✨ Add repository guidelines and enhance documentation for project structure, build commands, coding standards, and testing practices. Introduce AGENTS.md for contributor guidance, update README.md to reference new guidelines, and improve configuration documentation for NATS modes. Update Makefile and Taskfile with clearer run commands and requirements for development and production modes. Add production deployment guide and improve logging configuration for better observability.

internal/infra/nats/consumer.go

@@ -3,22 +3,13 @@ package nats
 import (
 	"caatsm/internal/app"
 	"caatsm/internal/infra/config"
-	"caatsm/internal/infra/log"
-	obsmetrics "caatsm/internal/infra/metrics"
 	"caatsm/internal/infra/telemetry"
 	"context"
-	"encoding/json"
-	"errors"
 	"fmt"
-	"os"
 	"strings"
 	"time"
 
-	"github.com/google/uuid"
 	"github.com/nats-io/nats.go"
-	"go.opentelemetry.io/otel"
-	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/metric"
 	"go.uber.org/zap"
 )
@@ -50,41 +41,22 @@ type Consumer struct {
 	consecutiveProcessErrors int
 }
 
-func isDevLikeEnv() bool {
-	switch strings.ToLower(os.Getenv("GO_ENV")) {
-	case "", "dev", "development", "test", "testing":
-		return true
-	default:
-		return false
-	}
+// consumerConfig holds normalized consumer configuration values.
+type consumerConfig struct {
+	subject         string
+	consumerName    string
+	mode            string
+	streamName      string
+	dlqSubject      string
+	ackWait         time.Duration
+	batchSize       int
+	batchTimeout    time.Duration
+	monitorInterval time.Duration
 }
 
-func isJetStreamResourceNotFound(err error) bool {
-	if err == nil {
-		return false
-	}
-	if errors.Is(err, nats.ErrStreamNotFound) || errors.Is(err, nats.ErrConsumerNotFound) {
-		return true
-	}
-
-	// Some JetStream API errors are only exposed via error strings.
-	msg := strings.ToLower(err.Error())
-	if strings.Contains(msg, "stream not found") || strings.Contains(msg, "consumer not found") {
-		return true
-	}
-
-	return false
-}
-
-// ProvideConsumer creates a NATS consumer
-func ProvideConsumer(
-	conn *nats.Conn,
-	js nats.JetStreamContext,
-	processor *app.MessageProcessor,
-	cfg *config.Config,
-	rec telemetry.Recorder,
-	logger *zap.Logger,
-) (*Consumer, error) {
+// normalizeConsumerConfig extracts and normalizes consumer configuration from the application config.
+// This function can be unit-tested without requiring a JetStream context.
+func normalizeConsumerConfig(cfg *config.Config) *consumerConfig {
 	subject := cfg.EffectiveSubscriptionTopic()
 
 	consumerName := cfg.NATS.Consumer
@@ -132,13 +104,7 @@ func ProvideConsumer(
 		monitorInterval = 30 * time.Second
 	}
 
-	consumer := &Consumer{
-		conn:            conn,
-		js:              js,
-		processor:       processor,
-		cfg:             cfg,
-		logger:          logger,
-		telemetry:       rec,
+	return &consumerConfig{
 		subject:         subject,
 		consumerName:    consumerName,
 		mode:            mode,
@@ -149,6 +115,36 @@ func ProvideConsumer(
 		batchTimeout:    batchTimeout,
 		monitorInterval: monitorInterval,
 	}
+}
+
+// ProvideConsumer creates a NATS consumer.
+func ProvideConsumer(
+	conn *nats.Conn,
+	js nats.JetStreamContext,
+	processor *app.MessageProcessor,
+	cfg *config.Config,
+	rec telemetry.Recorder,
+	logger *zap.Logger,
+) (*Consumer, error) {
+	normCfg := normalizeConsumerConfig(cfg)
+
+	consumer := &Consumer{
+		conn:            conn,
+		js:              js,
+		processor:       processor,
+		cfg:             cfg,
+		logger:          logger,
+		telemetry:       rec,
+		subject:         normCfg.subject,
+		consumerName:    normCfg.consumerName,
+		mode:            normCfg.mode,
+		streamName:      normCfg.streamName,
+		dlqSubject:      normCfg.dlqSubject,
+		ackWait:         normCfg.ackWait,
+		batchSize:       normCfg.batchSize,
+		batchTimeout:    normCfg.batchTimeout,
+		monitorInterval: normCfg.monitorInterval,
+	}
 	consumer.initMetrics()
 
 	if consumer.mode == "jetstream" {
@@ -158,10 +154,12 @@ func ProvideConsumer(
 		}
 		// Validate DLQ configuration early so misconfiguration is visible at startup
 		// rather than only when the first poison message appears.
-		consumer.validateDLQ()
+		if err := consumer.validateDLQ(); err != nil {
+			return nil, fmt.Errorf("DLQ validation failed: %w", err)
+		}
 	} else {
 		logger.Info("Running consumer in core NATS mode",
-			zap.String("subject", subject),
+			zap.String("subject", normCfg.subject),
 			zap.String("queue_group", cfg.Subscription.QueueGroup),
 		)
 	}
@@ -169,176 +167,7 @@ func ProvideConsumer(
 	return consumer, nil
 }
 
-// ensureConsumer creates the consumer if it doesn't exist; if it already exists, it is reused.
-func (c *Consumer) ensureConsumer() error {
-	consumerConfig := &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,
-	}
-	if consumerConfig.DeliverPolicy == nats.DeliverByStartSequencePolicy && c.cfg.NATS.ConsumerRules.StartSequence > 0 {
-		consumerConfig.OptStartSeq = c.cfg.NATS.ConsumerRules.StartSequence
-	}
-	if consumerConfig.DeliverPolicy == nats.DeliverByStartTimePolicy && strings.TrimSpace(c.cfg.NATS.ConsumerRules.StartTime) != "" {
-		startTime, err := time.Parse(time.RFC3339, c.cfg.NATS.ConsumerRules.StartTime)
-		if err != nil {
-			c.logger.Warn("Invalid start time, falling back to deliver policy defaults",
-				zap.String("start_time", c.cfg.NATS.ConsumerRules.StartTime),
-				zap.Error(err),
-			)
-		} else {
-			consumerConfig.OptStartTime = &startTime
-		}
-	}
-
-	// First check if the consumer already exists to make this initialization idempotent.
-	info, err := c.js.ConsumerInfo(c.streamName, c.consumerName)
-	if err == nil && info != nil {
-		c.logger.Info("Using existing JetStream consumer",
-			zap.String("consumer", c.consumerName),
-			zap.String("stream", c.streamName),
-			zap.String("subject", c.subject),
-		)
-		return nil
-	}
-	if err != nil && !errors.Is(err, nats.ErrConsumerNotFound) {
-		return fmt.Errorf("failed to fetch consumer info: %w", err)
-	}
-
-	// Consumer does not exist; create it.
-	if _, err := c.js.AddConsumer(c.streamName, consumerConfig); err != nil {
-		return fmt.Errorf("failed to create consumer: %w", err)
-	}
-
-	c.logger.Info("Created JetStream consumer",
-		zap.String("consumer", c.consumerName),
-		zap.String("stream", c.streamName),
-		zap.String("subject", c.subject),
-		zap.Duration("ack_wait", c.ackWait),
-		zap.String("deliver_policy", c.cfg.NATS.ConsumerRules.DeliverPolicy),
-		zap.String("replay_policy", c.cfg.NATS.ConsumerRules.ReplayPolicy),
-	)
-
-	return nil
-}
-
-// recoverJetStreamResources attempts to recreate the stream and consumer in
-// dev/test environments if they are missing. It is safe to call multiple times.
-func (c *Consumer) recoverJetStreamResources() error {
-	if c.js == nil {
-		return fmt.Errorf("jetstream context is nil")
-	}
-	if c.cfg == nil {
-		return fmt.Errorf("config is nil")
-	}
-
-	// Ensure stream exists (dev/test may auto-create, prod will error).
-	if err := EnsureStream(c.js, c.cfg, c.logger); err != nil {
-		return fmt.Errorf("ensure stream %s: %w", c.streamName, err)
-	}
-
-	// Ensure durable consumer exists and is properly bound.
-	if err := c.ensureConsumer(); err != nil {
-		return fmt.Errorf("ensure consumer %s: %w", c.consumerName, err)
-	}
-
-	return nil
-}
-
-// createPullSubscriptionWithRecovery creates a pull subscription and, in
-// dev/test environments, attempts to self-heal missing stream/consumer
-// by recreating them once.
-func (c *Consumer) createPullSubscriptionWithRecovery() (*nats.Subscription, error) {
-	sub, err := c.js.PullSubscribe(c.subject, c.consumerName, nats.Bind(c.streamName, c.consumerName))
-	if err == nil {
-		return sub, nil
-	}
-
-	if isJetStreamResourceNotFound(err) && isDevLikeEnv() && shouldBootstrapStream() {
-		c.logger.Warn("PullSubscribe failed due to missing JetStream resources; attempting to recreate",
-			zap.Error(err),
-			zap.String("stream", c.streamName),
-			zap.String("consumer", c.consumerName),
-		)
-		if recErr := c.recoverJetStreamResources(); recErr != nil {
-			return nil, fmt.Errorf("failed to recover JetStream resources: %w", recErr)
-		}
-		// Retry subscription after successful recovery.
-		sub, err = c.js.PullSubscribe(c.subject, c.consumerName, nats.Bind(c.streamName, c.consumerName))
-		if err != nil {
-			return nil, fmt.Errorf("failed to create pull subscription after recovery: %w", err)
-		}
-		return sub, nil
-	}
-
-	return nil, fmt.Errorf("failed to create pull subscription: %w", err)
-}
-
-// validateDLQ verifies whether DLQ routing should be enabled and, if so, whether
-// the configured DLQ subject is bound to a JetStream stream. If validation fails,
-// DLQ routing is disabled (by clearing c.dlqSubject) and a warning is logged,
-// but the consumer is still allowed to start.
-func (c *Consumer) validateDLQ() {
-	if c == nil {
-		return
-	}
-
-	// DLQ routing is only active in JetStream mode.
-	if c.mode != "jetstream" {
-		return
-	}
-
-	// If DLQ is not enabled in config, make sure we don't accidentally route to it.
-	if !c.cfg.DLQ.Enabled {
-		if strings.TrimSpace(c.dlqSubject) != "" {
-			c.logger.Info("DLQ subject configured but dlq.enabled is false; DLQ routing disabled",
-				zap.String("dlq_subject", c.dlqSubject),
-			)
-		}
-		c.dlqSubject = ""
-		return
-	}
-
-	subject := strings.TrimSpace(c.dlqSubject)
-	if subject == "" {
-		c.logger.Warn("DLQ enabled but dlq.subject is empty; DLQ routing disabled")
-		return
-	}
-
-	if c.js == nil {
-		c.logger.Warn("DLQ enabled but JetStream context is nil; DLQ routing disabled",
-			zap.String("dlq_subject", subject),
-		)
-		c.dlqSubject = ""
-		return
-	}
-
-	// Ensure the DLQ subject is actually bound to a JetStream stream. This avoids
-	// the opaque `nats: no response from stream` error later when publishing.
-	c.telemetry.RecordJSAPICall("dlq_validate_stream")
-	streamName, err := c.js.StreamNameBySubject(subject)
-	if err != nil || strings.TrimSpace(streamName) == "" {
-		c.logger.Warn("DLQ subject not bound to any JetStream stream; DLQ routing disabled",
-			zap.String("dlq_subject", subject),
-			zap.Error(err),
-		)
-		c.dlqSubject = ""
-		return
-	}
-
-	c.logger.Info("DLQ configuration validated",
-		zap.String("dlq_subject", subject),
-		zap.String("dlq_stream", streamName),
-	)
-}
-
-// Start starts consuming messages
+// Start starts consuming messages.
 func (c *Consumer) Start(ctx context.Context) error {
 	if c.mode == "core" {
 		return c.startCore(ctx)
@@ -347,267 +176,6 @@ func (c *Consumer) Start(ctx context.Context) error {
 	return c.startJetStream(ctx)
 }
 
-func (c *Consumer) startJetStream(ctx context.Context) error {
-	// Create pull subscription (with simple self-healing in dev/test).
-	sub, err := c.createPullSubscriptionWithRecovery()
-	if err != nil {
-		return err
-	}
-	defer sub.Unsubscribe()
-
-	c.logger.Info("Started consuming messages",
-		zap.String("subject", c.subject),
-		zap.String("consumer", c.consumerName),
-		zap.String("stream", c.streamName),
-	)
-
-	c.logger.Info("Consumer pull configuration",
-		zap.Int("batch_size", c.batchSize),
-		zap.Duration("batch_timeout", c.batchTimeout),
-		zap.Int("max_deliver", c.cfg.NATS.ConsumerRules.MaxDeliver),
-		zap.Duration("ack_wait", c.ackWait),
-		zap.String("deliver_policy", c.cfg.NATS.ConsumerRules.DeliverPolicy),
-		zap.String("replay_policy", c.cfg.NATS.ConsumerRules.ReplayPolicy),
-		zap.Int("backoff_steps", len(c.cfg.NATS.ConsumerRules.Backoff)),
-	)
-
-	statsCtx, statsCancel := context.WithCancel(ctx)
-	defer statsCancel()
-	go c.emitConsumerStats(statsCtx)
-
-	var fetchErrorStreak int
-
-	for {
-		select {
-		case <-ctx.Done():
-			c.logger.Info("Stopping consumer", zap.Error(ctx.Err()))
-			return ctx.Err()
-		default:
-		}
-
-		// Fetch messages in batch
-		msgs, err := sub.Fetch(c.batchSize, nats.MaxWait(c.batchTimeout))
-		if err != nil {
-			if errors.Is(err, nats.ErrTimeout) {
-				// Timeout is expected when no messages are available.
-				continue
-			}
-
-			// JetStream API is currently unavailable (e.g., NATS just restarted or JetStream not ready).
-			if errors.Is(err, nats.ErrNoResponders) {
-				fetchErrorStreak++
-				backoff := time.Duration(fetchErrorStreak) * time.Second
-				if backoff > 30*time.Second {
-					backoff = 30 * time.Second
-				}
-				c.logger.Warn("JetStream not available, will retry with backoff",
-					zap.Error(err),
-					zap.String("stream", c.streamName),
-					zap.String("consumer", c.consumerName),
-					zap.Duration("backoff", backoff),
-				)
-				time.Sleep(backoff)
-				continue
-			}
-
-			// Underlying consumer/stream removed while app is running.
-			if isJetStreamResourceNotFound(err) {
-				if isDevLikeEnv() && shouldBootstrapStream() {
-					c.logger.Warn("JetStream consumer or stream missing; attempting to recreate",
-						zap.Error(err),
-						zap.String("stream", c.streamName),
-						zap.String("consumer", c.consumerName),
-					)
-					if recErr := c.recoverJetStreamResources(); recErr != nil {
-						c.logger.Error("Failed to recover JetStream resources", zap.Error(recErr))
-						return recErr
-					}
-
-					// Recreate subscription after successful recovery.
-					sub.Unsubscribe()
-					sub, err = c.createPullSubscriptionWithRecovery()
-					if err != nil {
-						return err
-					}
-
-					// Reset error streak after successful recovery.
-					fetchErrorStreak = 0
-					continue
-				}
-
-				// Production: treat as configuration/operational error.
-				c.logger.Error("JetStream consumer or stream missing; not auto-recreating in this environment",
-					zap.Error(err),
-					zap.String("stream", c.streamName),
-					zap.String("consumer", c.consumerName),
-				)
-				return err
-			}
-
-			// Generic error path with modest backoff.
-			fetchErrorStreak++
-			backoff := time.Duration(fetchErrorStreak) * time.Second
-			if backoff > 10*time.Second {
-				backoff = 10 * time.Second
-			}
-			c.logger.Error("Failed to fetch messages; backing off",
-				zap.Error(err),
-				zap.Duration("backoff", backoff),
-			)
-			time.Sleep(backoff)
-			continue
-		}
-
-		// Successful fetch -> reset error streak.
-		if fetchErrorStreak > 0 {
-			fetchErrorStreak = 0
-		}
-
-		// Process each message
-		// TODO: consider buffering messages to take advantage of Repository.InsertBatch for higher throughput.
-		for _, msg := range msgs {
-			start := time.Now()
-
-			if err := c.processMessage(ctx, msg); err != nil {
-				isPermanent := app.IsPermanent(err)
-				elapsed := time.Since(start)
-
-				c.logger.Error("Failed to process message",
-					zap.String("subject", msg.Subject),
-					zap.Error(err),
-					zap.Bool("permanent", isPermanent),
-				)
-
-				result := obsmetrics.ResultFail
-				if isPermanent {
-					result = obsmetrics.ResultPermanentFail
-				}
-				c.telemetry.RecordMessageHandled(ctx, c.streamName, c.consumerName, result, elapsed)
-
-				if isPermanent {
-					c.consecutiveProcessErrors = 0
-					// Poison/permanent message: route to DLQ if configured, then ACK
-					if err := c.routeToDLQ(ctx, msg, err); err != nil {
-						c.logger.Error("Failed to route permanent-error message to DLQ", zap.Error(err))
-					}
-					if ackErr := msg.Ack(); ackErr != nil {
-						c.logger.Error("Failed to ACK permanent-error message", zap.Error(ackErr))
-					}
-					continue
-				}
-
-				// Transient error: increment error streak and apply simple backpressure if needed.
-				if c.consecutiveProcessErrors < 0 {
-					c.consecutiveProcessErrors = 0
-				}
-				c.consecutiveProcessErrors++
-				if c.consecutiveProcessErrors >= 10 {
-					// Apply a brief sleep to slow down consumption when the system
-					// is failing many messages in a row (e.g. DB unavailable).
-					backoff := time.Duration(c.consecutiveProcessErrors) * 100 * time.Millisecond
-					if backoff > 5*time.Second {
-						backoff = 5 * time.Second
-					}
-					c.logger.Warn("Applying backpressure due to consecutive processing errors",
-						zap.Int("consecutive_errors", c.consecutiveProcessErrors),
-						zap.Duration("sleep", backoff),
-					)
-					time.Sleep(backoff)
-				}
-
-				// Transient error: request redelivery with optional delay
-				c.telemetry.RecordRetry(ctx, c.streamName, c.consumerName, obsmetrics.RetryReasonProcessorError)
-				if nakErr := c.nakWithStrategy(msg); nakErr != nil {
-					c.logger.Error("Failed to NAK message", zap.Error(nakErr))
-				}
-				continue
-			}
-
-			// Successful processing resets the error streak.
-			if c.consecutiveProcessErrors > 0 {
-				c.consecutiveProcessErrors = 0
-			}
-
-			// ACK the message
-			if ackErr := msg.Ack(); ackErr != nil {
-				c.logger.Error("Failed to ACK message", zap.Error(ackErr))
-			} else {
-				elapsed := time.Since(start)
-				c.telemetry.RecordMessageHandled(ctx, c.streamName, c.consumerName, "ok", elapsed)
-			}
-		}
-	}
-}
-
-func (c *Consumer) startCore(ctx context.Context) error {
-	queueGroup := c.cfg.Subscription.QueueGroup
-	if queueGroup == "" {
-		queueGroup = c.consumerName
-	}
-
-	handler := func(msg *nats.Msg) {
-		if err := c.processMessage(ctx, msg); err != nil {
-			isPermanent := app.IsPermanent(err)
-			c.logger.Error("Failed to process message (core mode)",
-				zap.String("subject", msg.Subject),
-				zap.Error(err),
-				zap.Bool("permanent", isPermanent),
-			)
-		}
-	}
-
-	sub, err := c.conn.QueueSubscribe(c.subject, queueGroup, handler)
-	if err != nil {
-		return fmt.Errorf("failed to subscribe to %s: %w", c.subject, err)
-	}
-	if err := c.conn.Flush(); err != nil {
-		return fmt.Errorf("failed to flush NATS connection: %w", err)
-	}
-
-	c.logger.Info("Started core NATS subscription",
-		zap.String("subject", c.subject),
-		zap.String("queue_group", queueGroup),
-	)
-
-	<-ctx.Done()
-	c.logger.Info("Stopping core NATS consumer", zap.Error(ctx.Err()))
-
-	if err := sub.Drain(); err != nil && !errors.Is(err, nats.ErrConnectionClosed) {
-		return fmt.Errorf("failed to drain core subscription: %w", err)
-	}
-
-	return ctx.Err()
-}
-
-func (c *Consumer) emitConsumerStats(ctx context.Context) {
-	ticker := time.NewTicker(c.monitorInterval)
-	defer ticker.Stop()
-
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		case <-ticker.C:
-			info, err := c.js.ConsumerInfo(c.streamName, c.consumerName)
-			if err != nil {
-				c.logger.Warn("Failed to fetch consumer info", zap.Error(err))
-				continue
-			}
-
-			c.logger.Debug("JetStream consumer metrics",
-				zap.String("stream", c.streamName),
-				zap.String("consumer", c.consumerName),
-				zap.Uint64("num_ack_pending", uint64(info.NumAckPending)),
-				zap.Uint64("num_redelivered", uint64(info.NumRedelivered)),
-				zap.Uint64("num_pending", uint64(info.NumPending)),
-				zap.Uint64("delivered_consumer_seq", uint64(info.Delivered.Consumer)),
-				zap.Uint64("delivered_stream_seq", uint64(info.Delivered.Stream)),
-			)
-			c.recordConsumerMetrics(ctx, info)
-		}
-	}
-}
-
 // Shutdown drains the underlying NATS connection gracefully.
 func (c *Consumer) Shutdown(ctx context.Context) error {
 	if c.conn == nil {
@@ -636,246 +204,3 @@ func (c *Consumer) Shutdown(ctx context.Context) error {
 		return fmt.Errorf("nats drain timeout: %w", closeCtx.Err())
 	}
 }
-
-func (c *Consumer) initMetrics() {
-	meter := otel.Meter("caatsm/nats")
-	c.meter = meter
-
-	if hist, err := meter.Int64Histogram("caatsm_nats_consumer_ack_pending"); err == nil {
-		c.ackPending = hist
-	}
-	if hist, err := meter.Int64Histogram("caatsm_nats_consumer_redelivered"); err == nil {
-		c.redelivered = hist
-	}
-	if hist, err := meter.Int64Histogram("caatsm_nats_consumer_pending"); err == nil {
-		c.pending = hist
-	}
-	if hist, err := meter.Int64Histogram("caatsm_nats_consumer_delivered"); err == nil {
-		c.delivered = hist
-	}
-}
-
-func (c *Consumer) recordConsumerMetrics(ctx context.Context, info *nats.ConsumerInfo) {
-	if info == nil {
-		return
-	}
-	if c.ackPending != nil {
-		c.ackPending.Record(ctx, int64(info.NumAckPending))
-	}
-	if c.redelivered != nil {
-		c.redelivered.Record(ctx, int64(info.NumRedelivered))
-	}
-	if c.pending != nil {
-		c.pending.Record(ctx, int64(info.NumPending))
-	}
-	if c.delivered != nil {
-		c.delivered.Record(ctx, int64(info.Delivered.Stream))
-	}
-
-	// Export an explicit pending messages gauge for Prometheus-based lag /
-	// backlog alerts.
-	obsmetrics.RecordNATSConsumerPending(c.streamName, c.consumerName, info.NumPending)
-}
-
-// routeToDLQ publishes a copy of the failed message to the configured DLQ subject,
-// including useful metadata for offline analysis. If DLQ is not configured or the
-// consumer is not running in JetStream mode, this is a no-op.
-func (c *Consumer) routeToDLQ(ctx context.Context, msg *nats.Msg, cause error) error {
-	if c == nil || c.js == nil {
-		return nil
-	}
-	if c.mode != "jetstream" {
-		return nil
-	}
-	if strings.TrimSpace(c.dlqSubject) == "" {
-		return nil
-	}
-
-	meta, _ := msg.Metadata()
-	jsSeq := uint64(0)
-	deliveries := uint64(0)
-	if meta != nil {
-		jsSeq = meta.Sequence.Stream
-		deliveries = meta.NumDelivered
-	}
-
-	payload := map[string]interface{}{
-		"transport_msg_id": msg.Header.Get("Nats-Msg-Id"),
-		"subject":          msg.Subject,
-		"stream":           c.streamName,
-		"consumer":         c.consumerName,
-		"nats_sequence":    jsSeq,
-		"deliveries":       deliveries,
-		"error":            fmt.Sprint(cause),
-		"received_at":      time.Now().UTC(),
-		"body":             string(msg.Data),
-	}
-
-	data, err := json.Marshal(payload)
-	if err != nil {
-		c.logger.Error("failed to marshal DLQ payload",
-			zap.String("stream", c.streamName),
-			zap.String("consumer", c.consumerName),
-			zap.String("dlq_subject", c.dlqSubject),
-			zap.Error(err),
-		)
-		return fmt.Errorf("marshal dlq payload: %w", err)
-	}
-
-	if _, err := c.js.Publish(c.dlqSubject, data); err != nil {
-		// nats.ErrNoResponders typically means that no JetStream stream is
-		// configured to receive this subject, or JetStream is temporarily
-		// unavailable. Surface this explicitly to make operational diagnosis
-		// easier.
-		if errors.Is(err, nats.ErrNoResponders) {
-			c.logger.Error("transient DLQ publish error (no responders)",
-				zap.String("stream", c.streamName),
-				zap.String("consumer", c.consumerName),
-				zap.String("dlq_subject", c.dlqSubject),
-				zap.Int("payload_size", len(data)),
-				zap.Error(err),
-			)
-			c.telemetry.RecordDLQPublishFailure(ctx, c.streamName, c.consumerName)
-			return fmt.Errorf("publish to dlq subject %s: no JetStream stream found for subject or JetStream unavailable: %w", c.dlqSubject, err)
-		}
-		c.logger.Error("failed to publish to DLQ",
-			zap.String("stream", c.streamName),
-			zap.String("consumer", c.consumerName),
-			zap.String("dlq_subject", c.dlqSubject),
-			zap.Int("payload_size", len(data)),
-			zap.Error(err),
-		)
-		c.telemetry.RecordDLQPublishFailure(ctx, c.streamName, c.consumerName)
-		return fmt.Errorf("publish to dlq subject %s: %w", c.dlqSubject, err)
-	}
-
-	c.telemetry.RecordDLQMessage(ctx, c.streamName, c.consumerName)
-
-	return nil
-}
-
-func (c *Consumer) nakWithStrategy(msg *nats.Msg) error {
-	backoff := c.cfg.NATS.ConsumerRules.Backoff
-	if len(backoff) == 0 {
-		return msg.Nak()
-	}
-
-	meta, err := msg.Metadata()
-	if err != nil {
-		c.logger.Warn("Failed to read metadata for backoff strategy", zap.Error(err))
-		return msg.Nak()
-	}
-
-	attempt := int(meta.NumDelivered)
-	index := attempt - 1
-	if index < 0 {
-		index = 0
-	}
-	if index >= len(backoff) {
-		index = len(backoff) - 1
-	}
-	delay := backoff[index]
-	if delay <= 0 {
-		return msg.Nak()
-	}
-
-	return msg.NakWithDelay(delay)
-}
-
-// processMessage processes a single message
-func (c *Consumer) processMessage(ctx context.Context, msg *nats.Msg) error {
-	ctx, span := otel.Tracer("caatsm/nats").Start(ctx, "Consumer.processMessage")
-	defer span.End()
-	span.SetAttributes(attribute.String("nats.subject", msg.Subject))
-
-	msgID, source, err := c.resolveMsgID(msg)
-	if err != nil {
-		span.RecordError(err)
-		span.SetStatus(codes.Error, err.Error())
-		return fmt.Errorf("unable to resolve message id: %w", err)
-	}
-	if source != "header" {
-		c.logger.Warn("Message missing NATS id header; using fallback",
-			zap.String("subject", msg.Subject),
-			zap.String("msg_id_source", source),
-			zap.String("msg_id", msgID),
-		)
-	}
-
-	// Attach structured logging context including stream/consumer and NATS metadata.
-	jsSeq := uint64(0)
-	if meta, metaErr := msg.Metadata(); metaErr == nil {
-		jsSeq = meta.Sequence.Stream
-		span.SetAttributes(
-			attribute.Int64("nats.js.stream_seq", int64(meta.Sequence.Stream)),
-			attribute.Int64("nats.js.consumer_seq", int64(meta.Sequence.Consumer)),
-		)
-	}
-
-	msgLogger := log.WithMessageContext(c.logger, log.MessageFields{
-		Service:        "caatsm-consumer",
-		TransportMsgID: msgID,
-		Stream:         c.streamName,
-		Consumer:       c.consumerName,
-		Subject:        msg.Subject,
-		JSSequence:     jsSeq,
-	})
-
-	msgLogger.Debug("Processing message",
-		zap.Int("data_size", len(msg.Data)),
-		zap.String("msg_id_source", source),
-	)
-
-	// Call processor
-	if err := c.processor.Handle(ctx, msg.Data, msgID); err != nil {
-		span.RecordError(err)
-		span.SetStatus(codes.Error, err.Error())
-		return fmt.Errorf("processor error: %w", err)
-	}
-
-	span.SetAttributes(attribute.String("telegram.msg_id", msgID))
-	return nil
-}
-
-func (c *Consumer) resolveMsgID(msg *nats.Msg) (string, string, error) {
-	if id := msg.Header.Get("Nats-Msg-Id"); id != "" {
-		return id, "header", nil
-	}
-
-	if c.mode == "core" {
-		return uuid.NewString(), "generated", nil
-	}
-
-	meta, err := msg.Metadata()
-	if err != nil {
-		return "", "", fmt.Errorf("fetch metadata: %w", err)
-	}
-
-	return fmt.Sprintf("js-%d", meta.Sequence.Stream), "metadata", nil
-}
-
-func mapDeliverPolicy(value string) nats.DeliverPolicy {
-	switch strings.ToLower(value) {
-	case "new":
-		return nats.DeliverNewPolicy
-	case "last":
-		return nats.DeliverLastPolicy
-	case "last_per_subject":
-		return nats.DeliverLastPerSubjectPolicy
-	case "sequence":
-		return nats.DeliverByStartSequencePolicy
-	case "time":
-		return nats.DeliverByStartTimePolicy
-	default:
-		return nats.DeliverAllPolicy
-	}
-}
-
-func mapReplayPolicy(value string) nats.ReplayPolicy {
-	switch strings.ToLower(value) {
-	case "original":
-		return nats.ReplayOriginalPolicy
-	default:
-		return nats.ReplayInstantPolicy
-	}
-}