[ACS-12256] search_after pagination parameter addition (#4309)

data-model/src/main/java/org/alfresco/service/cmr/search/SearchParameters.java

@@ -44,7 +44,7 @@ import org.alfresco.service.cmr.repository.StoreRef;
 import org.alfresco.service.namespace.NamespaceService;
 
 /**
- * This class provides parameters to define a search. TODO - paging of results page number and page size - paging isolation - REPEATABLE READ, READ COMMITTED, may SEE ONCE tracking node refs in previous result sets - how long repeatable read may be held - limit by the number of permission evaluations
+ * This class provides parameters to define a search.
  * 
  * @author Andy Hind
  */
@@ -198,6 +198,8 @@ public class SearchParameters implements BasicSearchParameters
 
     private boolean trackScore = true;
 
+    private String searchAfterToken;
+
     /**
      * Default constructor
      */
@@ -250,6 +252,7 @@ public class SearchParameters implements BasicSearchParameters
         sp.timezone = this.timezone;
         sp.trackTotalHits = this.trackTotalHits;
         sp.trackScore = this.trackScore;
+        sp.searchAfterToken = this.searchAfterToken;
         return sp;
     }
 
@@ -600,6 +603,16 @@ public class SearchParameters implements BasicSearchParameters
         this.limit = limit;
     }
 
+    public String getSearchAfterToken()
+    {
+        return searchAfterToken;
+    }
+
+    public void setSearchAfterToken(String searchAfterToken)
+    {
+        this.searchAfterToken = searchAfterToken;
+    }
+
     /**
      * The way in which multilingual fields are treated durig a search. By default, only the specified locale is used and it must be an exact match.
      * 
@@ -1197,6 +1210,7 @@ public class SearchParameters implements BasicSearchParameters
         result = prime * result + ((ranges == null) ? 0 : ranges.hashCode());
         result = prime * result + ((searchTerm == null) ? 0 : searchTerm.hashCode());
         result = prime * result + (spellCheck ? 1231 : 1237);
+        result = prime * result + ((searchAfterToken == null) ? 0 : searchAfterToken.hashCode());
         return result;
     }
 
@@ -1359,6 +1373,17 @@ public class SearchParameters implements BasicSearchParameters
             return false;
         if (spellCheck != other.spellCheck)
             return false;
+        if (searchAfterToken == null)
+        {
+            if (other.searchAfterToken != null)
+            {
+                return false;
+            }
+        }
+        else if (!searchAfterToken.equals(other.searchAfterToken))
+        {
+            return false;
+        }
         return true;
     }
 
@@ -1401,7 +1426,8 @@ public class SearchParameters implements BasicSearchParameters
                 .append(", interval=").append(this.interval)
                 .append(", range=").append(this.ranges)
                 .append(", timezone=").append(this.timezone)
-                .append(", spellCheck=").append(this.spellCheck).append("]");
+                .append(", spellCheck=").append(this.spellCheck)
+                .append(", searchAfterToken=").append(this.searchAfterToken).append("]");
         return builder.toString();
     }
 

pom.xml

@@ -98,7 +98,7 @@
         <dependency.awaitility.version>4.2.2</dependency.awaitility.version>
 
         <!-- Elasticsearch / OpenSearch search support -->
-        <dependency.opensearch.version>2.21.0</dependency.opensearch.version>
+        <dependency.opensearch.version>2.26.0</dependency.opensearch.version>
         <dependency.lucene.version>9.7.0</dependency.lucene.version>
         <dependency.swagger-ui.version>4.1.3</dependency.swagger-ui.version>
         <dependency.swagger-parser.version>1.0.73</dependency.swagger-parser.version>

remote-api/src/main/java/org/alfresco/rest/api/search/SearchApiWebscript.java

@@ -85,7 +85,7 @@ public class SearchApiWebscript extends AbstractWebScript implements RecognizedP
     {
         try
         {
-            // Turn JSON into a Java object respresentation
+            // Turn JSON into a Java object representation
             SearchQuery searchQuery = extractJsonContent(webScriptRequest, assistant.getJsonHelper(), SearchQuery.class);
 
             // Parse the parameters

remote-api/src/main/java/org/alfresco/rest/api/search/impl/ResultMapper.java

@@ -231,7 +231,11 @@ public class ResultMapper
                 .map(resultSet -> toSearchContext(resultSet, searchRequestContext, searchQuery))
                 .orElse(null);
 
-        return CollectionWithPagingInfo.asPaged(params.getPaging(), noderesults, results.hasMore(), setTotal(results), null, context);
+        String nextSearchAfterToken = toSearchEngineResultSet(results)
+                .map(SearchEngineResultSet::getNextSearchAfterToken)
+                .orElse(null);
+
+        return CollectionWithPagingInfo.asPaged(params.getPaging(), noderesults, results.hasMore(), setTotal(results), null, context, nextSearchAfterToken);
     }
 
     /**

remote-api/src/main/java/org/alfresco/rest/api/search/impl/SearchMapper.java

@@ -199,6 +199,10 @@ public class SearchMapper
             sp.setLimitBy(LimitBy.FINAL_SIZE);
             sp.setLimit(paging.getMaxItems());
             sp.setSkipCount(paging.getSkipCount());
+            if (paging.getSearchAfterToken() != null)
+            {
+                sp.setSearchAfterToken(paging.getSearchAfterToken());
+            }
         }
     }
 

remote-api/src/main/java/org/alfresco/rest/framework/jacksonextensions/SerializerOfCollectionWithPaging.java

@@ -103,6 +103,10 @@ public class SerializerOfCollectionWithPaging extends StdSerializer<Serializable
             jgen.writeNumberField(RecognizedParamsExtractor.PARAM_PAGING_SKIP, pagedCol.getPaging().getSkipCount());
             jgen.writeNumberField(RecognizedParamsExtractor.PARAM_PAGING_MAX, pagedCol.getPaging().getMaxItems());
         }
+        if (pagedCol.getNextSearchAfterToken() != null)
+        {
+            jgen.writeStringField("nextSearchAfterToken", pagedCol.getNextSearchAfterToken());
+        }
         jgen.writeEndObject();
     }
 }

remote-api/src/main/java/org/alfresco/rest/framework/resource/SerializablePagedCollection.java

@@ -2,7 +2,7 @@
  * #%L
  * Alfresco Remote API
  * %%
- * Copyright (C) 2005 - 2016 Alfresco Software Limited
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
  * %%
  * This file is part of the Alfresco software. 
  * If the software was purchased under a paid Alfresco license, the terms of 
@@ -70,4 +70,12 @@ public interface SerializablePagedCollection<T>
      * The search context for the collection
      */
     SearchContext getContext();
+
+    /**
+     * The search_after token for fetching the next page, or null if not applicable.
+     */
+    default String getNextSearchAfterToken()
+    {
+        return null;
+    }
 }

remote-api/src/main/java/org/alfresco/rest/framework/resource/parameters/CollectionWithPagingInfo.java

@@ -50,6 +50,7 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
     private final Paging paging;
     private final Object sourceEntity;
     private final SearchContext context;
+    private final String nextSearchAfterToken;
 
     /**
      * Constructs a new CollectionWithPagingInfo.
@@ -64,6 +65,11 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
      *            - The total number of items available.
      */
     protected CollectionWithPagingInfo(Collection<T> collection, Paging paging, boolean hasMoreItems, Integer totalItems, Object sourceEntity, SearchContext context)
+    {
+        this(collection, paging, hasMoreItems, totalItems, sourceEntity, context, null);
+    }
+
+    protected CollectionWithPagingInfo(Collection<T> collection, Paging paging, boolean hasMoreItems, Integer totalItems, Object sourceEntity, SearchContext context, String nextSearchAfterToken)
     {
         super();
         this.hasMoreItems = hasMoreItems;
@@ -81,6 +87,7 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
         }
         this.sourceEntity = sourceEntity;
         this.context = context;
+        this.nextSearchAfterToken = nextSearchAfterToken;
     }
 
     /**
@@ -93,7 +100,7 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
     public static <T> CollectionWithPagingInfo<T> from(SerializablePagedCollection<T> pagedCollection)
     {
         return new CollectionWithPagingInfo<>(pagedCollection.getCollection(), pagedCollection.getPaging(), pagedCollection.hasMoreItems(), pagedCollection.getTotalItems(),
-                pagedCollection.getSourceEntity(), pagedCollection.getContext());
+                pagedCollection.getSourceEntity(), pagedCollection.getContext(), pagedCollection.getNextSearchAfterToken());
     }
 
     /**
@@ -143,7 +150,7 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
     }
 
     /**
-     * Constructs a new CollectionWithPagingInfo. Not for public use.
+     * Constructs a new CollectionWithPagingInfo.
      *
      * @param paging
      *            - Paging request info
@@ -163,7 +170,7 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
     }
 
     /**
-     * Constructs a new CollectionWithPagingInfo. Not for public use.
+     * Constructs a new CollectionWithPagingInfo.
      * 
      * @param paging
      *            - Paging request info
@@ -184,6 +191,30 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
         return new CollectionWithPagingInfo<T>(aCollection, paging, hasMoreItems, totalItems, sourceEntity, context);
     }
 
+    /**
+     * Constructs a new CollectionWithPagingInfo carrying a search_after token.
+     *
+     * @param paging
+     *            - Paging request info
+     * @param aCollection
+     *            - the collection that needs to be paged.
+     * @param hasMoreItems
+     *            - Are there more items after this Collection?
+     * @param totalItems
+     *            - The total number of items available.
+     * @param sourceEntity
+     *            - The parent/source entity responsible for the collection
+     * @param context
+     *            - The search context
+     * @param nextSearchAfterToken
+     *            - The search_after token for fetching the next page
+     * @return CollectionWithPagingInfo
+     */
+    public static <T> CollectionWithPagingInfo<T> asPaged(Paging paging, Collection<T> aCollection, boolean hasMoreItems, Integer totalItems, Object sourceEntity, SearchContext context, String nextSearchAfterToken)
+    {
+        return new CollectionWithPagingInfo<>(aCollection, paging, hasMoreItems, totalItems, sourceEntity, context, nextSearchAfterToken);
+    }
+
     /**
      * Returns the Collection object
      * 
@@ -240,4 +271,10 @@ public class CollectionWithPagingInfo<T> implements SerializablePagedCollection<
         return context;
     }
 
+    @Override
+    public String getNextSearchAfterToken()
+    {
+        return nextSearchAfterToken;
+    }
+
 }

remote-api/src/main/java/org/alfresco/rest/framework/resource/parameters/Paging.java

@@ -27,6 +27,8 @@ package org.alfresco.rest.framework.resource.parameters;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.deser.std.StringDeserializer;
 
 import org.alfresco.rest.framework.core.exceptions.InvalidArgumentException;
 
@@ -46,8 +48,9 @@ public class Paging
 
     private final int skipCount;
     private final int maxItems;
+    private final String searchAfterToken;
 
-    private Paging(int skipCount, int maxItems)
+    private Paging(int skipCount, int maxItems, String searchAfterToken)
     {
         super();
         if (skipCount < 0)
@@ -60,6 +63,7 @@ public class Paging
         }
         this.skipCount = skipCount;
         this.maxItems = maxItems;
+        this.searchAfterToken = searchAfterToken;
     }
 
     /**
@@ -82,21 +86,39 @@ public class Paging
         return this.maxItems;
     }
 
-    @JsonCreator
-    public static Paging valueOf(@JsonProperty("skipCount") int skipCount, @JsonProperty("maxItems") int maxItems)
+    /**
+     * The opaque search_after cursor for the next page, or null if not using cursor-based paging.
+     *
+     * @return String
+     */
+    public String getSearchAfterToken()
     {
-        return new Paging(skipCount, maxItems);
+        return this.searchAfterToken;
+    }
+
+    public static Paging valueOf(int skipCount, int maxItems)
+    {
+        return new Paging(skipCount, maxItems, null);
+    }
+
+    @JsonCreator
+    public static Paging valueOf(@JsonProperty("skipCount") int skipCount, @JsonProperty("maxItems") int maxItems,
+            @JsonProperty("searchAfterToken") @JsonDeserialize(using = StringDeserializer.class) String searchAfterToken)
+    {
+        return new Paging(skipCount, maxItems, searchAfterToken);
     }
 
     @Override
     public String toString()
     {
         StringBuilder builder = new StringBuilder();
-        builder.append("Paging [skipCount=");
-        builder.append(this.skipCount);
-        builder.append(", maxItems=");
-        builder.append(this.maxItems);
-        builder.append("]");
+        builder.append("Paging [skipCount=")
+                .append(this.skipCount)
+                .append(", maxItems=")
+                .append(this.maxItems)
+                .append(", searchAfterToken=")
+                .append(this.searchAfterToken)
+                .append("]");
         return builder.toString();
     }
 

remote-api/src/main/java/org/alfresco/rest/framework/webscripts/ResourceWebScriptHelper.java

@@ -153,7 +153,7 @@ public class ResourceWebScriptHelper
                 }
             }
             return CollectionWithPagingInfo.asPaged(collectionToWrap.getPaging(), resultCollection, collectionToWrap.hasMoreItems(),
-                    collectionToWrap.getTotalItems(), sourceEntity, collectionToWrap.getContext());
+                    collectionToWrap.getTotalItems(), sourceEntity, collectionToWrap.getContext(), collectionToWrap.getNextSearchAfterToken());
         }
         else
         {

remote-api/src/main/resources/alfresco/public-rest-context.xml

@@ -144,6 +144,7 @@
                 <entry key="java.lang.IllegalArgumentException" value="#{T(org.springframework.extensions.webscripts.Status).STATUS_BAD_REQUEST}" />
                 <entry key="org.alfresco.service.cmr.repository.CyclicChildRelationshipException" value="#{T(org.springframework.extensions.webscripts.Status).STATUS_BAD_REQUEST}" />
                 <entry key="org.alfresco.rest.framework.core.exceptions.InvalidArgumentException" value="#{T(org.springframework.extensions.webscripts.Status).STATUS_BAD_REQUEST}" />
+                <entry key="org.alfresco.repo.search.impl.elasticsearch.query.SearchStrategyException" value="#{T(org.springframework.extensions.webscripts.Status).STATUS_BAD_REQUEST}" />
                 <entry key="org.alfresco.service.cmr.version.VersionServiceException" value="#{T(org.springframework.extensions.webscripts.Status).STATUS_BAD_REQUEST}" />
                 <entry key="org.alfresco.service.cmr.repository.datatype.TypeConversionException" value="#{T(org.springframework.extensions.webscripts.Status).STATUS_BAD_REQUEST}" />
                 <entry key="org.alfresco.rest.framework.core.exceptions.NotFoundException" value="#{T(org.springframework.extensions.webscripts.Status).STATUS_NOT_FOUND}" />

remote-api/src/test/java/org/alfresco/rest/api/search/SearchMapperTests.java

@@ -194,6 +194,21 @@ public class SearchMapperTests
         assertEquals(searchParameters.getSkipCount(), paging.getSkipCount());
     }
 
+    @Test
+    public void fromSearchAfter() throws Exception
+    {
+        SearchParameters searchParameters = new SearchParameters();
+        searchMapper.fromPaging(searchParameters, Paging.valueOf(0, 100));
+        assertNull(searchParameters.getSearchAfterToken());
+
+        searchMapper.fromPaging(searchParameters, Paging.valueOf(0, 100, "SEARCH_AFTER_TOKEN"));
+        assertEquals("SEARCH_AFTER_TOKEN", searchParameters.getSearchAfterToken());
+
+        // An explicit empty searchAfter starts a new cursor-paging session (first page).
+        searchMapper.fromPaging(searchParameters, Paging.valueOf(0, 100, ""));
+        assertEquals("", searchParameters.getSearchAfterToken());
+    }
+
     @Test
     public void fromSort() throws Exception
     {

repository/src/main/java/org/alfresco/repo/search/SearchEngineResultSet.java

@@ -2,7 +2,7 @@
  * #%L
  * Alfresco Data model classes
  * %%
- * Copyright (C) 2005 - 2021 Alfresco Software Limited
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
  * %%
  * This file is part of the Alfresco software.
  * If the software was purchased under a paid Alfresco license, the terms of
@@ -52,4 +52,9 @@ public interface SearchEngineResultSet extends ResultSet, SearchEngineResultMeta
     long getLastIndexedTxId();
 
     boolean getProcessedDenies();
+
+    default String getNextSearchAfterToken()
+    {
+        return null;
+    }
 }

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/admin/SearchEngine.java

@@ -0,0 +1,31 @@
+/*
+ * #%L
+ * Alfresco Repository
+ * %%
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
+ * %%
+ * This file is part of the Alfresco software.
+ * If the software was purchased under a paid Alfresco license, the terms of
+ * the paid license agreement will prevail.  Otherwise, the software is
+ * provided under the following open source license terms:
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ * #L%
+ */
+package org.alfresco.repo.search.impl.elasticsearch.admin;
+
+public enum SearchEngine
+{
+    ELASTICSEARCH, OPENSEARCH, UNKNOWN
+}

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/admin/SearchEngineDetector.java

@@ -0,0 +1,126 @@
+/*
+ * #%L
+ * Alfresco Repository
+ * %%
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
+ * %%
+ * This file is part of the Alfresco software.
+ * If the software was purchased under a paid Alfresco license, the terms of
+ * the paid license agreement will prevail.  Otherwise, the software is
+ * provided under the following open source license terms:
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ * #L%
+ */
+package org.alfresco.repo.search.impl.elasticsearch.admin;
+
+import java.io.IOException;
+import java.util.Locale;
+
+import org.json.JSONObject;
+import org.opensearch.client.opensearch.generic.Body;
+import org.opensearch.client.opensearch.generic.Request;
+import org.opensearch.client.opensearch.generic.Requests;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.alfresco.repo.search.impl.elasticsearch.client.ElasticsearchHttpClientFactory;
+import org.alfresco.repo.security.authentication.AuthenticationUtil;
+import org.alfresco.repo.transaction.RetryingTransactionHelper;
+import org.alfresco.service.cmr.attributes.AttributeService;
+import org.alfresco.service.transaction.TransactionService;
+
+/**
+ * Detects the search engine provider (OpenSearch vs Elasticsearch) and version, and persists it via {@link AttributeService}. Invoked by {@link org.alfresco.repo.search.impl.elasticsearch.contentmodelsync.ElasticsearchInitialiser} once the engine is confirmed reachable.
+ */
+public class SearchEngineDetector
+{
+    private static final Logger LOGGER = LoggerFactory.getLogger(SearchEngineDetector.class);
+
+    public static final String ATTR_ROOT = ".searchEngine";
+    public static final String ATTR_SEARCH_ENGINE_NAME = "name"; // "OpenSearch" | "Elasticsearch"
+    public static final String ATTR_SEARCH_ENGINE_VERSION = "version"; // e.g. "2.13.0"
+    // Access the search engine info using something like:
+    // Search engine name: attributeService.getAttribute(ATTR_ROOT, ATTR_SEARCH_ENGINE_NAME)
+    // Search engine version: attributeService.getAttribute(ATTR_ROOT, ATTR_SEARCH_ENGINE_VERSION)
+
+    private ElasticsearchHttpClientFactory httpClientFactory;
+    private AttributeService attributeService;
+    private TransactionService transactionService;
+
+    public void detectAndStore()
+    {
+        try
+        {
+            SearchEngineInfo searchEngineInfo = detect();// [provider, version]
+            store(searchEngineInfo);
+            LOGGER.info("Detected search engine: {} {}", searchEngineInfo.getSearchEngineName(), searchEngineInfo.getSearchEngineVersion());
+        }
+        catch (Exception e)
+        {
+            LOGGER.warn("Could not detect the search engine provider/version", e);
+        }
+    }
+
+    private SearchEngineInfo detect() throws IOException
+    {
+        Request request = Requests.builder().method("GET").endpoint("/").build();
+        try (var response = httpClientFactory.getElasticsearchClient().generic().execute(request))
+        {
+            String raw = response.getBody()
+                    .map(Body::bodyAsString)
+                    .orElseThrow(() -> new IOException("Empty response from root endpoint"));
+
+            JSONObject root = new JSONObject(raw);
+            String versionNumber = root.getJSONObject("version").getString("number");
+
+            SearchEngine searchEngine = switch (root.getString("tagline").toLowerCase(Locale.ROOT))
+            {
+            case "you know, for search" -> SearchEngine.ELASTICSEARCH;
+            case "the opensearch project: https://opensearch.org/" -> SearchEngine.OPENSEARCH;
+            default -> SearchEngine.UNKNOWN;
+            };
+            String provider = searchEngine.name().toLowerCase(Locale.ROOT);
+            return new SearchEngineInfo(provider, versionNumber);
+        }
+    }
+
+    private void store(SearchEngineInfo searchEngineInfo)
+    {
+        AuthenticationUtil.runAs((AuthenticationUtil.RunAsWork<Void>) () -> {
+            RetryingTransactionHelper txnHelper = transactionService.getRetryingTransactionHelper();
+            txnHelper.setForceWritable(true);
+            return txnHelper.doInTransaction(() -> {
+                attributeService.setAttribute(searchEngineInfo.getSearchEngineName(), ATTR_ROOT, ATTR_SEARCH_ENGINE_NAME);
+                attributeService.setAttribute(searchEngineInfo.getSearchEngineVersion(), ATTR_ROOT, ATTR_SEARCH_ENGINE_VERSION);
+                return null;
+            }, false, true);
+        }, AuthenticationUtil.getSystemUserName());
+    }
+
+    public void setHttpClientFactory(ElasticsearchHttpClientFactory httpClientFactory)
+    {
+        this.httpClientFactory = httpClientFactory;
+    }
+
+    public void setAttributeService(AttributeService attributeService)
+    {
+        this.attributeService = attributeService;
+    }
+
+    public void setTransactionService(TransactionService transactionService)
+    {
+        this.transactionService = transactionService;
+    }
+}

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/admin/SearchEngineInfo.java

@@ -0,0 +1,48 @@
+/*
+ * #%L
+ * Alfresco Repository
+ * %%
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
+ * %%
+ * This file is part of the Alfresco software.
+ * If the software was purchased under a paid Alfresco license, the terms of
+ * the paid license agreement will prevail.  Otherwise, the software is
+ * provided under the following open source license terms:
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ * #L%
+ */
+package org.alfresco.repo.search.impl.elasticsearch.admin;
+
+public class SearchEngineInfo
+{
+    private String searchEngineName;
+    private String searchEngineVersion;
+
+    public SearchEngineInfo(String searchEngineName, String searchEngineVersion)
+    {
+        this.searchEngineName = searchEngineName;
+        this.searchEngineVersion = searchEngineVersion;
+    }
+
+    public String getSearchEngineName()
+    {
+        return searchEngineName;
+    }
+
+    public String getSearchEngineVersion()
+    {
+        return searchEngineVersion;
+    }
+}

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/client/ElasticsearchHttpClientFactory.java

@@ -77,6 +77,9 @@ public class ElasticsearchHttpClientFactory
     private String baseUrl;
     private int port;
 
+    // Search engine implementation (elasticsearch, opensearch)
+    private String engine;
+
     // SSL parameters for Elasticsearch server endpoint
     private String secureComms;
     private AlfrescoKeyStore sslTrustStore;
@@ -235,6 +238,16 @@ public class ElasticsearchHttpClientFactory
         return (secureComms.equals("https") ? "https" : "http") + "://" + host + ":" + port + baseUrl;
     }
 
+    /**
+     * Gets the configured search engine implementation (elasticsearch, opensearch).
+     *
+     * @return the search engine implementation name
+     */
+    public String getEngine()
+    {
+        return engine;
+    }
+
     /**
      * Creates an Elasticsearch client applying parameters from properties file
      *
@@ -460,6 +473,11 @@ public class ElasticsearchHttpClientFactory
         this.host = host;
     }
 
+    public void setEngine(String engine)
+    {
+        this.engine = engine;
+    }
+
     public void setBaseUrl(String baseUrl)
     {
         this.baseUrl = baseUrl;

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/contentmodelsync/ElasticsearchInitialiser.java

@@ -46,6 +46,7 @@ import org.alfresco.repo.dictionary.DictionaryListener;
 import org.alfresco.repo.lock.JobLockService;
 import org.alfresco.repo.lock.JobLockService.JobLockRefreshCallback;
 import org.alfresco.repo.lock.LockAcquisitionException;
+import org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector;
 import org.alfresco.service.cmr.dictionary.PropertyDefinition;
 import org.alfresco.service.namespace.NamespaceService;
 import org.alfresco.service.namespace.QName;
@@ -92,10 +93,11 @@ public class ElasticsearchInitialiser implements DictionaryListener
     private final Set<QName> modelCache = new HashSet<>();
     // This counter will be used during the map model execution
     private final AtomicInteger globalModelInitialisedCounter = new AtomicInteger(0);
+    private SearchEngineDetector searchEngineDetector;
 
     public ElasticsearchInitialiser(DictionaryDAOImpl dictionary, ElasticsearchIndexService elasticsearchIndexService,
             ContentModelSynchronizer contentModelSynchronizer, JobLockService jobLockService, int retryAttempts, int retryPeriodSeconds,
-            int lockRetryAttempts, int lockRetryPeriodSeconds, boolean createIndexIfNotExists)
+            int lockRetryAttempts, int lockRetryPeriodSeconds, boolean createIndexIfNotExists, SearchEngineDetector searchEngineDetector)
     {
         this.dictionaryDAO = dictionary;
         this.dictionaryDAO.registerListener(this);
@@ -107,6 +109,7 @@ public class ElasticsearchInitialiser implements DictionaryListener
         this.lockRetryPeriodSeconds = lockRetryPeriodSeconds;
         this.createIndexIfNotExists = createIndexIfNotExists;
         this.elasticsearchIndexService = elasticsearchIndexService;
+        this.searchEngineDetector = searchEngineDetector;
     }
 
     public ElasticsearchInitialiser()
@@ -263,6 +266,11 @@ public class ElasticsearchInitialiser implements DictionaryListener
             }
         }
         LOGGER.info("Successfully connected to Elasticsearch index.");
+
+        if (!isTerminated.get() && searchEngineDetector != null)
+        {
+            searchEngineDetector.detectAndStore();
+        }
         // Attempt to map the models.
         mapModels();
     }

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/query/SearchRequestBuilderService.java

@@ -95,19 +95,9 @@ public class SearchRequestBuilderService
             int size,
             String indexName)
     {
-        int trackTotalHitsLimit = DEFAULT_TRACK_TOTAL_HITS_UP_TO;
-        if (searchParameters.getTrackTotalHits() == -1 || searchParameters.getTrackTotalHits() >= TRACK_TOTAL_HITS_ACCURATE)
-        {
-            trackTotalHitsLimit = TRACK_TOTAL_HITS_ACCURATE;
-        }
-        else if (searchParameters.getTrackTotalHits() > 0)
-        {
-            trackTotalHitsLimit = searchParameters.getTrackTotalHits();
-        }
-
         SearchRequestWrapper.Builder wrapperBuilder = SearchRequestWrapper.builder();
         SearchRequest.Builder builder = baseBuilder(queryWithPermissions)
-                .trackTotalHits(new TrackHits.Builder().count(trackTotalHitsLimit).build())
+                .trackTotalHits(new TrackHits.Builder().count(resolveTrackTotalHitsLimit(searchParameters)).build())
                 .from(from)
                 .size(size);
 
@@ -148,6 +138,19 @@ public class SearchRequestBuilderService
 
     // Previous unified method with boolean flag removed. Update callers accordingly.
 
+    private int resolveTrackTotalHitsLimit(SearchParameters searchParameters)
+    {
+        if (searchParameters.getTrackTotalHits() == -1)
+        {
+            return TRACK_TOTAL_HITS_ACCURATE;
+        }
+        if (searchParameters.getTrackTotalHits() > 0)
+        {
+            return searchParameters.getTrackTotalHits();
+        }
+        return DEFAULT_TRACK_TOTAL_HITS_UP_TO;
+    }
+
     private SearchRequest.Builder baseBuilder(Query queryWithPermissions)
     {
         return new SearchRequest.Builder()

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/query/SearchStrategySelector.java

@@ -39,7 +39,8 @@ public class SearchStrategySelector implements SearchStrategy
     private final SearchStrategy scrollStrategy;
     private final int maxResultWindow;
 
-    public SearchStrategySelector(SearchExecutionStrategy standardStrategy, SearchExecutionStrategy scrollStrategy, int maxResultWindow)
+    public SearchStrategySelector(SearchExecutionStrategy standardStrategy, SearchExecutionStrategy scrollStrategy,
+            int maxResultWindow)
     {
         this.standardStrategy = standardStrategy;
         this.scrollStrategy = scrollStrategy;

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/resultset/ElasticsearchResultSet.java

@@ -65,11 +65,13 @@ public class ElasticsearchResultSet implements SearchEngineResultSet
     private final Map<String, Integer> facetQueries;
     private final Map<String, List<Pair<String, Integer>>> fieldFacets;
     private final Map<NodeRef, List<Pair<String, List<String>>>> highlights;
+    private final String nextSearchAfterToken;
+    private final Boolean explicitHasMore;
 
     public ElasticsearchResultSet(NodeService nodeService, List<NodeRefAndScore> nodeRefAndScores, SimpleResultSetMetaData resultSetMetaData,
             SpellCheckResult spellCheckResult, long queryTime, long numFound, int start,
             Map<String, Integer> facetQueries, Map<String, List<Pair<String, Integer>>> fieldFacets,
-            Map<NodeRef, List<Pair<String, List<String>>>> highlights)
+            Map<NodeRef, List<Pair<String, List<String>>>> highlights, String nextSearchAfterToken, Boolean explicitHasMore)
     {
         this.nodeService = nodeService;
         this.nodeRefAndScores = nodeRefAndScores;
@@ -81,6 +83,8 @@ public class ElasticsearchResultSet implements SearchEngineResultSet
         this.facetQueries = facetQueries;
         this.fieldFacets = fieldFacets;
         this.highlights = highlights;
+        this.nextSearchAfterToken = nextSearchAfterToken;
+        this.explicitHasMore = explicitHasMore;
     }
 
     @Override
@@ -154,9 +158,19 @@ public class ElasticsearchResultSet implements SearchEngineResultSet
         return start;
     }
 
+    @Override
+    public String getNextSearchAfterToken()
+    {
+        return nextSearchAfterToken;
+    }
+
     @Override
     public boolean hasMore()
     {
+        if (explicitHasMore != null)
+        {
+            return explicitHasMore;
+        }
         return getNumberFound() > (getStart() + length());
     }
 

repository/src/main/java/org/alfresco/repo/search/impl/elasticsearch/resultset/ElasticsearchResultSetBuilder.java

@@ -63,8 +63,24 @@ public class ElasticsearchResultSetBuilder
         this.aggregationHandler = aggregationHandler;
     }
 
+    public ElasticsearchResultSet build(SearchParameters searchParameters, SearchResponse<Object> searchResponse)
+    {
+        return build(searchParameters, searchResponse, null, false, Map.of(), Map.of());
+    }
+
     public ElasticsearchResultSet build(SearchParameters searchParameters, SearchResponse<Object> searchResponse, Map<String, String> bucketsTranslator,
             Map<String, Pair<String, String>> complementaryBucketsTranslator)
+    {
+        return build(searchParameters, searchResponse, null, false, bucketsTranslator, complementaryBucketsTranslator);
+    }
+
+    public ElasticsearchResultSet build(SearchParameters searchParameters, SearchResponse<Object> searchResponse, String nextSearchAfterToken)
+    {
+        return build(searchParameters, searchResponse, nextSearchAfterToken, true, Map.of(), Map.of());
+    }
+
+    private ElasticsearchResultSet build(SearchParameters searchParameters, SearchResponse<Object> searchResponse, String nextSearchAfterToken,
+            boolean searchAfterMode, Map<String, String> bucketsTranslator, Map<String, Pair<String, String>> complementaryBucketsTranslator)
     {
         var hits = ofNullable(searchResponse.hits()).map(HitsMetadata::hits).orElse(List.of());
         List<NodeRefAndScore> nodeRefAndScores = mapNodeRefsAndScores(hits, searchParameters.isBulkFetchEnabled());
@@ -80,6 +96,11 @@ public class ElasticsearchResultSetBuilder
         Map<String, Integer> facetQueries = aggregation.facetQueries();
         Map<String, List<Pair<String, Integer>>> fieldFacets = aggregation.fieldFacets();
         Map<NodeRef, List<Pair<String, List<String>>>> highlights = highlightsHandler.handle(searchParameters, searchResponse);
+        Boolean explicitHasMore = null;
+        if (searchAfterMode)
+        {
+            explicitHasMore = nextSearchAfterToken != null;
+        }
         return new ElasticsearchResultSet(
                 nodeService,
                 nodeRefAndScores,
@@ -90,7 +111,9 @@ public class ElasticsearchResultSetBuilder
                 start,
                 facetQueries,
                 fieldFacets,
-                highlights);
+                highlights,
+                nextSearchAfterToken,
+                explicitHasMore);
     }
 
     public ElasticsearchResultSet build(SearchParameters searchParameters, List<Hit<Object>> hits, long totalHits, long queryTime)
@@ -112,7 +135,9 @@ public class ElasticsearchResultSetBuilder
                 start,
                 Map.of(),
                 Map.of(),
-                Map.of());
+                Map.of(),
+                null,
+                null);
     }
 
     private List<NodeRefAndScore> mapNodeRefsAndScores(List<Hit<Object>> hits, boolean isBulkFetchEnabled)

repository/src/main/resources/alfresco/subsystems/Search/elasticsearch/elasticsearch-community-context.xml

@@ -89,6 +89,14 @@
         <constructor-arg value="${elasticsearch.lockRetryAttempts}" />
         <constructor-arg value="${elasticsearch.lockRetryPeriodSeconds}" />
         <constructor-arg value="${elasticsearch.createIndexIfNotExists}" />
+        <constructor-arg ref="searchEngineDetector"/>
+    </bean>
+
+    <bean id="searchEngineDetector"
+          class="org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector">
+        <property name="httpClientFactory"  ref="elasticsearchHttpClientFactory"/>
+        <property name="attributeService"   ref="AttributeService"/>
+        <property name="transactionService" ref="TransactionService"/>
     </bean>
 
     <bean id="elasticsearchIndexService"

repository/src/main/resources/alfresco/subsystems/Search/elasticsearch/elasticsearch.properties

@@ -77,6 +77,8 @@ elasticsearch.index.mapping.total_fields.limit=7500
 elasticsearch.index.max_result_window=10000
 elasticsearch.scroll.api_time=10s
 elasticsearch.scroll.batch_size=100
+# How long a search_after Point-In-Time is kept alive between deep-pagination pages. Refreshed on every page while the client is actively paging
+elasticsearch.searchafter.keep_alive=1m
 
 # Maximum numbers of facets that can be returned by a single query
 elasticsearch.defaultFacetLimit=100

repository/src/test/java/org/alfresco/AllUnitTestsSuite.java

@@ -292,6 +292,7 @@ import org.alfresco.util.testing.category.NonBuildTests;
 
         // Elasticsearch unit tests
         org.alfresco.repo.search.impl.elasticsearch.admin.ElasticsearchDocumentsServiceTest.class,
+        org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetectorTest.class,
         org.alfresco.repo.search.impl.elasticsearch.client.ElasticsearchHttpClientFactoryTest.class,
         org.alfresco.repo.search.impl.elasticsearch.ElasticsearchSearchServiceTest.class,
         org.alfresco.repo.search.impl.elasticsearch.ElasticsearchCategoryServiceTest.class,

repository/src/test/java/org/alfresco/repo/search/impl/elasticsearch/ElasticsearchSpringTest.java

@@ -37,6 +37,7 @@ import org.springframework.context.ApplicationContext;
 import org.alfresco.repo.dictionary.DictionaryDAOImpl;
 import org.alfresco.repo.lock.JobLockService;
 import org.alfresco.repo.management.subsystems.SwitchableApplicationContextFactory;
+import org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector;
 import org.alfresco.repo.search.impl.elasticsearch.client.ElasticsearchHttpClientFactory;
 import org.alfresco.repo.search.impl.elasticsearch.contentmodelsync.ContentModelSynchronizer;
 import org.alfresco.repo.search.impl.elasticsearch.contentmodelsync.ElasticsearchIndexService;
@@ -78,7 +79,7 @@ public abstract class ElasticsearchSpringTest extends BaseSpringTest
         baseElasticsearchIndexService = new ElasticsearchIndexService(elasticsearchHttpClientFactory, 2000, 10000);
 
         baseElasticsearchInitialiser = new ElasticsearchInitialiser(dictionaryDAOImpl, baseElasticsearchIndexService, contentModelSynchronizer,
-                jobLockService, 1, 1, 1, 1, true);
+                jobLockService, 1, 1, 1, 1, true, new SearchEngineDetector());
     }
 
     /** Get the name of the index. */

repository/src/test/java/org/alfresco/repo/search/impl/elasticsearch/admin/SearchEngineDetectorTest.java

@@ -0,0 +1,258 @@
+/*
+ * #%L
+ * Alfresco Repository
+ * %%
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
+ * %%
+ * This file is part of the Alfresco software.
+ * If the software was purchased under a paid Alfresco license, the terms of
+ * the paid license agreement will prevail.  Otherwise, the software is
+ * provided under the following open source license terms:
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ * #L%
+ */
+package org.alfresco.repo.search.impl.elasticsearch.admin;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.lenient;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+import static org.mockito.Mockito.when;
+import static org.mockito.MockitoAnnotations.openMocks;
+
+import static org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector.ATTR_ROOT;
+import static org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector.ATTR_SEARCH_ENGINE_NAME;
+import static org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector.ATTR_SEARCH_ENGINE_VERSION;
+
+import java.io.IOException;
+import java.util.Optional;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockedStatic;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch.generic.Body;
+import org.opensearch.client.opensearch.generic.OpenSearchGenericClient;
+import org.opensearch.client.opensearch.generic.Request;
+import org.opensearch.client.opensearch.generic.Response;
+
+import org.alfresco.repo.search.impl.elasticsearch.client.ElasticsearchHttpClientFactory;
+import org.alfresco.repo.security.authentication.AuthenticationUtil;
+import org.alfresco.repo.security.authentication.AuthenticationUtil.RunAsWork;
+import org.alfresco.repo.transaction.RetryingTransactionHelper;
+import org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransactionCallback;
+import org.alfresco.service.cmr.attributes.AttributeService;
+import org.alfresco.service.transaction.TransactionService;
+
+/**
+ * Unit tests for {@link SearchEngineDetector}.
+ * <p>
+ * The search engine root endpoint ({@code GET /}) is mocked at the OpenSearch generic-client level so the provider/version detection and the {@link AttributeService} persistence can be verified without a running Elasticsearch/OpenSearch instance.
+ */
+public class SearchEngineDetectorTest
+{
+    private static final String SYSTEM_USER = "System";
+
+    private static final String ES_BODY = "{"
+            + "\"name\":\"node-1\",\"cluster_name\":\"docker-cluster\","
+            + "\"version\":{\"number\":\"8.17.0\",\"build_flavor\":\"default\"},"
+            + "\"tagline\":\"You Know, for Search\"}";
+
+    private static final String OS_BODY = "{"
+            + "\"name\":\"node-1\",\"cluster_name\":\"docker-cluster\","
+            + "\"version\":{\"distribution\":\"opensearch\",\"number\":\"2.17.0\"},"
+            + "\"tagline\":\"The OpenSearch Project: https://opensearch.org/\"}";
+
+    private static final String UNKNOWN_BODY = "{"
+            + "\"version\":{\"number\":\"1.2.3\"},"
+            + "\"tagline\":\"Some other search engine\"}";
+
+    @Mock
+    private ElasticsearchHttpClientFactory httpClientFactory;
+    @Mock
+    private AttributeService attributeService;
+    @Mock
+    private TransactionService transactionService;
+    @Mock
+    private RetryingTransactionHelper txnHelper;
+    @Mock
+    private OpenSearchClient openSearchClient;
+    @Mock
+    private OpenSearchGenericClient genericClient;
+    @Mock
+    private Response response;
+    @Mock
+    private Body body;
+
+    private AutoCloseable mocks;
+    private MockedStatic<AuthenticationUtil> authUtil;
+
+    private SearchEngineDetector detector;
+
+    @Before
+    public void setUp()
+    {
+        mocks = openMocks(this);
+
+        // Run the "run as system" work and the transactional work inline so the persistence can be verified.
+        authUtil = mockStatic(AuthenticationUtil.class);
+        authUtil.when(AuthenticationUtil::getSystemUserName).thenReturn(SYSTEM_USER);
+        authUtil.when(() -> AuthenticationUtil.runAs(any(), any()))
+                .thenAnswer(call -> ((RunAsWork<?>) call.getArgument(0)).doWork());
+
+        lenient().when(transactionService.getRetryingTransactionHelper()).thenReturn(txnHelper);
+        lenient().when(txnHelper.doInTransaction(any(), anyBoolean(), anyBoolean()))
+                .thenAnswer(call -> ((RetryingTransactionCallback<?>) call.getArgument(0)).execute());
+
+        detector = new SearchEngineDetector();
+        detector.setHttpClientFactory(httpClientFactory);
+        detector.setAttributeService(attributeService);
+        detector.setTransactionService(transactionService);
+    }
+
+    @After
+    public void tearDown() throws Exception
+    {
+        authUtil.close();
+        mocks.close();
+    }
+
+    @Test
+    public void shouldStoreElasticsearchProviderAndVersion() throws Exception
+    {
+        givenRootBody(ES_BODY);
+
+        detector.detectAndStore();
+
+        verify(attributeService).setAttribute(eq("elasticsearch"), eq(ATTR_ROOT), eq(ATTR_SEARCH_ENGINE_NAME));
+        verify(attributeService).setAttribute(eq("8.17.0"), eq(ATTR_ROOT), eq(ATTR_SEARCH_ENGINE_VERSION));
+    }
+
+    @Test
+    public void shouldStoreOpenSearchProviderAndVersion() throws Exception
+    {
+        givenRootBody(OS_BODY);
+
+        detector.detectAndStore();
+
+        verify(attributeService).setAttribute(eq("opensearch"), eq(ATTR_ROOT), eq(ATTR_SEARCH_ENGINE_NAME));
+        verify(attributeService).setAttribute(eq("2.17.0"), eq(ATTR_ROOT), eq(ATTR_SEARCH_ENGINE_VERSION));
+    }
+
+    @Test
+    public void shouldStoreUnknownWhenTaglineNotRecognised() throws Exception
+    {
+        givenRootBody(UNKNOWN_BODY);
+
+        detector.detectAndStore();
+
+        verify(attributeService).setAttribute(eq("unknown"), eq(ATTR_ROOT), eq(ATTR_SEARCH_ENGINE_NAME));
+        verify(attributeService).setAttribute(eq("1.2.3"), eq(ATTR_ROOT), eq(ATTR_SEARCH_ENGINE_VERSION));
+    }
+
+    @Test
+    public void shouldMatchTaglineCaseInsensitively() throws Exception
+    {
+        givenRootBody("{\"version\":{\"number\":\"8.1.0\"},\"tagline\":\"YOU KNOW, FOR SEARCH\"}");
+
+        detector.detectAndStore();
+
+        verify(attributeService).setAttribute(eq("elasticsearch"), eq(ATTR_ROOT), eq(ATTR_SEARCH_ENGINE_NAME));
+    }
+
+    @Test
+    public void shouldPersistAsSystemUserInWritableRequiresNewTransaction() throws Exception
+    {
+        givenRootBody(ES_BODY);
+
+        detector.detectAndStore();
+
+        authUtil.verify(() -> AuthenticationUtil.runAs(any(RunAsWork.class), eq(SYSTEM_USER)));
+        verify(txnHelper).setForceWritable(true);
+        // readOnly = false, requiresNew = true
+        verify(txnHelper).doInTransaction(any(RetryingTransactionCallback.class), eq(false), eq(true));
+    }
+
+    @Test
+    public void shouldNotStoreWhenBodyIsEmpty() throws Exception
+    {
+        givenClientChain();
+        when(response.getBody()).thenReturn(Optional.empty());
+
+        detector.detectAndStore();
+
+        verifyNoInteractions(attributeService);
+    }
+
+    @Test
+    public void shouldNotStoreWhenBodyIsMalformedJson() throws Exception
+    {
+        givenRootBody("this is not json");
+
+        detector.detectAndStore();
+
+        verifyNoInteractions(attributeService);
+    }
+
+    @Test
+    public void shouldNotStoreWhenVersionIsMissing() throws Exception
+    {
+        givenRootBody("{\"tagline\":\"You Know, for Search\"}");
+
+        detector.detectAndStore();
+
+        verifyNoInteractions(attributeService);
+    }
+
+    @Test
+    public void shouldNotStoreWhenTaglineIsMissing() throws Exception
+    {
+        givenRootBody("{\"version\":{\"number\":\"8.17.0\"}}");
+
+        detector.detectAndStore();
+
+        verifyNoInteractions(attributeService);
+    }
+
+    @Test
+    public void shouldNotStoreAndNotThrowWhenClientFails() throws Exception
+    {
+        givenClientChain();
+        when(genericClient.execute(any(Request.class))).thenThrow(new IOException("engine unreachable"));
+
+        detector.detectAndStore();
+
+        verifyNoInteractions(attributeService);
+    }
+
+    private void givenClientChain()
+    {
+        when(httpClientFactory.getElasticsearchClient()).thenReturn(openSearchClient);
+        when(openSearchClient.generic()).thenReturn(genericClient);
+    }
+
+    private void givenRootBody(String rawJson) throws IOException
+    {
+        givenClientChain();
+        when(genericClient.execute(any(Request.class))).thenReturn(response);
+        when(response.getBody()).thenReturn(Optional.of(body));
+        when(body.bodyAsString()).thenReturn(rawJson);
+    }
+}

repository/src/test/java/org/alfresco/repo/search/impl/elasticsearch/contentmodelsync/ElasticsearchInitialiserIT.java

@@ -65,6 +65,7 @@ import org.opensearch.client.opensearch.indices.PutMappingRequest;
 import org.alfresco.repo.dictionary.DictionaryDAOImpl;
 import org.alfresco.repo.lock.JobLockService;
 import org.alfresco.repo.search.impl.elasticsearch.ElasticsearchSpringTest;
+import org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector;
 import org.alfresco.repo.search.impl.elasticsearch.client.ElasticsearchHttpClientFactory;
 import org.alfresco.repo.search.impl.elasticsearch.util.LogListAppender;
 
@@ -102,7 +103,7 @@ public class ElasticsearchInitialiserIT extends ElasticsearchSpringTest
                 fieldMappingBuilder, elasticsearchHttpClientFactory, Locale.ENGLISH.getLanguage(), indexConfigurationInitializer);
 
         toTest = new ElasticsearchInitialiser(dictionaryDAOImpl, elasticSearchIndexServiceSpy, contentModelSynchronizer,
-                jobLockService, 1, 1, 1, 1, true);
+                jobLockService, 1, 1, 1, 1, true, new SearchEngineDetector());
         client = elasticsearchHttpClientFactory.getElasticsearchClient();
         this.indicesSpy = spy(client.indices());
     }

repository/src/test/java/org/alfresco/repo/search/impl/elasticsearch/contentmodelsync/ElasticsearchInitialiserTest.java

@@ -62,6 +62,7 @@ import org.alfresco.repo.dictionary.CompiledModel;
 import org.alfresco.repo.dictionary.DictionaryDAOImpl;
 import org.alfresco.repo.lock.JobLockService;
 import org.alfresco.repo.lock.LockAcquisitionException;
+import org.alfresco.repo.search.impl.elasticsearch.admin.SearchEngineDetector;
 import org.alfresco.service.namespace.QName;
 import org.alfresco.util.GUID;
 
@@ -386,10 +387,10 @@ public class ElasticsearchInitialiserTest
         when(secondElasticsearchIndexService.createIndex()).thenReturn(true);
 
         ElasticsearchInitialiser elasticsearchInitialiser = new ElasticsearchInitialiser(mockDictionary,
-                mockElasticSearchIndexService, mockContentModelSynchronizer, jobLockService, 0, 0, 3, 0, true);
+                mockElasticSearchIndexService, mockContentModelSynchronizer, jobLockService, 0, 0, 3, 0, true, new SearchEngineDetector());
 
         ElasticsearchInitialiser secondElasticsearchInitialiser = new ElasticsearchInitialiser(mockDictionary,
-                secondElasticsearchIndexService, secondContentModelSynchronizer, jobLockService, 0, 0, 3, 0, true);
+                secondElasticsearchIndexService, secondContentModelSynchronizer, jobLockService, 0, 0, 3, 0, true, new SearchEngineDetector());
 
         Thread thread1 = new Thread(() -> elasticsearchInitialiser.initWithLock());
         thread1.start();

repository/src/test/java/org/alfresco/repo/search/impl/elasticsearch/resultset/ElasticsearchResultSetBuilderTest.java

@@ -281,6 +281,64 @@ public class ElasticsearchResultSetBuilderTest
                 .anyMatch(pair -> "field1".equals(pair.getFirst())));
     }
 
+    @Test
+    public void testBuild_searchAfterNotLastPage_hasMoreIsTrue()
+    {
+        // Given: a search_after page with a non-null nextSearchAfterToken (more pages remain),
+        // and skipCount is 0 as always the case for search_after cursor paging.
+        List<Hit<Object>> hits = createHitsList(
+                createHit(TEST_NODE_ID_1, TEST_SCORE_1),
+                createHit(TEST_NODE_ID_2, TEST_SCORE_2));
+        setupSearchResponse(hits);
+        setupNodeExistence(true, true);
+        setupAggregationAndHighlights();
+
+        // When
+        ElasticsearchResultSet result = builder.build(searchParameters, searchResponse, "opaque-cursor-token");
+
+        // Then
+        assertTrue("hasMore should be true when a nextSearchAfterToken is present", result.hasMore());
+    }
+
+    @Test
+    public void testBuild_searchAfterLastPage_hasMoreIsFalse()
+    {
+        // Given: a search_after page with a null nextSearchAfterToken (last page).
+        // Without the fix, hasMore() would incorrectly return true here because
+        // getNumberFound() (TEST_TOTAL_HITS=3) > getStart()+length() (0+1) for search_after,
+        // since skipCount always stays 0 across search_after pages.
+        List<Hit<Object>> hits = createHitsList(createHit(TEST_NODE_ID_1, TEST_SCORE_1));
+        setupSearchResponse(hits);
+        setupNodeExistence(true);
+        setupAggregationAndHighlights();
+
+        // When
+        ElasticsearchResultSet result = builder.build(searchParameters, searchResponse, null);
+
+        // Then
+        assertTrue("hasMore should be false on the last search_after page", !result.hasMore());
+    }
+
+    @Test
+    public void testBuild_standardSearch_hasMoreUsesStartPlusLength()
+    {
+        // Given: a standard (non search_after) search where all TEST_TOTAL_HITS (3) results
+        // are returned in one page starting at skipCount 0, so there is nothing more to fetch.
+        List<Hit<Object>> hits = createHitsList(
+                createHit(TEST_NODE_ID_1, TEST_SCORE_1),
+                createHit(TEST_NODE_ID_2, TEST_SCORE_2),
+                createHit(TEST_NODE_ID_3, TEST_SCORE_3));
+        setupSearchResponse(hits);
+        setupNodeExistence(true, true, true);
+        setupAggregationAndHighlights();
+
+        // When
+        ElasticsearchResultSet result = builder.build(searchParameters, searchResponse);
+
+        // Then
+        assertTrue("hasMore should be false when all results were returned in this page", !result.hasMore());
+    }
+
     @Test
     public void testBuildWithHitsList_doesNotIncludeAggregationsOrHighlights()
     {