diff --git a/output/openapi/elasticsearch-openapi.json b/output/openapi/elasticsearch-openapi.json
index e8db6e7163..68e2e9cd79 100644
--- a/output/openapi/elasticsearch-openapi.json
+++ b/output/openapi/elasticsearch-openapi.json
@@ -104271,6 +104271,11 @@
                   }
                 ]
               },
+              "media_type": {
+                "description": "The media type for encoding `value`.\nApplies only when value is a template snippet.\nMust be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.",
+                "default": "\"application/json\"",
+                "type": "string"
+              },
               "allow_duplicates": {
                 "description": "If `false`, the processor does not append values already present in the field.",
                 "default": true,
@@ -104278,8 +104283,7 @@
               }
             },
             "required": [
-              "field",
-              "value"
+              "field"
             ]
           }
         ]
@@ -106168,6 +106172,7 @@
               },
               "media_type": {
                 "description": "The media type for encoding `value`.\nApplies only when value is a template snippet.\nMust be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.",
+                "default": "\"application/json\"",
                 "type": "string"
               },
               "override": {
diff --git a/output/openapi/elasticsearch-serverless-openapi.json b/output/openapi/elasticsearch-serverless-openapi.json
index f940b2f927..f5b7b3b6fd 100644
--- a/output/openapi/elasticsearch-serverless-openapi.json
+++ b/output/openapi/elasticsearch-serverless-openapi.json
@@ -67680,6 +67680,11 @@
                   }
                 ]
               },
+              "media_type": {
+                "description": "The media type for encoding `value`.\nApplies only when value is a template snippet.\nMust be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.",
+                "default": "\"application/json\"",
+                "type": "string"
+              },
               "allow_duplicates": {
                 "description": "If `false`, the processor does not append values already present in the field.",
                 "default": true,
@@ -67687,8 +67692,7 @@
               }
             },
             "required": [
-              "field",
-              "value"
+              "field"
             ]
           }
         ]
@@ -69577,6 +69581,7 @@
               },
               "media_type": {
                 "description": "The media type for encoding `value`.\nApplies only when value is a template snippet.\nMust be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.",
+                "default": "\"application/json\"",
                 "type": "string"
               },
               "override": {
diff --git a/output/schema/schema.json b/output/schema/schema.json
index 81fc6627ee..6d1f154305 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -181913,7 +181913,7 @@
         {
           "description": "The value to be appended. Supports template snippets.",
           "name": "value",
-          "required": true,
+          "required": false,
           "type": {
             "kind": "union_of",
             "items": [
@@ -181929,6 +181929,19 @@
             ]
           }
         },
+        {
+          "description": "The media type for encoding `value`.\nApplies only when value is a template snippet.\nMust be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.",
+          "name": "media_type",
+          "required": false,
+          "serverDefault": "\"application/json\"",
+          "type": {
+            "kind": "instance_of",
+            "type": {
+              "name": "string",
+              "namespace": "_builtins"
+            }
+          }
+        },
         {
           "description": "If `false`, the processor does not append values already present in the field.",
           "name": "allow_duplicates",
@@ -181943,7 +181956,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L329-L344"
+      "specLocation": "ingest/_types/Processors.ts#L329-L351"
     },
     {
       "kind": "interface",
@@ -182063,7 +182076,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L346-L387"
+      "specLocation": "ingest/_types/Processors.ts#L353-L394"
     },
     {
       "kind": "interface",
@@ -182117,7 +182130,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L556-L572"
+      "specLocation": "ingest/_types/Processors.ts#L563-L579"
     },
     {
       "kind": "interface",
@@ -182194,7 +182207,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L574-L597"
+      "specLocation": "ingest/_types/Processors.ts#L581-L604"
     },
     {
       "kind": "interface",
@@ -182353,7 +182366,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L599-L660"
+      "specLocation": "ingest/_types/Processors.ts#L606-L667"
     },
     {
       "kind": "interface",
@@ -182419,7 +182432,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L673-L693"
+      "specLocation": "ingest/_types/Processors.ts#L680-L700"
     },
     {
       "kind": "enum",
@@ -182453,7 +182466,7 @@
         "name": "ConvertType",
         "namespace": "ingest._types"
       },
-      "specLocation": "ingest/_types/Processors.ts#L662-L671"
+      "specLocation": "ingest/_types/Processors.ts#L669-L678"
     },
     {
       "kind": "interface",
@@ -182551,7 +182564,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L695-L728"
+      "specLocation": "ingest/_types/Processors.ts#L702-L735"
     },
     {
       "kind": "interface",
@@ -182776,7 +182789,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L730-L768"
+      "specLocation": "ingest/_types/Processors.ts#L737-L775"
     },
     {
       "kind": "interface",
@@ -182871,7 +182884,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L770-L803"
+      "specLocation": "ingest/_types/Processors.ts#L777-L810"
     },
     {
       "kind": "interface",
@@ -182937,7 +182950,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L805-L824"
+      "specLocation": "ingest/_types/Processors.ts#L812-L831"
     },
     {
       "kind": "interface",
@@ -183172,7 +183185,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L826-L844"
+      "specLocation": "ingest/_types/Processors.ts#L833-L851"
     },
     {
       "kind": "interface",
@@ -183187,7 +183200,7 @@
         "namespace": "ingest._types"
       },
       "properties": [],
-      "specLocation": "ingest/_types/Processors.ts#L846-L846"
+      "specLocation": "ingest/_types/Processors.ts#L853-L853"
     },
     {
       "kind": "interface",
@@ -183291,7 +183304,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L848-L887"
+      "specLocation": "ingest/_types/Processors.ts#L855-L894"
     },
     {
       "kind": "interface",
@@ -183319,7 +183332,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L889-L895"
+      "specLocation": "ingest/_types/Processors.ts#L896-L902"
     },
     {
       "kind": "enum",
@@ -183349,7 +183362,7 @@
         "name": "FingerprintDigest",
         "namespace": "ingest._types"
       },
-      "specLocation": "ingest/_types/Processors.ts#L897-L903"
+      "specLocation": "ingest/_types/Processors.ts#L904-L910"
     },
     {
       "kind": "interface",
@@ -183428,7 +183441,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L905-L933"
+      "specLocation": "ingest/_types/Processors.ts#L912-L940"
     },
     {
       "kind": "interface",
@@ -183481,7 +183494,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L935-L949"
+      "specLocation": "ingest/_types/Processors.ts#L942-L956"
     },
     {
       "kind": "interface",
@@ -183608,7 +183621,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L389-L430"
+      "specLocation": "ingest/_types/Processors.ts#L396-L437"
     },
     {
       "kind": "enum",
@@ -183624,7 +183637,7 @@
         "name": "GeoGridTargetFormat",
         "namespace": "ingest._types"
       },
-      "specLocation": "ingest/_types/Processors.ts#L438-L441"
+      "specLocation": "ingest/_types/Processors.ts#L445-L448"
     },
     {
       "kind": "enum",
@@ -183643,7 +183656,7 @@
         "name": "GeoGridTileType",
         "namespace": "ingest._types"
       },
-      "specLocation": "ingest/_types/Processors.ts#L432-L436"
+      "specLocation": "ingest/_types/Processors.ts#L439-L443"
     },
     {
       "kind": "interface",
@@ -183750,7 +183763,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L443-L477"
+      "specLocation": "ingest/_types/Processors.ts#L450-L484"
     },
     {
       "kind": "interface",
@@ -183855,7 +183868,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L951-L982"
+      "specLocation": "ingest/_types/Processors.ts#L958-L989"
     },
     {
       "kind": "interface",
@@ -183933,7 +183946,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L984-L1008"
+      "specLocation": "ingest/_types/Processors.ts#L991-L1015"
     },
     {
       "kind": "interface",
@@ -183987,7 +184000,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1010-L1026"
+      "specLocation": "ingest/_types/Processors.ts#L1017-L1033"
     },
     {
       "kind": "interface",
@@ -184021,7 +184034,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1067-L1079",
+      "specLocation": "ingest/_types/Processors.ts#L1074-L1086",
       "variants": {
         "kind": "container"
       }
@@ -184098,7 +184111,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1094-L1120"
+      "specLocation": "ingest/_types/Processors.ts#L1101-L1127"
     },
     {
       "kind": "interface",
@@ -184134,7 +184147,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1081-L1092"
+      "specLocation": "ingest/_types/Processors.ts#L1088-L1099"
     },
     {
       "kind": "interface",
@@ -184245,7 +184258,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1028-L1060"
+      "specLocation": "ingest/_types/Processors.ts#L1035-L1067"
     },
     {
       "kind": "interface",
@@ -184326,7 +184339,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1062-L1065"
+      "specLocation": "ingest/_types/Processors.ts#L1069-L1072"
     },
     {
       "kind": "interface",
@@ -184433,7 +184446,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L479-L513"
+      "specLocation": "ingest/_types/Processors.ts#L486-L520"
     },
     {
       "kind": "interface",
@@ -184495,7 +184508,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1122-L1137"
+      "specLocation": "ingest/_types/Processors.ts#L1129-L1144"
     },
     {
       "kind": "interface",
@@ -184574,7 +184587,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1139-L1168"
+      "specLocation": "ingest/_types/Processors.ts#L1146-L1175"
     },
     {
       "kind": "enum",
@@ -184592,7 +184605,7 @@
         "name": "JsonProcessorConflictStrategy",
         "namespace": "ingest._types"
       },
-      "specLocation": "ingest/_types/Processors.ts#L1170-L1175"
+      "specLocation": "ingest/_types/Processors.ts#L1177-L1182"
     },
     {
       "kind": "interface",
@@ -184749,7 +184762,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1177-L1229"
+      "specLocation": "ingest/_types/Processors.ts#L1184-L1236"
     },
     {
       "kind": "interface",
@@ -184824,7 +184837,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1231-L1247"
+      "specLocation": "ingest/_types/Processors.ts#L1238-L1254"
     },
     {
       "kind": "interface",
@@ -184940,7 +184953,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1249-L1283"
+      "specLocation": "ingest/_types/Processors.ts#L1256-L1290"
     },
     {
       "kind": "interface",
@@ -185119,7 +185132,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1285-L1296"
+      "specLocation": "ingest/_types/Processors.ts#L1292-L1303"
     },
     {
       "kind": "interface",
@@ -186102,7 +186115,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1298-L1339"
+      "specLocation": "ingest/_types/Processors.ts#L1305-L1346"
     },
     {
       "kind": "interface",
@@ -186155,7 +186168,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1341-L1357"
+      "specLocation": "ingest/_types/Processors.ts#L1348-L1364"
     },
     {
       "kind": "interface",
@@ -186208,7 +186221,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1359-L1373"
+      "specLocation": "ingest/_types/Processors.ts#L1366-L1380"
     },
     {
       "kind": "interface",
@@ -186261,7 +186274,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1375-L1391"
+      "specLocation": "ingest/_types/Processors.ts#L1382-L1398"
     },
     {
       "kind": "interface",
@@ -186343,7 +186356,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1393-L1421"
+      "specLocation": "ingest/_types/Processors.ts#L1400-L1428"
     },
     {
       "kind": "interface",
@@ -186415,7 +186428,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1423-L1443"
+      "specLocation": "ingest/_types/Processors.ts#L1430-L1450"
     },
     {
       "kind": "interface",
@@ -186471,6 +186484,7 @@
           "description": "The media type for encoding `value`.\nApplies only when value is a template snippet.\nMust be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.",
           "name": "media_type",
           "required": false,
+          "serverDefault": "\"application/json\"",
           "type": {
             "kind": "instance_of",
             "type": {
@@ -186501,7 +186515,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1445-L1479"
+      "specLocation": "ingest/_types/Processors.ts#L1452-L1487"
     },
     {
       "kind": "interface",
@@ -186544,7 +186558,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1481-L1490"
+      "specLocation": "ingest/_types/Processors.ts#L1489-L1498"
     },
     {
       "kind": "enum",
@@ -186560,7 +186574,7 @@
         "name": "ShapeType",
         "namespace": "ingest._types"
       },
-      "specLocation": "ingest/_types/Processors.ts#L1492-L1495"
+      "specLocation": "ingest/_types/Processors.ts#L1500-L1503"
     },
     {
       "kind": "interface",
@@ -186659,7 +186673,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1497-L1513"
+      "specLocation": "ingest/_types/Processors.ts#L1505-L1521"
     },
     {
       "kind": "interface",
@@ -186738,7 +186752,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1515-L1540"
+      "specLocation": "ingest/_types/Processors.ts#L1523-L1548"
     },
     {
       "kind": "interface",
@@ -186753,7 +186767,7 @@
         "namespace": "ingest._types"
       },
       "properties": [],
-      "specLocation": "ingest/_types/Processors.ts#L1542-L1542"
+      "specLocation": "ingest/_types/Processors.ts#L1550-L1550"
     },
     {
       "kind": "interface",
@@ -186807,7 +186821,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1544-L1560"
+      "specLocation": "ingest/_types/Processors.ts#L1552-L1568"
     },
     {
       "kind": "interface",
@@ -186861,7 +186875,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1562-L1578"
+      "specLocation": "ingest/_types/Processors.ts#L1570-L1586"
     },
     {
       "kind": "interface",
@@ -186941,7 +186955,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1598-L1624"
+      "specLocation": "ingest/_types/Processors.ts#L1606-L1632"
     },
     {
       "kind": "interface",
@@ -186995,7 +187009,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L1580-L1596"
+      "specLocation": "ingest/_types/Processors.ts#L1588-L1604"
     },
     {
       "kind": "interface",
@@ -187103,7 +187117,7 @@
           }
         }
       ],
-      "specLocation": "ingest/_types/Processors.ts#L515-L546"
+      "specLocation": "ingest/_types/Processors.ts#L522-L553"
     },
     {
       "kind": "enum",
@@ -187128,7 +187142,7 @@
         "name": "UserAgentProperty",
         "namespace": "ingest._types"
       },
-      "specLocation": "ingest/_types/Processors.ts#L548-L554"
+      "specLocation": "ingest/_types/Processors.ts#L555-L561"
     },
     {
       "kind": "interface",
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index 2f0eeb8fa1..b8964bf940 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -14977,7 +14977,8 @@ export type InferenceUpdateResponse = InferenceInferenceEndpointInfo
 
 export interface IngestAppendProcessor extends IngestProcessorBase {
   field: Field
-  value: any | any[]
+  value?: any | any[]
+  media_type?: string
   allow_duplicates?: boolean
 }
 
diff --git a/specification/ingest/_types/Processors.ts b/specification/ingest/_types/Processors.ts
index a79232ac82..ebe7460b8a 100644
--- a/specification/ingest/_types/Processors.ts
+++ b/specification/ingest/_types/Processors.ts
@@ -335,7 +335,14 @@ export class AppendProcessor extends ProcessorBase {
   /**
    * The value to be appended. Supports template snippets.
    */
-  value: UserDefinedValue | UserDefinedValue[]
+  value?: UserDefinedValue | UserDefinedValue[]
+  /**
+   * The media type for encoding `value`.
+   * Applies only when value is a template snippet.
+   * Must be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.
+   * @server_default "application/json"
+   */
+  media_type?: string
   /**
    * If `false`, the processor does not append values already present in the field.
    * @server_default true
@@ -1462,6 +1469,7 @@ export class SetProcessor extends ProcessorBase {
    * The media type for encoding `value`.
    * Applies only when value is a template snippet.
    * Must be one of `application/json`, `text/plain`, or `application/x-www-form-urlencoded`.
+   * @server_default "application/json"
    */
   media_type?: string
   /**