diff --git a/server/skillhub-app/src/main/java/com/iflytek/skillhub/stream/ScanTaskConsumer.java b/server/skillhub-app/src/main/java/com/iflytek/skillhub/stream/ScanTaskConsumer.java
index f32a2876..3b1b2c66 100644
--- a/server/skillhub-app/src/main/java/com/iflytek/skillhub/stream/ScanTaskConsumer.java
+++ b/server/skillhub-app/src/main/java/com/iflytek/skillhub/stream/ScanTaskConsumer.java
@@ -144,7 +144,11 @@ public class ScanTaskConsumer extends AbstractStreamConsumer<ScanTaskConsumer.Sc
                 log.info("Skipping concurrently processed security scan task: taskId={}, versionId={}",
                         payload.taskId(), payload.versionId());
                 payload.skipCleanup();
-                return;
+                // A normal return is treated as success by AbstractStreamConsumer and ACKs
+                // the Redis entry. Requeue through the common failure path instead, so a
+                // reclaimed duplicate cannot erase the only durable delivery while the active
+                // scanner still owns the task lock.
+                throw new ConcurrentScanInProgressException(payload.taskId());
             }
             if (securityScanService.isTaskAlreadyProcessed(payload.taskId())) {
                 return;
@@ -165,6 +169,12 @@ public class ScanTaskConsumer extends AbstractStreamConsumer<ScanTaskConsumer.Sc
         securityScanService.processScanResult(payload.versionId(), payload.scannerType(), response);
     }
 
+    private static final class ConcurrentScanInProgressException extends RuntimeException {
+        private ConcurrentScanInProgressException(String taskId) {
+            super("Security scan is already in progress: taskId=" + taskId);
+        }
+    }
+
     @Override
     protected void markCompleted(ScanTaskPayload payload) {
         cleanupTempPath(payload.cleanupPath());
diff --git a/server/skillhub-app/src/test/java/com/iflytek/skillhub/stream/ScanTaskConsumerTest.java b/server/skillhub-app/src/test/java/com/iflytek/skillhub/stream/ScanTaskConsumerTest.java
index 8456d11d..07d7d9d6 100644
--- a/server/skillhub-app/src/test/java/com/iflytek/skillhub/stream/ScanTaskConsumerTest.java
+++ b/server/skillhub-app/src/test/java/com/iflytek/skillhub/stream/ScanTaskConsumerTest.java
@@ -293,8 +293,9 @@ class ScanTaskConsumerTest {
                 "task-inflight", 42L, tempDir.toString(), null, ScannerType.SKILL_SCANNER);
 
         try {
-            consumer.invokeProcessBusiness(payload);
-            consumer.invokeMarkCompleted(payload);
+            assertThatThrownBy(() -> consumer.invokeProcessBusiness(payload))
+                    .isInstanceOf(RuntimeException.class)
+                    .hasMessage("Security scan is already in progress: taskId=task-inflight");
 
             assertThat(securityScanner.lastRequest).isNull();
             assertThat(skillFile).exists();
@@ -305,6 +306,33 @@ class ScanTaskConsumerTest {
         }
     }
 
+    @Test
+    void handleMessage_whenTaskLockIsHeld_republishesInsteadOfDroppingDelivery() {
+        StubSecurityScanner securityScanner = new StubSecurityScanner();
+        InMemoryScanTaskProducer producer = new InMemoryScanTaskProducer();
+        RLock processingLock = mock(RLock.class);
+        when(processingLock.tryLock()).thenReturn(false);
+        TestableScanTaskConsumer consumer = new TestableScanTaskConsumer(
+                securityScanner,
+                new StubSecurityScanService(),
+                new InMemorySkillVersionRepository(),
+                producer,
+                new InMemoryObjectStorageService(),
+                redissonClient(processingLock)
+        );
+
+        consumer.handleMessage(new StreamMessageId(11, 0), Map.of(
+                "taskId", "task-reclaimed",
+                "versionId", "42",
+                "skillPath", "/tmp/skillhub-scans/42",
+                "scannerType", ScannerType.SKILL_SCANNER.getValue()
+        ));
+
+        assertThat(producer.publishedTask.taskId()).isEqualTo("task-reclaimed");
+        assertThat(producer.publishedTask.metadata()).containsEntry("retryCount", "1");
+        verify(consumer.stream).ack("skillhub-scanners", new StreamMessageId(11, 0));
+    }
+
     @Test
     void processBusiness_whenScannerFails_releasesProcessingLock() {
         StubSecurityScanner securityScanner = new StubSecurityScanner();