feat(schema): add removal of $comment and enumDescriptions in JSON schema processing

- Updated JSON schema handling to remove `$comment` and `enumDescriptions` fields during schema transformations.
- Adjusted test cases to validate the removal of these fields both at root and nested levels.
- Expanded unsupported schema keywords to include `$comment` and `enumDescriptions` for Gemini compatibility.

Closes: #3512

internal/runtime/executor/antigravity_executor_buildrequest_test.go

@@ -300,17 +300,20 @@ func buildRequestBodyFromPayload(t *testing.T, modelName string) map[string]any
 							"parametersJsonSchema": {
 								"$schema": "http://json-schema.org/draft-07/schema#",
 								"$id": "root-schema",
+								"$comment": "root comment should be removed",
 								"type": "object",
 								"properties": {
 									"$id": {"type": "string"},
 									"arg": {
 										"type": "object",
+										"$comment": "nested comment should be removed",
 										"prefill": "hello",
 										"properties": {
 											"mode": {
 												"type": "string",
 												"deprecated": true,
 												"enum": ["a", "b"],
+												"enumDescriptions": ["Alpha", "Beta"],
 												"enumTitles": ["A", "B"]
 											}
 										}
@@ -389,6 +392,9 @@ func assertSchemaSanitizedAndPropertyPreserved(t *testing.T, params map[string]a
 	if _, ok := params["$id"]; ok {
 		t.Fatalf("root $id should be removed from schema")
 	}
+	if _, ok := params["$comment"]; ok {
+		t.Fatalf("root $comment should be removed from schema")
+	}
 	if _, ok := params["patternProperties"]; ok {
 		t.Fatalf("patternProperties should be removed from schema")
 	}
@@ -408,6 +414,9 @@ func assertSchemaSanitizedAndPropertyPreserved(t *testing.T, params map[string]a
 	if _, ok := arg["prefill"]; ok {
 		t.Fatalf("prefill should be removed from nested schema")
 	}
+	if _, ok := arg["$comment"]; ok {
+		t.Fatalf("nested $comment should be removed from schema")
+	}
 
 	argProps, ok := arg["properties"].(map[string]any)
 	if !ok {
@@ -420,6 +429,9 @@ func assertSchemaSanitizedAndPropertyPreserved(t *testing.T, params map[string]a
 	if _, ok := mode["enumTitles"]; ok {
 		t.Fatalf("enumTitles should be removed from nested schema")
 	}
+	if _, ok := mode["enumDescriptions"]; ok {
+		t.Fatalf("enumDescriptions should be removed from nested schema")
+	}
 	if _, ok := mode["deprecated"]; ok {
 		t.Fatalf("deprecated should be removed from nested schema")
 	}

internal/util/gemini_schema.go

@@ -440,7 +440,7 @@ func removeUnsupportedKeywords(jsonStr string) string {
 	keywords := append(unsupportedConstraints,
 		"$schema", "$defs", "definitions", "const", "$ref", "$id", "additionalProperties",
 		"propertyNames", "patternProperties", // Gemini doesn't support these schema keywords
-		"enumTitles", "prefill", "deprecated", // Schema metadata fields unsupported by Gemini
+		"$comment", "enumDescriptions", "enumTitles", "prefill", "deprecated", // Schema metadata fields unsupported by Gemini
 	)
 
 	deletePaths := make([]string, 0)

internal/util/gemini_schema_test.go

@@ -874,15 +874,18 @@ func TestCleanJSONSchemaForGemini_RemovesGeminiUnsupportedMetadataFields(t *test
 	input := `{
 		"$schema": "http://json-schema.org/draft-07/schema#",
 		"$id": "root-schema",
+		"$comment": "root comment should be removed",
 		"type": "object",
 		"properties": {
 			"payload": {
 				"type": "object",
+				"$comment": "nested comment should be removed",
 				"prefill": "hello",
 				"properties": {
 					"mode": {
 						"type": "string",
 						"enum": ["a", "b"],
+						"enumDescriptions": ["Alpha", "Beta"],
 						"enumTitles": ["A", "B"]
 					}
 				},
@@ -893,6 +896,14 @@ func TestCleanJSONSchemaForGemini_RemovesGeminiUnsupportedMetadataFields(t *test
 			"$id": {
 				"type": "string",
 				"description": "property name should not be removed"
+			},
+			"$comment": {
+				"type": "string",
+				"description": "property name should not be removed"
+			},
+			"enumDescriptions": {
+				"type": "array",
+				"description": "property name should not be removed"
 			}
 		}
 	}`
@@ -913,6 +924,14 @@ func TestCleanJSONSchemaForGemini_RemovesGeminiUnsupportedMetadataFields(t *test
 			"$id": {
 				"type": "string",
 				"description": "property name should not be removed"
+			},
+			"$comment": {
+				"type": "string",
+				"description": "property name should not be removed"
+			},
+			"enumDescriptions": {
+				"type": "array",
+				"description": "property name should not be removed"
 			}
 		}
 	}`