fix: normalize invalid required fields in tool schemas

Author: james-6-23

proxy/translator.go

@@ -1371,6 +1371,7 @@ func stripUnsupportedSchemaKeys(schema map[string]interface{}) {
 
 func sanitizeSchemaForUpstream(schema map[string]interface{}) {
 	stripUnsupportedSchemaKeys(schema)
+	normalizeSchemaRequiredFields(schema)
 	ensureArrayItems(schema)
 }
 
@@ -1485,6 +1486,56 @@ func ensureFunctionParametersRootObject(schema map[string]any) {
 	}
 }
 
+func normalizeSchemaRequiredFields(schema map[string]interface{}) {
+	if rawRequired, exists := schema["required"]; exists {
+		required, ok := rawRequired.([]interface{})
+		if !ok {
+			delete(schema, "required")
+		} else {
+			cleaned := make([]interface{}, 0, len(required))
+			for _, item := range required {
+				if name, ok := item.(string); ok && strings.TrimSpace(name) != "" {
+					cleaned = append(cleaned, name)
+				}
+			}
+			if len(cleaned) == 0 {
+				delete(schema, "required")
+			} else {
+				schema["required"] = cleaned
+			}
+		}
+	}
+	if props, ok := schema["properties"].(map[string]interface{}); ok {
+		for _, v := range props {
+			if sub, ok := v.(map[string]interface{}); ok {
+				normalizeSchemaRequiredFields(sub)
+			}
+		}
+	}
+	if items, ok := schema["items"].(map[string]interface{}); ok {
+		normalizeSchemaRequiredFields(items)
+	}
+	for _, key := range []string{"allOf", "anyOf", "oneOf"} {
+		if arr, ok := schema[key].([]interface{}); ok {
+			for _, item := range arr {
+				if sub, ok := item.(map[string]interface{}); ok {
+					normalizeSchemaRequiredFields(sub)
+				}
+			}
+		}
+	}
+	if addProps, ok := schema["additionalProperties"].(map[string]interface{}); ok {
+		normalizeSchemaRequiredFields(addProps)
+	}
+	if defs, ok := schema["$defs"].(map[string]interface{}); ok {
+		for _, v := range defs {
+			if sub, ok := v.(map[string]interface{}); ok {
+				normalizeSchemaRequiredFields(sub)
+			}
+		}
+	}
+}
+
 // ensureArrayItems 递归为缺失 items 的数组 schema 补上空 schema，
 // 兼容上游对 array 必须声明 items 的校验。
 func ensureArrayItems(schema map[string]interface{}) {

proxy/translator_test.go

@@ -141,6 +141,46 @@ func TestTranslateRequest_FillsMissingArrayItemsInToolSchema(t *testing.T) {
 	}
 }
 
+func TestTranslateRequest_DropsInvalidRequiredInToolSchema(t *testing.T) {
+	raw := []byte(`{
+		"model":"gpt-5.4",
+		"messages":[{"role":"user","content":"test"}],
+		"tools":[
+			{
+				"type":"function",
+				"function":{
+					"name":"session_status",
+					"parameters":{
+						"type":"object",
+						"required":null,
+						"properties":{
+							"session_id":{"type":"string"},
+							"metadata":{
+								"type":"object",
+								"required":[null, "", "kind"],
+								"properties":{"kind":{"type":"string"}}
+							}
+						}
+					}
+				}
+			}
+		]
+	}`)
+
+	got, err := TranslateRequest(raw)
+	if err != nil {
+		t.Fatalf("TranslateRequest returned error: %v", err)
+	}
+
+	if required := gjson.GetBytes(got, "tools.0.parameters.required"); required.Exists() {
+		t.Fatalf("null required should be removed from tool schema, got %s; body=%s", required.Raw, got)
+	}
+	nestedRequired := gjson.GetBytes(got, "tools.0.parameters.properties.metadata.required")
+	if nestedRequired.Raw != `["kind"]` {
+		t.Fatalf("nested required should keep only string entries, got %s; body=%s", nestedRequired.Raw, got)
+	}
+}
+
 func TestPrepareResponsesBody_FillsMissingArrayItemsInToolSchema(t *testing.T) {
 	raw := []byte(`{
 		"model":"gpt-5.4",
@@ -167,6 +207,41 @@ func TestPrepareResponsesBody_FillsMissingArrayItemsInToolSchema(t *testing.T) {
 	}
 }
 
+func TestPrepareResponsesBody_DropsInvalidRequiredInToolSchema(t *testing.T) {
+	raw := []byte(`{
+		"model":"gpt-5.4",
+		"input":"test",
+		"tools":[
+			{
+				"type":"function",
+				"name":"session_status",
+				"parameters":{
+					"type":"object",
+					"required":null,
+					"properties":{
+						"session_id":{"type":"string"},
+						"metadata":{
+							"type":"object",
+							"required":[null, "", "kind"],
+							"properties":{"kind":{"type":"string"}}
+						}
+					}
+				}
+			}
+		]
+	}`)
+
+	got, _ := PrepareResponsesBody(raw)
+
+	if required := gjson.GetBytes(got, "tools.0.parameters.required"); required.Exists() {
+		t.Fatalf("null required should be removed from tool schema, got %s; body=%s", required.Raw, got)
+	}
+	nestedRequired := gjson.GetBytes(got, "tools.0.parameters.properties.metadata.required")
+	if nestedRequired.Raw != `["kind"]` {
+		t.Fatalf("nested required should keep only string entries, got %s; body=%s", nestedRequired.Raw, got)
+	}
+}
+
 func TestPrepareResponsesBody_DefaultsNullFunctionToolParameters(t *testing.T) {
 	raw := []byte(`{
 		"model":"gpt-5.4",