diff --git a/output/openapi/elasticsearch-serverless-openapi.json b/output/openapi/elasticsearch-serverless-openapi.json
index 9abc66cf84..4c9f29d771 100644
--- a/output/openapi/elasticsearch-serverless-openapi.json
+++ b/output/openapi/elasticsearch-serverless-openapi.json
@@ -262,6 +262,9 @@
           {
             "$ref": "#/components/parameters/async_search.submit-preference"
           },
+          {
+            "$ref": "#/components/parameters/async_search.submit-project_routing"
+          },
           {
             "$ref": "#/components/parameters/async_search.submit-request_cache"
           },
@@ -421,6 +424,9 @@
           {
             "$ref": "#/components/parameters/async_search.submit-preference"
           },
+          {
+            "$ref": "#/components/parameters/async_search.submit-project_routing"
+          },
           {
             "$ref": "#/components/parameters/async_search.submit-request_cache"
           },
@@ -23717,6 +23723,9 @@
           {
             "$ref": "#/components/parameters/search-pre_filter_shard_size"
           },
+          {
+            "$ref": "#/components/parameters/search-project_routing"
+          },
           {
             "$ref": "#/components/parameters/search-request_cache"
           },
@@ -23878,6 +23887,9 @@
           {
             "$ref": "#/components/parameters/search-pre_filter_shard_size"
           },
+          {
+            "$ref": "#/components/parameters/search-project_routing"
+          },
           {
             "$ref": "#/components/parameters/search-request_cache"
           },
@@ -24044,6 +24056,9 @@
           {
             "$ref": "#/components/parameters/search-pre_filter_shard_size"
           },
+          {
+            "$ref": "#/components/parameters/search-project_routing"
+          },
           {
             "$ref": "#/components/parameters/search-request_cache"
           },
@@ -24208,6 +24223,9 @@
           {
             "$ref": "#/components/parameters/search-pre_filter_shard_size"
           },
+          {
+            "$ref": "#/components/parameters/search-project_routing"
+          },
           {
             "$ref": "#/components/parameters/search-request_cache"
           },
@@ -35141,6 +35159,9 @@
           "none"
         ]
       },
+      "_types.ProjectRouting": {
+        "type": "string"
+      },
       "_types.SearchType": {
         "type": "string",
         "enum": [
@@ -82899,6 +82920,17 @@
         },
         "style": "form"
       },
+      "async_search.submit-project_routing": {
+        "in": "query",
+        "name": "project_routing",
+        "description": "Specifies a subset of projects to target for a search using project metadata\ntags in a subset Lucene syntax. Allowed Lucene queries: the _alias tag\nand a single value (possible wildcarded). Examples:\n _alias:my-project\n _alias:_origin\n _alias:*pr*\nSupported in serverless only.",
+        "deprecated": false,
+        "schema": {
+          "$ref": "#/components/schemas/_types.ProjectRouting"
+        },
+        "x-state": "Generally available",
+        "style": "form"
+      },
       "async_search.submit-request_cache": {
         "in": "query",
         "name": "request_cache",
@@ -87283,6 +87315,17 @@
         },
         "style": "form"
       },
+      "search-project_routing": {
+        "in": "query",
+        "name": "project_routing",
+        "description": "Specifies a subset of projects to target for a search using project metadata\ntags in a subset Lucene syntax. Allowed Lucene queries: the _alias tag\nand a single value (possible wildcarded). Examples:\n _alias:my-project\n _alias:_origin\n _alias:*pr*\nSupported in serverless only.",
+        "deprecated": false,
+        "schema": {
+          "$ref": "#/components/schemas/_types.ProjectRouting"
+        },
+        "x-state": "Generally available",
+        "style": "form"
+      },
       "search-request_cache": {
         "in": "query",
         "name": "request_cache",
diff --git a/output/schema/schema.json b/output/schema/schema.json
index f2fc92a22d..891c0d5084 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -38913,6 +38913,21 @@
             }
           }
         },
+        {
+          "availability": {
+            "serverless": {}
+          },
+          "description": "Specifies a subset of projects to target for a search using project metadata\ntags in a subset Lucene syntax. Allowed Lucene queries: the _alias tag\nand a single value (possible wildcarded). Examples:\n _alias:my-project\n _alias:_origin\n _alias:*pr*\nSupported in serverless only.",
+          "name": "project_routing",
+          "required": false,
+          "type": {
+            "kind": "instance_of",
+            "type": {
+              "name": "ProjectRouting",
+              "namespace": "_types"
+            }
+          }
+        },
         {
           "description": "If `true`, the caching of search results is enabled for requests where `size` is `0`.\nIt defaults to index level settings.",
           "extDocId": "shard-request-cache",
@@ -39292,7 +39307,7 @@
           }
         }
       ],
-      "specLocation": "_global/search/SearchRequest.ts#L53-L595"
+      "specLocation": "_global/search/SearchRequest.ts#L54-L607"
     },
     {
       "kind": "response",
@@ -50368,7 +50383,7 @@
         "name": "AggregateName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L142-L146",
+      "specLocation": "_types/common.ts#L144-L148",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -50566,7 +50581,7 @@
         "name": "ByteSize",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L90-L91",
+      "specLocation": "_types/common.ts#L92-L93",
       "type": {
         "kind": "union_of",
         "items": [
@@ -50619,7 +50634,7 @@
         "name": "Bytes",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L166-L178"
+      "specLocation": "_types/common.ts#L168-L180"
     },
     {
       "kind": "type_alias",
@@ -50642,7 +50657,7 @@
         "name": "ClusterAlias",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L72-L72",
+      "specLocation": "_types/common.ts#L74-L74",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -50762,7 +50777,7 @@
         "name": "ClusterInfoTarget",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L380-L386"
+      "specLocation": "_types/common.ts#L382-L388"
     },
     {
       "kind": "type_alias",
@@ -50770,7 +50785,7 @@
         "name": "ClusterInfoTargets",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L388-L388",
+      "specLocation": "_types/common.ts#L390-L390",
       "type": {
         "kind": "union_of",
         "items": [
@@ -50989,7 +51004,7 @@
         "name": "Conflicts",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L180-L189"
+      "specLocation": "_types/common.ts#L182-L191"
     },
     {
       "kind": "interface",
@@ -51120,7 +51135,7 @@
         "name": "DataStreamName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L86-L86",
+      "specLocation": "_types/common.ts#L88-L88",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -51135,7 +51150,7 @@
         "name": "DataStreamNames",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L88-L88",
+      "specLocation": "_types/common.ts#L90-L90",
       "type": {
         "kind": "union_of",
         "items": [
@@ -51596,7 +51611,7 @@
         "namespace": "_types"
       },
       "properties": [],
-      "specLocation": "_types/common.ts#L157-L158"
+      "specLocation": "_types/common.ts#L159-L160"
     },
     {
       "kind": "type_alias",
@@ -51805,7 +51820,7 @@
         "name": "ExpandWildcard",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L198-L212"
+      "specLocation": "_types/common.ts#L200-L214"
     },
     {
       "kind": "type_alias",
@@ -51813,7 +51828,7 @@
         "name": "ExpandWildcards",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L214-L214",
+      "specLocation": "_types/common.ts#L216-L216",
       "type": {
         "kind": "union_of",
         "items": [
@@ -51844,7 +51859,7 @@
         "name": "Field",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L135-L136",
+      "specLocation": "_types/common.ts#L137-L138",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -52165,7 +52180,7 @@
         "name": "Fields",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L137-L137",
+      "specLocation": "_types/common.ts#L139-L139",
       "type": {
         "kind": "union_of",
         "items": [
@@ -52260,7 +52275,7 @@
         "name": "Fuzziness",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L130-L131",
+      "specLocation": "_types/common.ts#L132-L133",
       "type": {
         "kind": "union_of",
         "items": [
@@ -52964,7 +52979,7 @@
         "name": "GrokPattern",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L81-L81",
+      "specLocation": "_types/common.ts#L83-L83",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -53008,7 +53023,7 @@
         "name": "HealthStatus",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L216-L238"
+      "specLocation": "_types/common.ts#L218-L240"
     },
     {
       "kind": "type_alias",
@@ -53031,7 +53046,7 @@
         "name": "HttpHeaders",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L155-L155",
+      "specLocation": "_types/common.ts#L157-L157",
       "type": {
         "kind": "dictionary_of",
         "key": {
@@ -53530,7 +53545,7 @@
           }
         }
       ],
-      "specLocation": "_types/common.ts#L334-L361"
+      "specLocation": "_types/common.ts#L336-L363"
     },
     {
       "kind": "interface",
@@ -53673,7 +53688,7 @@
           }
         }
       ],
-      "specLocation": "_types/common.ts#L319-L332"
+      "specLocation": "_types/common.ts#L321-L334"
     },
     {
       "kind": "interface",
@@ -54178,7 +54193,7 @@
         "name": "Level",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L248-L252"
+      "specLocation": "_types/common.ts#L250-L254"
     },
     {
       "kind": "enum",
@@ -54511,7 +54526,7 @@
         "name": "Metadata",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L93-L93",
+      "specLocation": "_types/common.ts#L95-L95",
       "type": {
         "kind": "dictionary_of",
         "key": {
@@ -54533,7 +54548,7 @@
         "name": "Metrics",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L70-L70",
+      "specLocation": "_types/common.ts#L72-L72",
       "type": {
         "kind": "union_of",
         "items": [
@@ -54566,7 +54581,7 @@
         "name": "MinimumShouldMatch",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L160-L164",
+      "specLocation": "_types/common.ts#L162-L166",
       "type": {
         "kind": "union_of",
         "items": [
@@ -54595,7 +54610,7 @@
         "name": "MultiTermQueryRewrite",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L132-L133",
+      "specLocation": "_types/common.ts#L134-L135",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -54610,7 +54625,7 @@
         "name": "Name",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L74-L74",
+      "specLocation": "_types/common.ts#L76-L76",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -54625,7 +54640,7 @@
         "name": "Names",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L75-L75",
+      "specLocation": "_types/common.ts#L77-L77",
       "type": {
         "kind": "union_of",
         "items": [
@@ -54655,7 +54670,7 @@
         "name": "Namespace",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L77-L77",
+      "specLocation": "_types/common.ts#L79-L79",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -54852,7 +54867,7 @@
         "name": "NodeName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L83-L84",
+      "specLocation": "_types/common.ts#L85-L86",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -55189,7 +55204,7 @@
         "name": "OpType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L254-L263"
+      "specLocation": "_types/common.ts#L256-L265"
     },
     {
       "kind": "type_alias",
@@ -55197,7 +55212,7 @@
         "name": "Password",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L192-L192",
+      "specLocation": "_types/common.ts#L194-L194",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -55306,7 +55321,7 @@
         "name": "PipelineName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L80-L80",
+      "specLocation": "_types/common.ts#L82-L82",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -55427,13 +55442,28 @@
       ],
       "specLocation": "_types/Stats.ts#L207-L217"
     },
+    {
+      "kind": "type_alias",
+      "name": {
+        "name": "ProjectRouting",
+        "namespace": "_types"
+      },
+      "specLocation": "_types/common.ts#L66-L66",
+      "type": {
+        "kind": "instance_of",
+        "type": {
+          "name": "string",
+          "namespace": "_builtins"
+        }
+      }
+    },
     {
       "kind": "type_alias",
       "name": {
         "name": "PropertyName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L127-L127",
+      "specLocation": "_types/common.ts#L129-L129",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -55785,7 +55815,7 @@
         "name": "Refresh",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L265-L272"
+      "specLocation": "_types/common.ts#L267-L274"
     },
     {
       "kind": "interface",
@@ -55887,7 +55917,7 @@
         "name": "RelationName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L128-L128",
+      "specLocation": "_types/common.ts#L130-L130",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -56314,7 +56344,7 @@
         "name": "Routing",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L66-L66",
+      "specLocation": "_types/common.ts#L68-L68",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -57218,7 +57248,7 @@
         "name": "SearchType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L274-L279"
+      "specLocation": "_types/common.ts#L276-L281"
     },
     {
       "kind": "interface",
@@ -57523,7 +57553,7 @@
         "name": "SequenceNumber",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L125-L125",
+      "specLocation": "_types/common.ts#L127-L127",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -57538,7 +57568,7 @@
         "name": "Service",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L78-L78",
+      "specLocation": "_types/common.ts#L80-L80",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -57778,7 +57808,7 @@
         "name": "Slices",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L363-L368",
+      "specLocation": "_types/common.ts#L365-L370",
       "type": {
         "kind": "union_of",
         "items": [
@@ -57811,7 +57841,7 @@
         "name": "SlicesCalculation",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L370-L378"
+      "specLocation": "_types/common.ts#L372-L380"
     },
     {
       "kind": "type_alias",
@@ -58306,7 +58336,7 @@
         "name": "SuggestMode",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L281-L294"
+      "specLocation": "_types/common.ts#L283-L296"
     },
     {
       "kind": "type_alias",
@@ -58315,7 +58345,7 @@
         "name": "SuggestionName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L148-L152",
+      "specLocation": "_types/common.ts#L150-L154",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -58384,7 +58414,7 @@
         "name": "TaskId",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L129-L129",
+      "specLocation": "_types/common.ts#L131-L131",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -58524,7 +58554,7 @@
         "name": "ThreadType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L296-L302"
+      "specLocation": "_types/common.ts#L298-L304"
     },
     {
       "kind": "type_alias",
@@ -58929,7 +58959,7 @@
         "name": "Username",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L191-L191",
+      "specLocation": "_types/common.ts#L193-L193",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -58944,7 +58974,7 @@
         "name": "Uuid",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L122-L122",
+      "specLocation": "_types/common.ts#L124-L124",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -58959,7 +58989,7 @@
         "name": "VersionNumber",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L96-L96",
+      "specLocation": "_types/common.ts#L98-L98",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -58974,7 +59004,7 @@
         "name": "VersionString",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L98-L98",
+      "specLocation": "_types/common.ts#L100-L100",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -59007,7 +59037,7 @@
         "name": "VersionType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L100-L119"
+      "specLocation": "_types/common.ts#L102-L121"
     },
     {
       "kind": "enum",
@@ -59023,7 +59053,7 @@
         "name": "WaitForActiveShardOptions",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L304-L308"
+      "specLocation": "_types/common.ts#L306-L310"
     },
     {
       "kind": "type_alias",
@@ -59035,7 +59065,7 @@
         "name": "WaitForActiveShards",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L139-L140",
+      "specLocation": "_types/common.ts#L141-L142",
       "type": {
         "kind": "union_of",
         "items": [
@@ -59082,7 +59112,7 @@
         "name": "WaitForEvents",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L310-L317"
+      "specLocation": "_types/common.ts#L312-L319"
     },
     {
       "kind": "interface",
@@ -98814,6 +98844,21 @@
             }
           }
         },
+        {
+          "availability": {
+            "serverless": {}
+          },
+          "description": "Specifies a subset of projects to target for a search using project metadata\ntags in a subset Lucene syntax. Allowed Lucene queries: the _alias tag\nand a single value (possible wildcarded). Examples:\n _alias:my-project\n _alias:_origin\n _alias:*pr*\nSupported in serverless only.",
+          "name": "project_routing",
+          "required": false,
+          "type": {
+            "kind": "instance_of",
+            "type": {
+              "name": "ProjectRouting",
+              "namespace": "_types"
+            }
+          }
+        },
         {
           "description": "Specify if request cache should be used for this request or not, defaults to true",
           "name": "request_cache",
@@ -99122,7 +99167,7 @@
           }
         }
       ],
-      "specLocation": "async_search/submit/AsyncSearchSubmitRequest.ts#L54-L294"
+      "specLocation": "async_search/submit/AsyncSearchSubmitRequest.ts#L55-L306"
     },
     {
       "kind": "response",
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index 1bea18a6f8..706308051d 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -1151,6 +1151,7 @@ export interface SearchRequest extends RequestBase {
   max_concurrent_shard_requests?: integer
   preference?: string
   pre_filter_shard_size?: long
+  project_routing?: ProjectRouting
   request_cache?: boolean
   routing?: Routing
   scroll?: Duration
@@ -2674,6 +2675,8 @@ export interface PluginStats {
   licensed: boolean
 }
 
+export type ProjectRouting = string
+
 export type PropertyName = string
 
 export interface QueryCacheStats {
@@ -7052,6 +7055,7 @@ export interface AsyncSearchSubmitRequest extends RequestBase {
   lenient?: boolean
   max_concurrent_shard_requests?: integer
   preference?: string
+  project_routing?: ProjectRouting
   request_cache?: boolean
   routing?: Routing
   search_type?: SearchType
diff --git a/specification/_global/search/SearchRequest.ts b/specification/_global/search/SearchRequest.ts
index a83a518c48..f4738466e1 100644
--- a/specification/_global/search/SearchRequest.ts
+++ b/specification/_global/search/SearchRequest.ts
@@ -25,6 +25,7 @@ import {
   Fields,
   IndexName,
   Indices,
+  ProjectRouting,
   Routing,
   SearchType,
   SuggestMode
@@ -219,6 +220,17 @@ export interface Request extends RequestBase {
      * * The primary sort of the query targets an indexed field.
      */
     pre_filter_shard_size?: long
+    /**
+     * Specifies a subset of projects to target for a search using project metadata
+     * tags in a subset Lucene syntax. Allowed Lucene queries: the _alias tag
+     * and a single value (possible wildcarded). Examples:
+     *  _alias:my-project
+     *  _alias:_origin
+     *  _alias:*pr*
+     * Supported in serverless only.
+     * @availability serverless
+     */
+    project_routing?: ProjectRouting
     /**
      * If `true`, the caching of search results is enabled for requests where `size` is `0`.
      * It defaults to index level settings.
diff --git a/specification/_json_spec/async_search.submit.json b/specification/_json_spec/async_search.submit.json
index d0d3a7c58b..70a6c2f25d 100644
--- a/specification/_json_spec/async_search.submit.json
+++ b/specification/_json_spec/async_search.submit.json
@@ -118,6 +118,10 @@
         "type": "string",
         "description": "Specify the node or shard the operation should be performed on (default: random)"
       },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
+      },
       "rest_total_hits_as_int": {
         "type": "boolean",
         "description": "Indicates whether hits.total should be rendered as an integer or an object in the rest search response",
diff --git a/specification/_json_spec/search.json b/specification/_json_spec/search.json
index 8c678bca72..be7ae17635 100644
--- a/specification/_json_spec/search.json
+++ b/specification/_json_spec/search.json
@@ -100,6 +100,10 @@
         "type": "string",
         "description": "Specify the node or shard the operation should be performed on (default: random)"
       },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
+      },
       "q": {
         "type": "string",
         "description": "Query in the Lucene query string syntax"
diff --git a/specification/_types/common.ts b/specification/_types/common.ts
index 829996095b..7a48e4a689 100644
--- a/specification/_types/common.ts
+++ b/specification/_types/common.ts
@@ -63,6 +63,8 @@ export type IndexAlias = string
 export type IndexPattern = string
 export type IndexPatterns = IndexPattern[]
 
+export type ProjectRouting = string
+
 export type Routing = string
 export type LongId = string
 //TODO encode metrics as API specific enums
diff --git a/specification/async_search/submit/AsyncSearchSubmitRequest.ts b/specification/async_search/submit/AsyncSearchSubmitRequest.ts
index 1279697dac..dd028e2437 100644
--- a/specification/async_search/submit/AsyncSearchSubmitRequest.ts
+++ b/specification/async_search/submit/AsyncSearchSubmitRequest.ts
@@ -25,6 +25,7 @@ import {
   Fields,
   IndexName,
   Indices,
+  ProjectRouting,
   Routing,
   SearchType,
   SuggestMode
@@ -126,6 +127,17 @@ export interface Request extends RequestBase {
     lenient?: boolean
     max_concurrent_shard_requests?: integer
     preference?: string
+    /**
+     * Specifies a subset of projects to target for a search using project metadata
+     * tags in a subset Lucene syntax. Allowed Lucene queries: the _alias tag
+     * and a single value (possible wildcarded). Examples:
+     *  _alias:my-project
+     *  _alias:_origin
+     *  _alias:*pr*
+     * Supported in serverless only.
+     * @availability serverless
+     */
+    project_routing?: ProjectRouting
     /** @server_default true */
     request_cache?: boolean
     routing?: Routing