chore(push-gateway): ai02 module updates - config, hub, ws, kafka, health, docs

services/push-gateway/internal/kafkaconsumer/consumer.go

@@ -120,6 +120,39 @@ func (c *Consumer) Close() error {
 	return c.reader.Close()
 }
 
+// HealthCheck verifies that the Kafka broker is reachable. Used by /readyz as
+// a soft-failure probe: a failing check marks the consumer as degraded but
+// does not return 503 (per ARB-015 §17.4 / ISSUE-058).
+//
+// The check issues a metadata request for the consumer topic; on success the
+// broker is considered reachable. This is cheaper than a Lag() call which
+// requires partition assignment to have completed.
+func (c *Consumer) HealthCheck(ctx context.Context) error {
+	conn, err := kafka.DialContext(ctx, "tcp", c.reader.Config().Brokers[0])
+	if err != nil {
+		return fmt.Errorf("kafka: dial broker: %w", err)
+	}
+	defer conn.Close()
+	partitions, err := conn.ReadPartitions(c.topic)
+	if err != nil {
+		return fmt.Errorf("kafka: read partitions: %w", err)
+	}
+	if len(partitions) == 0 {
+		return fmt.Errorf("kafka: topic %q has no partitions", c.topic)
+	}
+	return nil
+}
+
+// Topic returns the configured topic name. Exposed for diagnostics.
+func (c *Consumer) Topic() string {
+	return c.topic
+}
+
+// GroupID returns the configured consumer group name.
+func (c *Consumer) GroupID() string {
+	return c.groupID
+}
+
 // processMessage handles a single Kafka message with retry and idempotency.
 func (c *Consumer) processMessage(ctx context.Context, msg kafka.Message) {
 	var event NotificationRequested