feat(approval): PC 待办改派接口与集成测试 (#22)

- 新增 POST /api/approval/task/{id}/assign：权限 approval:instance:assign，
  任务须 PENDING、目标同租户启用用户、原因必填；事务内锁实例后条件更新
  处理人并写 ASSIGN 记录（opinion=原因），@OperationLog 记录原/新处理人与原因
- 新增 ApprovalTaskAssignParam / ApprovalAssignVO
- 新增 ApprovalPcTodoIT：改派成功与归属变化、无效目标、非待办任务、原因必填、
  无权限 403、ASSIGN 记录、操作日志、改派候选用户

src/main/java/com/gxwebsoft/approval/controller/ApprovalTaskController.java

@@ -1,11 +1,14 @@
 package com.gxwebsoft.approval.controller;
 
 import com.gxwebsoft.approval.param.ApprovalTaskActionParam;
+import com.gxwebsoft.approval.param.ApprovalTaskAssignParam;
 import com.gxwebsoft.approval.param.ApprovalTaskListParam;
 import com.gxwebsoft.approval.service.ApprovalInstanceService;
 import com.gxwebsoft.approval.service.ApprovalTaskService;
+import com.gxwebsoft.approval.vo.ApprovalAssignVO;
 import com.gxwebsoft.approval.vo.ApprovalInstanceVO;
 import com.gxwebsoft.approval.vo.ApprovalItemVO;
+import com.gxwebsoft.common.core.annotation.OperationLog;
 import com.gxwebsoft.common.core.web.ApiResult;
 import com.gxwebsoft.common.core.web.BaseController;
 import com.gxwebsoft.common.core.web.PageResult;
@@ -85,4 +88,13 @@ public class ApprovalTaskController extends BaseController {
     ApprovalTaskService.Result result = taskService.withdraw(id, user);
     return success("撤回成功", instanceService.detail(result.getInstanceId(), user));
   }
+
+  @PreAuthorize("hasAuthority('approval:instance:assign')")
+  @OperationLog(value = "改派审批待办", module = "审批管理")
+  @ApiOperation("改派")
+  @PostMapping("/task/{id}/assign")
+  public ApiResult<ApprovalAssignVO> assign(@PathVariable("id") Long id,
+                                            @RequestBody(required = false) ApprovalTaskAssignParam param) {
+    return success("改派成功", taskService.assign(id, param, getLoginUser()));
+  }
 }

src/main/java/com/gxwebsoft/approval/param/ApprovalTaskAssignParam.java

@@ -0,0 +1,20 @@
+package com.gxwebsoft.approval.param;
+
+import io.swagger.annotations.ApiModelProperty;
+import lombok.Data;
+
+import java.io.Serializable;
+
+/**
+ * 待办改派参数。
+ */
+@Data
+public class ApprovalTaskAssignParam implements Serializable {
+  private static final long serialVersionUID = 1L;
+
+  @ApiModelProperty("改派对象用户id")
+  private Integer targetUserId;
+
+  @ApiModelProperty("改派原因；必填")
+  private String reason;
+}

src/main/java/com/gxwebsoft/approval/service/ApprovalTaskService.java

@@ -8,8 +8,10 @@ import com.gxwebsoft.approval.entity.ApprovalInstance;
 import com.gxwebsoft.approval.entity.ApprovalTask;
 import com.gxwebsoft.approval.mapper.ApprovalInstanceMapper;
 import com.gxwebsoft.approval.mapper.ApprovalTaskMapper;
+import com.gxwebsoft.approval.param.ApprovalTaskAssignParam;
 import com.gxwebsoft.approval.support.ApprovalApprover;
 import com.gxwebsoft.approval.support.ApprovalNode;
+import com.gxwebsoft.approval.vo.ApprovalAssignVO;
 import com.gxwebsoft.approval.vo.ApprovalUserVO;
 import com.gxwebsoft.common.core.exception.BusinessException;
 import com.gxwebsoft.common.system.entity.User;
@@ -109,6 +111,28 @@ public class ApprovalTaskService {
     return new Result(instanceId, null);
   }
 
+  /**
+   * 改派：管理员把待处理任务换给同租户其他启用用户，原因必填并写 ASSIGN 记录。
+   *
+   * <p>改派不改变任务状态，只替换处理人；操作人不必是任务当前处理人。</p>
+   */
+  public ApprovalAssignVO assign(Long taskId, ApprovalTaskAssignParam param, User user) {
+    if (param == null || param.getTargetUserId() == null) {
+      throw new BusinessException("请选择改派对象");
+    }
+    String reason = requireAssignReason(param.getReason());
+    ApprovalTask task = requireAssignableTask(taskId);
+    // 事务外解析目标用户：启用、未删除且属于当前租户（@DS("server") 查询显式带租户）
+    List<ApprovalUserVO> targets =
+      directoryService.listActiveUsersByIds(Collections.singletonList(param.getTargetUserId()));
+    if (targets.isEmpty()) {
+      throw new BusinessException("改派对象不存在或已停用");
+    }
+    ApprovalUserVO target = targets.get(0);
+    String targetName = displayName(target);
+    return inTransaction(() -> doAssign(taskId, task, target.getUserId(), targetName, reason, user));
+  }
+
   public Integer todoCount(User user) {
     return taskMapper.countPendingInstances(user.getUserId());
   }
@@ -171,6 +195,58 @@ public class ApprovalTaskService {
     }
   }
 
+  /**
+   * 事务内改派：锁实例后条件更新处理人，并追加 ASSIGN 记录。
+   */
+  private ApprovalAssignVO doAssign(Long taskId, ApprovalTask task, Integer targetUserId,
+                                    String targetName, String reason, User user) {
+    ApprovalInstance locked = engineService.lockInstance(task.getInstanceId());
+    ensureTaskHandleable(task, locked);
+    int rows = taskMapper.update(null, new UpdateWrapper<ApprovalTask>()
+      .eq("id", taskId)
+      .eq("status", ApprovalConstants.TASK_PENDING)
+      .set("assignee_id", targetUserId)
+      .set("assignee_name", targetName));
+    if (rows == 0) {
+      throw new BusinessException("任务已处理");
+    }
+    engineService.addRecord(locked, taskId, task.getNodeKey(), user,
+      ApprovalConstants.ACTION_ASSIGN, reason);
+    ApprovalAssignVO vo = new ApprovalAssignVO();
+    vo.setInstanceId(locked.getId());
+    vo.setTaskId(taskId);
+    vo.setOriginalAssigneeId(task.getAssigneeId());
+    vo.setOriginalAssigneeName(task.getAssigneeName());
+    vo.setAssigneeId(targetUserId);
+    vo.setAssigneeName(targetName);
+    vo.setReason(reason);
+    return vo;
+  }
+
+  /**
+   * 改派前的基本校验：任务存在、待处理且单据仍在审批中。
+   */
+  private ApprovalTask requireAssignableTask(Long taskId) {
+    if (taskId == null) {
+      throw new BusinessException("任务不存在");
+    }
+    ApprovalTask task = taskMapper.selectById(taskId);
+    if (task == null) {
+      throw new BusinessException("任务不存在");
+    }
+    if (!ApprovalConstants.TASK_PENDING.equals(task.getStatus())) {
+      throw new BusinessException("任务已处理");
+    }
+    ApprovalInstance instance = instanceMapper.selectById(task.getInstanceId());
+    if (instance == null) {
+      throw new BusinessException("单据不存在");
+    }
+    if (!ApprovalConstants.STATUS_PENDING.equals(instance.getStatus())) {
+      throw new BusinessException("单据不在审批中，无法改派");
+    }
+    return task;
+  }
+
   /**
    * 任务必须属于实例当前轮次、当前节点，否则视为已被处理或已失效。
    */
@@ -310,6 +386,14 @@ public class ApprovalTaskService {
     return normalized;
   }
 
+  private String requireAssignReason(String reason) {
+    String normalized = normalizeOpinion(reason);
+    if (normalized == null) {
+      throw new BusinessException("请填写改派原因");
+    }
+    return normalized;
+  }
+
   private <T> T inTransaction(Supplier<T> action) {
     return new TransactionTemplate(transactionManager).execute(status -> action.get());
   }

src/main/java/com/gxwebsoft/approval/vo/ApprovalAssignVO.java

@@ -0,0 +1,29 @@
+package com.gxwebsoft.approval.vo;
+
+import io.swagger.annotations.ApiModel;
+import lombok.Data;
+
+import java.io.Serializable;
+
+/**
+ * 改派结果：原处理人、新处理人与原因，同时用于操作日志留痕。
+ */
+@Data
+@ApiModel(description = "改派结果")
+public class ApprovalAssignVO implements Serializable {
+  private static final long serialVersionUID = 1L;
+
+  private Long instanceId;
+
+  private Long taskId;
+
+  private Integer originalAssigneeId;
+
+  private String originalAssigneeName;
+
+  private Integer assigneeId;
+
+  private String assigneeName;
+
+  private String reason;
+}