diff --git a/package-lock.json b/package-lock.json
index fef96d4..6aceac1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "behavior3editor",
-  "version": "1.8.5",
+  "version": "1.8.7",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "behavior3editor",
-      "version": "1.8.5",
+      "version": "1.8.7",
       "hasInstallScript": true,
       "license": "MIT",
       "dependencies": {
diff --git a/package.json b/package.json
index 3b47d98..20102b3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "behavior3editor",
-  "version": "1.8.5",
+  "version": "1.8.7",
   "main": "dist-electron/main/index.js",
   "description": "行为树编辑器",
   "author": "zhandouxiaojiji & codetypes",
diff --git a/src/components/inspector.tsx b/src/components/inspector.tsx
index 75ce55e..2c719fe 100644
--- a/src/components/inspector.tsx
+++ b/src/components/inspector.tsx
@@ -549,7 +549,7 @@ const validateArg = (
   } else if (value === null && !required) {
     value = undefined;
   }
-  if (!checkNodeArgValue(node, arg, value, true)) {
+  if (!checkNodeArgValue(node, arg, value, console.error)) {
     return Promise.reject(new Error(i18n.t("node.invalidValue")));
   }
   return Promise.resolve(value);
diff --git a/src/components/register-node.ts b/src/components/register-node.ts
index 246cc7a..fff80f8 100644
--- a/src/components/register-node.ts
+++ b/src/components/register-node.ts
@@ -748,7 +748,7 @@ class TreeNode extends Rect {
       !b3util.nodeDefs.has(data.name) ||
       (data.path && !node.children?.length) ||
       (nodeDef.group && !nodeDef.group.some((g) => b3util.usingGroups?.[g])) ||
-      !b3util.checkTreeData(data) ||
+      !b3util.isValidNodeData(data) ||
       foundUndefined(data.input) ||
       foundUndefined(data.output) ||
       foundUndefinedInArgs(nodeDef, data) ||
diff --git a/src/misc/b3type.ts b/src/misc/b3type.ts
index d955289..3edbc13 100644
--- a/src/misc/b3type.ts
+++ b/src/misc/b3type.ts
@@ -1,6 +1,6 @@
 import { NodeDef } from "../behavior3/src/behavior3";
 
-export const VERSION = "1.8.5";
+export const VERSION = "1.8.7";
 
 export const keyWords = ["true", "false", "null", "undefined", "NaN", "Infinity"];
 
@@ -73,6 +73,7 @@ export interface TreeData {
   group: string[];
   import: string[];
   vars: VarDecl[];
+  custom: Record<string, string | number | boolean | object>;
   root: NodeData;
 
   $override: {
diff --git a/src/misc/b3util.ts b/src/misc/b3util.ts
index df69105..bd73059 100644
--- a/src/misc/b3util.ts
+++ b/src/misc/b3util.ts
@@ -20,10 +20,11 @@ import {
   VERSION,
 } from "./b3type";
 import Path from "./path";
+import { stringifyJson } from "./stringify";
 import { nanoid, readJson, readTree, readWorkspace } from "./util";
 
 export class NodeDefs extends Map<string, NodeDef> {
-  get(key: string): NodeDef {
+  override get(key: string): NodeDef {
     return super.get(key) ?? unknownNodeDef;
   }
 }
@@ -188,8 +189,10 @@ export const isNodeEqual = (node1: NodeData, node2: NodeData) => {
   return false;
 };
 
-const error = (data: NodeData, msg: string) => {
-  console.error(`check ${data.id}|${data.name}: ${msg}`);
+type ErrorPrinter = (msg: string) => void;
+
+const formatError = (data: NodeData, msg: string) => {
+  return `check ${data.id}|${data.name}: ${msg}`;
 };
 
 export const getNodeArgRawType = (arg: NodeArg) => {
@@ -208,75 +211,62 @@ export const checkNodeArgValue = (
   data: NodeData,
   arg: NodeArg,
   value: unknown,
-  verbose?: boolean
+  printer?: ErrorPrinter
 ) => {
   let hasError = false;
   const type = getNodeArgRawType(arg);
+  const error = !printer ? () => {} : (msg: string) => printer(formatError(data, msg));
   if (isFloatType(type)) {
     const isNumber = typeof value === "number";
     const isOptional = value === undefined && isNodeArgOptional(arg);
     if (!(isNumber || isOptional)) {
-      if (verbose) {
-        error(data, `'${arg.name}=${JSON.stringify(value)}' is not a number`);
-      }
+      error(`'${arg.name}=${JSON.stringify(value)}' is not a number`);
       hasError = true;
     }
   } else if (isIntType(type)) {
     const isInt = typeof value === "number" && value === Math.floor(value);
     const isOptional = value === undefined && isNodeArgOptional(arg);
     if (!(isInt || isOptional)) {
-      if (verbose) {
-        error(data, `'${arg.name}=${JSON.stringify(value)}' is not a int`);
-      }
+      error(`'${arg.name}=${JSON.stringify(value)}' is not a int`);
       hasError = true;
     }
   } else if (isStringType(type)) {
     const isString = typeof value === "string" && value;
     const isOptional = (value === undefined || value === "") && isNodeArgOptional(arg);
     if (!(isString || isOptional)) {
-      if (verbose) {
-        error(data, `'${arg.name}=${JSON.stringify(value)}' is not a string`);
-      }
+      error(`'${arg.name}=${JSON.stringify(value)}' is not a string`);
       hasError = true;
     }
   } else if (isExprType(type)) {
     const isExpr = typeof value === "string" && value;
     const isOptional = (value === undefined || value === "") && isNodeArgOptional(arg);
     if (!(isExpr || isOptional)) {
-      if (verbose) {
-        error(data, `'${arg.name}=${JSON.stringify(value)}' is not an expr string`);
-      }
+      error(`'${arg.name}=${JSON.stringify(value)}' is not an expr string`);
       hasError = true;
     }
   } else if (isJsonType(type)) {
     const isJson = value !== undefined && value !== "";
     const isOptional = isNodeArgOptional(arg);
     if (!(isJson || isOptional)) {
-      if (verbose) {
-        error(data, `'${arg.name}=${value}' is not an invalid object`);
-      }
+      error(`'${arg.name}=${value}' is not an invalid object`);
       hasError = true;
     }
   } else if (isBoolType(type)) {
     const isBool = typeof value === "boolean" || value === undefined;
     if (!isBool) {
-      if (verbose) {
-        error(data, `'${arg.name}=${JSON.stringify(value)}' is not a boolean`);
-      }
+      error(`'${arg.name}=${JSON.stringify(value)}' is not a boolean`);
       hasError = true;
     }
   } else {
     hasError = true;
-    error(data, `unknown arg type '${arg.type}'`);
+    error(`unknown arg type '${arg.type}'`);
   }
 
   if (hasArgOptions(arg)) {
     const found = !!arg.options?.find((option) => option.value === value);
     const isOptional = value === undefined && isNodeArgOptional(arg);
     if (!(found || isOptional)) {
-      if (verbose) {
-        error(data, `'${arg.name}=${JSON.stringify(value)}' is not a one of the option values`);
-      }
+      error(`'${arg.name}=${JSON.stringify(value)}' is not a one of the option values`);
       hasError = true;
     }
   }
@@ -284,37 +274,34 @@ export const checkNodeArgValue = (
   return !hasError;
 };
 
-export const checkNodeArg = (data: NodeData, conf: NodeDef, i: number, verbose?: boolean) => {
+export const checkNodeArg = (data: NodeData, conf: NodeDef, i: number, printer?: ErrorPrinter) => {
   let hasError = false;
   const arg = conf.args![i] as NodeArg;
   const value = data.args?.[arg.name];
+  const error = !printer ? () => {} : (msg: string) => printer(formatError(data, msg));
   if (isNodeArgArray(arg)) {
     if (!Array.isArray(value) || value.length === 0) {
       if (!isNodeArgOptional(arg)) {
-        if (verbose) {
-          error(data, `'${arg.name}=${JSON.stringify(value)}' is not an array or empty array`);
-        }
+        error(`'${arg.name}=${JSON.stringify(value)}' is not an array or empty array`);
         hasError = true;
       }
     } else {
       for (let j = 0; j < value.length; j++) {
-        if (!checkNodeArgValue(data, arg, value[j], verbose)) {
+        if (!checkNodeArgValue(data, arg, value[j], printer)) {
           hasError = true;
         }
       }
     }
-  } else if (!checkNodeArgValue(data, arg, value, verbose)) {
+  } else if (!checkNodeArgValue(data, arg, value, printer)) {
     hasError = true;
   }
   if (arg.oneof !== undefined) {
     const idx = conf.input?.findIndex((v) => v.startsWith(arg.oneof!)) ?? -1;
     if (!checkOneof(arg, data.args?.[arg.name], data.input?.[idx])) {
-      if (verbose) {
-        error(
-          data,
-          `only one is allowed for between argument '${arg.name}' and input '${data.input?.[idx]}'`
-        );
-      }
+      error(
+        `only one is allowed for between argument '${arg.name}' and input '${data.input?.[idx]}'`
+      );
+
       hasError = true;
     }
   }
@@ -333,13 +320,44 @@ export const checkOneof = (arg: NodeArg, argValue: unknown, inputValue: unknown)
   return (argValue !== "" && inputValue === "") || (argValue === "" && inputValue !== "");
 };
 
-export const checkNodeData = (data: NodeData | null | undefined) => {
+export const isValidNodeData = (data: NodeData) => {
+  const def = nodeDefs.get(data.name);
+  if (def.input) {
+    for (let i = 0; i < def.input.length; i++) {
+      if (!isValidInputOrOutput(def.input, data.input, i)) {
+        return false;
+      }
+    }
+  }
+  if (def.output) {
+    for (let i = 0; i < def.output.length; i++) {
+      if (!isValidInputOrOutput(def.output, data.output, i)) {
+        return false;
+      }
+    }
+  }
+  if (!isValidChildren(data)) {
+    return false;
+  }
+  if (def.args) {
+    for (let i = 0; i < def.args.length; i++) {
+      if (!checkNodeArg(data, def, i)) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+};
+
+const checkNodeData = (data: NodeData | null | undefined, printer: ErrorPrinter) => {
   if (!data) {
     return false;
   }
+  const error = !printer ? () => {} : (msg: string) => printer(formatError(data, msg));
   const conf = nodeDefs.get(data.name);
   if (conf.name === unknownNodeDef.name) {
-    error(data, `undefined node: ${data.name}`);
+    error(`undefined node: ${data.name}`);
     return false;
   }
 
@@ -347,7 +365,7 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
 
   if (conf.group) {
     if (!conf.group.some((g) => usingGroups?.[g])) {
-      error(data, `node group '${conf.group}' is not enabled`);
+      error(`node group '${conf.group}' is not enabled`);
       hasError = true;
     }
   }
@@ -356,7 +374,7 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
     if (data.input) {
       for (const v of data.input) {
         if (v && !usingVars[v]) {
-          error(data, `input variable '${v}' is not defined`);
+          error(`input variable '${v}' is not defined`);
           hasError = true;
         }
       }
@@ -364,7 +382,7 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
     if (data.output) {
       for (const v of data.output) {
         if (v && !usingVars[v]) {
-          error(data, `output variable '${v}' is not defined`);
+          error(`output variable '${v}' is not defined`);
           hasError = true;
         }
       }
@@ -386,7 +404,7 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
           }
           for (const v of vars) {
             if (v && !usingVars[v]) {
-              error(data, `expr variable '${arg.name}' is not defined`);
+              error(`expr variable '${arg.name}' is not defined`);
               hasError = true;
             }
           }
@@ -403,11 +421,11 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
           for (const expr of exprs) {
             try {
               if (!new ExpressionEvaluator(expr).dryRun()) {
-                error(data, `expr '${expr}' is not valid`);
+                error(`expr '${expr}' is not valid`);
                 hasError = true;
               }
             } catch (e) {
-              error(data, `expr '${expr}' is not valid`);
+              error(`expr '${expr}' is not valid`);
               hasError = true;
             }
           }
@@ -420,7 +438,7 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
     const count = data.children?.length || 0;
     if (conf.children !== count) {
       hasError = true;
-      error(data, `expect ${conf.children} children, but got ${count}`);
+      error(`expect ${conf.children} children, but got ${count}`);
     }
   }
 
@@ -435,14 +453,13 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
       }
       if (data.input[i] && !isValidVariableName(data.input[i])) {
         error(
-          data,
           `input field '${data.input[i]}' is not a valid variable name,` +
             `should start with a letter or underscore`
         );
         hasError = true;
       }
       if (!isValidInputOrOutput(conf.input, data.input, i)) {
-        error(data, `intput field '${conf.input[i]}' is required`);
+        error(`intput field '${conf.input[i]}' is required`);
         hasError = true;
       }
       if (i === conf.input.length - 1 && conf.input.at(-1)?.endsWith("...")) {
@@ -465,14 +482,13 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
       }
       if (data.output[i] && !isValidVariableName(data.output[i])) {
         error(
-          data,
           `output field '${data.output[i]}' is not a valid variable name,` +
             `should start with a letter or underscore`
         );
         hasError = true;
       }
       if (!isValidInputOrOutput(conf.output, data.output, i)) {
-        error(data, `output field '${conf.output[i]}' is required`);
+        error(`output field '${conf.output[i]}' is required`);
         hasError = true;
       }
       if (i === conf.output.length - 1 && conf.output.at(-1)?.endsWith("...")) {
@@ -496,7 +512,7 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
         args[key] = value;
       }
 
-      if (!checkNodeArg(data, conf, i, true)) {
+      if (!checkNodeArg(data, conf, i, printer)) {
         hasError = true;
       }
     }
@@ -505,7 +521,7 @@ export const checkNodeData = (data: NodeData | null | undefined) => {
 
   if (data.children) {
     for (const child of data.children) {
-      if (!checkNodeData(child)) {
+      if (!checkNodeData(child, printer)) {
         hasError = true;
       }
     }
@@ -665,36 +681,6 @@ const isValidInputOrOutput = (def: string[], data: string[] | undefined, index:
   return def[index].includes("?") || data?.[index] || isVariadic(def, index);
 };
 
-export const checkTreeData = (data: NodeData) => {
-  const def = nodeDefs.get(data.name);
-  if (def.input) {
-    for (let i = 0; i < def.input.length; i++) {
-      if (!isValidInputOrOutput(def.input, data.input, i)) {
-        return false;
-      }
-    }
-  }
-  if (def.output) {
-    for (let i = 0; i < def.output.length; i++) {
-      if (!isValidInputOrOutput(def.output, data.output, i)) {
-        return false;
-      }
-    }
-  }
-  if (!isValidChildren(data)) {
-    return false;
-  }
-  if (def.args) {
-    for (let i = 0; i < def.args.length; i++) {
-      if (!checkNodeArg(data, def, i, false)) {
-        return false;
-      }
-    }
-  }
-
-  return true;
-};
-
 export const refreshNodeData = (tree: TreeData, node: NodeData, id: number) => {
   node.id = (id++).toString();
   node.$size = calcSize(node);
@@ -721,8 +707,8 @@ export const refreshNodeData = (tree: TreeData, node: NodeData, id: number) => {
       const subtreePath = workdir + "/" + node.path;
       const subtree = readTree(subtreePath);
       id = refreshNodeData(subtree, subtree.root, --id);
-      node.name = subtree.name;
-      node.desc = subtree.desc;
+      node.name = subtree.root.name;
+      node.desc = subtree.root.desc;
       node.args = subtree.root.args;
       node.input = subtree.root.input;
       node.output = subtree.root.output;
@@ -761,6 +747,8 @@ export const createBuildData = (path: string) => {
     dfs(treeModel.root, (node) => (node.id = treeModel.prefix + node.id));
     treeModel.name = Path.basenameWithoutExt(path);
     treeModel.root = createFileData(treeModel.root, true);
+    dfs(treeModel.root, (node) => delete (node as Partial<NodeData>).$id);
+    delete (treeModel as Partial<TreeData>).$override;
     return treeModel as TreeData;
   } catch (e) {
     console.log("build error:", path, e);
@@ -826,6 +814,7 @@ export const buildProject = async (project: string, buildDir: string) => {
     });
   }
 
+  const allErrors: string[] = [];
   for (const path of Path.ls(Path.dirname(project), true)) {
     if (path.endsWith(".json")) {
       const buildpath = buildDir + "/" + path.substring(workdir.length + 1);
@@ -843,7 +832,6 @@ export const buildProject = async (project: string, buildDir: string) => {
       }
       console.log("build:", buildpath);
       if (errors.length) {
-        errors.forEach((msg) => console.error(msg));
         hasError = true;
       }
       const declare: FileVarDecl = {
@@ -852,14 +840,19 @@ export const buildProject = async (project: string, buildDir: string) => {
         subtree: [],
       };
       refreshVarDecl(tree.root, tree.group, declare);
-      if (!checkNodeData(tree?.root)) {
+      if (!checkNodeData(tree?.root, (msg) => errors.push(msg))) {
         hasError = true;
       }
+      if (errors.length) {
+        allErrors.push(`${path}:`);
+        errors.forEach((v) => allErrors.push(`  ${v}`));
+      }
       buildScript?.onWriteFile?.(buildpath, tree);
       fs.mkdirSync(Path.dirname(buildpath), { recursive: true });
-      fs.writeFileSync(buildpath, JSON.stringify(tree, null, 2));
+      fs.writeFileSync(buildpath, stringifyJson(tree, { indent: 2 }));
     }
   }
+  allErrors.forEach((v) => console.error(v));
   buildScript?.onComplete?.(hasError ? "failure" : "success");
   return hasError;
 };
@@ -930,6 +923,7 @@ export const createNewTree = (path: string) => {
       name: "Sequence",
       $id: nanoid(),
     },
+    custom: {},
     $override: {},
   };
   return tree;
@@ -1017,7 +1011,7 @@ const collectSubtree = (data: NodeData) => {
 export const refreshVarDecl = (root: NodeData, group: string[], declare: FileVarDecl) => {
   const filter: Record<string, boolean> = {};
   const vars: Array<VarDecl> = new (class extends Array {
-    push(...items: VarDecl[]): number {
+    override push(...items: VarDecl[]): number {
       for (const v of items) {
         if (filter[v.name]) {
           continue;
diff --git a/src/misc/stringify.ts b/src/misc/stringify.ts
new file mode 100644
index 0000000..c17a3de
--- /dev/null
+++ b/src/misc/stringify.ts
@@ -0,0 +1,332 @@
+import * as fs from "node:fs";
+import { basename, dirname, extname } from "node:path";
+
+export type Tag = {
+  /** data name */
+  ["!name"]?: string;
+  /** type tag */
+  ["!type"]?: string;
+  /** special stringify function */
+  ["!stringify"]?: (v: TValue, ctx: StringifyContext) => void;
+  /** ignore fields when stringify */
+  ["!ignore"]?: { [k: string]: boolean };
+};
+
+export type TValue = boolean | number | string | null | undefined | TObject | TArray;
+export type TObject = { [k: string | number]: TValue } & Tag;
+export type TArray = TValue[] & Tag;
+
+export class StringBuffer {
+  readonly data: string[] = [];
+
+  private _indent: number;
+  private _indentCount: number = 0;
+
+  constructor(indent: number) {
+    this._indent = indent;
+  }
+
+  get indentCount() {
+    return this._indentCount;
+  }
+
+  indent() {
+    this._indentCount += this._indent;
+  }
+
+  unindent() {
+    this._indentCount -= this._indent;
+  }
+
+  padding() {
+    if (this._indent > 0) {
+      this.data.push(" ".repeat(this._indentCount));
+    }
+  }
+
+  linefeed() {
+    if (this._indent > 0) {
+      this.data.push("\n");
+    }
+  }
+
+  writeLine(value: string) {
+    this.padding();
+    this.data.push(value);
+    this.linefeed();
+  }
+
+  writeLines(value: string) {
+    for (const line of value.split("\n")) {
+      this.writeLine(line);
+    }
+  }
+
+  writeString(value: string) {
+    this.data.push(value);
+  }
+
+  toString() {
+    return this.data.join("");
+  }
+}
+
+export const isNumericKey = (key: string) => {
+  if (typeof key !== "string") return false;
+
+  // integer or bigint
+  if (/^-?\d+$/.test(key)) {
+    try {
+      return String(BigInt(key)) === key;
+    } catch {
+      return false;
+    }
+  }
+
+  // float
+  const num = Number(key);
+  return !isNaN(num) && String(num) === key;
+};
+
+export const escape = (value: string) => {
+  return value
+    .replaceAll("\r\n", "\n")
+    .replaceAll("\\", "\\\\")
+    .replaceAll('"', '\\"')
+    .replaceAll("\n", "\\n")
+    .replaceAll("\t", "\\t")
+    .replaceAll("\r", "\\r")
+    .replaceAll("\b", "\\b")
+    .replaceAll("\f", "\\f");
+};
+
+export const outdent = (value: string) => {
+  value = value.replace(/^\n/, "");
+  value = value.replace(/\n *$/, "");
+  const space = value.match(/^ +/gm)?.[0];
+  return space ? value.replace(new RegExp(`^${space}`, "gm"), "") : value;
+};
+
+export const format = (str: string, vars: Record<string, string>) => {
+  const lines: string[] = [];
+  for (const line of str.split(/\n|\r\n/)) {
+    if (line.match(/^\s*%{\w+}\s*$/)) {
+      const [_, space, key] = line.match(/^(\s*)%{(\w+)}$/)!;
+      if (vars[key] !== undefined && vars[key] !== null) {
+        for (const l of vars[key].split(/\n|\r\n/)) {
+          lines.push(space + l);
+        }
+      } else {
+        throw new Error(`variable '${key}' not found`);
+      }
+    } else {
+      lines.push(
+        line.replaceAll(/%{(\w+)}/g, (_, key) => {
+          if (vars[key] !== undefined && vars[key] !== null) {
+            return vars[key];
+          }
+          throw new Error(`variable '${key}' not found`);
+        })
+      );
+    }
+  }
+  return lines.join("\n");
+};
+
+export const keys = (
+  o: object,
+  filter?: (v: TValue) => boolean,
+  ignore?: { [k: string]: boolean }
+) => {
+  const value = o as TObject;
+  const ks = Object.keys(value).filter(
+    (k) => !k.startsWith("!") && (!ignore || !ignore[k]) && (!filter || filter(value[k]))
+  );
+
+  const numKeys: string[] = [];
+  const strKeys: string[] = [];
+  for (const k of ks) {
+    const num = Number(k);
+    if (!isNaN(num) && isFinite(num)) {
+      numKeys.push(k);
+    } else {
+      strKeys.push(k);
+    }
+  }
+  numKeys.sort((a, b) => Number(a) - Number(b) || a.localeCompare(b));
+  strKeys.sort((a, b) => a.localeCompare(b));
+  return [...numKeys, ...strKeys];
+};
+
+export const values = <T>(
+  o: TObject,
+  filter?: (v: TValue) => boolean,
+  ignore?: { [k: string]: boolean }
+): T[] => {
+  return keys(o, filter, ignore).map((k) => o[k] as T);
+};
+
+export const toPascalCase = (str: string): string => {
+  return str
+    .replace(/^_+/, "")
+    .replace(/_([a-zA-Z])/g, (_, letter) => letter.toUpperCase())
+    .replace(/^[a-zA-Z]/, (match) => match.toUpperCase());
+};
+
+export const readFile = (path: string) => {
+  if (fs.existsSync(path)) {
+    return fs.readFileSync(path, "utf-8");
+  }
+  return null;
+};
+
+export const writeFile = (path: string, data: string) => {
+  const dir = dirname(path);
+  if (!fs.existsSync(dir)) {
+    fs.mkdirSync(dir, { recursive: true });
+  }
+  if (fs.existsSync(path) && readFile(path) === data) {
+    console.log(`up-to-date: ${path}`);
+  } else {
+    console.log(`write: ${path}`);
+    fs.writeFileSync(path, data, { encoding: "utf-8" });
+  }
+};
+
+export const writeJson = (path: string, data: TValue, options?: JsonStringifyOption) => {
+  options = options ?? {};
+  options.indent = options.indent ?? 2;
+  options.precision = options.precision ?? 10;
+  writeFile(path, stringifyJson(data, options));
+};
+
+export const filename = (path: string, suffix: boolean = false) => {
+  return basename(path, !suffix ? extname(path) : undefined);
+};
+
+export type StringifyContext = {
+  readonly format: "json" | "lua" | "ts" | string;
+  readonly indent: number;
+  readonly precision?: number;
+  readonly buffer: StringBuffer;
+  readonly writeValue: (value: TValue) => void;
+  readonly writeArray: (value: TArray) => void;
+  readonly writeObject: (value: TObject) => void;
+};
+
+const numberToString = (value: number, precision?: number) => {
+  if (value === (value | 0)) {
+    return value.toFixed(0);
+  } else {
+    return value.toFixed(precision).replace(/\.?0+$/, "");
+  }
+};
+
+//-----------------------------------------------------------------------------
+// Json
+//-----------------------------------------------------------------------------
+export type JsonStringifyOption = {
+  indent?: number;
+  precision?: number;
+};
+
+export const stringifyJson = (data: unknown, option?: JsonStringifyOption) => {
+  const stacks: string[] = [];
+  option = option ?? {};
+  option.indent = Math.max(option.indent ?? 4, 0);
+  option.precision = option.precision ?? 10;
+  const buffer = new StringBuffer(option.indent);
+  const ctx: StringifyContext = {
+    format: "json",
+    indent: option.indent,
+    precision: option.precision,
+    buffer,
+    writeValue: writeJsonValue,
+    writeArray: writeJsonArray,
+    writeObject: writeJsonObject,
+  };
+
+  function writeJsonValue(value: TValue) {
+    if (typeof value === "number") {
+      buffer.writeString(numberToString(value, ctx.precision));
+    } else if (typeof value === "boolean") {
+      buffer.writeString(value.toString());
+    } else if (value === null || value === undefined) {
+      buffer.writeString("null");
+    } else if (typeof value === "string") {
+      buffer.writeString('"');
+      buffer.writeString(escape(value));
+      buffer.writeString('"');
+    } else if (Array.isArray(value)) {
+      writeJsonArray(value);
+    } else {
+      if (typeof value !== "object" || value === null || value === undefined) {
+        writeJsonValue(value);
+      } else if (Array.isArray(value)) {
+        writeJsonArray(value);
+      } else {
+        writeJsonObject(value as TObject);
+      }
+    }
+  }
+
+  function writeJsonObject(value: TObject) {
+    if (stacks.length > 256) {
+      throw new Error(`json stringify stack overflow: ${stacks.join("->")}`);
+    }
+
+    if (value["!stringify"]) {
+      value["!stringify"](value, ctx);
+      return;
+    }
+
+    const ks = keys(value, undefined, value["!ignore"]);
+    const space = ctx.indent > 0 ? " " : "";
+    buffer.writeString("{");
+    buffer.linefeed();
+    buffer.indent();
+    for (let i = 0; i < ks.length; i++) {
+      const k = ks[i];
+      const v = value[k];
+      stacks.push(k);
+      buffer.padding();
+      buffer.writeString(`"${k}":${space}`);
+      writeJsonValue(v);
+      if (i < ks.length - 1) {
+        buffer.writeString(",");
+      }
+      buffer.linefeed();
+      stacks.pop();
+    }
+    buffer.unindent();
+    buffer.padding();
+    buffer.writeString("}");
+  }
+
+  function writeJsonArray(value: TArray) {
+    if (value["!stringify"]) {
+      value["!stringify"](value, ctx);
+      return;
+    }
+
+    buffer.writeString("[");
+    buffer.linefeed();
+    buffer.indent();
+    for (let i = 0; i < value.length; i++) {
+      const v = value[i];
+      buffer.padding();
+      writeJsonValue(v);
+      if (i < value.length - 1) {
+        buffer.writeString(",");
+      }
+      buffer.linefeed();
+    }
+    buffer.unindent();
+    buffer.padding();
+    buffer.writeString("]");
+  }
+
+  writeJsonValue(data as TValue);
+
+  return buffer.toString();
+};
diff --git a/src/misc/util.ts b/src/misc/util.ts
index e6e1fec..f167e4a 100644
--- a/src/misc/util.ts
+++ b/src/misc/util.ts
@@ -4,6 +4,7 @@ import { type WorkspaceModel } from "../contexts/workspace-context";
 import { VERSION, type TreeData } from "./b3type";
 import { dfs } from "./b3util";
 import Path from "./path";
+import { stringifyJson } from "./stringify";
 
 export const nanoid = customAlphabet(
   "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ",
@@ -16,7 +17,7 @@ export const readJson = <T>(path: string): T => {
 };
 
 export const writeJson = <T>(path: string, data: T) => {
-  const str = JSON.stringify(data, undefined, 2);
+  const str = stringifyJson(data, { indent: 2 });
   fs.writeFileSync(path, str, "utf-8");
 };
 
@@ -34,6 +35,8 @@ export const readTree = (path: string) => {
   data.import = data.import || [];
   data.vars = data.vars || [];
   data.root = data.root || {};
+  data.$override = data.$override || {};
+  data.custom = data.custom || {};
 
   // compatible with old version
   dfs(data.root, (node) => {
@@ -57,6 +60,7 @@ export const writeTree = (path: string, data: TreeData) => {
     import: data.import,
     vars: data.vars,
     root: data.root,
+    custom: data.custom,
     $override: data.$override,
   });
 };