src/main/kotlin/kr/co/vividnext/sodalive/fcm/FcmService.kt

@@ -29,8 +29,14 @@ class FcmService {
         creatorId: Long? = null,
         auditionId: Long? = null
     ) {
-        if (tokens.isNotEmpty()) {
+        if (tokens.isEmpty()) return
         logger.info("os: $container")
+
+        var targets = tokens
+        val maxAttempts = 3
+        var attempt = 1
+
+        while (attempt <= maxAttempts && targets.isNotEmpty()) {
             val multicastMessage = MulticastMessage.builder()
                 .addAllTokens(tokens)
 
@@ -85,8 +91,34 @@ class FcmService {
             }
 
             val response = FirebaseMessaging.getInstance().sendEachForMulticast(multicastMessage.build())
-            logger.info("[FCM] ✅ 성공: ${response.successCount}")
-            logger.info("[FCM] ❌ 실패: ${response.failureCount}")
+            val failedTokens = mutableListOf<String>()
+
+            response.responses.forEachIndexed { index, res ->
+                if (!res.isSuccessful) {
+                    val exception = res.exception
+                    val token = targets[index]
+
+                    if (exception?.messagingErrorCode == MessagingErrorCode.UNREGISTERED) {
+                        logger.error("[FCM] ❌ UNREGISTERED → $token")
+                        // 필요 시 DB에서 삭제
+                    } else {
+                        logger.error("[FCM] ❌ 실패: $token / ${exception?.messagingErrorCode}")
+                        failedTokens.add(token)
+                    }
+                }
+            }
+
+            if (failedTokens.isEmpty()) {
+                logger.info("[FCM] ✅ 전체 전송 성공")
+                return
+            }
+
+            targets = failedTokens
+            attempt++
+        }
+
+        if (targets.isNotEmpty()) {
+            logger.error("[FCM] ❌ 최종 실패 대상 ${targets.size}명 → $targets")
         }
     }