[Index Management] Report the index mode Elasticsearch returns for data streams

deserializeDataStream only let logsdb and standard through and mapped every other index_mode (time_series, lookup, vectordb_document) to standard, so the data streams list and details flyout showed Standard for time series data streams. Pass through any known IndexMode value and keep the logs-* inference only for undefined or unknown values. Unskip the Scout downgrade-to-time-series test.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Author: kapral18

x-pack/platform/plugins/shared/index_management/server/lib/data_stream_serialization.test.ts

@@ -7,7 +7,13 @@
 
 import type { EnhancedDataStreamFromEs } from '../../common';
 import { deserializeDataStream } from './data_stream_serialization';
-import { LOGSDB_INDEX_MODE, STANDARD_INDEX_MODE } from '../../common/constants';
+import {
+  LOGSDB_INDEX_MODE,
+  LOOKUP_INDEX_MODE,
+  STANDARD_INDEX_MODE,
+  TIME_SERIES_MODE,
+  VECTOR_DB_INDEX_MODE,
+} from '../../common/constants';
 
 describe('deserializeDataStream', () => {
   const mockDataStreamFromEs: EnhancedDataStreamFromEs = {
@@ -353,6 +359,44 @@ describe('deserializeDataStream', () => {
       expect(result.indexMode).toBe('logsdb');
     });
 
+    it.each([TIME_SERIES_MODE, LOOKUP_INDEX_MODE, VECTOR_DB_INDEX_MODE])(
+      'should use provided %s index mode instead of falling back to standard',
+      (indexMode) => {
+        const dataStream = {
+          ...mockDataStreamFromEs,
+          index_mode: indexMode,
+        } as EnhancedDataStreamFromEs;
+
+        const result = deserializeDataStream(dataStream, false);
+
+        expect(result.indexMode).toBe(indexMode);
+      }
+    );
+
+    it('should keep provided time_series index mode when logsdb is enabled and name matches logs pattern', () => {
+      const dataStream: EnhancedDataStreamFromEs = {
+        ...mockDataStreamFromEs,
+        name: 'logs-nginx-production',
+        index_mode: TIME_SERIES_MODE,
+      };
+
+      const result = deserializeDataStream(dataStream, true);
+
+      expect(result.indexMode).toBe(TIME_SERIES_MODE);
+    });
+
+    it('should default to standard mode when the provided index mode is unknown', () => {
+      const unknownIndexMode: string = 'unknown_mode';
+      const dataStream = {
+        ...mockDataStreamFromEs,
+        index_mode: unknownIndexMode,
+      } as EnhancedDataStreamFromEs;
+
+      const result = deserializeDataStream(dataStream, false);
+
+      expect(result.indexMode).toBe(STANDARD_INDEX_MODE);
+    });
+
     it('should default to logsdb mode for logs pattern when logsdb is enabled and no index mode provided', () => {
       const dataStream = {
         ...mockDataStreamFromEs,

x-pack/platform/plugins/shared/index_management/server/lib/data_stream_serialization.ts

@@ -6,10 +6,19 @@
  */
 
 import { ByteSizeValue } from '@kbn/config-schema';
-import { LOGSDB_INDEX_MODE, STANDARD_INDEX_MODE } from '../../common/constants';
+import {
+  IndexMode as INDEX_MODES,
+  LOGSDB_INDEX_MODE,
+  STANDARD_INDEX_MODE,
+} from '../../common/constants';
 import type { IndexMode } from '../../common/types/data_streams';
 import type { DataStream, EnhancedDataStreamFromEs, EsDataRetention, Health } from '../../common';
 
+const INDEX_MODE_VALUES: ReadonlySet<string> = new Set(Object.values(INDEX_MODES));
+
+const isIndexMode = (value: string | undefined): value is IndexMode =>
+  value !== undefined && INDEX_MODE_VALUES.has(value);
+
 const toLowercaseHealth = (status: EnhancedDataStreamFromEs['status']): Health => {
   switch (status) {
     case 'green':
@@ -154,12 +163,11 @@ export function deserializeDataStream(
   }
   const failureStoreLifecycle = failureStore?.lifecycle;
 
-  const resolvedIndexMode: IndexMode =
-    indexMode === LOGSDB_INDEX_MODE || indexMode === STANDARD_INDEX_MODE
-      ? indexMode
-      : isLogsdbEnabled && /^logs-[^-]+-[^-]+$/.test(name)
-      ? LOGSDB_INDEX_MODE
-      : STANDARD_INDEX_MODE;
+  const resolvedIndexMode: IndexMode = isIndexMode(indexMode)
+    ? indexMode
+    : isLogsdbEnabled && /^logs-[^-]+-[^-]+$/.test(name)
+    ? LOGSDB_INDEX_MODE
+    : STANDARD_INDEX_MODE;
 
   const resolvedFailureStoreDefaultRetentionPeriod =
     failureStoreLifecycle?.retention_determined_by === 'default_failures_retention' &&

x-pack/platform/plugins/shared/index_management/test/scout/ui/tests/data_streams/data_streams_index_mode.spec.ts

@@ -180,9 +180,7 @@ test.describe('Data streams index mode', { tag: tags.deploymentAgnostic }, () =>
     await expect(dataStreamIndexMode(page)).toHaveText(INDEX_MODE.LOGSDB);
   });
 
-  // Skipped: the details flyout reports "Standard" for a time series data stream.
-  // See https://github.com/elastic/kibana/issues/283371
-  test.skip('allows to downgrade data stream from logsdb to time series index mode', async ({
+  test('allows to downgrade data stream from logsdb to time series index mode', async ({
     page,
     esClient,
     pageObjects,