address review comments

Author: jimczi

docs/changelog/119183.yaml

@@ -440,7 +440,7 @@ private void readStoredFieldsDirectly(StoredFieldVisitor visitor) throws IOExcep
                 SourceFieldMapper mapper = mappingLookup.getMapping().getMetadataMapperByClass(SourceFieldMapper.class);
                 if (mapper != null) {
                     try {
-                        sourceBytes = mapper.applyFilters(null, sourceBytes, null);
+                        sourceBytes = mapper.applyFilters(mappingLookup, sourceBytes, null);
                     } catch (IOException e) {
                         throw new IOException("Failed to reapply filters after reading from translog", e);
                     }

server/src/main/java/org/elasticsearch/index/engine/TranslogDirectoryReader.java

@@ -405,7 +405,7 @@ public boolean isComplete() {
     public void preParse(DocumentParserContext context) throws IOException {
         BytesReference originalSource = context.sourceToParse().source();
         XContentType contentType = context.sourceToParse().getXContentType();
-        final BytesReference adaptedSource = applyFilters(context, originalSource, contentType);
+        final BytesReference adaptedSource = applyFilters(context.mappingLookup(), originalSource, contentType);
 
         if (adaptedSource != null) {
             final BytesRef ref = adaptedSource.toBytesRef();
@@ -434,17 +434,17 @@ public void preParse(DocumentParserContext context) throws IOException {
 
     @Nullable
     public BytesReference applyFilters(
-        @Nullable DocumentParserContext context,
+        @Nullable MappingLookup mappingLookup,
         @Nullable BytesReference originalSource,
         @Nullable XContentType contentType
     ) throws IOException {
         if (stored() == false || originalSource == null) {
             return null;
         }
         var modSourceFilter = sourceFilter;
-        if (context != null
-            && InferenceMetadataFieldsMapper.isEnabled(context.mappingLookup())
-            && context.mappingLookup().inferenceFields().isEmpty() == false) {
+        if (mappingLookup != null
+            && InferenceMetadataFieldsMapper.isEnabled(mappingLookup)
+            && mappingLookup.inferenceFields().isEmpty() == false) {
             /**
              * Removes {@link InferenceMetadataFieldsMapper} content from _source.
              * This content is re-generated at query time (if requested) using stored fields and doc values.

server/src/main/java/org/elasticsearch/index/mapper/SourceFieldMapper.java

@@ -62,7 +62,9 @@ public ValueFetcher valueFetcher(MappingLookup mappingLookup, Function<Query, Bi
                 if (ft instanceof SemanticTextFieldMapper.SemanticTextFieldType semanticTextFieldType) {
                     fieldFetchers.put(inferenceField, semanticTextFieldType.valueFetcherWithInferenceResults(bitSetCache, searcher));
                 } else {
-                    throw new IllegalArgumentException("Illegal format for field [" + name() + "], got " + ft.typeName());
+                    throw new IllegalArgumentException(
+                        "Invalid inference field [" + ft.name() + "]. Expected field type [semantic_text] but got [" + ft.typeName() + "]"
+                    );
                 }
             }
             if (fieldFetchers.isEmpty()) {

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/mapper/SemanticInferenceMetadataFieldsMapper.java

@@ -282,14 +282,20 @@ public void testInvalidInferenceEndpoints() {
         {
             Exception e = expectThrows(
                 MapperParsingException.class,
-                () -> createMapperService(fieldMapping(b -> b.field("type", "semantic_text").field(INFERENCE_ID_FIELD, "")), false)
+                () -> createMapperService(
+                    fieldMapping(b -> b.field("type", "semantic_text").field(INFERENCE_ID_FIELD, "")),
+                    useLegacyFormat
+                )
             );
             assertThat(e.getMessage(), containsString("[inference_id] on mapper [field] of type [semantic_text] must not be empty"));
         }
         {
             Exception e = expectThrows(
                 MapperParsingException.class,
-                () -> createMapperService(fieldMapping(b -> b.field("type", "semantic_text").field(SEARCH_INFERENCE_ID_FIELD, "")), false)
+                () -> createMapperService(
+                    fieldMapping(b -> b.field("type", "semantic_text").field(SEARCH_INFERENCE_ID_FIELD, "")),
+                    useLegacyFormat
+                )
             );
             assertThat(e.getMessage(), containsString("[search_inference_id] on mapper [field] of type [semantic_text] must not be empty"));
         }
@@ -511,8 +517,9 @@ private static void assertSemanticTextField(MapperService mapperService, String
             assertFalse(textFieldMapper.fieldType().isIndexed());
             assertFalse(textFieldMapper.fieldType().hasDocValues());
         } else {
-            // TODO: Check for offsets mapper here
             assertNull(textMapper);
+            var offsetMapper = semanticTextFieldType.getOffsetsField();
+            assertThat(offsetMapper, instanceOf(OffsetSourceFieldMapper.class));
         }
 
         if (expectedModelSettings) {