enable subqueries by feature flag

Author: bartoval

src/platform/packages/shared/kbn-esql-ast/src/commands_registry/commands/from/autocomplete.ts

@@ -21,6 +21,7 @@ import type { ICommandCallbacks } from '../../types';
 import { type ISuggestionItem, type ICommandContext } from '../../types';
 import { getOverlapRange, isRestartingExpression } from '../../../definitions/utils/shared';
 import { isSubQuery, isSource } from '../../../ast/is';
+import { esqlCommandRegistry } from '../../../..';
 
 const SOURCE_TYPE_INDEX = 'index';
 const METADATA_KEYWORD = 'METADATA';
@@ -110,8 +111,7 @@ function suggestInitialSources(
 
   const suggestions = getSourceSuggestions(sources, [], innerText);
 
-  // Only suggest subqueries when not already inside a subquery
-  if (!context?.isCursorInSubquery) {
+  if (shouldSuggestSubquery(context)) {
     suggestions.push(subqueryCompleteItem);
   }
 
@@ -174,10 +174,18 @@ async function suggestAdditionalSources(
     recommendedQueries
   );
 
-  // Add subquery suggestion when restarting after comma (only if not already in subquery)
-  if (isRestartingExpression(innerText) && !context?.isCursorInSubquery) {
+  if (isRestartingExpression(innerText) && shouldSuggestSubquery(context)) {
     suggestions.push(subqueryCompleteItem);
   }
 
   return suggestions;
 }
+
+function shouldSuggestSubquery(context: ICommandContext | undefined): boolean {
+  if (context?.isCursorInSubquery) {
+    return false;
+  }
+
+  const fromCommand = esqlCommandRegistry.getCommandByName('from');
+  return fromCommand?.metadata?.subquerySupport ?? true;
+}

src/platform/packages/shared/kbn-esql-ast/src/commands_registry/commands/from/index.ts

@@ -23,6 +23,7 @@ export const fromCommand = {
   name: 'from',
   methods: fromCommandMethods,
   metadata: {
+    subquerySupport: false,
     description: i18n.translate('kbn-esql-ast.esql.definitions.fromDoc', {
       defaultMessage:
         'Retrieves data from one or more data streams, indices, or aliases. In a query or subquery, you must use the from command first and it does not need a leading pipe. For example, to retrieve data from an index:',

src/platform/packages/shared/kbn-esql-ast/src/commands_registry/registry.ts

@@ -72,6 +72,7 @@ export interface ICommandMethods<TContext = any> {
 
 export interface ICommandMetadata {
   preview?: boolean; // Optional property to indicate if the command is in preview mode
+  subquerySupport?: boolean; // Optional property to indicate if the command supports subqueries (ONLY FROM)
   description: string; // Optional property for a brief description of the command
   declaration: string; // The pattern for declaring this command statement. Displayed in the autocomplete.
   examples: string[]; // A list of examples of how to use the command. Displayed in the autocomplete.