fix(aihr): prevent duplicate employee principal links

backend/ruoyi-modules/ruoyi-aihr/src/main/java/org/dromara/aihr/service/AihrInterviewService.java

@@ -143,12 +143,7 @@ public class AihrInterviewService {
               FROM aihr_candidate_employee_link
              WHERE tenant_id = '000000' AND candidate_id = ?
              LIMIT 1
-            """, (rs, rowNum) -> new CandidateLinkResponse(
-            rs.getString("candidate_id"),
-            rs.getString("ext_party_id"),
-            rs.getString("status"),
-            rs.getTimestamp("linked_time") == null ? "" : rs.getTimestamp("linked_time").toLocalDateTime().format(TIME_FORMAT)
-        ), normalizedCandidateId).stream().findFirst().orElse(null);
+            """, this::mapCandidateLink, normalizedCandidateId).stream().findFirst().orElse(null);
     }
 
     public CandidateLinkResponse linkCandidate(CandidateLinkRequest request, String operator) {
@@ -171,6 +166,15 @@ public class AihrInterviewService {
         if (activeEmployee == null || activeEmployee == 0) {
             throw new IllegalArgumentException("员工主体不存在或已离职，请先同步在职组织快照");
         }
+        CandidateLinkResponse existingPartyLink = jdbcTemplate.query("""
+            SELECT candidate_id, ext_party_id, status, linked_time
+              FROM aihr_candidate_employee_link
+             WHERE tenant_id = '000000' AND ext_party_id = ?
+             LIMIT 1
+            """, this::mapCandidateLink, extPartyId).stream().findFirst().orElse(null);
+        if (existingPartyLink != null && !candidateId.equals(existingPartyLink.candidateId())) {
+            throw new IllegalArgumentException("员工主体已关联其他候选人，请先由HR核对后处理");
+        }
         CandidateLinkResponse current = candidateLink(candidateId);
         if (current != null && !extPartyId.equals(current.extPartyId())) {
             throw new IllegalArgumentException("候选人已关联其他员工主体，请先由HR核对后处理");
@@ -198,6 +202,15 @@ public class AihrInterviewService {
         );
     }
 
+    private CandidateLinkResponse mapCandidateLink(ResultSet rs, int rowNum) throws SQLException {
+        return new CandidateLinkResponse(
+            rs.getString("candidate_id"),
+            rs.getString("ext_party_id"),
+            rs.getString("status"),
+            rs.getTimestamp("linked_time") == null ? "" : rs.getTimestamp("linked_time").toLocalDateTime().format(TIME_FORMAT)
+        );
+    }
+
     private void saveResult(String sessionId, InterviewSession session, ScoreResult score) {
         ensureResultTable();
         jdbcTemplate.update("""
@@ -303,7 +316,7 @@ public class AihrInterviewService {
                   `update_time` datetime DEFAULT NULL COMMENT '更新时间',
                   PRIMARY KEY (`id`),
                   UNIQUE KEY `uk_aihr_candidate_employee_link_candidate` (`tenant_id`, `candidate_id`),
-                  KEY `idx_aihr_candidate_employee_link_party` (`tenant_id`, `ext_party_id`)
+                  UNIQUE KEY `uk_aihr_candidate_employee_link_party` (`tenant_id`, `ext_party_id`)
                 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='AI HR 候选人与员工主体关联';
                 """);
             candidateLinkTableReady = true;

backend/ruoyi-modules/ruoyi-aihr/src/test/java/org/dromara/aihr/service/AihrInterviewServiceTest.java

@@ -6,6 +6,7 @@ import org.dromara.aihr.domain.AihrInterviewDto.CandidateLinkResponse;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.core.RowMapper;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertSame;
@@ -53,6 +54,25 @@ class AihrInterviewServiceTest {
         verify(jdbcTemplate, never()).update(anyString(), eq("candidate-2"), eq("employee-new"), eq("hr"));
     }
 
+    @Test
+    @Tag("dev")
+    void linkCandidateRejectsAnEmployeeAlreadyLinkedToAnotherCandidate() {
+        JdbcTemplate jdbcTemplate = mock(JdbcTemplate.class);
+        AihrInterviewService service = spy(new AihrInterviewService(new ObjectMapper(), null, jdbcTemplate));
+        CandidateLinkResponse existing = new CandidateLinkResponse("candidate-old", "employee-4", "已关联", "07-14 06:00");
+        doReturn(null).when(service).candidateLink("candidate-4");
+        when(jdbcTemplate.queryForObject(anyString(), eq(Integer.class), eq("employee-4"))).thenReturn(1);
+        when(jdbcTemplate.query(anyString(), org.mockito.ArgumentMatchers.<RowMapper<CandidateLinkResponse>>any(), eq("employee-4")))
+            .thenReturn(java.util.List.of(existing));
+
+        IllegalArgumentException error = assertThrows(IllegalArgumentException.class, () -> service.linkCandidate(
+            new CandidateLinkRequest("candidate-4", "employee-4"), "hr"
+        ));
+
+        assertEquals("员工主体已关联其他候选人，请先由HR核对后处理", error.getMessage());
+        verify(jdbcTemplate, never()).update(anyString(), eq("candidate-4"), eq("employee-4"), eq("hr"));
+    }
+
     @Test
     @Tag("dev")
     void linkCandidateIsIdempotentForTheSameEmployee() {

backend/script/sql/aihr_interview_result_mysql8.sql

@@ -38,5 +38,5 @@ CREATE TABLE IF NOT EXISTS `aihr_candidate_employee_link` (
   `update_time` datetime DEFAULT NULL COMMENT '更新时间',
   PRIMARY KEY (`id`),
   UNIQUE KEY `uk_aihr_candidate_employee_link_candidate` (`tenant_id`, `candidate_id`),
-  KEY `idx_aihr_candidate_employee_link_party` (`tenant_id`, `ext_party_id`)
+  UNIQUE KEY `uk_aihr_candidate_employee_link_party` (`tenant_id`, `ext_party_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='AI HR 候选人与员工主体关联';