[DP-306] Refresh Token rotation 제거로 로그인 튕김 현상 수정

src/main/java/com/devpick/domain/user/service/TokenService.java

@@ -91,19 +91,10 @@ public String[] reissueTokens(String refreshToken) {
 
         User user = stored.getUser();
 
-        // 4. 기존 토큰 삭제 + 신규 토큰 발급 (Token Rotation)
-        refreshTokenRepository.deleteByUser(user);
-
+        // 4. Access Token만 새로 발급, Refresh Token은 유지 (레이스 컨디션 방지)
         String newAccessToken = jwtTokenProvider.generateAccessToken(user.getId());
-        String newRefreshToken = jwtTokenProvider.generateRefreshToken();
-
-        refreshTokenRepository.save(RefreshToken.builder()
-                .user(user)
-                .token(newRefreshToken)
-                .expiresAt(jwtTokenProvider.getRefreshTokenExpiresAt())
-                .build());
 
-        return new String[]{newAccessToken, newRefreshToken};
+        return new String[]{newAccessToken, refreshToken};
     }
 
     /**

src/test/java/com/devpick/domain/user/service/TokenServiceTest.java

@@ -24,6 +24,7 @@
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 
 @ExtendWith(MockitoExtension.class)
@@ -84,18 +85,13 @@ void reissueTokens_success() throws Exception {
                 .willReturn(Optional.of(stored));
         given(jwtTokenProvider.generateAccessToken(user.getId()))
                 .willReturn("new-access-token");
-        given(jwtTokenProvider.generateRefreshToken())
-                .willReturn("new-refresh-token");
-        given(jwtTokenProvider.getRefreshTokenExpiresAt())
-                .willReturn(LocalDateTime.now().plusDays(7));
-        given(refreshTokenRepository.save(any(RefreshToken.class)))
-                .willAnswer(invocation -> invocation.getArgument(0));
 
         String[] tokens = tokenService.reissueTokens("old-refresh-token");
 
         assertThat(tokens[0]).isEqualTo("new-access-token");
-        assertThat(tokens[1]).isEqualTo("new-refresh-token");
-        verify(refreshTokenRepository).deleteByUser(user);
+        assertThat(tokens[1]).isEqualTo("old-refresh-token");
+        verify(refreshTokenRepository, never()).deleteByUser(any());
+        verify(refreshTokenRepository, never()).save(any());
     }
 
     @Test