Index each API operation's words, group and id word count for search

src/Elastic.ApiExplorer/Export/ApiSearchWords.cs

@@ -27,4 +27,6 @@ .. path
 				.Select(word => word.ToLowerInvariant())
 				.Distinct(StringComparer.Ordinal)
 		];
+
+	internal static string[] OfOperationId(string operationId) => Of(operationId, string.Empty);
 }

src/Elastic.ApiExplorer/Export/OpenApiDocumentExporter.cs

@@ -167,7 +167,10 @@ public IEnumerable<DocumentationDocument> ConvertToDocuments(OpenApiDocument ope
 					Method = method,
 					Path = path.Key,
 					OperationId = operationId,
-					Deprecated = operation.Value.Deprecated
+					Deprecated = operation.Value.Deprecated,
+					Words = ApiSearchWords.Of(operationId, path.Key),
+					Group = groupParent?.Title ?? "",
+					IdWords = ApiSearchWords.OfOperationId(operationId).Length
 				};
 
 				yield return new DocumentationDocument

src/services/search/Elastic.Documentation.Search.Contract/Docs/ApiOperationMetadata.cs

@@ -46,6 +46,28 @@ public record ApiOperationMetadata
 	[JsonPropertyName("operation_id")]
 	public required string OperationId { get; init; }
 
+	/// <summary>
+	/// Plain lowercase words of the operation id and its literal path segments, e.g. <c>cluster health</c>.
+	/// A typed <c>cluster</c> or <c>esql</c> names an operation by these words, which otherwise live only
+	/// concatenated into <c>search_title</c>.
+	/// </summary>
+	[Text]
+	[JsonPropertyName("words")]
+	public string[] Words { get; init; } = [];
+
+	/// <summary>Title of the operation's group as the explorer shows it, e.g. <c>ES|QL</c>. Empty without a group.</summary>
+	[Text]
+	[JsonPropertyName("group")]
+	public string Group { get; init; } = "";
+
+	/// <summary>
+	/// Number of words in the operation id alone, e.g. 2 for <c>cluster.health</c>. Mapped as
+	/// <c>rank_feature</c> with negative score impact. Fewer id words is a more specific operation,
+	/// so ties break toward <c>esql-query</c> over <c>esql-async-query-stop</c>.
+	/// </summary>
+	[JsonPropertyName("id_words")]
+	public int IdWords { get; init; }
+
 	/// <summary>Whether the spec marks the operation deprecated.</summary>
 	[Boolean]
 	[JsonPropertyName("deprecated")]

src/services/search/Elastic.Documentation.Search.Contract/Docs/DocumentationMappingExtensions.cs

@@ -30,5 +30,24 @@ public static MappingsBuilder<DocumentationDocument> AddDocumentationMappings(th
 			.AddProperty("applies_to.sub_type", f => f.Keyword().Normalizer(SharedMappingConfig.KeywordNormalizer))
 			.AddProperty("applies_to.lifecycle", f => f.Keyword().Normalizer(SharedMappingConfig.KeywordNormalizer))
 			.AddProperty("applies_to.version", f => f.Version())
-			.AddProperty("api.properties.path", f => f.Keyword().MultiField("match", mf => mf.Text()));
+			.AddProperty("api.properties.path", f => f.Keyword().MultiField("match", mf => mf.Text()))
+			.AddProperty(
+				"api.words",
+				f => f
+					.Text()
+					.Analyzer(SharedMappingConfig.SynonymsFixedAnalyzer)
+					.SearchAnalyzer(SharedMappingConfig.SynonymsAnalyzer)
+					.MultiField(
+						"completion",
+						mf => mf
+							.SearchAsYouType()
+							.Analyzer(SharedMappingConfig.SynonymsFixedAnalyzer)
+							.SearchAnalyzer(SharedMappingConfig.SynonymsAnalyzer)
+					)
+			)
+			.AddProperty(
+				"api.group",
+				f => f.Text().Analyzer(SharedMappingConfig.SynonymsFixedAnalyzer).SearchAnalyzer(SharedMappingConfig.SynonymsAnalyzer)
+			)
+			.AddProperty("api.id_words", f => f.RankFeature().PositiveScoreImpact(false));
 }

tests/Elastic.ApiExplorer.Tests/ApiSearchWordsTests.cs

@@ -17,4 +17,11 @@ public class ApiSearchWordsTests
 	[Arguments("_bulk", "/_bulk", "bulk")]
 	public void Of_OperationIdAndPath_ReturnsLowercaseDistinctWords(string operationId, string path, string words) =>
 		string.Join(' ', ApiSearchWords.Of(operationId, path)).Should().Be(words);
+
+	[Test]
+	[Arguments("cluster.health", "cluster health")]
+	[Arguments("esql-async-query-stop", "esql async query stop")]
+	[Arguments("_bulk", "bulk")]
+	public void OfOperationId_OperationId_ReturnsIdWordsOnly(string operationId, string words) =>
+		string.Join(' ', ApiSearchWords.OfOperationId(operationId)).Should().Be(words);
 }

tests/Elastic.ApiExplorer.Tests/OpenApiOperationIdSearchTitleTests.cs

@@ -182,9 +182,15 @@ public async Task ConvertToDocuments_TaggedOperations_IndexGroupAndWordsInSearch
 				o => o.WithStrictOrdering()
 			);
 		flush.Api!.Deprecated.Should().BeFalse();
+		flush.Api.Words.Should().Equal("ml", "flush", "job", "anomaly", "detectors");
+		flush.Api.Group.Should().Be("Machine learning anomaly detection");
+		flush.Api.IdWords.Should().Be(3);
 		docs["ml-close-job"].Api!.Deprecated.Should().BeTrue();
 		var bulk = docs["_bulk"];
 		bulk.SearchTitle.Should().Be("Bulk index or delete documents - Elasticsearch API - _bulk - PUT /_bulk - bulk");
+		bulk.Api!.Words.Should().Equal("bulk");
+		bulk.Api.Group.Should().Be("");
+		bulk.Api.IdWords.Should().Be(1);
 		bulk
 			.Parents
 			.Should()

tests/Elastic.Documentation.Api.Tests/ApiPropertySearchTests.cs

@@ -193,7 +193,7 @@
 			.Should()
 			.Be("knn", "the endpoint is required, so the children lift is the reading's only should");
 		readings.EnumerateArray().Should().AllSatisfy(r => r.GetProperty("bool").TryGetProperty("_name", out _).Should().BeTrue());
 		var names = System
 			.Text
 			.RegularExpressions
 			.Regex
@@ -303,17 +303,44 @@
 	[Test]
 	[Arguments(false)]
 	[Arguments(true)]
-	public void Mapping_ApiDeprecated_IsBooleanWithoutGroup(bool semantic)
+	public void Mapping_ApiDeprecated_IsBoolean(bool semantic)
 	{
-		var context = semantic
-			? DocumentationMappingContext.DocumentationDocumentSemantic.CreateContext(type: "assembler", env: "test")
-			: DocumentationMappingContext.DocumentationDocument.CreateContext(type: "assembler", env: "test");
-		using var json = JsonDocument.Parse(context.GetMappingsJson());
-		var api = json.RootElement.GetProperty("properties").GetProperty("api").GetProperty("properties");
-		api.TryGetProperty("group", out _).Should().BeFalse();
+		var api = ApiMapping(semantic);
 		api.GetProperty("deprecated").GetProperty("type").GetString().Should().Be("boolean");
 	}
 
+	[Test]
+	[Arguments(false)]
+	[Arguments(true)]
+	public void Mapping_ApiWordsAndGroup_AreSynonymText(bool semantic)
+	{
+		var api = ApiMapping(semantic);
+		var words = api.GetProperty("words");
+		words.GetProperty("type").GetString().Should().Be("text");
+		words.GetProperty("analyzer").GetString().Should().Be("synonyms_fixed_analyzer");
+		words.GetProperty("search_analyzer").GetString().Should().Be("synonyms_analyzer");
+		var completion = words.GetProperty("fields").GetProperty("completion");
+		completion.GetProperty("type").GetString().Should().Be("search_as_you_type");
+		completion.GetProperty("analyzer").GetString().Should().Be("synonyms_fixed_analyzer");
+		completion.GetProperty("search_analyzer").GetString().Should().Be("synonyms_analyzer");
+		completion.TryGetProperty("index_options", out _).Should().BeFalse();
+
+		var group = api.GetProperty("group");
+		group.GetProperty("type").GetString().Should().Be("text");
+		group.GetProperty("analyzer").GetString().Should().Be("synonyms_fixed_analyzer");
+		group.GetProperty("search_analyzer").GetString().Should().Be("synonyms_analyzer");
+	}
+
+	[Test]
+	[Arguments(false)]
+	[Arguments(true)]
+	public void Mapping_ApiIdWords_IsRankFeatureWithNegativeImpact(bool semantic)
+	{
+		var idWords = ApiMapping(semantic).GetProperty("id_words");
+		idWords.GetProperty("type").GetString().Should().Be("rank_feature");
+		idWords.GetProperty("positive_score_impact").GetBoolean().Should().BeFalse();
+	}
+
 	[Test]
 	[Arguments(false)]
 	[Arguments(true)]
@@ -768,4 +795,13 @@
 
 		result.Properties.Should().ContainSingle().Which.Anchor.Should().Be("req-track_total_hits");
 	}
+
+	private static JsonElement ApiMapping(bool semantic)
+	{
+		var context = semantic
+			? DocumentationMappingContext.DocumentationDocumentSemantic.CreateContext(type: "assembler", env: "test")
+			: DocumentationMappingContext.DocumentationDocument.CreateContext(type: "assembler", env: "test");
+		using var json = JsonDocument.Parse(context.GetMappingsJson());
+		return json.RootElement.GetProperty("properties").GetProperty("api").GetProperty("properties").Clone();
+	}
 }