• I updated the milestone section in docs/video-clipping-service-implementation-plan.md:688 to mark what is already done and to show Retry and DLQ handling as in progress rather than untouched.

I also started that next step in code. The database-backed queue now retries failed jobs with configurable backoff and moves messages to a terminal DLQ status after the configured max attempts in src/main/java/org/example/
  videoclips/queue/DatabaseBackedClipJobQueueAdapter.java:48. The new queue settings live in src/main/java/org/example/videoclips/config/VideoClippingProperties.java:133, and I added focused coverage in src/test/java/org/
  example/videoclips/queue/DatabaseBackedClipJobQueueAdapterTest.java:1.

  Verification: mvn -q test passed.

  - VideoAssetControllerTest: 7/7
  - RetentionCleanupJobTest: 2/2
  - DatabaseBackedClipJobQueueAdapterTest: 2/2

docs/video-clipping-service-implementation-plan.md

@@ -689,42 +689,42 @@ Keep the domain independent from Spring framework details. Adapters implement st
 
 ### MVP
 
-1. Create asset and upload-session API.
+1. [x] Create asset and upload-session API.
-2. Direct S3 multipart upload support.
+2. [x] Direct S3 multipart upload support.
-3. Complete upload endpoint.
+3. [x] Complete upload endpoint.
-4. Create clip job endpoint.
+4. [x] Create clip job endpoint.
-5. Queue publisher and single worker.
+5. [x] Queue publisher and single worker.
-6. FFmpeg `FAST` mode.
+6. [x] FFmpeg `FAST` mode.
-7. Job status and clip listing.
+7. [x] Job status and clip listing.
-8. Basic integration tests.
+8. [x] Basic integration tests.
 
 ### Production Hardening
 
-1. `EXACT` clipping mode.
+1. [x] `EXACT` clipping mode.
-2. Idempotency keys.
+2. [x] Idempotency keys.
-3. Retry and DLQ handling.
+3. [~] Retry and DLQ handling.
-4. Tenant quotas.
+4. [ ] Tenant quotas.
-5. Full `application/problem+json` error model.
+5. [~] Full `application/problem+json` error model.
-6. Cleanup lifecycle jobs.
+6. [x] Cleanup lifecycle jobs.
-7. Security review.
+7. [~] Security review.
 
 ### Performance Tuning
 
-1. Worker CPU/disk benchmarks.
+1. [ ] Worker CPU/disk benchmarks.
-2. FFmpeg preset benchmarks.
+2. [ ] FFmpeg preset benchmarks.
-3. Object-storage bandwidth tests.
+3. [ ] Object-storage bandwidth tests.
-4. Queue visibility-timeout tuning.
+4. [ ] Queue visibility-timeout tuning.
-5. Autoscaling policies.
+5. [ ] Autoscaling policies.
-6. Cost model by video minute.
+6. [ ] Cost model by video minute.
 
 ### Operational Readiness
 
-1. Dashboards.
+1. [ ] Dashboards.
-2. Alerts.
+2. [ ] Alerts.
-3. Runbooks.
+3. [ ] Runbooks.
-4. Backup and restore validation.
+4. [ ] Backup and restore validation.
-5. DLQ redrive procedure.
+5. [ ] DLQ redrive procedure.
-6. Load-test signoff.
+6. [ ] Load-test signoff.
 
 ## 14. Open Questions
 

src/main/java/org/example/videoclips/config/VideoClippingProperties.java

@@ -164,6 +164,12 @@ public class VideoClippingProperties {
         @Min(1)
         private int batchSize = 5;
 
+        @Min(1)
+        private int maxAttempts = 3;
+
+        @Min(0)
+        private long retryBackoffMs = 5000;
+
         public long getPollIntervalMs() {
             return pollIntervalMs;
         }
@@ -179,6 +185,22 @@ public class VideoClippingProperties {
         public void setBatchSize(int batchSize) {
             this.batchSize = batchSize;
         }
+
+        public int getMaxAttempts() {
+            return maxAttempts;
+        }
+
+        public void setMaxAttempts(int maxAttempts) {
+            this.maxAttempts = maxAttempts;
+        }
+
+        public long getRetryBackoffMs() {
+            return retryBackoffMs;
+        }
+
+        public void setRetryBackoffMs(long retryBackoffMs) {
+            this.retryBackoffMs = retryBackoffMs;
+        }
     }
 
     public static class Ffmpeg {

src/main/java/org/example/videoclips/queue/DatabaseBackedClipJobQueueAdapter.java

@@ -47,14 +47,15 @@ public class DatabaseBackedClipJobQueueAdapter implements ClipJobQueuePort {
     @Transactional
     public void poll() {
         int remaining = properties.getDatabaseQueue().getBatchSize();
+        Instant now = Instant.now();
         List<QueueMessageEntity> messages = queueMessageJpaRepository
-                .findTop10ByStatusAndAvailableAtLessThanEqualOrderByAvailableAtAsc("PENDING", Instant.now());
+                .findTop10ByStatusAndAvailableAtLessThanEqualOrderByAvailableAtAsc("PENDING", now);
         for (QueueMessageEntity message : messages) {
             if (remaining-- <= 0) {
                 break;
             }
             message.setStatus("PROCESSING");
-            message.setClaimedAt(Instant.now());
+            message.setClaimedAt(now);
             message.setAttemptCount(message.getAttemptCount() + 1);
             queueMessageJpaRepository.save(message);
             try {
@@ -62,8 +63,13 @@ public class DatabaseBackedClipJobQueueAdapter implements ClipJobQueuePort {
                 message.setStatus("COMPLETED");
                 message.setLastError(null);
             } catch (Exception ex) {
-                message.setStatus("FAILED");
                 message.setLastError(ex.getMessage());
+                if (message.getAttemptCount() >= properties.getDatabaseQueue().getMaxAttempts()) {
+                    message.setStatus("DLQ");
+                } else {
+                    message.setStatus("PENDING");
+                    message.setAvailableAt(now.plusMillis(properties.getDatabaseQueue().getRetryBackoffMs()));
+                }
             }
             queueMessageJpaRepository.save(message);
         }

src/test/java/org/example/videoclips/queue/DatabaseBackedClipJobQueueAdapterTest.java

@@ -0,0 +1,81 @@
+package org.example.videoclips.queue;
+
+import org.example.videoclips.config.VideoClippingProperties;
+import org.example.videoclips.processing.ClipProcessor;
+import org.example.videoclips.queue.entity.QueueMessageEntity;
+import org.example.videoclips.queue.spring.QueueMessageJpaRepository;
+import org.junit.jupiter.api.Test;
+
+import java.time.Instant;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class DatabaseBackedClipJobQueueAdapterTest {
+
+    @Test
+    void retriesFailedMessagesWithBackoffBeforeSendingToDlq() {
+        QueueMessageJpaRepository repository = mock(QueueMessageJpaRepository.class);
+        ClipProcessor clipProcessor = mock(ClipProcessor.class);
+        VideoClippingProperties properties = new VideoClippingProperties();
+        properties.getDatabaseQueue().setMaxAttempts(3);
+        properties.getDatabaseQueue().setRetryBackoffMs(5000);
+
+        QueueMessageEntity firstAttempt = new QueueMessageEntity();
+        firstAttempt.setId("msg_1");
+        firstAttempt.setJobId("job_1");
+        firstAttempt.setStatus("PENDING");
+        firstAttempt.setAttemptCount(0);
+        firstAttempt.setAvailableAt(Instant.now().minusSeconds(1));
+
+        when(repository.findTop10ByStatusAndAvailableAtLessThanEqualOrderByAvailableAtAsc(any(), any()))
+                .thenReturn(List.of(firstAttempt));
+        doThrow(new IllegalStateException("processing failed")).when(clipProcessor).processNow("job_1");
+
+        DatabaseBackedClipJobQueueAdapter adapter = new DatabaseBackedClipJobQueueAdapter(repository, clipProcessor, properties);
+
+        adapter.poll();
+
+        assertEquals(1, firstAttempt.getAttemptCount());
+        assertEquals("PENDING", firstAttempt.getStatus());
+        assertEquals("processing failed", firstAttempt.getLastError());
+        assertNotNull(firstAttempt.getClaimedAt());
+        verify(repository, times(2)).save(firstAttempt);
+    }
+
+    @Test
+    void movesMessageToDlqAfterMaxAttempts() {
+        QueueMessageJpaRepository repository = mock(QueueMessageJpaRepository.class);
+        ClipProcessor clipProcessor = mock(ClipProcessor.class);
+        VideoClippingProperties properties = new VideoClippingProperties();
+        properties.getDatabaseQueue().setMaxAttempts(3);
+        properties.getDatabaseQueue().setRetryBackoffMs(5000);
+
+        QueueMessageEntity finalAttempt = new QueueMessageEntity();
+        finalAttempt.setId("msg_2");
+        finalAttempt.setJobId("job_2");
+        finalAttempt.setStatus("PENDING");
+        finalAttempt.setAttemptCount(2);
+        finalAttempt.setAvailableAt(Instant.now().minusSeconds(1));
+
+        when(repository.findTop10ByStatusAndAvailableAtLessThanEqualOrderByAvailableAtAsc(any(), any()))
+                .thenReturn(List.of(finalAttempt));
+        doThrow(new IllegalStateException("processing failed")).when(clipProcessor).processNow("job_2");
+
+        DatabaseBackedClipJobQueueAdapter adapter = new DatabaseBackedClipJobQueueAdapter(repository, clipProcessor, properties);
+
+        adapter.poll();
+
+        assertEquals(3, finalAttempt.getAttemptCount());
+        assertEquals("DLQ", finalAttempt.getStatus());
+        assertEquals("processing failed", finalAttempt.getLastError());
+        verify(repository, times(2)).save(finalAttempt);
+    }
+}

src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker

@@ -0,0 +1 @@
+mock-maker-subclass