fix: allow additionalProperties to be object instead of only bool

core/internal/testutil/structured_outputs.go

@@ -421,7 +421,7 @@ func RunStructuredOutputResponsesTest(t *testing.T, client *bifrost.Bifrost, ctx
 								Type:                 &typeStr,
 								Properties:           &props,
 								Required:             structuredOutputSchema["required"].([]string),
-								AdditionalProperties: &additionalProps,
+								AdditionalProperties: &schemas.AdditionalProperties{BoolValue: &additionalProps},
 							},
 						},
 					},
@@ -535,7 +535,7 @@ func RunStructuredOutputResponsesStreamTest(t *testing.T, client *bifrost.Bifros
 							Type:                 &typeStr,
 							Properties:           &props,
 							Required:             structuredOutputSchema["required"].([]string),
-							AdditionalProperties: &additionalProps,
+							AdditionalProperties: &schemas.AdditionalProperties{BoolValue: &additionalProps},
 						},
 					},
 				},

core/providers/anthropic/utils.go

@@ -766,7 +766,9 @@ func convertAnthropicOutputFormatToResponsesTextConfig(outputFormat interface{})
 		}
 
 		if additionalProps, ok := schemaMap["additionalProperties"].(bool); ok {
-			jsonSchema.AdditionalProperties = &additionalProps
+			jsonSchema.AdditionalProperties = &schemas.AdditionalProperties{BoolValue: &additionalProps}
+		} else if additionalProps, ok := schemaMap["additionalProperties"].(map[string]any); ok {
+			jsonSchema.AdditionalProperties = &schemas.AdditionalProperties{ObjectValue: &additionalProps}
 		}
 
 		format.JSONSchema = jsonSchema

core/providers/cohere/utils.go

@@ -74,7 +74,9 @@ func convertInterfaceToToolFunctionParameters(params interface{}) *schemas.ToolF
 
 	// Extract additionalProperties
 	if addPropsVal, ok := paramsMap["additionalProperties"].(bool); ok {
-		result.AdditionalProperties = &addPropsVal
+		result.AdditionalProperties = &schemas.AdditionalProperties{BoolValue: &addPropsVal}
+	} else if addPropsVal, ok := paramsMap["additionalProperties"].(map[string]any); ok {
+		result.AdditionalProperties = &schemas.AdditionalProperties{ObjectValue: &addPropsVal}
 	}
 
 	return result

core/providers/gemini/gemini_test.go

@@ -556,7 +556,7 @@ func TestResponsesStructuredOutputConversion(t *testing.T) {
 									},
 								},
 								Required:             []string{"user_id", "status"},
-								AdditionalProperties: schemas.Ptr(false),
+								AdditionalProperties: &schemas.AdditionalProperties{BoolValue: schemas.Ptr(false)},
 							},
 						},
 					},

core/providers/gemini/utils.go

@@ -1143,7 +1143,9 @@ func buildJSONSchemaFromMap(schemaMap map[string]interface{}) *schemas.Responses
 
 	// Extract additionalProperties
 	if additionalProps, ok := normalizedSchemaMap["additionalProperties"].(bool); ok {
-		jsonSchema.AdditionalProperties = schemas.Ptr(additionalProps)
+		jsonSchema.AdditionalProperties = &schemas.AdditionalProperties{BoolValue: &additionalProps}
+	} else if additionalProps, ok := normalizedSchemaMap["additionalProperties"].(map[string]any); ok {
+		jsonSchema.AdditionalProperties = &schemas.AdditionalProperties{ObjectValue: &additionalProps}
 	}
 
 	// Extract name/title

core/schemas/chatcompletions.go

@@ -273,12 +273,12 @@ type ChatToolFunction struct {
 
 // ToolFunctionParameters represents the parameters for a function definition.
 type ToolFunctionParameters struct {
-	Type                 string      `json:"type"`                           // Type of the parameters
-	Description          *string     `json:"description,omitempty"`          // Description of the parameters
-	Required             []string    `json:"required,omitempty"`             // Required parameter names
-	Properties           *OrderedMap `json:"properties,omitempty"`           // Parameter properties
-	Enum                 []string    `json:"enum,omitempty"`                 // Enum values for the parameters
-	AdditionalProperties *bool       `json:"additionalProperties,omitempty"` // Whether to allow additional properties
+	Type                 string                `json:"type"`                           // Type of the parameters
+	Description          *string               `json:"description,omitempty"`          // Description of the parameters
+	Required             []string              `json:"required,omitempty"`             // Required parameter names
+	Properties           *OrderedMap           `json:"properties,omitempty"`           // Parameter properties
+	Enum                 []string              `json:"enum,omitempty"`                 // Enum values for the parameters
+	AdditionalProperties *AdditionalProperties `json:"additionalProperties,omitempty"` // Whether to allow additional properties
 }
 
 // UnmarshalJSON implements custom JSON unmarshalling for ToolFunctionParameters.
@@ -307,6 +307,45 @@ func (t *ToolFunctionParameters) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// AdditionalProperties handle `additionalProperties` being either a bool value
+// or an object, according to JSONSchema:
+// https://json-schema.org/understanding-json-schema/reference/object#additionalproperties
+type AdditionalProperties struct {
+	BoolValue   *bool
+	ObjectValue *map[string]any
+}
+
+// UnmarshalJSON implements custom JSON unmarshalling for AdditionalProperties.
+// Handles both the value being either bool or a generic jsonschema object.
+func (t *AdditionalProperties) UnmarshalJSON(data []byte) error {
+	// Try to unmarshal as a bool
+	var boolValue bool
+	if err := Unmarshal(data, &boolValue); err == nil {
+		t.BoolValue = &boolValue
+		return nil
+	}
+
+	// Otherwise unmarshal as a generic object
+	var objectValue map[string]any
+	if err := Unmarshal(data, &objectValue); err != nil {
+		return err
+	}
+	t.ObjectValue = &objectValue
+	return nil
+}
+
+// MarshalJSON implements custom JSON marshalling for AdditionalProperties.
+// If object value exists then it take precedence, else bool value.
+func (t *AdditionalProperties) MarshalJSON() ([]byte, error) {
+	if t.ObjectValue != nil {
+		return Marshal(t.ObjectValue)
+	}
+	if t.BoolValue != nil {
+		return Marshal(t.BoolValue)
+	}
+	return Marshal(nil)
+}
+
 type OrderedMap map[string]interface{}
 
 // normalizeOrderedMap recursively converts JSON-like data into a tree where

core/schemas/responses.go

@@ -129,14 +129,14 @@ type ResponsesTextConfigFormat struct {
 
 // ResponsesTextConfigFormatJSONSchema represents a JSON schema specification
 type ResponsesTextConfigFormatJSONSchema struct {
-	Name                 *string         `json:"name,omitempty"`
-	Schema               *any            `json:"schema,omitempty"`
-	Description          *string         `json:"description,omitempty"`
-	Strict               *bool           `json:"strict,omitempty"`
-	AdditionalProperties *bool           `json:"additionalProperties,omitempty"`
-	Properties           *map[string]any `json:"properties,omitempty"`
-	Required             []string        `json:"required,omitempty"`
-	Type                 *string         `json:"type,omitempty"`
+	Name                 *string               `json:"name,omitempty"`
+	Schema               *any                  `json:"schema,omitempty"`
+	Description          *string               `json:"description,omitempty"`
+	Strict               *bool                 `json:"strict,omitempty"`
+	AdditionalProperties *AdditionalProperties `json:"additionalProperties,omitempty"`
+	Properties           *map[string]any       `json:"properties,omitempty"`
+	Required             []string              `json:"required,omitempty"`
+	Type                 *string               `json:"type,omitempty"`
 }
 
 type ResponsesResponseConversation struct {