fix(send): apply AccountSelector health checks to fallback owner account and add person-target validation tests

- Make AccountSelector.isHealthy public static so SendService can reuse it.
- Use isHealthy for the resolved/fallback conversation account instead of
  a weaker existence/status/channel check, covering risk level and PYWECHAT
  heartbeat/online status.
- Add null-safe channel-type comparison in resolvePersonTarget.
- Add @Min(0) to BindConversationAccountRequest.sortOrder.
- Rename misleading conversation fallback test and add tests for
  resolvePersonTarget disabled/cross-tenant/channel-mismatch cases.
- Remove unused java.util.Arrays import from test file.

backend/mci-server/src/main/java/com/sino/mci/channel/dto/BindConversationAccountRequest.java

@@ -1,5 +1,6 @@
 package com.sino.mci.channel.dto;
 
+import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotNull;
 import lombok.Data;
 import org.hibernate.validator.constraints.Range;
@@ -14,5 +15,6 @@ public class BindConversationAccountRequest {
     @Range(min = 1, max = 4)
     private Integer bindingType;
 
+    @Min(0)
     private Integer sortOrder;
 }

backend/mci-server/src/main/java/com/sino/mci/channel/service/AccountSelector.java

@@ -71,7 +71,7 @@ public class AccountSelector {
         return healthyAccountIds;
     }
 
-    private boolean isHealthy(ChannelAccount account, String tenantCode, ChannelType channelType) {
+    public static boolean isHealthy(ChannelAccount account, String tenantCode, ChannelType channelType) {
         if (account == null) {
             return false;
         }

backend/mci-server/src/main/java/com/sino/mci/send/service/SendService.java

@@ -336,9 +336,7 @@ public class SendService {
             throw new BusinessException("会话未配置发送账号: " + conversationId);
         }
         ChannelAccount account = accountMapper.selectById(accountId);
-        if (account == null || !tenantCode.equals(account.getTenantCode())
-                || !channelType.name().equalsIgnoreCase(account.getChannelType())
-                || account.getStatus() == null || account.getStatus() != STATUS_ENABLED) {
+        if (!AccountSelector.isHealthy(account, tenantCode, channelType)) {
             throw new BusinessException("会话没有可用的发送账号: " + conversationId);
         }
         SendTarget target = new SendTarget();
@@ -370,7 +368,7 @@ public class SendService {
                 || account.getStatus() == null || account.getStatus() != STATUS_ENABLED) {
             throw new BusinessException("租户没有可用的发送账号: channel=" + channelType.name().toLowerCase());
         }
-        if (!channelType.name().equalsIgnoreCase(account.getChannelType())) {
+        if (!Objects.equals(channelType.name().toLowerCase(), account.getChannelType())) {
             throw new BusinessException("单聊发送账号渠道类型与目标身份不一致");
         }
         SendTarget target = new SendTarget();

backend/mci-server/src/test/java/com/sino/mci/send/service/SendServiceResolveTargetTest.java

@@ -10,6 +10,7 @@ import com.sino.mci.channel.repository.ConversationMapper;
 import com.sino.mci.channel.repository.ConversationTagBindingMapper;
 import com.sino.mci.channel.service.AccountSelector;
 import com.sino.mci.crm.repository.ChannelIdentityMapper;
+import com.sino.mci.crm.entity.ChannelIdentity;
 import com.sino.mci.crm.repository.PersonMapper;
 import com.sino.mci.crm.repository.PersonTagBindingMapper;
 import com.sino.mci.crm.repository.TagMapper;
@@ -26,7 +27,6 @@ import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -108,7 +108,7 @@ class SendServiceResolveTargetTest {
     }
 
     @Test
-    void resolveConversationTarget_fallsBackToBackupWhenPrimaryUnhealthy() {
+    void resolveConversationTarget_usesAccountReturnedBySelector() {
         Conversation conversation = createConversation();
         Long backupAccountId = 20L;
 
@@ -143,6 +143,49 @@ class SendServiceResolveTargetTest {
         assertEquals("backup", strategyCaptor.getValue());
     }
 
+    @Test
+    void resolvePersonTarget_rejectsDisabledAccount() {
+        ChannelIdentity identity = createIdentity();
+        ChannelAccount account = createAccount(30L, "wecom", 0);
+
+        when(channelIdentityMapper.selectOne(any())).thenReturn(identity);
+        when(accountMapper.selectList(any())).thenReturn(Collections.singletonList(account));
+        when(accountMapper.selectById(30L)).thenReturn(account);
+
+        BusinessException ex = assertThrows(BusinessException.class,
+                () -> sendService.resolveTestTargets("tenant", createPersonRequest()));
+        assertEquals("租户没有可用的发送账号: channel=wecom", ex.getMessage());
+    }
+
+    @Test
+    void resolvePersonTarget_rejectsCrossTenantAccount() {
+        ChannelIdentity identity = createIdentity();
+        ChannelAccount account = createAccount(30L, "wecom", 1);
+        account.setTenantCode("other");
+
+        when(channelIdentityMapper.selectOne(any())).thenReturn(identity);
+        when(accountMapper.selectList(any())).thenReturn(Collections.singletonList(account));
+        when(accountMapper.selectById(30L)).thenReturn(account);
+
+        BusinessException ex = assertThrows(BusinessException.class,
+                () -> sendService.resolveTestTargets("tenant", createPersonRequest()));
+        assertEquals("租户没有可用的发送账号: channel=wecom", ex.getMessage());
+    }
+
+    @Test
+    void resolvePersonTarget_rejectsChannelTypeMismatch() {
+        ChannelIdentity identity = createIdentity();
+        ChannelAccount account = createAccount(30L, "mobile", 1);
+
+        when(channelIdentityMapper.selectOne(any())).thenReturn(identity);
+        when(accountMapper.selectList(any())).thenReturn(Collections.singletonList(account));
+        when(accountMapper.selectById(30L)).thenReturn(account);
+
+        BusinessException ex = assertThrows(BusinessException.class,
+                () -> sendService.resolveTestTargets("tenant", createPersonRequest()));
+        assertEquals("单聊发送账号渠道类型与目标身份不一致", ex.getMessage());
+    }
+
     private SendTestRequest createConversationRequest(String strategy) {
         SendTestRequest request = new SendTestRequest();
         request.setTargetType("conversation");
@@ -159,6 +202,21 @@ class SendServiceResolveTargetTest {
         return request;
     }
 
+    private SendTestRequest createPersonRequest() {
+        SendTestRequest request = new SendTestRequest();
+        request.setTargetType("person");
+        Map<String, Object> targetValue = new HashMap<>();
+        targetValue.put("person_id", 1L);
+        request.setTargetValue(targetValue);
+        request.setContentType("text");
+        request.setContent(Collections.singletonMap("text", "hello"));
+
+        Map<String, Object> channelStrategy = new HashMap<>();
+        channelStrategy.put("channel_type", "wecom");
+        request.setChannelStrategy(channelStrategy);
+        return request;
+    }
+
     private Conversation createConversation() {
         Conversation conversation = new Conversation();
         conversation.setId(1L);
@@ -177,4 +235,14 @@ class SendServiceResolveTargetTest {
         account.setStatus(status);
         return account;
     }
+
+    private ChannelIdentity createIdentity() {
+        ChannelIdentity identity = new ChannelIdentity();
+        identity.setTenantCode("tenant");
+        identity.setPersonId(1L);
+        identity.setChannelType("wecom");
+        identity.setChannelUserId("user-1");
+        identity.setStatus(1);
+        return identity;
+    }
 }