Add tests + capability

Author: alex-spies

x-pack/plugin/esql/qa/testFixtures/src/main/resources/enrich.csv-spec

@@ -643,3 +643,21 @@ FROM airports
 abbrev:k  |  city_name:k  |  city_location:geo_point |  country:k  |  location:geo_point                       |  name:text                    |  region:text  |  boundary_wkt_length:i
 IDR       |  Indore       |  POINT(75.8472 22.7167)  |  India      |  POINT(75.8092915005895 22.727749187571)  |  Devi Ahilyabai Holkar Int'l  |  Indore City  |  231
 ;
+
+// Regression test for https://github.com/elastic/elasticsearch/issues/126030
+// We had wrong layouts from ReplaceMissingFieldsWithNull in case of indices that had relevant fields for the query,
+// but were **missing the field we enrich on**.
+fieldsInOtherIndicesBug
+required_capability: enrich_load
+required_capability: fix_replace_missing_field_with_null_duplicate_name_id_in_layout
+
+from *
+| keep author.keyword, book_no, scalerank, street, bytes_in, @timestamp, abbrev, city_location, distance, description, birth_date, language_code, intersects, client_ip, event_duration, version
+| enrich languages_policy on author.keyword
+| sort book_no
+| limit 1
+;
+
+author.keyword:keyword|book_no:keyword|scalerank:integer|street:keyword|bytes_in:ul|@timestamp:unsupported|abbrev:keyword|city_location:geo_point|distance:double|description:unsupported|birth_date:date|language_code:integer|intersects:boolean|client_ip:unsupported|event_duration:long|version:version|language_name:keyword
+Fyodor Dostoevsky     |1211           |null             |null          |null       |null                  |null          |null                   |null           |null                   |null           |null                 |null              |null                 |null               |null           |null
+;

x-pack/plugin/esql/qa/testFixtures/src/main/resources/lookup-join.csv-spec

@@ -1453,6 +1453,10 @@ emp_no:integer | language_code:integer | language_name:keyword
 10093          | 3                     | Spanish
 ;
 
+###############################################
+# Bugfixes
+###############################################
+
 multipleBatchesWithSort
 required_capability: join_lookup_v12
 required_capability: remove_redundant_sort
@@ -1539,3 +1543,21 @@ from *
 m:integer |birth_date:datetime
 null      |1952-02-27T00:00:00.000Z
 ;
+
+// Regression test for https://github.com/elastic/elasticsearch/issues/126030
+// We had wrong layouts from ReplaceMissingFieldsWithNull
+
+enrichLookupStatsBug
+required_capability: join_lookup_v12
+required_capability: fix_replace_missing_field_with_null_duplicate_name_id_in_layout
+
+from *
+| enrich languages_policy on cluster
+| rename languages.byte as language_code
+| lookup join languages_lookup on language_code
+| stats  salary_change.long = max(ratings), foo = max(num)
+;
+
+salary_change.long:double|foo:long
+5.0                      |1698069301543123456
+;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -942,7 +942,12 @@ public enum Cap {
         /**
          * Support for sorting when aggregate_metric_doubles are present
          */
-        AGGREGATE_METRIC_DOUBLE_SORTING(AGGREGATE_METRIC_DOUBLE_FEATURE_FLAG);
+        AGGREGATE_METRIC_DOUBLE_SORTING(AGGREGATE_METRIC_DOUBLE_FEATURE_FLAG),
+
+        /**
+         * Supercedes {@link Cap#MAKE_NUMBER_OF_CHANNELS_CONSISTENT_WITH_LAYOUT}.
+         */
+        FIX_REPLACE_MISSING_FIELD_WITH_NULL_DUPLICATE_NAME_ID_IN_LAYOUT;
 
         private final boolean enabled;