✨ Update dependencies, enhance NATS consumer configuration, and improve error handling in message processing. Introduce telemetry support with OpenTelemetry for tracing and metrics. Refactor README to include new configuration options and update tests for improved coverage of error scenarios.

internal/infra/config/config.go

@@ -19,6 +19,7 @@ type Config struct {
 	App       AppConfig       `koanf:"app"`
 	Log       LogConfig       `koanf:"log"`
 	Publisher PublisherConfig `koanf:"publisher"`
+	Telemetry TelemetryConfig `koanf:"telemetry"`
 	// Legacy fields for backward compatibility during migration
 	Subscription SubscriptionConfig `koanf:"subscription"`
 	Timeouts     TimeoutsConfig     `koanf:"timeouts"`
@@ -51,6 +52,11 @@ type ConsumerRulesConfig struct {
 	MaxDeliver    int           `koanf:"max_deliver"`
 	AckWait       time.Duration `koanf:"ack_wait"`
 	MaxAckPending int           `koanf:"max_ack_pending"`
+	DeliverPolicy string        `koanf:"deliver_policy"`
+	ReplayPolicy  string        `koanf:"replay_policy"`
+	Backoff       []time.Duration `koanf:"backoff"`
+	StartSequence uint64        `koanf:"start_sequence"`
+	StartTime     string        `koanf:"start_time"`
 }
 
 // PostgresConfig holds PostgreSQL configuration
@@ -78,6 +84,13 @@ type PublisherConfig struct {
 	Topic string `koanf:"topic"`
 }
 
+// TelemetryConfig controls tracing/metrics exporters.
+type TelemetryConfig struct {
+	Enabled  bool   `koanf:"enabled"`
+	Endpoint string `koanf:"endpoint"`
+	Insecure bool   `koanf:"insecure"`
+}
+
 // SubscriptionConfig holds subscription configuration (legacy)
 type SubscriptionConfig struct {
 	Topic      string `koanf:"topic"`
@@ -183,6 +196,15 @@ func LoadConfig() (*Config, error) {
 	if cfg.NATS.ConsumerRules.MaxAckPending == 0 {
 		cfg.NATS.ConsumerRules.MaxAckPending = 1024
 	}
+	if cfg.NATS.ConsumerRules.DeliverPolicy == "" {
+		cfg.NATS.ConsumerRules.DeliverPolicy = "all"
+	}
+	if cfg.NATS.ConsumerRules.ReplayPolicy == "" {
+		cfg.NATS.ConsumerRules.ReplayPolicy = "instant"
+	}
+	if cfg.Telemetry.Endpoint == "" {
+		cfg.Telemetry.Endpoint = ""
+	}
 
 	// Validate configuration
 	if err := cfg.Validate(); err != nil {
@@ -236,6 +258,29 @@ func (c *Config) Validate() error {
 	if c.NATS.ConsumerRules.MaxAckPending < 0 {
 		return fmt.Errorf("nats.consumer.max_ack_pending must be >= 0")
 	}
+	switch strings.ToLower(c.NATS.ConsumerRules.DeliverPolicy) {
+	case "", "all", "new", "last", "last_per_subject", "sequence", "time":
+	default:
+		return fmt.Errorf("nats.consumer.deliver_policy must be one of all,new,last,last_per_subject,sequence,time")
+	}
+	switch strings.ToLower(c.NATS.ConsumerRules.ReplayPolicy) {
+	case "", "instant", "original":
+	default:
+		return fmt.Errorf("nats.consumer.replay_policy must be instant or original")
+	}
+	if c.NATS.ConsumerRules.StartTime != "" {
+		if _, err := time.Parse(time.RFC3339, c.NATS.ConsumerRules.StartTime); err != nil {
+			return fmt.Errorf("nats.consumer.start_time must be RFC3339: %w", err)
+		}
+	}
+	for _, d := range c.NATS.ConsumerRules.Backoff {
+		if d < 0 {
+			return fmt.Errorf("nats.consumer.backoff durations must be >= 0")
+		}
+	}
+	if c.Telemetry.Endpoint == "" && c.Telemetry.Enabled {
+		return fmt.Errorf("telemetry.endpoint is required when telemetry.enabled=true")
+	}
 	return nil
 }