diff --git a/packages/engine5/src/alwatr-store.ts b/packages/engine5/src/alwatr-store.ts
index 53549f95..8989937a 100644
--- a/packages/engine5/src/alwatr-store.ts
+++ b/packages/engine5/src/alwatr-store.ts
@@ -1,10 +1,10 @@
 import {CollectionReference} from './lib/collection-reference.js';
 import {DocumentReference} from './lib/document-reference.js';
-import {logger} from './lib/logger.js';
 import {WriteFileMode, existsSync, readJsonFile, resolve, unlink, writeJsonFile} from './lib/util.js';
+import {logger} from './logger.js';
 import {
   StoreFileType,
-  StoreFileEncoding,
+  StoreFileExtension,
   Region,
   StoreFileTTL,
   type StoreFileStat,
@@ -18,6 +18,21 @@ export {Region, StoreFileTTL};
 
 logger.logModule?.('alwatr-store');
 
+export interface AlwatrStoreConfig {
+  /**
+   * The root path of the storage.
+   * This is where the AlwatrStore will store its data.
+   */
+  rootPath: string;
+
+  /**
+   * The save debounce timeout in milliseconds for minimal disk I/O usage.
+   * This is used to limit the frequency of disk writes for performance reasons.
+   * The recommended value is `50`.
+   */
+  saveDebounce: number;
+}
+
 /**
  * AlwatrStore engine.
  *
@@ -38,8 +53,8 @@ export class AlwatrStore {
   protected static readonly rootDbStat_: StoreFileStat = {
     id: '.store',
     region: Region.Secret,
-    type: StoreFileType.collection,
-    encoding: StoreFileEncoding.json,
+    type: StoreFileType.Collection,
+    extension: StoreFileExtension.Json,
     ttl: StoreFileTTL.maximum,
   };
 
@@ -63,12 +78,12 @@ export class AlwatrStore {
       });
 
       switch (context.meta?.type) {
-        case StoreFileType.document: {
+        case StoreFileType.Document: {
           DocumentReference.migrateContext_(context);
           break;
         }
 
-        case StoreFileType.collection: {
+        case StoreFileType.Collection: {
           CollectionReference.migrateContext_(context);
           break;
         }
@@ -178,8 +193,8 @@ export class AlwatrStore {
     logger.logMethodArgs?.('defineDocument', config);
     const stat: StoreFileStat = {
       ...config,
-      type: StoreFileType.document,
-      encoding: StoreFileEncoding.json,
+      type: StoreFileType.Document,
+      extension: StoreFileExtension.Json,
     };
     this.addStoreFile_(stat);
     return this.writeContext_(
@@ -206,8 +221,8 @@ export class AlwatrStore {
     logger.logMethodArgs?.('defineCollection', config);
     const stat: StoreFileStat = {
       ...config,
-      type: StoreFileType.collection,
-      encoding: StoreFileEncoding.json,
+      type: StoreFileType.Collection,
+      extension: StoreFileExtension.Json,
     };
     this.addStoreFile_(stat);
     return this.writeContext_(stat.id, CollectionReference.newContext_(config.id, config.region, stat.ownerId));
@@ -234,7 +249,7 @@ export class AlwatrStore {
       throw new Error('document_not_found', {cause: {id}});
     }
     const stat = this.stat(id);
-    if (stat.type != StoreFileType.document) {
+    if (stat.type != StoreFileType.Document) {
       logger.accident('doc', 'document_wrong_type', stat);
       throw new Error('document_not_found', {cause: stat});
     }
@@ -268,7 +283,7 @@ export class AlwatrStore {
       throw new Error('collection_not_found', {cause: {id}});
     }
     const stat = this.stat(id);
-    if (stat.type != StoreFileType.collection) {
+    if (stat.type != StoreFileType.Collection) {
       logger.accident('collection', 'collection_wrong_type', stat);
       throw new Error('collection_not_found', {cause: stat});
     }
@@ -394,7 +409,7 @@ export class AlwatrStore {
     if (stat.ownerId !== undefined) {
       regionPath += `/${stat.ownerId.slice(0, 3)}/${stat.ownerId}`;
     }
-    return resolve(this.config_.rootPath, regionPath, `${stat.id}.${stat.type}.${stat.encoding}`);
+    return resolve(this.config_.rootPath, regionPath, `${stat.id}.${stat.type}.${stat.extension}`);
   }
 
   /**
diff --git a/packages/engine5/src/lib/util.ts b/packages/engine5/src/lib/util.ts
index 2619f11b..b04b9081 100644
--- a/packages/engine5/src/lib/util.ts
+++ b/packages/engine5/src/lib/util.ts
@@ -9,7 +9,7 @@ import {
 import {copyFile, mkdir, readFile as readFile_, rename, writeFile as writeFile_, unlink} from 'node:fs/promises';
 import {dirname} from 'node:path';
 
-import {logger} from './logger.js';
+import {logger} from '../logger.js';
 import {MaybePromise} from '../type.js';
 
 export {resolve} from 'node:path';
diff --git a/packages/engine5/src/type.ts b/packages/engine5/src/type.ts
deleted file mode 100644
index bcc448dc..00000000
--- a/packages/engine5/src/type.ts
+++ /dev/null
@@ -1,268 +0,0 @@
-export type MaybePromise<T> = T | Promise<T>;
-
-// *** Configs ***
-
-export interface AlwatrStoreConfig {
-  /**
-   * The root path of the storage.
-   * This is where the AlwatrStore will store its data.
-   */
-  rootPath: string;
-
-  /**
-   * The save debounce timeout in milliseconds for minimal disk I/O usage.
-   * This is used to limit the frequency of disk writes for performance reasons.
-   * The recommended value is `50`.
-   */
-  saveDebounce: number;
-}
-
-
-// *** Store File ***
-
-/**
- * The subdirectory location for each store file.
- */
-export enum Region {
-  /**
-   * Store file location that can be accessed by anyone.
-   */
-  Public = 'p',
-
-  /**
-   * Store file location that can be accessed by authenticated users.
-   */
-  Authenticated = 'a',
-
-  /**
-   * Store file location that can be accessed by super admin only.
-   */
-  SuperAdmin = 'sa',
-
-  /**
-   * Store file location specific to each user id. Can be accessed using the user token.
-   */
-  PerUser = 'u',
-
-  /**
-   * Store file location specific to each device id.
-   */
-  PerDevice = 'd',
-
-  /**
-   * Store file location specific to each token.
-   */
-  PerToken = 't',
-
-  /**
-   * Private store file location. Cannot be accessed publicly and must be directly accessed by the admin API only.
-   */
-  Secret = 'secret',
-}
-
-/**
- * The different types of store file formats.
- */
-export enum StoreFileType {
-  /**
-   * Type used for `single document` storage.
-   */
-  Document = 'doc',
-
-  /**
-   * Type used for storing a `collection` of simpler documents, referred to as collection items.
-   */
-  Collection = 'col',
-
-  /**
-   * Type used for storing a collection of items that are `append-only`.
-   */
-  AppendOnlyCollection = 'aoc',
-}
-
-/**
- * Store file extension (encode).
- */
-export enum StoreFileExtension {
-  /**
-   * AlwatrStore JSON format.
-   */
-  Json = 'asj',
-}
-
-/**
- * Unique identifier of the store file.
- *
- * Get from user for select store file.
- */
-export interface StoreFileId {
-  // [P: string]: unknown;
-
-  /**
-   * The store filename.
-   */
-  readonly name: string;
-
-  /**
-   * The region where the store file is located.
-   * @see {@link Region}
-   */
-  readonly region: Region;
-
-  /**
-   * The owner of the store file.
-   * If the region is `Region.PerX` then this is the user id, device id, or token id etc.
-   * @see {@link Region}
-   *
-   */
-  readonly ownerId?: string
-}
-
-/**
- * Store the complete metadata of the file in the root database.
- */
-export interface StoreFileStat extends StoreFileId {
-  /**
-   * The type of the store file.
-   *
-   * @see {@link StoreFileType}
-   */
-  readonly type: StoreFileType;
-
-  /**
-   * The extension used for the store file.
-   *
-   * @see {@link StoreFileExtension}
-   */
-  readonly extension: StoreFileExtension;
-
-  /**
-   * The time-to-live (TTL) of the store file in memory.
-   */
-  readonly ttl: number;
-}
-
-/**
- * Represents the metadata of a store file.
- */
-export interface StoreFileMeta extends StoreFileStat {
-  /**
-   * The AlwatrStore engine version.
-   */
-  ver: string;
-
-  /**
-   * Store file format version.
-   */
-  fv: number;
-
-  /**
-   * The revision number of the store file.
-   *
-   * This number is incremented every time the store file is updated.
-   */
-  rev: number;
-
-  /**
-   * The Unix timestamp (in milliseconds since the epoch) for when the store file was updated.
-   */
-  updated: number;
-
-  /**
-   * The Unix timestamp (in milliseconds since the epoch) for when the store file was created.
-   */
-  created: number;
-
-  /**
-   * Last auto increment id.
-   */
-  lastAutoId?: number;
-}
-
-/**
- * Represents the context of a store file.
- * @template TData The type of the data content in the store file.
- */
-export interface StoreFileContext<TData extends Record<string, unknown> = Record<string, unknown>> {
-  /**
-   * The status of the store file.
-   *
-   * if false, the Alwatr store throws an error.
-   */
-  ok: true;
-
-  /**
-   * The metadata of the store file.
-   * @see {@link StoreFileMeta}
-   */
-  meta: StoreFileMeta;
-
-  /**
-   * The data content of the store file.
-   */
-  data: TData;
-}
-
-/**
- * Store file meta only content type.
- */
-export type StoreFileMetaOnlyContext = Omit<StoreFileContext<never>, 'data'>;
-
-// *** Documents ***
-
-/**
- * StoreFileContext for document type.
- */
-export type DocumentContext<TDoc extends Record<string, unknown> = Record<string, unknown>> = StoreFileContext<TDoc>;
-
-
-// *** Collections ***
-
-/**
- * The metadata of an item in a collection.
- */
-export interface CollectionItemMeta {
-  /**
-   * The unique identifier for the collection item.
-   */
-  id: string | number;
-
-  /**
-   * The revision number for the collection item.
-   *
-   * This number is incremented each time the item is updated.
-   */
-  rev: number;
-
-  /**
-   * The Unix timestamp (in milliseconds since the epoch) for when the collection item was updated.
-   */
-  updated: number;
-
-  /**
-   * The Unix timestamp (in milliseconds since the epoch) for when the collection item was created.
-   */
-  created: number;
-}
-
-/**
- * Collection item context type.
- */
-export interface CollectionItem<TItem> {
-/**
-   * Collection item's metadata.
-   */
-  meta: CollectionItemMeta;
-
-  /**
-   * Collection item data.
-   */
-  data: TItem;
-}
-
-/**
- * Collection item context type.
- */
-export type CollectionContext<TItem extends Record<string, unknown> = Record<string, unknown>> = StoreFileContext<
-  Record<string | number, CollectionItem<TItem>>
->;