfiguration} 在过滤器层强制。<br>
+ * 绑定身份以服务端校验为准：openid/unionId 来自一次性 loginTicket，账号密码/手机号在本服务校验，
+ * 前端永不接触 openid/unionid（抢绑防护，方案 §3.4）。<br>
+ * POST 写操作由 {@code OapiLogAspect} 自动记录审计日志。
+ *
+ * @author chenx
+ * @date 2026/9/25
+ */
+@RestController
+@RequestMapping(Config.OPEN_API_PATH + "channel/")
+public class ChannelBindController {
+
+    @Autowired
+    private ChannelBindService channelBindService;
+
+    /**
+     * 按 (channel, openid) 查已绑定用户。
+     *
+     * @return 已绑定时返回用户明细（含 currentRole）；未绑定返回 null（data 为 null，code=0）
+     */
+    @GetMapping("user")
+    public BoaUser user(@RequestParam("channel") String channel,
+                        @RequestParam("openid") String openid) {
+        return channelBindService.findBoundUser(channel, openid);
+    }
+
+    /** 凭证绑定：账号密码校验 + 三层查重（openid/账号/unionid）通过后写绑定关系 */
+    @OapiLog
+    @PostMapping("bind")
+    public BoaUser bind(@RequestBody @Validated ChannelBindRequest request) {
+        return channelBindService.bindByCredential(request.getChannel(), request.getOpenid(),
+                request.getUnionId(), request.getAccount(), request.getPassword());
+    }
+
+    /** 手机号证明绑定（小程序一键手机号）：手机号归属由渠道验签器证明 */
+    @OapiLog
+    @PostMapping("bindByPhone")
+    public BoaUser bindByPhone(@RequestBody @Validated ChannelBindByPhoneRequest request) {
+        return channelBindService.bindByPhone(request.getChannel(), request.getOpenid(),
+                request.getUnionId(), request.getPhone());
+    }
+
+    /** 解绑：按登录账号 + 渠道删绑定行（account 来自 token payload，服务端定位） */
+    @OapiLog
+    @PostMapping("unbind")
+    public void unbind(@RequestBody @Validated ChannelUnbindRequest request) {
+        channelBindService.unbind(request.getChannel(), request.getAccount());
+    }
+}
diff --git a/src/main/java/com/yunhai/userbase/entity/SysUserChannelRel.java b/src/main/java/com/yunhai/userbase/entity/SysUserChannelRel.java
new file mode 100644
index 0000000..c83591c
--- /dev/null
+++ b/src/main/java/com/yunhai/userbase/entity/SysUserChannelRel.java
@@ -0,0 +1,71 @@
+package com.yunhai.userbase.entity;
+
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.Index;
+import javax.persistence.Table;
+import javax.persistence.UniqueConstraint;
+import java.time.LocalDateTime;
+
+/**
+ * 用户-移动渠道绑定关系（移动端接入 步 3，方案 §3.13）。
+ *
+ * <p>openid / unionid ↔ sys_user.id 的绑定属 UserBase 身份域；SDK 登录端点经
+ * {@code /oapi/channel/**}（应用签名）读写。channel 取值与前端 MobileChannel 对齐：
+ * wxgzh / miniapp / qywx / dingtalk。</p>
+ *
+ * <p>⚠ uk_user_channel 只约束半边：同一 unionid 仍可绑到两个账号（公众号一个、小程序一个），
+ * 应用层在 {@code ChannelBindService} 绑定时用 idx_unionid 查重补齐，勿仅依赖唯一约束。</p>
+ *
+ * @author chenx
+ * @date 2026/9/25
+ */
+@Data
+@NoArgsConstructor
+@Entity
+@Table(
+        name = "sys_user_channel_rel",
+        uniqueConstraints = {
+                @UniqueConstraint(columnNames = {"channel", "openid"}),
+                @UniqueConstraint(columnNames = {"user_id", "channel"})
+        },
+        indexes = {@Index(columnList = "unionid")}
+)
+@EqualsAndHashCode(onlyExplicitlyIncluded = true, callSuper = false)
+public class SysUserChannelRel {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    /** sys_user.id */
+    @Column(name = "user_id", nullable = false)
+    private Integer userId;
+
+    /** wxgzh / miniapp / qywx / dingtalk */
+    @Column(nullable = false, length = 20)
+    private String channel;
+
+    /** 渠道内用户标识 */
+    @Column(nullable = false, length = 64)
+    private String openid;
+
+    /** 同一开放平台下跨端一致；可空 */
+    @Column(name = "unionid", length = 64)
+    private String unionId;
+
+    /** 绑定时间（服务端 now() 写入） */
+    @Column(name = "bound_at", nullable = false)
+    private LocalDateTime boundAt;
+
+    /** 最近一次经该渠道登录时间（token 签发时更新，可空） */
+    @Column(name = "last_login_at")
+    private LocalDateTime lastLoginAt;
+}
diff --git a/src/main/java/com/yunhai/userbase/model/channel/ChannelBindByPhoneRequest.java b/src/main/java/com/yunhai/userbase/model/channel/ChannelBindByPhoneRequest.java
new file mode 100644
index 0000000..cdeb244
--- /dev/null
+++ b/src/main/java/com/yunhai/userbase/model/channel/ChannelBindByPhoneRequest.java
@@ -0,0 +1,30 @@
+package com.yunhai.userbase.model.channel;
+
+import lombok.Data;
+
+import javax.validation.constraints.NotBlank;
+
+/**
+ * 渠道绑定（手机号证明模式）开放接口入参（/oapi/channel/bindByPhone）。
+ * 供小程序「一键手机号」使用：手机号归属由渠道验签器（phoneCode → phone）证明，无密码。
+ *
+ * @author chenx
+ * @date 2026/9/25
+ */
+@Data
+public class ChannelBindByPhoneRequest {
+
+    /** 渠道码：miniapp */
+    @NotBlank(message = "渠道不能为空")
+    private String channel;
+
+    @NotBlank(message = "openid 不能为空")
+    private String openid;
+
+    /** 同一开放平台下跨端一致标识；可空 */
+    private String unionId;
+
+    /** 渠道验签器解析出的已验证手机号 */
+    @NotBlank(message = "手机号不能为空")
+    private String phone;
+}
diff --git a/src/main/java/com/yunhai/userbase/model/channel/ChannelBindRequest.java b/src/main/java/com/yunhai/userbase/model/channel/ChannelBindRequest.java
new file mode 100644
index 0000000..684e350
--- /dev/null
+++ b/src/main/java/com/yunhai/userbase/model/channel/ChannelBindRequest.java
@@ -0,0 +1,33 @@
+package com.yunhai.userbase.model.channel;
+
+import lombok.Data;
+
+import javax.validation.constraints.NotBlank;
+
+/**
+ * 渠道绑定（凭证模式）开放接口入参（/oapi/channel/bind）。
+ * openid/unionId 由 SDK 登录端点从一次性 loginTicket 解出后传入，前端永不直传。
+ *
+ * @author chenx
+ * @date 2026/9/25
+ */
+@Data
+public class ChannelBindRequest {
+
+    /** 渠道码：wxgzh / miniapp / qywx / dingtalk */
+    @NotBlank(message = "渠道不能为空")
+    private String channel;
+
+    @NotBlank(message = "openid 不能为空")
+    private String openid;
+
+    /** 同一开放平台下跨端一致标识；可空 */
+    private String unionId;
+
+    /** 登录账号（学生学号 / 教师手机号） */
+    @NotBlank(message = "账号不能为空")
+    private String account;
+
+    @NotBlank(message = "密码不能为空")
+    private String password;
+}
diff --git a/src/main/java/com/yunhai/userbase/model/channel/ChannelUnbindRequest.java b/src/main/java/com/yunhai/userbase/model/channel/ChannelUnbindRequest.java
new file mode 100644
index 0000000..539bfb6
--- /dev/null
+++ b/src/main/java/com/yunhai/userbase/model/channel/ChannelUnbindRequest.java
@@ -0,0 +1,24 @@
+package com.yunhai.userbase.model.channel;
+
+import lombok.Data;
+
+import javax.validation.constraints.NotBlank;
+
+/**
+ * 解绑开放接口入参（/oapi/channel/unbind）。
+ * account 由 SDK 登录端点从 token payload 解出后传入（服务端定位用户），非客户端自报。
+ *
+ * @author chenx
+ * @date 2026/9/25
+ */
+@Data
+public class ChannelUnbindRequest {
+
+    /** 渠道码：wxgzh / miniapp / qywx / dingtalk */
+    @NotBlank(message = "渠道不能为空")
+    private String channel;
+
+    /** 登录账号（token payload 内 account） */
+    @NotBlank(message = "账号不能为空")
+    private String account;
+}
diff --git a/src/main/java/com/yunhai/userbase/repository/SysUserChannelRelRepository.java b/src/main/java/com/yunhai/userbase/repository/SysUserChannelRelRepository.java
new file mode 100644
index 0000000..8be7728
--- /dev/null
+++ b/src/main/java/com/yunhai/userbase/repository/SysUserChannelRelRepository.java
@@ -0,0 +1,39 @@
+package com.yunhai.userbase.repository;
+
+import com.yunhai.userbase.entity.SysUserChannelRel;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * 用户-移动渠道绑定仓储（sys_user_channel_rel，移动端接入 步 3）。
+ *
+ * @author chenx
+ * @date 2026/9/25
+ */
+public interface SysUserChannelRelRepository extends JpaRepository<SysUserChannelRel, Long>, JpaSpecificationExecutor<SysUserChannelRel> {
+
+    /** 按 (channel, openid) 查绑定（uk_channel_openid 唯一） */
+    Optional<SysUserChannelRel> findByChannelAndOpenid(String channel, String openid);
+
+    /** 按用户 + 渠道查绑定（uk_user_channel 唯一）：判"该账号在此渠道是否已绑过" */
+    Optional<SysUserChannelRel> findByUserIdAndChannel(Integer userId, String channel);
+
+    /** unionid 应用层查重（uk_user_channel 只约束半边，方案 §3.13 ⚠）：同 unionid 已存在的绑定行 */
+    List<SysUserChannelRel> findByUnionId(String unionId);
+
+    /** 解绑（按用户 + 渠道） */
+    @Modifying
+    @Query("DELETE FROM SysUserChannelRel r WHERE r.userId = :userId AND r.channel = :channel")
+    void deleteByUserIdAndChannel(@Param("userId") Integer userId, @Param("channel") String channel);
+
+    /** 级联清理：删除用户时清残留绑定行 */
+    @Modifying
+    @Query("DELETE FROM SysUserChannelRel r WHERE r.userId = :userId")
+    void deleteByUserIdBulk(@Param("userId") Integer userId);
+}
diff --git a/src/main/java/com/yunhai/userbase/service/impl/ChannelBindService.java b/src/main/java/com/yunhai/userbase/service/impl/ChannelBindService.java
new file mode 100644
index 0000000..13e8b8d
--- /dev/null
+++ b/src/main/java/com/yunhai/userbase/service/impl/ChannelBindService.java
@@ -0,0 +1,146 @@
+package com.yunhai.userbase.service.impl;
+
+import com.yunhai.platform.utils.exception.DException;
+import com.yunhai.platform.utils.model.BoaUser;
+import com.yunhai.userbase.entity.SysUser;
+import com.yunhai.userbase.entity.SysUserChannelRel;
+import com.yunhai.userbase.enums.StatusEnum;
+import com.yunhai.userbase.repository.SysUserChannelRelRepository;
+import com.yunhai.userbase.repository.SysUserRepository;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.LocalDateTime;
+import java.util.Optional;
+
+/**
+ * 移动端渠道绑定服务（sys_user_channel_rel，移动端接入 步 3，方案 §3.13）。<br>
+ * <br>
+ * openid / unionid ↔ userId 的绑定属 UserBase 身份域；SDK 登录端点（门户/各子应用）经
+ * {@code /oapi/channel/**} 应用签名调用本服务。绑定一律以服务端解析出的身份为准
+ * （openid/unionid 来自一次性 loginTicket，账号密码/手机号在服务端校验），前端永不直传 openid。<br>
+ * <br>
+ * 唯一性三层防线：<br>
+ * ① uk_channel_openid：一个 openid 同渠道只能绑一个账号（DB 兜底 + 应用层前置校验友好报错）；<br>
+ * ② uk_user_channel：一个账号同渠道只能绑一个 openid（换绑须先解绑）；<br>
+ * ③ unionid 应用层查重：uk_user_channel 只约束半边（同一 unionid 仍可绑两个账号——公众号一个、
+ * 小程序一个），用 idx_unionid 在绑定时补齐（方案 §3.13 ⚠）。
+ *
+ * @author chenx
+ * @date 2026/9/25
+ */
+@Service
+public class ChannelBindService {
+
+    @Autowired
+    private SysUserChannelRelRepository relRepository;
+
+    @Autowired
+    private SysUserRepository sysUserRepository;
+
+    @Autowired
+    private UserCenterService userCenterService;
+
+    @Autowired
+    private PasswordEncoder passwordEncoder;
+
+    /**
+     * 按 (channel, openid) 查已绑定用户（登录端点"已绑定 → 直接发 token"分支）。
+     *
+     * @return 已绑定时返回用户明细（含 currentRole）；未绑定返回 null
+     */
+    public BoaUser findBoundUser(String channel, String openid) {
+        return relRepository.findByChannelAndOpenid(channel, openid)
+                .map(rel -> userCenterService.getUserInfoWithDeptById(rel.getUserId()))
+                .orElse(null);
+    }
+
+    /**
+     * 凭证绑定（loginTicket 身份 + 账号密码）。密码 BCrypt 校验失败统一报"账号或密码错误"
+     * （不区分账号不存在/密码错，防账号枚举）；防爆破计数（LoginGuard）在 SDK 侧。
+     */
+    @Transactional
+    public BoaUser bindByCredential(String channel, String openid, String unionId,
+                                    String account, String password) {
+        requireIdentity(channel, openid);
+        if (StringUtils.isBlank(account) || StringUtils.isBlank(password)) {
+            throw new DException("账号与密码不能为空");
+        }
+        SysUser user = sysUserRepository.findByAccount(account);
+        if (user == null || !passwordEncoder.matches(password, user.getPassword())) {
+            throw new DException("账号或密码错误");
+        }
+        return doBind(channel, openid, unionId, user);
+    }
+
+    /**
+     * 手机号证明绑定（loginTicket 身份 + 渠道验签器已验证的手机号，小程序一键手机号）。
+     * 手机号归属由渠道验签器证明（phoneCode → phone），无需密码。
+     */
+    @Transactional
+    public BoaUser bindByPhone(String channel, String openid, String unionId, String phone) {
+        requireIdentity(channel, openid);
+        if (StringUtils.isBlank(phone)) {
+            throw new DException("手机号不能为空");
+        }
+        SysUser user = sysUserRepository.findByPhone(phone);
+        if (user == null) {
+            throw new DException("未找到该手机号对应的账号");
+        }
+        return doBind(channel, openid, unionId, user);
+    }
+
+    /** 解绑：按登录账号 + 渠道删绑定行（服务端据 token 内 account 定位，非客户端自报 openid） */
+    @Transactional
+    public void unbind(String channel, String account) {
+        if (StringUtils.isBlank(channel) || StringUtils.isBlank(account)) {
+            throw new DException("渠道与账号不能为空");
+        }
+        SysUser user = sysUserRepository.findByAccount(account);
+        if (user == null) {
+            return;
+        }
+        relRepository.deleteByUserIdAndChannel(user.getId(), channel);
+    }
+
+    private void requireIdentity(String channel, String openid) {
+        if (StringUtils.isBlank(channel) || StringUtils.isBlank(openid)) {
+            throw new DException("渠道与 openid 不能为空");
+        }
+    }
+
+    private BoaUser doBind(String channel, String openid, String unionId, SysUser user) {
+        if (StatusEnum.DISABLED.equals(user.getDisabled())) {
+            throw new DException("账号已禁用，请联系管理员");
+        }
+        // ① openid 已绑定其他账号 → 拒绝（正常流程登录端点会先查绑定直接发 token，此处兜底并发窗口）
+        Optional<SysUserChannelRel> byOpenid = relRepository.findByChannelAndOpenid(channel, openid);
+        if (byOpenid.isPresent() && !byOpenid.get().getUserId().equals(user.getId())) {
+            throw new DException("该微信已绑定其他账号");
+        }
+        // ② 账号在此渠道已绑定其他 openid → 拒绝（换绑须先解绑）
+        Optional<SysUserChannelRel> byUser = relRepository.findByUserIdAndChannel(user.getId(), channel);
+        if (byUser.isPresent() && !byUser.get().getOpenid().equals(openid)) {
+            throw new DException("该账号已绑定其他微信，请先解绑");
+        }
+        // ③ unionid 应用层查重：防同一 unionid 绑到两个账号（uk_user_channel 只约束半边）
+        if (StringUtils.isNotBlank(unionId)) {
+            for (SysUserChannelRel rel : relRepository.findByUnionId(unionId)) {
+                if (!rel.getUserId().equals(user.getId())) {
+                    throw new DException("该微信已绑定其他账号");
+                }
+            }
+        }
+        SysUserChannelRel rel = byOpenid.orElseGet(SysUserChannelRel::new);
+        rel.setUserId(user.getId());
+        rel.setChannel(channel);
+        rel.setOpenid(openid);
+        rel.setUnionId(StringUtils.isBlank(unionId) ? null : unionId);
+        rel.setBoundAt(LocalDateTime.now());
+        relRepository.save(rel);
+        return userCenterService.getUserInfoWithDeptById(user.getId());
+    }
+}
diff --git a/src/test/java/com/yunhai/userbase/service/impl/ChannelBindServiceTest.java b/src/test/java/com/yunhai/userbase/service/impl/ChannelBindServiceTest.java
new file mode 100644
index 0000000..7855fa8
--- /dev/null
+++ b/src/test/java/com/yunhai/userbase/service/impl/ChannelBindServiceTest.java
@@ -0,0 +1,250 @@
+package com.yunhai.userbase.service.impl;
+
+import com.yunhai.platform.utils.exception.DException;
+import com.yunhai.platform.utils.model.BoaUser;
+import com.yunhai.userbase.entity.SysUser;
+import com.yunhai.userbase.entity.SysUserChannelRel;
+import com.yunhai.userbase.enums.StatusEnum;
+import com.yunhai.userbase.repository.SysUserChannelRelRepository;
+import com.yunhai.userbase.repository.SysUserRepository;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.springframework.security.crypto.password.PasswordEncoder;
+
+import java.util.Arrays;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * 移动端渠道绑定服务单测（步 3 门禁）：绑定唯一约束（uk_channel_openid / uk_user_channel 对应的
+ * 应用层前置校验）+ unionid 应用层查重（uk_user_channel 只约束半边，方案 §3.13 ⚠）。
+ * 纯 Mockito，不依赖数据库。
+ */
+class ChannelBindServiceTest {
+
+    @Mock
+    private SysUserChannelRelRepository relRepository;
+
+    @Mock
+    private SysUserRepository sysUserRepository;
+
+    @Mock
+    private UserCenterService userCenterService;
+
+    @Mock
+    private PasswordEncoder passwordEncoder;
+
+    @InjectMocks
+    private ChannelBindService service;
+
+    private SysUser user;
+
+    @BeforeEach
+    void setUp() {
+        MockitoAnnotations.openMocks(this);
+        user = new SysUser();
+        user.setId(1001);
+        user.setAccount("s1001");
+        user.setPassword("$bcrypt$");
+        user.setDisabled(StatusEnum.NORMAL);
+        when(passwordEncoder.matches(anyString(), anyString())).thenAnswer(inv -> {
+            Object[] args = inv.getArguments();
+            return "right-pwd".equals(args[0]) && "$bcrypt$".equals(args[1]);
+        });
+    }
+
+    private BoaUser boa(int id, String account) {
+        return new BoaUser(id, account, "用户" + id);
+    }
+
+    // ==================== findBoundUser ====================
+
+    @Test
+    void findBoundUser_unbound_returnsNull() {
+        when(relRepository.findByChannelAndOpenid("wxgzh", "o-1")).thenReturn(Optional.empty());
+        assertNull(service.findBoundUser("wxgzh", "o-1"));
+    }
+
+    @Test
+    void findBoundUser_bound_returnsBoaUser() {
+        SysUserChannelRel rel = new SysUserChannelRel();
+        rel.setUserId(1001);
+        when(relRepository.findByChannelAndOpenid("wxgzh", "o-1")).thenReturn(Optional.of(rel));
+        when(userCenterService.getUserInfoWithDeptById(1001)).thenReturn(boa(1001, "s1001"));
+        BoaUser result = service.findBoundUser("wxgzh", "o-1");
+        assertNotNull(result);
+        assertEquals(1001, result.getId());
+    }
+
+    // ==================== bindByCredential：密码与账号 ====================
+
+    @Test
+    void bindByCredential_wrongPassword_rejectedWithoutSaving() {
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        DException ex = assertThrows(DException.class,
+                () -> service.bindByCredential("wxgzh", "o-1", "u-1", "s1001", "wrong-pwd"));
+        assertTrue(ex.getMessage().contains("账号或密码错误"));
+        verify(relRepository, never()).save(any());
+    }
+
+    @Test
+    void bindByCredential_unknownAccount_sameErrorAsWrongPassword() {
+        when(sysUserRepository.findByAccount("nobody")).thenReturn(null);
+        DException ex = assertThrows(DException.class,
+                () -> service.bindByCredential("wxgzh", "o-1", "u-1", "nobody", "right-pwd"));
+        assertTrue(ex.getMessage().contains("账号或密码错误"));
+    }
+
+    @Test
+    void bindByCredential_success_savesRelWithBoundAt() {
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        when(relRepository.findByChannelAndOpenid("wxgzh", "o-1")).thenReturn(Optional.empty());
+        when(relRepository.findByUserIdAndChannel(1001, "wxgzh")).thenReturn(Optional.empty());
+        when(relRepository.findByUnionId("u-1")).thenReturn(Arrays.asList());
+        when(userCenterService.getUserInfoWithDeptById(1001)).thenReturn(boa(1001, "s1001"));
+
+        BoaUser result = service.bindByCredential("wxgzh", "o-1", "u-1", "s1001", "right-pwd");
+
+        assertNotNull(result);
+        ArgumentCaptor<SysUserChannelRel> captor = ArgumentCaptor.forClass(SysUserChannelRel.class);
+        verify(relRepository).save(captor.capture());
+        assertEquals(1001, captor.getValue().getUserId());
+        assertEquals("wxgzh", captor.getValue().getChannel());
+        assertEquals("o-1", captor.getValue().getOpenid());
+        assertEquals("u-1", captor.getValue().getUnionId());
+        assertNotNull(captor.getValue().getBoundAt());
+    }
+
+    // ==================== bindByCredential：唯一约束前置校验 ====================
+
+    @Test
+    void bindByCredential_openidBoundToAnotherUser_rejected() {
+        // uk_channel_openid 场景：openid 已绑其他账号（并发窗口兜底）
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        SysUserChannelRel other = new SysUserChannelRel();
+        other.setUserId(2002);
+        other.setChannel("wxgzh");
+        other.setOpenid("o-1");
+        when(relRepository.findByChannelAndOpenid("wxgzh", "o-1")).thenReturn(Optional.of(other));
+
+        DException ex = assertThrows(DException.class,
+                () -> service.bindByCredential("wxgzh", "o-1", "u-1", "s1001", "right-pwd"));
+        assertTrue(ex.getMessage().contains("已绑定"));
+        verify(relRepository, never()).save(any());
+    }
+
+    @Test
+    void bindByCredential_userAlreadyBoundAnotherOpenid_rejected() {
+        // uk_user_channel 场景：账号在此渠道已绑其他 openid（换绑须先解绑）
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        when(relRepository.findByChannelAndOpenid("wxgzh", "o-1")).thenReturn(Optional.empty());
+        SysUserChannelRel existing = new SysUserChannelRel();
+        existing.setUserId(1001);
+        existing.setChannel("wxgzh");
+        existing.setOpenid("o-old");
+        when(relRepository.findByUserIdAndChannel(1001, "wxgzh")).thenReturn(Optional.of(existing));
+
+        DException ex = assertThrows(DException.class,
+                () -> service.bindByCredential("wxgzh", "o-1", "u-1", "s1001", "right-pwd"));
+        assertTrue(ex.getMessage().contains("请先解绑"));
+        verify(relRepository, never()).save(any());
+    }
+
+    @Test
+    void bindByCredential_unionidBoundToAnotherUser_rejected() {
+        // uk_user_channel 只约束半边：同 unionid 绑两个账号须在应用层拦（方案 §3.13 ⚠）
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        when(relRepository.findByChannelAndOpenid("wxgzh", "o-1")).thenReturn(Optional.empty());
+        when(relRepository.findByUserIdAndChannel(1001, "wxgzh")).thenReturn(Optional.empty());
+        SysUserChannelRel otherUnion = new SysUserChannelRel();
+        otherUnion.setUserId(2002);
+        otherUnion.setChannel("miniapp");
+        otherUnion.setOpenid("o-2");
+        otherUnion.setUnionId("u-1");
+        when(relRepository.findByUnionId("u-1")).thenReturn(Arrays.asList(otherUnion));
+
+        DException ex = assertThrows(DException.class,
+                () -> service.bindByCredential("wxgzh", "o-1", "u-1", "s1001", "right-pwd"));
+        assertTrue(ex.getMessage().contains("已绑定"));
+        verify(relRepository, never()).save(any());
+    }
+
+    @Test
+    void bindByCredential_unionidOwnedBySameUser_allowed() {
+        // 同一用户另一端的绑定（公众号+小程序同 unionid）不拦
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        when(relRepository.findByChannelAndOpenid("wxgzh", "o-1")).thenReturn(Optional.empty());
+        when(relRepository.findByUserIdAndChannel(1001, "wxgzh")).thenReturn(Optional.empty());
+        SysUserChannelRel ownUnion = new SysUserChannelRel();
+        ownUnion.setUserId(1001);
+        ownUnion.setChannel("miniapp");
+        ownUnion.setOpenid("o-2");
+        ownUnion.setUnionId("u-1");
+        when(relRepository.findByUnionId("u-1")).thenReturn(Arrays.asList(ownUnion));
+        when(userCenterService.getUserInfoWithDeptById(1001)).thenReturn(boa(1001, "s1001"));
+
+        assertNotNull(service.bindByCredential("wxgzh", "o-1", "u-1", "s1001", "right-pwd"));
+    }
+
+    @Test
+    void bindByCredential_disabledUser_rejected() {
+        user.setDisabled(StatusEnum.DISABLED);
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        DException ex = assertThrows(DException.class,
+                () -> service.bindByCredential("wxgzh", "o-1", "u-1", "s1001", "right-pwd"));
+        assertTrue(ex.getMessage().contains("禁用"));
+    }
+
+    // ==================== bindByPhone ====================
+
+    @Test
+    void bindByPhone_success() {
+        when(sysUserRepository.findByPhone("13800000001")).thenReturn(user);
+        when(relRepository.findByChannelAndOpenid("miniapp", "o-1")).thenReturn(Optional.empty());
+        when(relRepository.findByUserIdAndChannel(1001, "miniapp")).thenReturn(Optional.empty());
+        when(relRepository.findByUnionId(anyString())).thenReturn(Arrays.asList());
+        when(userCenterService.getUserInfoWithDeptById(1001)).thenReturn(boa(1001, "s1001"));
+
+        BoaUser result = service.bindByPhone("miniapp", "o-1", "u-1", "13800000001");
+        assertNotNull(result);
+        verify(relRepository).save(any(SysUserChannelRel.class));
+    }
+
+    @Test
+    void bindByPhone_unknownPhone_rejected() {
+        when(sysUserRepository.findByPhone("13900000000")).thenReturn(null);
+        DException ex = assertThrows(DException.class,
+                () -> service.bindByPhone("miniapp", "o-1", "u-1", "13900000000"));
+        assertTrue(ex.getMessage().contains("手机号"));
+    }
+
+    // ==================== unbind ====================
+
+    @Test
+    void unbind_deletesByUserIdAndChannel() {
+        when(sysUserRepository.findByAccount("s1001")).thenReturn(user);
+        service.unbind("wxgzh", "s1001");
+        verify(relRepository).deleteByUserIdAndChannel(1001, "wxgzh");
+    }
+
+    @Test
+    void unbind_unknownAccount_silentNoop() {
+        when(sysUserRepository.findByAccount("nobody")).thenReturn(null);
+        service.unbind("wxgzh", "nobody");
+        verify(relRepository, never()).deleteByUserIdAndChannel(any(), any());
+    }
+}