✨ Refactor NATS consumer management by introducing a dedicated ConsumerManager and StreamManager for lifecycle management. Enhance error handling with a new ErrorHandler to streamline message processing and recovery logic. Update consumer initialization to utilize the new managers, improving code organization and maintainability. Add comprehensive tests for the new components to ensure reliability and robustness in handling NATS operations.

internal/infra/nats/consumer.go

@@ -37,6 +37,11 @@ type Consumer struct {
 	pending         metric.Int64Histogram
 	delivered       metric.Int64Histogram
 
+	// managers for resource lifecycle
+	consumerManager *ConsumerManager
+	streamManager   *StreamManager
+	errorHandler    *ErrorHandler
+
 	// simple backpressure / degradation state
 	consecutiveProcessErrors int
 }
@@ -147,9 +152,15 @@ func ProvideConsumer(
 	}
 	consumer.initMetrics()
 
+	// Initialize managers
+	consumer.errorHandler = NewErrorHandler(logger)
 	if consumer.mode == "jetstream" {
+		consumer.consumerManager = NewConsumerManager(js, normCfg.streamName, normCfg.consumerName, normCfg.subject, logger)
+		consumer.streamManager = NewStreamManager(js, normCfg.streamName, []string{normCfg.subject}, logger)
+
 		// Create consumer if it doesn't exist
-		if err := consumer.ensureConsumer(); err != nil {
+		consumerConfig := consumer.buildConsumerConfig()
+		if err := consumer.consumerManager.EnsureConsumer(consumerConfig); err != nil {
 			return nil, fmt.Errorf("failed to ensure consumer: %w", err)
 		}
 		// Validate DLQ configuration early so misconfiguration is visible at startup
@@ -167,6 +178,21 @@ func ProvideConsumer(
 	return consumer, nil
 }
 
+// buildConsumerConfig builds the NATS consumer configuration
+func (c *Consumer) buildConsumerConfig() *nats.ConsumerConfig {
+	return &nats.ConsumerConfig{
+		Durable:       c.consumerName,
+		DeliverPolicy: mapDeliverPolicy(c.cfg.NATS.ConsumerRules.DeliverPolicy),
+		AckPolicy:     nats.AckExplicitPolicy,
+		AckWait:       c.ackWait,
+		ReplayPolicy:  mapReplayPolicy(c.cfg.NATS.ConsumerRules.ReplayPolicy),
+		MaxDeliver:    c.cfg.NATS.ConsumerRules.MaxDeliver,
+		MaxAckPending: c.cfg.NATS.ConsumerRules.MaxAckPending,
+		FilterSubject: c.subject,
+		BackOff:       c.cfg.NATS.ConsumerRules.Backoff,
+	}
+}
+
 // Start starts consuming messages.
 func (c *Consumer) Start(ctx context.Context) error {
 	if c.mode == "core" {