docs: clarify kafka-only sink semantics

modules/sinks/sink-kafka/src/main/java/com/lingniu/ingest/sink/kafka/KafkaSinkProperties.java

@@ -12,9 +12,9 @@ public class KafkaSinkProperties {
 
     /**
      * Kafka Sink 总开关。默认 {@code true}。
-     * 设为 {@code false} 时 {@link KafkaSinkAutoConfiguration} 完全不装配任何 Bean（Kafka Producer、
-     * EnvelopeMapper、TopicRouter、KafkaEventSink 都不会创建），ingest-core 的 DisruptorEventBus
-     * 仍然正常运行但没有外部 sink（事件落地到 sink-archive 或 Noop 吞掉）。
+     * 设为 {@code false} 时 {@link KafkaSinkAutoConfiguration} 不装配 Kafka Producer、
+     * EnvelopeMapper、TopicRouter、KafkaEventSink 等生产端组件。生产接入应用保持默认开启，
+     * 只有专门的查询/测试运行时才应关闭 Kafka sink。
      */
     private boolean enabled = true;
 

modules/sinks/sink-kafka/src/test/java/com/lingniu/ingest/sink/kafka/KafkaSinkPropertiesTest.java

@@ -2,6 +2,8 @@ package com.lingniu.ingest.sink.kafka;
 
 import org.junit.jupiter.api.Test;
 
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.Arrays;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -23,4 +25,15 @@ class KafkaSinkPropertiesTest {
         assertThat(Arrays.stream(KafkaSinkProperties.class.getMethods()).map(method -> method.getName()))
                 .doesNotContain("getType", "setType");
     }
+
+    @Test
+    void sourceCommentsDoNotDescribeKafkaDisabledAsNoopEventDropping() throws Exception {
+        String source = Files.readString(Path.of(
+                "src/main/java/com/lingniu/ingest/sink/kafka/KafkaSinkProperties.java"));
+
+        assertThat(source)
+                .doesNotContain("Noop")
+                .doesNotContain("吞掉")
+                .doesNotContain("外部 sink");
+    }
 }