Merge branch 'main' into feat/category_proposal

backend/src/main/java/com/openisle/controller/SearchController.java

@@ -115,6 +115,9 @@ public class SearchController {
         dto.setSubText(r.subText());
         dto.setExtra(r.extra());
         dto.setPostId(r.postId());
+        dto.setHighlightedText(r.highlightedText());
+        dto.setHighlightedSubText(r.highlightedSubText());
+        dto.setHighlightedExtra(r.highlightedExtra());
         return dto;
       })
       .collect(Collectors.toList());

backend/src/main/java/com/openisle/dto/SearchResultDto.java

@@ -12,4 +12,7 @@ public class SearchResultDto {
   private String subText;
   private String extra;
   private Long postId;
+  private String highlightedText;
+  private String highlightedSubText;
+  private String highlightedExtra;
 }

backend/src/main/java/com/openisle/search/NoopSearchIndexer.java

@@ -0,0 +1,14 @@
+package com.openisle.search;
+
+public class NoopSearchIndexer implements SearchIndexer {
+
+  @Override
+  public void indexDocument(String index, SearchDocument document) {
+    // no-op
+  }
+
+  @Override
+  public void deleteDocument(String index, Long id) {
+    // no-op
+  }
+}

backend/src/main/java/com/openisle/search/OpenSearchConfig.java

@@ -0,0 +1,78 @@
+package com.openisle.search;
+
+import org.apache.hc.client5.http.auth.AuthScope;
+import org.apache.hc.client5.http.auth.UsernamePasswordCredentials;
+import org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider;
+import org.apache.hc.core5.http.HttpHost;
+import org.opensearch.client.RestClient;
+import org.opensearch.client.RestClientBuilder;
+import org.opensearch.client.json.jackson.JacksonJsonpMapper;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.transport.rest_client.RestClientTransport;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.util.StringUtils;
+
+@Configuration
+@EnableConfigurationProperties(OpenSearchProperties.class)
+public class OpenSearchConfig {
+
+  @Bean(destroyMethod = "close")
+  @ConditionalOnProperty(prefix = "app.search", name = "enabled", havingValue = "true")
+  public RestClient openSearchRestClient(OpenSearchProperties properties) {
+    RestClientBuilder builder = RestClient.builder(
+      new HttpHost(properties.getScheme(), properties.getHost(), properties.getPort())
+    );
+    if (StringUtils.hasText(properties.getUsername())) {
+      BasicCredentialsProvider credentialsProvider = new BasicCredentialsProvider();
+      credentialsProvider.setCredentials(
+        new AuthScope(properties.getHost(), properties.getPort()),
+        new UsernamePasswordCredentials(
+          properties.getUsername(),
+          properties.getPassword() != null ? properties.getPassword().toCharArray() : new char[0]
+        )
+      );
+      builder.setHttpClientConfigCallback(httpClientBuilder ->
+        httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider)
+      );
+    }
+    return builder.build();
+  }
+
+  @Bean(destroyMethod = "close")
+  @ConditionalOnBean(RestClient.class)
+  public RestClientTransport openSearchTransport(RestClient restClient) {
+    return new RestClientTransport(restClient, new JacksonJsonpMapper());
+  }
+
+  @Bean
+  @ConditionalOnBean(RestClientTransport.class)
+  public OpenSearchClient openSearchClient(RestClientTransport transport) {
+    return new OpenSearchClient(transport);
+  }
+
+  @Bean
+  @ConditionalOnBean(OpenSearchClient.class)
+  public SearchIndexInitializer searchIndexInitializer(
+    OpenSearchClient client,
+    OpenSearchProperties properties
+  ) {
+    return new SearchIndexInitializer(client, properties);
+  }
+
+  @Bean
+  @ConditionalOnBean(OpenSearchClient.class)
+  public SearchIndexer openSearchIndexer(OpenSearchClient client, OpenSearchProperties properties) {
+    return new OpenSearchIndexer(client);
+  }
+
+  @Bean
+  @ConditionalOnMissingBean(SearchIndexer.class)
+  public SearchIndexer noopSearchIndexer() {
+    return new NoopSearchIndexer();
+  }
+}

backend/src/main/java/com/openisle/search/OpenSearchIndexer.java

@@ -0,0 +1,49 @@
+package com.openisle.search;
+
+import java.io.IOException;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch.core.DeleteRequest;
+import org.opensearch.client.opensearch.core.IndexRequest;
+import org.opensearch.client.opensearch.core.IndexResponse;
+
+@Slf4j
+@RequiredArgsConstructor
+public class OpenSearchIndexer implements SearchIndexer {
+
+  private final OpenSearchClient client;
+
+  @Override
+  public void indexDocument(String index, SearchDocument document) {
+    if (document == null || document.entityId() == null) {
+      return;
+    }
+    try {
+      IndexRequest<SearchDocument> request = IndexRequest.of(builder ->
+        builder.index(index).id(document.entityId().toString()).document(document)
+      );
+      IndexResponse response = client.index(request);
+      log.info(
+        "Indexed document {} into {} with result {}",
+        document.entityId(),
+        index,
+        response.result()
+      );
+    } catch (IOException e) {
+      log.warn("Failed to index document {} into {}", document.entityId(), index, e);
+    }
+  }
+
+  @Override
+  public void deleteDocument(String index, Long id) {
+    if (id == null) {
+      return;
+    }
+    try {
+      client.delete(DeleteRequest.of(builder -> builder.index(index).id(id.toString())));
+    } catch (IOException e) {
+      log.warn("Failed to delete document {} from {}", id, index, e);
+    }
+  }
+}

backend/src/main/java/com/openisle/search/OpenSearchProperties.java

@@ -0,0 +1,63 @@
+package com.openisle.search;
+
+import lombok.Getter;
+import lombok.Setter;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+@Getter
+@Setter
+@ConfigurationProperties(prefix = "app.search")
+public class OpenSearchProperties {
+
+  private boolean enabled = false;
+  private String host = "localhost";
+  private int port = 9200;
+  private String scheme = "http";
+  private String username;
+  private String password;
+  private String indexPrefix = "openisle";
+  private boolean initialize = true;
+  private int highlightFragmentSize = 200;
+  private boolean reindexOnStartup = false;
+  private int reindexBatchSize = 500;
+
+  private Indices indices = new Indices();
+
+  public String postsIndex() {
+    return indexName(indices.posts);
+  }
+
+  public String commentsIndex() {
+    return indexName(indices.comments);
+  }
+
+  public String usersIndex() {
+    return indexName(indices.users);
+  }
+
+  public String categoriesIndex() {
+    return indexName(indices.categories);
+  }
+
+  public String tagsIndex() {
+    return indexName(indices.tags);
+  }
+
+  private String indexName(String suffix) {
+    if (indexPrefix == null || indexPrefix.isBlank()) {
+      return suffix;
+    }
+    return indexPrefix + "-" + suffix;
+  }
+
+  @Getter
+  @Setter
+  public static class Indices {
+
+    private String posts = "posts";
+    private String comments = "comments";
+    private String users = "users";
+    private String categories = "categories";
+    private String tags = "tags";
+  }
+}

backend/src/main/java/com/openisle/search/SearchDocument.java

@@ -0,0 +1,15 @@
+package com.openisle.search;
+
+import java.util.List;
+
+public record SearchDocument(
+  String type,
+  Long entityId,
+  String title,
+  String content,
+  String author,
+  String category,
+  List<String> tags,
+  Long postId,
+  Long createdAt
+) {}

backend/src/main/java/com/openisle/search/SearchDocumentFactory.java

@@ -0,0 +1,127 @@
+package com.openisle.search;
+
+import com.openisle.model.Category;
+import com.openisle.model.Comment;
+import com.openisle.model.Post;
+import com.openisle.model.Tag;
+import com.openisle.model.User;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+public final class SearchDocumentFactory {
+
+  private SearchDocumentFactory() {}
+
+  public static SearchDocument fromPost(Post post) {
+    if (post == null || post.getId() == null) {
+      return null;
+    }
+    List<String> tags = post.getTags() == null
+      ? Collections.emptyList()
+      : post
+        .getTags()
+        .stream()
+        .map(Tag::getName)
+        .filter(Objects::nonNull)
+        .collect(Collectors.toList());
+    return new SearchDocument(
+      "post",
+      post.getId(),
+      post.getTitle(),
+      post.getContent(),
+      post.getAuthor() != null ? post.getAuthor().getUsername() : null,
+      post.getCategory() != null ? post.getCategory().getName() : null,
+      tags,
+      post.getId(),
+      toEpochMillis(post.getCreatedAt())
+    );
+  }
+
+  public static SearchDocument fromComment(Comment comment) {
+    if (comment == null || comment.getId() == null) {
+      return null;
+    }
+    Post post = comment.getPost();
+    List<String> tags = post == null || post.getTags() == null
+      ? Collections.emptyList()
+      : post
+        .getTags()
+        .stream()
+        .map(Tag::getName)
+        .filter(Objects::nonNull)
+        .collect(Collectors.toList());
+    return new SearchDocument(
+      "comment",
+      comment.getId(),
+      post != null ? post.getTitle() : null,
+      comment.getContent(),
+      comment.getAuthor() != null ? comment.getAuthor().getUsername() : null,
+      post != null && post.getCategory() != null ? post.getCategory().getName() : null,
+      tags,
+      post != null ? post.getId() : null,
+      toEpochMillis(comment.getCreatedAt())
+    );
+  }
+
+  public static SearchDocument fromUser(User user) {
+    if (user == null || user.getId() == null) {
+      return null;
+    }
+    return new SearchDocument(
+      "user",
+      user.getId(),
+      user.getUsername(),
+      user.getIntroduction(),
+      null,
+      null,
+      Collections.emptyList(),
+      null,
+      toEpochMillis(user.getCreatedAt())
+    );
+  }
+
+  public static SearchDocument fromCategory(Category category) {
+    if (category == null || category.getId() == null) {
+      return null;
+    }
+    return new SearchDocument(
+      "category",
+      category.getId(),
+      category.getName(),
+      category.getDescription(),
+      null,
+      null,
+      Collections.emptyList(),
+      null,
+      null
+    );
+  }
+
+  public static SearchDocument fromTag(Tag tag) {
+    if (tag == null || tag.getId() == null) {
+      return null;
+    }
+    return new SearchDocument(
+      "tag",
+      tag.getId(),
+      tag.getName(),
+      tag.getDescription(),
+      null,
+      null,
+      Collections.emptyList(),
+      null,
+      toEpochMillis(tag.getCreatedAt())
+    );
+  }
+
+  private static Long toEpochMillis(LocalDateTime time) {
+    if (time == null) {
+      return null;
+    }
+    return time.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
+  }
+}

backend/src/main/java/com/openisle/search/SearchIndexEventListener.java

@@ -0,0 +1,33 @@
+package com.openisle.search;
+
+import com.openisle.search.event.DeleteDocumentEvent;
+import com.openisle.search.event.IndexDocumentEvent;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.event.TransactionPhase;
+import org.springframework.transaction.event.TransactionalEventListener;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class SearchIndexEventListener {
+
+  private final SearchIndexer searchIndexer;
+
+  @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT, fallbackExecution = true)
+  public void handleIndex(IndexDocumentEvent event) {
+    if (event == null || event.document() == null) {
+      return;
+    }
+    searchIndexer.indexDocument(event.index(), event.document());
+  }
+
+  @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT, fallbackExecution = true)
+  public void handleDelete(DeleteDocumentEvent event) {
+    if (event == null) {
+      return;
+    }
+    searchIndexer.deleteDocument(event.index(), event.id());
+  }
+}

backend/src/main/java/com/openisle/search/SearchIndexEventPublisher.java

@@ -0,0 +1,99 @@
+package com.openisle.search;
+
+import com.openisle.model.Category;
+import com.openisle.model.Comment;
+import com.openisle.model.Post;
+import com.openisle.model.PostStatus;
+import com.openisle.model.Tag;
+import com.openisle.model.User;
+import com.openisle.search.event.DeleteDocumentEvent;
+import com.openisle.search.event.IndexDocumentEvent;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.stereotype.Component;
+
+@Component
+@RequiredArgsConstructor
+public class SearchIndexEventPublisher {
+
+  private final ApplicationEventPublisher publisher;
+  private final OpenSearchProperties properties;
+
+  public void publishPostSaved(Post post) {
+    if (!properties.isEnabled() || post == null || post.getStatus() != PostStatus.PUBLISHED) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromPost(post);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.postsIndex(), document));
+    }
+  }
+
+  public void publishPostDeleted(Long postId) {
+    if (!properties.isEnabled() || postId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.postsIndex(), postId));
+  }
+
+  public void publishCommentSaved(Comment comment) {
+    if (!properties.isEnabled() || comment == null) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromComment(comment);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.commentsIndex(), document));
+    }
+  }
+
+  public void publishCommentDeleted(Long commentId) {
+    if (!properties.isEnabled() || commentId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.commentsIndex(), commentId));
+  }
+
+  public void publishUserSaved(User user) {
+    if (!properties.isEnabled() || user == null) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromUser(user);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.usersIndex(), document));
+    }
+  }
+
+  public void publishCategorySaved(Category category) {
+    if (!properties.isEnabled() || category == null) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromCategory(category);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.categoriesIndex(), document));
+    }
+  }
+
+  public void publishCategoryDeleted(Long categoryId) {
+    if (!properties.isEnabled() || categoryId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.categoriesIndex(), categoryId));
+  }
+
+  public void publishTagSaved(Tag tag) {
+    if (!properties.isEnabled() || tag == null || !tag.isApproved()) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromTag(tag);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.tagsIndex(), document));
+    }
+  }
+
+  public void publishTagDeleted(Long tagId) {
+    if (!properties.isEnabled() || tagId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.tagsIndex(), tagId));
+  }
+}

backend/src/main/java/com/openisle/search/SearchIndexInitializer.java

@@ -0,0 +1,219 @@
+package com.openisle.search;
+
+import jakarta.annotation.PostConstruct;
+import java.io.IOException;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.opensearch.client.json.JsonData;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch._types.mapping.Property;
+import org.opensearch.client.opensearch._types.mapping.TypeMapping;
+import org.opensearch.client.opensearch.indices.IndexSettings;
+
+@Slf4j
+@RequiredArgsConstructor
+public class SearchIndexInitializer {
+
+  private final OpenSearchClient client;
+  private final OpenSearchProperties properties;
+
+  @PostConstruct
+  public void initialize() {
+    if (!properties.isEnabled() || !properties.isInitialize()) {
+      return;
+    }
+    ensureIndex(properties.postsIndex(), this::postMapping);
+    ensureIndex(properties.commentsIndex(), this::commentMapping);
+    ensureIndex(properties.usersIndex(), this::userMapping);
+    ensureIndex(properties.categoriesIndex(), this::categoryMapping);
+    ensureIndex(properties.tagsIndex(), this::tagMapping);
+  }
+
+  private void ensureIndex(String index, java.util.function.Supplier<TypeMapping> mappingSupplier) {
+    try {
+      boolean exists = client
+        .indices()
+        .exists(builder -> builder.index(index))
+        .value();
+      if (exists) {
+        return;
+      }
+      client
+        .indices()
+        .create(builder ->
+          builder.index(index).settings(this::applyPinyinAnalysis).mappings(mappingSupplier.get())
+        );
+      log.info("Created OpenSearch index {}", index);
+    } catch (IOException e) {
+      log.warn("Failed to initialize OpenSearch index {}", index, e);
+    }
+  }
+
+  private TypeMapping postMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", textWithRawAndPinyin())
+        .properties("content", textWithPinyinOnly()) // content 不做 .raw，避免超长 keyword
+        .properties("author", keywordWithRawAndPinyin())
+        .properties("category", keywordWithRawAndPinyin())
+        .properties("tags", keywordWithRawAndPinyin())
+        .properties("postId", Property.of(p -> p.long_(l -> l)))
+        .properties(
+          "createdAt",
+          Property.of(p -> p.date(d -> d.format("strict_date_optional_time||epoch_millis")))
+        )
+    );
+  }
+
+  private TypeMapping commentMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", textWithRawAndPinyin())
+        .properties("content", textWithPinyinOnly())
+        .properties("author", keywordWithRawAndPinyin())
+        .properties("category", keywordWithRawAndPinyin())
+        .properties("tags", keywordWithRawAndPinyin())
+        .properties("postId", Property.of(p -> p.long_(l -> l)))
+        .properties(
+          "createdAt",
+          Property.of(p -> p.date(d -> d.format("strict_date_optional_time||epoch_millis")))
+        )
+    );
+  }
+
+  private TypeMapping userMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", textWithRawAndPinyin())
+        .properties("content", textWithPinyinOnly())
+        .properties(
+          "createdAt",
+          Property.of(p -> p.date(d -> d.format("strict_date_optional_time||epoch_millis")))
+        )
+    );
+  }
+
+  private TypeMapping categoryMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", textWithRawAndPinyin())
+        .properties("content", textWithPinyinOnly())
+    );
+  }
+
+  private TypeMapping tagMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", textWithRawAndPinyin())
+        .properties("content", textWithPinyinOnly())
+        .properties(
+          "createdAt",
+          Property.of(p -> p.date(d -> d.format("strict_date_optional_time||epoch_millis")))
+        )
+    );
+  }
+
+  /** 文本字段：.raw（keyword 精确） + .py（拼音短语精确） + .zh（ICU+2~3gram 召回） */
+  private Property textWithRawAndPinyin() {
+    return Property.of(p ->
+      p.text(t ->
+        t
+          .fields("raw", f -> f.keyword(k -> k.normalizer("lowercase_normalizer")))
+          .fields("py", f -> f.text(sub -> sub.analyzer("py_index").searchAnalyzer("py_search")))
+          .fields("zh", f ->
+            f.text(sub -> sub.analyzer("zh_ngram_index").searchAnalyzer("zh_search"))
+          )
+      )
+    );
+  }
+
+  /** 长文本 content：保留拼音 + 新增 zh 子字段（不加 .raw，避免过长 keyword） */
+  private Property textWithPinyinOnly() {
+    return Property.of(p ->
+      p.text(t ->
+        t
+          .fields("py", f -> f.text(sub -> sub.analyzer("py_index").searchAnalyzer("py_search")))
+          .fields("zh", f ->
+            f.text(sub -> sub.analyzer("zh_ngram_index").searchAnalyzer("zh_search"))
+          )
+      )
+    );
+  }
+
+  /** 关键词字段（author/category/tags）：keyword 等值 + .py + .zh（尽量对齐标题策略） */
+  private Property keywordWithRawAndPinyin() {
+    return Property.of(p ->
+      p.keyword(k ->
+        k
+          .normalizer("lowercase_normalizer")
+          .fields("raw", f -> f.keyword(kk -> kk.normalizer("lowercase_normalizer")))
+          .fields("py", f -> f.text(sub -> sub.analyzer("py_index").searchAnalyzer("py_search")))
+          .fields("zh", f ->
+            f.text(sub -> sub.analyzer("zh_ngram_index").searchAnalyzer("zh_search"))
+          )
+      )
+    );
+  }
+
+  /** 新增 zh 分析器（ICU + 2~3gram），并保留你已有的 pinyin/normalizer 设置 */
+  private IndexSettings.Builder applyPinyinAnalysis(IndexSettings.Builder builder) {
+    Map<String, JsonData> settings = new LinkedHashMap<>();
+
+    // --- 已有：keyword normalizer（用于 .raw）
+    settings.put("analysis.normalizer.lowercase_normalizer.type", JsonData.of("custom"));
+    settings.put(
+      "analysis.normalizer.lowercase_normalizer.filter",
+      JsonData.of(List.of("lowercase"))
+    );
+
+    // --- 已有：pinyin filter + analyzers
+    settings.put("analysis.filter.py_filter.type", JsonData.of("pinyin"));
+    settings.put("analysis.filter.py_filter.keep_full_pinyin", JsonData.of(true));
+    settings.put("analysis.filter.py_filter.keep_joined_full_pinyin", JsonData.of(true));
+    settings.put("analysis.filter.py_filter.keep_first_letter", JsonData.of(false));
+    settings.put("analysis.filter.py_filter.remove_duplicated_term", JsonData.of(true));
+
+    settings.put("analysis.analyzer.py_index.type", JsonData.of("custom"));
+    settings.put("analysis.analyzer.py_index.tokenizer", JsonData.of("standard"));
+    settings.put(
+      "analysis.analyzer.py_index.filter",
+      JsonData.of(List.of("lowercase", "py_filter"))
+    );
+
+    settings.put("analysis.analyzer.py_search.type", JsonData.of("custom"));
+    settings.put("analysis.analyzer.py_search.tokenizer", JsonData.of("standard"));
+    settings.put(
+      "analysis.analyzer.py_search.filter",
+      JsonData.of(List.of("lowercase", "py_filter"))
+    );
+
+    settings.put("analysis.filter.zh_ngram_2_3.type", JsonData.of("ngram"));
+    settings.put("analysis.filter.zh_ngram_2_3.min_gram", JsonData.of(2));
+    settings.put("analysis.filter.zh_ngram_2_3.max_gram", JsonData.of(3));
+
+    settings.put("analysis.analyzer.zh_ngram_index.type", JsonData.of("custom"));
+    settings.put("analysis.analyzer.zh_ngram_index.tokenizer", JsonData.of("icu_tokenizer"));
+    settings.put(
+      "analysis.analyzer.zh_ngram_index.filter",
+      JsonData.of(List.of("lowercase", "zh_ngram_2_3"))
+    );
+
+    settings.put("analysis.analyzer.zh_search.type", JsonData.of("custom"));
+    settings.put("analysis.analyzer.zh_search.tokenizer", JsonData.of("icu_tokenizer"));
+    settings.put(
+      "analysis.analyzer.zh_search.filter",
+      JsonData.of(List.of("lowercase", "zh_ngram_2_3"))
+    );
+
+    settings.forEach(builder::customSettings);
+    return builder;
+  }
+}

backend/src/main/java/com/openisle/search/SearchIndexer.java

@@ -0,0 +1,6 @@
+package com.openisle.search;
+
+public interface SearchIndexer {
+  void indexDocument(String index, SearchDocument document);
+  void deleteDocument(String index, Long id);
+}

backend/src/main/java/com/openisle/search/SearchReindexInitializer.java

@@ -0,0 +1,30 @@
+package com.openisle.search;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.stereotype.Component;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class SearchReindexInitializer implements CommandLineRunner {
+
+  private final OpenSearchProperties properties;
+  private final SearchReindexService searchReindexService;
+
+  @Override
+  public void run(String... args) {
+    if (!properties.isEnabled()) {
+      log.info("Search indexing disabled, skipping startup reindex.");
+      return;
+    }
+
+    if (!properties.isReindexOnStartup()) {
+      log.debug("Startup reindex disabled by configuration.");
+      return;
+    }
+
+    searchReindexService.reindexAll();
+  }
+}

backend/src/main/java/com/openisle/search/SearchReindexService.java

@@ -0,0 +1,94 @@
+package com.openisle.search;
+
+import com.openisle.model.Post;
+import com.openisle.model.PostStatus;
+import com.openisle.model.Tag;
+import com.openisle.repository.CategoryRepository;
+import com.openisle.repository.CommentRepository;
+import com.openisle.repository.PostRepository;
+import com.openisle.repository.TagRepository;
+import com.openisle.repository.UserRepository;
+import java.util.Objects;
+import java.util.function.Function;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Transactional;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class SearchReindexService {
+
+  private final SearchIndexer searchIndexer;
+  private final OpenSearchProperties properties;
+  private final PostRepository postRepository;
+  private final CommentRepository commentRepository;
+  private final UserRepository userRepository;
+  private final CategoryRepository categoryRepository;
+  private final TagRepository tagRepository;
+
+  @Transactional(readOnly = true)
+  public void reindexAll() {
+    if (!properties.isEnabled()) {
+      log.info("Search indexing is disabled, skipping reindex operation.");
+      return;
+    }
+
+    log.info("Starting full search reindex operation.");
+
+    reindex(properties.postsIndex(), postRepository::findAll, (Post post) ->
+      post.getStatus() == PostStatus.PUBLISHED ? SearchDocumentFactory.fromPost(post) : null
+    );
+
+    reindex(
+      properties.commentsIndex(),
+      commentRepository::findAll,
+      SearchDocumentFactory::fromComment
+    );
+
+    reindex(properties.usersIndex(), userRepository::findAll, SearchDocumentFactory::fromUser);
+
+    reindex(
+      properties.categoriesIndex(),
+      categoryRepository::findAll,
+      SearchDocumentFactory::fromCategory
+    );
+
+    reindex(properties.tagsIndex(), tagRepository::findAll, (Tag tag) ->
+      tag.isApproved() ? SearchDocumentFactory.fromTag(tag) : null
+    );
+
+    log.info("Completed full search reindex operation.");
+  }
+
+  private <T> void reindex(
+    String index,
+    Function<Pageable, Page<T>> pageSupplier,
+    Function<T, SearchDocument> mapper
+  ) {
+    int batchSize = Math.max(1, properties.getReindexBatchSize());
+    int pageNumber = 0;
+
+    Page<T> page;
+    do {
+      Pageable pageable = PageRequest.of(pageNumber, batchSize);
+      page = pageSupplier.apply(pageable);
+      if (page.isEmpty() && pageNumber == 0) {
+        log.info("No entities found for index {}.", index);
+      }
+
+      log.info("Reindexing {} entities for index {}.", page.getTotalElements(), index);
+      for (T entity : page) {
+        SearchDocument document = mapper.apply(entity);
+        if (Objects.nonNull(document)) {
+          searchIndexer.indexDocument(index, document);
+        }
+      }
+      pageNumber++;
+    } while (page.hasNext());
+  }
+}

backend/src/main/java/com/openisle/search/event/DeleteDocumentEvent.java

@@ -0,0 +1,3 @@
+package com.openisle.search.event;
+
+public record DeleteDocumentEvent(String index, Long id) {}

backend/src/main/java/com/openisle/search/event/IndexDocumentEvent.java

@@ -0,0 +1,5 @@
+package com.openisle.search.event;
+
+import com.openisle.search.SearchDocument;
+
+public record IndexDocumentEvent(String index, SearchDocument document) {}

backend/src/main/java/com/openisle/service/CategoryService.java

@@ -3,6 +3,7 @@ package com.openisle.service;
 import com.openisle.config.CachingConfig;
 import com.openisle.model.Category;
 import com.openisle.repository.CategoryRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import java.util.List;
 import lombok.RequiredArgsConstructor;
 import org.springframework.cache.annotation.CacheEvict;
@@ -14,6 +15,7 @@ import org.springframework.stereotype.Service;
 public class CategoryService {
 
   private final CategoryRepository categoryRepository;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   @CacheEvict(value = CachingConfig.CATEGORY_CACHE_NAME, allEntries = true)
   public Category createCategory(String name, String description, String icon, String smallIcon) {
@@ -22,7 +24,9 @@ public class CategoryService {
     category.setDescription(description);
     category.setIcon(icon);
     category.setSmallIcon(smallIcon);
-    return categoryRepository.save(category);
+    Category saved = categoryRepository.save(category);
+    searchIndexEventPublisher.publishCategorySaved(saved);
+    return saved;
   }
 
   @CacheEvict(value = CachingConfig.CATEGORY_CACHE_NAME, allEntries = true)
@@ -48,12 +52,15 @@ public class CategoryService {
     if (smallIcon != null) {
       category.setSmallIcon(smallIcon);
     }
-    return categoryRepository.save(category);
+    Category saved = categoryRepository.save(category);
+    searchIndexEventPublisher.publishCategorySaved(saved);
+    return saved;
   }
 
   @CacheEvict(value = CachingConfig.CATEGORY_CACHE_NAME, allEntries = true)
   public void deleteCategory(Long id) {
     categoryRepository.deleteById(id);
+    searchIndexEventPublisher.publishCategoryDeleted(id);
   }
 
   public Category getCategory(Long id) {

backend/src/main/java/com/openisle/service/CommentService.java

@@ -16,6 +16,7 @@ import com.openisle.repository.PointHistoryRepository;
 import com.openisle.repository.PostRepository;
 import com.openisle.repository.ReactionRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import com.openisle.service.NotificationService;
 import com.openisle.service.PointService;
 import com.openisle.service.SubscriptionService;
@@ -49,6 +50,7 @@ public class CommentService {
   private final PointHistoryRepository pointHistoryRepository;
   private final PointService pointService;
   private final ImageUploader imageUploader;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   @CacheEvict(value = CachingConfig.POST_CACHE_NAME, allEntries = true)
   @Transactional
@@ -124,6 +126,7 @@ public class CommentService {
     }
     notificationService.notifyMentions(content, author, post, comment);
     log.debug("addComment finished for comment {}", comment.getId());
+    searchIndexEventPublisher.publishCommentSaved(comment);
     return comment;
   }
 
@@ -221,6 +224,7 @@ public class CommentService {
     }
     notificationService.notifyMentions(content, author, parent.getPost(), comment);
     log.debug("addReply finished for comment {}", comment.getId());
+    searchIndexEventPublisher.publishCommentSaved(comment);
     return comment;
   }
 
@@ -360,7 +364,9 @@ public class CommentService {
 
     // 逻辑删除评论
     Post post = comment.getPost();
+    Long commentId = comment.getId();
     commentRepository.delete(comment);
+    searchIndexEventPublisher.publishCommentDeleted(commentId);
     // 删除积分历史
     pointHistoryRepository.deleteAll(pointHistories);
 

backend/src/main/java/com/openisle/service/PostService.java

@@ -3,7 +3,21 @@ package com.openisle.service;
 import com.openisle.config.CachingConfig;
 import com.openisle.exception.RateLimitException;
 import com.openisle.model.*;
-import com.openisle.repository.*;
+import com.openisle.repository.CategoryProposalPostRepository;
+import com.openisle.repository.CategoryRepository;
+import com.openisle.repository.CommentRepository;
+import com.openisle.repository.LotteryPostRepository;
+import com.openisle.repository.NotificationRepository;
+import com.openisle.repository.PointHistoryRepository;
+import com.openisle.repository.PollPostRepository;
+import com.openisle.repository.PollVoteRepository;
+import com.openisle.repository.PostRepository;
+import com.openisle.repository.PostSubscriptionRepository;
+import com.openisle.repository.ReactionRepository;
+import com.openisle.repository.TagRepository;
+import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
+import com.openisle.service.EmailSender;
 import java.time.Duration;
 import java.time.LocalDateTime;
 import java.time.ZoneId;
@@ -59,6 +73,8 @@ public class PostService {
   private final ConcurrentMap<Long, ScheduledFuture<?>> scheduledFinalizations =
     new ConcurrentHashMap<>();
 
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
+
   @Value("${app.website-url:https://www.open-isle.com}")
   private String websiteUrl;
 
@@ -90,7 +106,8 @@ public class PostService {
     PostChangeLogService postChangeLogService,
     PointHistoryRepository pointHistoryRepository,
     @Value("${app.post.publish-mode:DIRECT}") PublishMode publishMode,
-    RedisTemplate redisTemplate
+    RedisTemplate redisTemplate,
+    SearchIndexEventPublisher searchIndexEventPublisher
   ) {
     this.postRepository = postRepository;
     this.userRepository = userRepository;
@@ -118,6 +135,7 @@ public class PostService {
     this.publishMode = publishMode;
 
     this.redisTemplate = redisTemplate;
+    this.searchIndexEventPublisher = searchIndexEventPublisher;
   }
 
   @EventListener(ApplicationReadyEvent.class)
@@ -401,6 +419,9 @@ public class PostService {
       );
       scheduledFinalizations.put(pp.getId(), future);
     }
+    if (post.getStatus() == PostStatus.PUBLISHED) {
+      searchIndexEventPublisher.publishPostSaved(post);
+    }
     return post;
   }
 
@@ -992,10 +1013,12 @@ public class PostService {
       if (!tag.isApproved()) {
         tag.setApproved(true);
         tagRepository.save(tag);
+        searchIndexEventPublisher.publishTagSaved(tag);
       }
     }
     post.setStatus(PostStatus.PUBLISHED);
     post = postRepository.save(post);
+    searchIndexEventPublisher.publishPostSaved(post);
     notificationService.createNotification(
       post.getAuthor(),
       NotificationType.POST_REVIEWED,
@@ -1019,13 +1042,16 @@ public class PostService {
       if (!tag.isApproved()) {
         long count = postRepository.countDistinctByTags_Id(tag.getId());
         if (count <= 1) {
+          Long tagId = tag.getId();
           post.getTags().remove(tag);
           tagRepository.delete(tag);
+          searchIndexEventPublisher.publishTagDeleted(tagId);
         }
       }
     }
     post.setStatus(PostStatus.REJECTED);
     post = postRepository.save(post);
+    searchIndexEventPublisher.publishPostDeleted(post.getId());
     notificationService.createNotification(
       post.getAuthor(),
       NotificationType.POST_REVIEWED,
@@ -1166,6 +1192,9 @@ public class PostService {
     if (!oldTags.equals(newTags)) {
       postChangeLogService.recordTagChange(updated, user, oldTags, newTags);
     }
+    if (updated.getStatus() == PostStatus.PUBLISHED) {
+      searchIndexEventPublisher.publishPostSaved(updated);
+    }
     return updated;
   }
 
@@ -1218,8 +1247,10 @@ public class PostService {
       }
     }
     String title = post.getTitle();
+    Long postId = post.getId();
     postChangeLogService.deleteLogsForPost(post);
     postRepository.delete(post);
+    searchIndexEventPublisher.publishPostDeleted(postId);
     if (adminDeleting) {
       notificationService.createNotification(
         author,

backend/src/main/java/com/openisle/service/SearchService.java

@@ -11,14 +11,30 @@ import com.openisle.repository.CommentRepository;
 import com.openisle.repository.PostRepository;
 import com.openisle.repository.TagRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.OpenSearchProperties;
+import com.openisle.search.SearchDocument;
+import java.io.IOException;
+import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch._types.FieldValue;
+import org.opensearch.client.opensearch._types.query_dsl.TextQueryType;
+import org.opensearch.client.opensearch.core.SearchResponse;
+import org.opensearch.client.opensearch.core.search.Hit;
 import org.springframework.stereotype.Service;
+import org.springframework.web.util.HtmlUtils;
 
 @Service
+@Slf4j
 @RequiredArgsConstructor
 public class SearchService {
 
@@ -27,10 +43,14 @@ public class SearchService {
   private final CommentRepository commentRepository;
   private final CategoryRepository categoryRepository;
   private final TagRepository tagRepository;
+  private final Optional<OpenSearchClient> openSearchClient;
+  private final OpenSearchProperties openSearchProperties;
 
   @org.springframework.beans.factory.annotation.Value("${app.snippet-length}")
   private int snippetLength;
 
+  private static final int DEFAULT_OPEN_SEARCH_LIMIT = 50;
+
   public List<User> searchUsers(String keyword) {
     return userRepository.findByUsernameContainingIgnoreCase(keyword);
   }
@@ -64,49 +84,113 @@ public class SearchService {
   }
 
   public List<SearchResult> globalSearch(String keyword) {
+    if (keyword == null || keyword.isBlank()) {
+      return List.of();
+    }
+    if (isOpenSearchEnabled()) {
+      try {
+        List<SearchResult> results = searchWithOpenSearch(keyword);
+        if (!results.isEmpty()) {
+          return results;
+        }
+      } catch (IOException e) {
+        log.warn("OpenSearch global search failed, falling back to database query", e);
+      }
+    }
+    return fallbackGlobalSearch(keyword);
+  }
+
+  private List<SearchResult> fallbackGlobalSearch(String keyword) {
+    final String effectiveKeyword = keyword == null ? "" : keyword.trim();
     Stream<SearchResult> users = searchUsers(keyword)
       .stream()
       .map(u ->
-        new SearchResult("user", u.getId(), u.getUsername(), u.getIntroduction(), null, null)
+        new SearchResult(
+          "user",
+          u.getId(),
+          u.getUsername(),
+          u.getIntroduction(),
+          null,
+          null,
+          highlightHtml(u.getUsername(), effectiveKeyword),
+          highlightHtml(u.getIntroduction(), effectiveKeyword),
+          null
+        )
       );
 
     Stream<SearchResult> categories = searchCategories(keyword)
       .stream()
       .map(c ->
-        new SearchResult("category", c.getId(), c.getName(), null, c.getDescription(), null)
+        new SearchResult(
+          "category",
+          c.getId(),
+          c.getName(),
+          null,
+          c.getDescription(),
+          null,
+          highlightHtml(c.getName(), effectiveKeyword),
+          null,
+          highlightHtml(c.getDescription(), effectiveKeyword)
+        )
       );
 
     Stream<SearchResult> tags = searchTags(keyword)
       .stream()
-      .map(t -> new SearchResult("tag", t.getId(), t.getName(), null, t.getDescription(), null));
+      .map(t ->
+        new SearchResult(
+          "tag",
+          t.getId(),
+          t.getName(),
+          null,
+          t.getDescription(),
+          null,
+          highlightHtml(t.getName(), effectiveKeyword),
+          null,
+          highlightHtml(t.getDescription(), effectiveKeyword)
+        )
+      );
 
     // Merge post results while removing duplicates between search by content
     // and search by title
     List<SearchResult> mergedPosts = Stream.concat(
       searchPosts(keyword)
         .stream()
-        .map(p ->
-          new SearchResult(
+        .map(p -> {
+          String snippet = extractSnippet(p.getContent(), keyword, false);
+          return new SearchResult(
             "post",
             p.getId(),
             p.getTitle(),
             p.getCategory() != null ? p.getCategory().getName() : null,
-            extractSnippet(p.getContent(), keyword, false),
-            null
-          )
-        ),
+            snippet,
+            null,
+            highlightHtml(p.getTitle(), effectiveKeyword),
+            highlightHtml(
+              p.getCategory() != null ? p.getCategory().getName() : null,
+              effectiveKeyword
+            ),
+            highlightHtml(snippet, effectiveKeyword)
+          );
+        }),
       searchPostsByTitle(keyword)
         .stream()
-        .map(p ->
-          new SearchResult(
+        .map(p -> {
+          String snippet = extractSnippet(p.getContent(), keyword, true);
+          return new SearchResult(
             "post_title",
             p.getId(),
             p.getTitle(),
             p.getCategory() != null ? p.getCategory().getName() : null,
-            extractSnippet(p.getContent(), keyword, true),
-            null
-          )
-        )
+            snippet,
+            null,
+            highlightHtml(p.getTitle(), effectiveKeyword),
+            highlightHtml(
+              p.getCategory() != null ? p.getCategory().getName() : null,
+              effectiveKeyword
+            ),
+            highlightHtml(snippet, effectiveKeyword)
+          );
+        })
     )
       .collect(
         java.util.stream.Collectors.toMap(
@@ -122,22 +206,366 @@ public class SearchService {
 
     Stream<SearchResult> comments = searchComments(keyword)
       .stream()
-      .map(c ->
-        new SearchResult(
+      .map(c -> {
+        String snippet = extractSnippet(c.getContent(), keyword, false);
+        return new SearchResult(
           "comment",
           c.getId(),
           c.getPost().getTitle(),
           c.getAuthor().getUsername(),
-          extractSnippet(c.getContent(), keyword, false),
-          c.getPost().getId()
-        )
-      );
+          snippet,
+          c.getPost().getId(),
+          highlightHtml(c.getPost().getTitle(), effectiveKeyword),
+          highlightHtml(c.getAuthor().getUsername(), effectiveKeyword),
+          highlightHtml(snippet, effectiveKeyword)
+        );
+      });
 
     return Stream.of(users, categories, tags, mergedPosts.stream(), comments)
       .flatMap(s -> s)
       .toList();
   }
 
+  private boolean isOpenSearchEnabled() {
+    return openSearchProperties.isEnabled() && openSearchClient.isPresent();
+  }
+
+  // 在类里加上（字段或静态常量都可）
+  private static final java.util.regex.Pattern HANS_PATTERN = java.util.regex.Pattern.compile(
+    "\\p{IsHan}"
+  );
+
+  private static boolean containsHan(String s) {
+    return s != null && HANS_PATTERN.matcher(s).find();
+  }
+
+  private List<SearchResult> searchWithOpenSearch(String keyword) throws IOException {
+    var client = openSearchClient.orElse(null);
+    if (client == null) return List.of();
+
+    final String qRaw = keyword == null ? "" : keyword.trim();
+    if (qRaw.isEmpty()) return List.of();
+
+    final boolean hasHan = containsHan(qRaw);
+
+    SearchResponse<SearchDocument> resp = client.search(
+      b ->
+        b
+          .index(searchIndices())
+          .trackTotalHits(t -> t.enabled(true))
+          .query(qb ->
+            qb.bool(bool -> {
+              // ---------- 严格层 ----------
+              // 中文/任意短语（轻微符号/空白扰动）
+              bool.should(s ->
+                s.matchPhrase(mp -> mp.field("title").query(qRaw).slop(2).boost(6.0f))
+              );
+              bool.should(s ->
+                s.matchPhrase(mp -> mp.field("content").query(qRaw).slop(2).boost(2.5f))
+              );
+
+              // 结构化等值（.raw）
+              bool.should(s ->
+                s.term(t ->
+                  t
+                    .field("author.raw")
+                    .value(v -> v.stringValue(qRaw))
+                    .boost(4.0f)
+                )
+              );
+              bool.should(s ->
+                s.term(t ->
+                  t
+                    .field("category.raw")
+                    .value(v -> v.stringValue(qRaw))
+                    .boost(3.0f)
+                )
+              );
+              bool.should(s ->
+                s.term(t ->
+                  t
+                    .field("tags.raw")
+                    .value(v -> v.stringValue(qRaw))
+                    .boost(3.0f)
+                )
+              );
+
+              // 拼音短语（严格）
+              bool.should(s ->
+                s.matchPhrase(mp -> mp.field("title.py").query(qRaw).slop(1).boost(4.0f))
+              );
+              bool.should(s ->
+                s.matchPhrase(mp -> mp.field("content.py").query(qRaw).slop(1).boost(1.8f))
+              );
+              bool.should(s ->
+                s.matchPhrase(mp -> mp.field("author.py").query(qRaw).slop(1).boost(2.2f))
+              );
+              bool.should(s ->
+                s.matchPhrase(mp -> mp.field("category.py").query(qRaw).slop(1).boost(2.0f))
+              );
+              bool.should(s ->
+                s.matchPhrase(mp -> mp.field("tags.py").query(qRaw).slop(1).boost(2.0f))
+              );
+
+              // ---------- 放宽层（仅当包含中文时启用） ----------
+              if (hasHan) {
+                // title.zh
+                bool.should(s ->
+                  s.match(m ->
+                    m
+                      .field("title.zh")
+                      .query(org.opensearch.client.opensearch._types.FieldValue.of(qRaw))
+                      .operator(org.opensearch.client.opensearch._types.query_dsl.Operator.Or)
+                      .minimumShouldMatch("2<-1 3<-1 4<-1 5<-2 6<-2 7<-3")
+                      .boost(3.0f)
+                  )
+                );
+                // content.zh
+                bool.should(s ->
+                  s.match(m ->
+                    m
+                      .field("content.zh")
+                      .query(org.opensearch.client.opensearch._types.FieldValue.of(qRaw))
+                      .operator(org.opensearch.client.opensearch._types.query_dsl.Operator.Or)
+                      .minimumShouldMatch("2<-1 3<-1 4<-1 5<-2 6<-2 7<-3")
+                      .boost(1.6f)
+                  )
+                );
+              }
+
+              return bool.minimumShouldMatch("1");
+            })
+          )
+          // ---------- 高亮：允许跨子字段回填 + 匹配字段组 ----------
+          .highlight(h -> {
+            var hb = h
+              .preTags("<mark>")
+              .postTags("</mark>")
+              .requireFieldMatch(false)
+              .fields("title", f ->
+                f
+                  .fragmentSize(highlightFragmentSize())
+                  .numberOfFragments(1)
+                  .matchedFields(List.of("title", "title.zh", "title.py"))
+              )
+              .fields("content", f ->
+                f
+                  .fragmentSize(highlightFragmentSize())
+                  .numberOfFragments(1)
+                  .matchedFields(List.of("content", "content.zh", "content.py"))
+              )
+              .fields("title.zh", f -> f.fragmentSize(highlightFragmentSize()).numberOfFragments(1))
+              .fields("content.zh", f ->
+                f.fragmentSize(highlightFragmentSize()).numberOfFragments(1)
+              )
+              .fields("title.py", f -> f.fragmentSize(highlightFragmentSize()).numberOfFragments(1))
+              .fields("content.py", f ->
+                f.fragmentSize(highlightFragmentSize()).numberOfFragments(1)
+              )
+              .fields("author", f -> f.numberOfFragments(0))
+              .fields("author.py", f -> f.numberOfFragments(0))
+              .fields("category", f -> f.numberOfFragments(0))
+              .fields("category.py", f -> f.numberOfFragments(0))
+              .fields("tags", f -> f.numberOfFragments(0))
+              .fields("tags.py", f -> f.numberOfFragments(0));
+            return hb;
+          })
+          .size(DEFAULT_OPEN_SEARCH_LIMIT > 0 ? DEFAULT_OPEN_SEARCH_LIMIT : 10),
+      SearchDocument.class
+    );
+
+    return mapHits(resp.hits().hits(), qRaw);
+  }
+
+  /** Lucene query_string 安全转义（保留 * 由我们自己追加） */
+  private static String escapeForQueryString(String s) {
+    if (s == null || s.isEmpty()) return "";
+    StringBuilder sb = new StringBuilder(s.length() * 2);
+    for (char c : s.toCharArray()) {
+      switch (c) {
+        case '+':
+        case '-':
+        case '=':
+        case '&':
+        case '|':
+        case '>':
+        case '<':
+        case '!':
+        case '(':
+        case ')':
+        case '{':
+        case '}':
+        case '[':
+        case ']':
+        case '^':
+        case '"':
+        case '~': /* case '*': */ /* case '?': */
+        case ':':
+        case '\\':
+        case '/':
+          sb.append('\\').append(c);
+          break;
+        default:
+          sb.append(c);
+      }
+    }
+    return sb.toString();
+  }
+
+  private int highlightFragmentSize() {
+    int configured = openSearchProperties.getHighlightFragmentSize();
+    if (configured > 0) {
+      return configured;
+    }
+    if (snippetLength > 0) {
+      return snippetLength;
+    }
+    return 200;
+  }
+
+  private List<String> searchIndices() {
+    return List.of(
+      openSearchProperties.postsIndex(),
+      openSearchProperties.commentsIndex(),
+      openSearchProperties.usersIndex(),
+      openSearchProperties.categoriesIndex(),
+      openSearchProperties.tagsIndex()
+    );
+  }
+
+  private List<SearchResult> mapHits(List<Hit<SearchDocument>> hits, String keyword) {
+    List<SearchResult> results = new ArrayList<>();
+    for (Hit<SearchDocument> hit : hits) {
+      SearchResult result = mapHit(hit, keyword);
+      if (result != null) {
+        results.add(result);
+      }
+    }
+    return results;
+  }
+
+  private SearchResult mapHit(Hit<SearchDocument> hit, String keyword) {
+    SearchDocument document = hit.source();
+    if (document == null || document.entityId() == null) {
+      return null;
+    }
+    Map<String, List<String>> highlight = hit.highlight();
+    String highlightedContent = firstHighlight(
+      highlight,
+      "content",
+      "content.py",
+      "content.zh",
+      "content.raw"
+    );
+    String highlightedTitle = firstHighlight(
+      highlight,
+      "title",
+      "title.py",
+      "title.zh",
+      "title.raw"
+    );
+    String highlightedAuthor = firstHighlight(highlight, "author", "author.py");
+    String highlightedCategory = firstHighlight(highlight, "category", "category.py");
+    boolean highlightTitle = highlightedTitle != null && !highlightedTitle.isBlank();
+    String documentType = document.type() != null ? document.type() : "";
+    String effectiveType = documentType;
+    if ("post".equals(documentType) && highlightTitle) {
+      effectiveType = "post_title";
+    }
+    String snippetHtml = highlightedContent != null && !highlightedContent.isBlank()
+      ? highlightedContent
+      : null;
+    if (snippetHtml == null && highlightTitle) {
+      snippetHtml = highlightedTitle;
+    }
+
+    String snippet = snippetHtml != null && !snippetHtml.isBlank()
+      ? cleanHighlight(snippetHtml)
+      : null;
+    boolean fromStart = "post_title".equals(effectiveType);
+    if (snippet == null || snippet.isBlank()) {
+      snippet = fallbackSnippet(document.content(), keyword, fromStart);
+      if (snippetHtml == null) {
+        snippetHtml = highlightHtml(snippet, keyword);
+      }
+    } else if (snippetHtml == null) {
+      snippetHtml = highlightHtml(snippet, keyword);
+    }
+    if (snippet == null) {
+      snippet = "";
+    }
+    String subText = null;
+    Long postId = null;
+    if ("post".equals(documentType) || "post_title".equals(effectiveType)) {
+      subText = document.category();
+    } else if ("comment".equals(documentType)) {
+      subText = document.author();
+      postId = document.postId();
+    }
+    String highlightedText = highlightTitle
+      ? highlightedTitle
+      : highlightHtml(document.title(), keyword);
+    String highlightedSubText;
+    if ("comment".equals(documentType)) {
+      highlightedSubText = highlightedAuthor != null && !highlightedAuthor.isBlank()
+        ? highlightedAuthor
+        : highlightHtml(subText, keyword);
+    } else if ("post".equals(documentType) || "post_title".equals(effectiveType)) {
+      highlightedSubText = highlightedCategory != null && !highlightedCategory.isBlank()
+        ? highlightedCategory
+        : highlightHtml(subText, keyword);
+    } else {
+      highlightedSubText = highlightHtml(subText, keyword);
+    }
+    String highlightedExtra = snippetHtml != null ? snippetHtml : highlightHtml(snippet, keyword);
+    return new SearchResult(
+      effectiveType,
+      document.entityId(),
+      document.title(),
+      subText,
+      snippet,
+      postId,
+      highlightedText,
+      highlightedSubText,
+      highlightedExtra
+    );
+  }
+
+  private String firstHighlight(Map<String, List<String>> highlight, String... fields) {
+    if (highlight == null || fields == null) {
+      return null;
+    }
+    for (String field : fields) {
+      if (field == null) {
+        continue;
+      }
+      List<String> values = highlight.get(field);
+      if (values == null || values.isEmpty()) {
+        continue;
+      }
+      for (String value : values) {
+        if (value != null && !value.isBlank()) {
+          return value;
+        }
+      }
+    }
+    return null;
+  }
+
+  private String cleanHighlight(String value) {
+    if (value == null) {
+      return null;
+    }
+    return value.replaceAll("<[^>]+>", "");
+  }
+
+  private String fallbackSnippet(String content, String keyword, boolean fromStart) {
+    if (content == null) {
+      return "";
+    }
+    return extractSnippet(content, keyword, fromStart);
+  }
+
   private String extractSnippet(String content, String keyword, boolean fromStart) {
     if (content == null) return "";
     int limit = snippetLength;
@@ -165,12 +593,45 @@ public class SearchService {
     return snippet;
   }
 
+  private String highlightHtml(String text, String keyword) {
+    if (text == null) {
+      return null;
+    }
+    String normalizedKeyword = keyword == null ? "" : keyword.trim();
+    if (normalizedKeyword.isEmpty()) {
+      return HtmlUtils.htmlEscape(text);
+    }
+    Pattern pattern = Pattern.compile(
+      Pattern.quote(normalizedKeyword),
+      Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE
+    );
+    Matcher matcher = pattern.matcher(text);
+    if (!matcher.find()) {
+      return HtmlUtils.htmlEscape(text);
+    }
+    matcher.reset();
+    StringBuilder sb = new StringBuilder();
+    int lastEnd = 0;
+    while (matcher.find()) {
+      sb.append(HtmlUtils.htmlEscape(text.substring(lastEnd, matcher.start())));
+      sb.append("<mark>");
+      sb.append(HtmlUtils.htmlEscape(matcher.group()));
+      sb.append("</mark>");
+      lastEnd = matcher.end();
+    }
+    sb.append(HtmlUtils.htmlEscape(text.substring(lastEnd)));
+    return sb.toString();
+  }
+
   public record SearchResult(
     String type,
     Long id,
     String text,
     String subText,
     String extra,
-    Long postId
+    Long postId,
+    String highlightedText,
+    String highlightedSubText,
+    String highlightedExtra
   ) {}
 }

backend/src/main/java/com/openisle/service/TagService.java

@@ -5,6 +5,7 @@ import com.openisle.model.Tag;
 import com.openisle.model.User;
 import com.openisle.repository.TagRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import java.util.List;
 import lombok.RequiredArgsConstructor;
 import org.springframework.cache.annotation.CacheEvict;
@@ -20,6 +21,7 @@ public class TagService {
   private final TagRepository tagRepository;
   private final TagValidator tagValidator;
   private final UserRepository userRepository;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   @CacheEvict(value = CachingConfig.TAG_CACHE_NAME, allEntries = true)
   public Tag createTag(
@@ -43,7 +45,9 @@ public class TagService {
         .orElseThrow(() -> new com.openisle.exception.NotFoundException("User not found"));
       tag.setCreator(creator);
     }
-    return tagRepository.save(tag);
+    Tag saved = tagRepository.save(tag);
+    searchIndexEventPublisher.publishTagSaved(saved);
+    return saved;
   }
 
   public Tag createTag(
@@ -78,12 +82,15 @@ public class TagService {
     if (smallIcon != null) {
       tag.setSmallIcon(smallIcon);
     }
-    return tagRepository.save(tag);
+    Tag saved = tagRepository.save(tag);
+    searchIndexEventPublisher.publishTagSaved(saved);
+    return saved;
   }
 
   @CacheEvict(value = CachingConfig.TAG_CACHE_NAME, allEntries = true)
   public void deleteTag(Long id) {
     tagRepository.deleteById(id);
+    searchIndexEventPublisher.publishTagDeleted(id);
   }
 
   public Tag approveTag(Long id) {
@@ -91,7 +98,9 @@ public class TagService {
       .findById(id)
       .orElseThrow(() -> new IllegalArgumentException("Tag not found"));
     tag.setApproved(true);
-    return tagRepository.save(tag);
+    Tag saved = tagRepository.save(tag);
+    searchIndexEventPublisher.publishTagSaved(saved);
+    return saved;
   }
 
   public List<Tag> listPendingTags() {

backend/src/main/java/com/openisle/service/UserService.java

@@ -5,6 +5,7 @@ import com.openisle.exception.FieldException;
 import com.openisle.model.Role;
 import com.openisle.model.User;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import com.openisle.service.AvatarGenerator;
 import com.openisle.service.PasswordValidator;
 import com.openisle.service.UsernameValidator;
@@ -34,6 +35,7 @@ public class UserService {
   private final RedisTemplate redisTemplate;
 
   private final EmailSender emailService;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   public User register(
     String username,
@@ -58,7 +60,9 @@ public class UserService {
       //            u.setVerificationCode(genCode());
       u.setRegisterReason(reason);
       u.setApproved(mode == com.openisle.model.RegisterMode.DIRECT);
-      return userRepository.save(u);
+      User saved = userRepository.save(u);
+      searchIndexEventPublisher.publishUserSaved(saved);
+      return saved;
     }
 
     // ── 再按邮箱查 ───────────────────────────────────────────
@@ -75,7 +79,9 @@ public class UserService {
       //            u.setVerificationCode(genCode());
       u.setRegisterReason(reason);
       u.setApproved(mode == com.openisle.model.RegisterMode.DIRECT);
-      return userRepository.save(u);
+      User saved = userRepository.save(u);
+      searchIndexEventPublisher.publishUserSaved(saved);
+      return saved;
     }
 
     // ── 完全新用户 ───────────────────────────────────────────
@@ -89,14 +95,18 @@ public class UserService {
     user.setAvatar(avatarGenerator.generate(username));
     user.setRegisterReason(reason);
     user.setApproved(mode == com.openisle.model.RegisterMode.DIRECT);
-    return userRepository.save(user);
+    User saved = userRepository.save(user);
+    searchIndexEventPublisher.publishUserSaved(saved);
+    return saved;
   }
 
   public User registerWithInvite(String username, String email, String password) {
     User user = register(username, email, password, "", com.openisle.model.RegisterMode.DIRECT);
     user.setVerified(true);
     //        user.setVerificationCode(genCode());
-    return userRepository.save(user);
+    User saved = userRepository.save(user);
+    searchIndexEventPublisher.publishUserSaved(saved);
+    return saved;
   }
 
   private String genCode() {
@@ -209,7 +219,9 @@ public class UserService {
       .findByUsername(username)
       .orElseThrow(() -> new com.openisle.exception.NotFoundException("User not found"));
     user.setRegisterReason(reason);
-    return userRepository.save(user);
+    User saved = userRepository.save(user);
+    searchIndexEventPublisher.publishUserSaved(saved);
+    return saved;
   }
 
   public User updateProfile(String currentUsername, String newUsername, String introduction) {