Update offscreen

6 files changed, 298 insertions, 93 deletions

diff --git a/ext/js/background/offscreen-proxy.js b/ext/js/background/offscreen-proxy.js
index 0fb2f269..757d78d5 100644
--- a/ext/js/background/offscreen-proxy.js
+++ b/ext/js/background/offscreen-proxy.js
@@ -18,13 +18,17 @@
 
 import {isObject} from '../core.js';
 import {ArrayBufferUtil} from '../data/sandbox/array-buffer-util.js';
+import {ExtensionError} from '../core/extension-error.js';
 
 export class OffscreenProxy {
     constructor() {
+        /** @type {?Promise<void>} */
         this._creatingOffscreen = null;
     }
 
-    // https://developer.chrome.com/docs/extensions/reference/offscreen/
+    /**
+     * @see https://developer.chrome.com/docs/extensions/reference/offscreen/
+     */
     async prepare() {
         if (await this._hasOffscreenDocument()) {
             return;
@@ -36,20 +40,30 @@ export class OffscreenProxy {
 
         this._creatingOffscreen = chrome.offscreen.createDocument({
             url: 'offscreen.html',
-            reasons: ['CLIPBOARD'],
+            reasons: [
+                /** @type {chrome.offscreen.Reason} */ ('CLIPBOARD')
+            ],
             justification: 'Access to the clipboard'
         });
         await this._creatingOffscreen;
         this._creatingOffscreen = null;
     }
 
+    /**
+     * @returns {Promise<boolean>}
+     */
     async _hasOffscreenDocument() {
         const offscreenUrl = chrome.runtime.getURL('offscreen.html');
-        if (!chrome.runtime.getContexts) { // chrome version <116
+        // @ts-ignore - API not defined yet
+        if (!chrome.runtime.getContexts) { // chrome version below 116
+            // Clients: https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerGlobalScope/clients
+            // @ts-ignore - Types not set up for service workers yet
             const matchedClients = await clients.matchAll();
+            // @ts-ignore - Types not set up for service workers yet
             return await matchedClients.some((client) => client.url === offscreenUrl);
         }
 
+        // @ts-ignore - API not defined yet
         const contexts = await chrome.runtime.getContexts({
             contextTypes: ['OFFSCREEN_DOCUMENT'],
             documentUrls: [offscreenUrl]
@@ -57,103 +71,152 @@ export class OffscreenProxy {
         return !!contexts.length;
     }
 
-    sendMessagePromise(...args) {
+    /**
+     * @template {import('offscreen').MessageType} TMessageType
+     * @param {import('offscreen').Message<TMessageType>} message
+     * @returns {Promise<import('offscreen').MessageReturn<TMessageType>>}
+     */
+    sendMessagePromise(message) {
         return new Promise((resolve, reject) => {
-            const callback = (response) => {
+            chrome.runtime.sendMessage(message, (response) => {
                 try {
                     resolve(this._getMessageResponseResult(response));
                 } catch (error) {
                     reject(error);
                 }
-            };
-
-            chrome.runtime.sendMessage(...args, callback);
+            });
         });
     }
 
+    /**
+     * @template [TReturn=unknown]
+     * @param {import('core').Response<TReturn>} response
+     * @returns {TReturn}
+     * @throws {Error}
+     */
     _getMessageResponseResult(response) {
-        let error = chrome.runtime.lastError;
+        const error = chrome.runtime.lastError;
         if (error) {
             throw new Error(error.message);
         }
         if (!isObject(response)) {
             throw new Error('Offscreen document did not respond');
         }
-        error = response.error;
-        if (error) {
-            throw deserializeError(error);
+        const error2 = response.error;
+        if (error2) {
+            throw ExtensionError.deserialize(error2);
         }
         return response.result;
     }
 }
 
 export class DictionaryDatabaseProxy {
+    /**
+     * @param {OffscreenProxy} offscreen
+     */
     constructor(offscreen) {
+        /** @type {OffscreenProxy} */
         this._offscreen = offscreen;
     }
 
-    prepare() {
-        return this._offscreen.sendMessagePromise({action: 'databasePrepareOffscreen'});
+    /**
+     * @returns {Promise<void>}
+     */
+    async prepare() {
+        await this._offscreen.sendMessagePromise({action: 'databasePrepareOffscreen'});
     }
 
-    getDictionaryInfo() {
+    /**
+     * @returns {Promise<import('dictionary-importer').Summary[]>}
+     */
+    async getDictionaryInfo() {
         return this._offscreen.sendMessagePromise({action: 'getDictionaryInfoOffscreen'});
     }
 
-    purge() {
-        return this._offscreen.sendMessagePromise({action: 'databasePurgeOffscreen'});
+    /**
+     * @returns {Promise<boolean>}
+     */
+    async purge() {
+        return await this._offscreen.sendMessagePromise({action: 'databasePurgeOffscreen'});
     }
 
+    /**
+     * @param {import('dictionary-database').MediaRequest[]} targets
+     * @returns {Promise<import('dictionary-database').Media[]>}
+     */
     async getMedia(targets) {
-        const serializedMedia = await this._offscreen.sendMessagePromise({action: 'databaseGetMediaOffscreen', params: {targets}});
+        const serializedMedia = /** @type {import('dictionary-database').Media<string>[]} */ (await this._offscreen.sendMessagePromise({action: 'databaseGetMediaOffscreen', params: {targets}}));
         const media = serializedMedia.map((m) => ({...m, content: ArrayBufferUtil.base64ToArrayBuffer(m.content)}));
         return media;
     }
 }
 
 export class TranslatorProxy {
+    /**
+     * @param {OffscreenProxy} offscreen
+     */
     constructor(offscreen) {
+        /** @type {OffscreenProxy} */
         this._offscreen = offscreen;
     }
 
-    prepare(deinflectionReasons) {
-        return this._offscreen.sendMessagePromise({action: 'translatorPrepareOffscreen', params: {deinflectionReasons}});
+    /**
+     * @param {import('deinflector').ReasonsRaw} deinflectionReasons
+     */
+    async prepare(deinflectionReasons) {
+        await this._offscreen.sendMessagePromise({action: 'translatorPrepareOffscreen', params: {deinflectionReasons}});
     }
 
-    async findKanji(text, findKanjiOptions) {
-        const enabledDictionaryMapList = [...findKanjiOptions.enabledDictionaryMap];
-        const modifiedKanjiOptions = {
-            ...findKanjiOptions,
+    /**
+     * @param {string} text
+     * @param {import('translation').FindKanjiOptions} options
+     * @returns {Promise<import('dictionary').KanjiDictionaryEntry[]>}
+     */
+    async findKanji(text, options) {
+        const enabledDictionaryMapList = [...options.enabledDictionaryMap];
+        /** @type {import('offscreen').FindKanjiOptionsOffscreen} */
+        const modifiedOptions = {
+            ...options,
             enabledDictionaryMap: enabledDictionaryMapList
         };
-        return this._offscreen.sendMessagePromise({action: 'findKanjiOffscreen', params: {text, findKanjiOptions: modifiedKanjiOptions}});
+        return this._offscreen.sendMessagePromise({action: 'findKanjiOffscreen', params: {text, options: modifiedOptions}});
     }
 
-    async findTerms(mode, text, findTermsOptions) {
-        const {enabledDictionaryMap, excludeDictionaryDefinitions, textReplacements} = findTermsOptions;
+    /**
+     * @param {import('translator').FindTermsMode} mode
+     * @param {string} text
+     * @param {import('translation').FindTermsOptions} options
+     * @returns {Promise<import('translator').FindTermsResult>}
+     */
+    async findTerms(mode, text, options) {
+        const {enabledDictionaryMap, excludeDictionaryDefinitions, textReplacements} = options;
         const enabledDictionaryMapList = [...enabledDictionaryMap];
         const excludeDictionaryDefinitionsList = excludeDictionaryDefinitions ? [...excludeDictionaryDefinitions] : null;
         const textReplacementsSerialized = textReplacements.map((group) => {
-            if (!group) {
-                return group;
-            }
-            return group.map((opt) => ({...opt, pattern: opt.pattern.toString()}));
+            return group !== null ? group.map((opt) => ({...opt, pattern: opt.pattern.toString()})) : null;
         });
-        const modifiedFindTermsOptions = {
-            ...findTermsOptions,
+        /** @type {import('offscreen').FindTermsOptionsOffscreen} */
+        const modifiedOptions = {
+            ...options,
             enabledDictionaryMap: enabledDictionaryMapList,
             excludeDictionaryDefinitions: excludeDictionaryDefinitionsList,
             textReplacements: textReplacementsSerialized
         };
-        return this._offscreen.sendMessagePromise({action: 'findTermsOffscreen', params: {mode, text, findTermsOptions: modifiedFindTermsOptions}});
+        return this._offscreen.sendMessagePromise({action: 'findTermsOffscreen', params: {mode, text, options: modifiedOptions}});
     }
 
+    /**
+     * @param {import('translator').TermReadingList} termReadingList
+     * @param {string[]} dictionaries
+     * @returns {Promise<import('translator').TermFrequencySimple[]>}
+     */
     async getTermFrequencies(termReadingList, dictionaries) {
         return this._offscreen.sendMessagePromise({action: 'getTermFrequenciesOffscreen', params: {termReadingList, dictionaries}});
     }
 
-    clearDatabaseCaches() {
-        return this._offscreen.sendMessagePromise({action: 'clearDatabaseCachesOffscreen'});
+    /** */
+    async clearDatabaseCaches() {
+        await this._offscreen.sendMessagePromise({action: 'clearDatabaseCachesOffscreen'});
     }
 }
 
@@ -173,7 +236,7 @@ export class ClipboardReaderProxy {
     set browser(value) {
         if (this._browser === value) { return; }
         this._browser = value;
-        this._offscreen.sendMessagePromise({action: 'clipboardSetBrowserOffsecreen', params: {value}});
+        this._offscreen.sendMessagePromise({action: 'clipboardSetBrowserOffscreen', params: {value}});
     }
 
     /**
diff --git a/ext/js/background/offscreen.js b/ext/js/background/offscreen.js
index 6302aa84..1b68887b 100644
--- a/ext/js/background/offscreen.js
+++ b/ext/js/background/offscreen.js
@@ -23,7 +23,6 @@ import {ArrayBufferUtil} from '../data/sandbox/array-buffer-util.js';
 import {DictionaryDatabase} from '../language/dictionary-database.js';
 import {JapaneseUtil} from '../language/sandbox/japanese-util.js';
 import {Translator} from '../language/translator.js';
-import {yomitan} from '../yomitan.js';
 
 /**
  * This class controls the core logic of the extension, including API calls
@@ -34,12 +33,16 @@ export class Offscreen {
      * Creates a new instance.
      */
     constructor() {
+        /** @type {JapaneseUtil} */
         this._japaneseUtil = new JapaneseUtil(wanakana);
+        /** @type {DictionaryDatabase} */
         this._dictionaryDatabase = new DictionaryDatabase();
+        /** @type {Translator} */
         this._translator = new Translator({
             japaneseUtil: this._japaneseUtil,
             database: this._dictionaryDatabase
         });
+        /** @type {ClipboardReader} */
         this._clipboardReader = new ClipboardReader({
             // eslint-disable-next-line no-undef
             document: (typeof document === 'object' && document !== null ? document : null),
@@ -47,42 +50,45 @@ export class Offscreen {
             richContentPasteTargetSelector: '#clipboard-rich-content-paste-target'
         });
 
+        /** @type {import('offscreen').MessageHandlerMap} */
         this._messageHandlers = new Map([
-            ['clipboardGetTextOffscreen',    {async: true,  contentScript: true,  handler: this._getTextHandler.bind(this)}],
-            ['clipboardGetImageOffscreen',   {async: true,  contentScript: true,  handler: this._getImageHandler.bind(this)}],
-            ['clipboardSetBrowserOffsecreen', {async: false, contentScript: true, handler: this._setClipboardBrowser.bind(this)}],
-            ['databasePrepareOffscreen',     {async: true,  contentScript: true,  handler: this._prepareDatabaseHandler.bind(this)}],
-            ['getDictionaryInfoOffscreen',   {async: true,  contentScript: true,  handler: this._getDictionaryInfoHandler.bind(this)}],
-            ['databasePurgeOffscreen',       {async: true,  contentScript: true,  handler: this._purgeDatabaseHandler.bind(this)}],
-            ['databaseGetMediaOffscreen',    {async: true,  contentScript: true,  handler: this._getMediaHandler.bind(this)}],
-            ['translatorPrepareOffscreen',   {async: false,  contentScript: true,  handler: this._prepareTranslatorHandler.bind(this)}],
-            ['findKanjiOffscreen',           {async: true,  contentScript: true,  handler: this._findKanjiHandler.bind(this)}],
-            ['findTermsOffscreen',           {async: true,  contentScript: true,  handler: this._findTermsHandler.bind(this)}],
-            ['getTermFrequenciesOffscreen',  {async: true,  contentScript: true,  handler: this._getTermFrequenciesHandler.bind(this)}],
-            ['clearDatabaseCachesOffscreen', {async: false,  contentScript: true,  handler: this._clearDatabaseCachesHandler.bind(this)}]
+            ['clipboardGetTextOffscreen',    {async: true,  handler: this._getTextHandler.bind(this)}],
+            ['clipboardGetImageOffscreen',   {async: true,  handler: this._getImageHandler.bind(this)}],
+            ['clipboardSetBrowserOffscreen', {async: false, handler: this._setClipboardBrowser.bind(this)}],
+            ['databasePrepareOffscreen',     {async: true,  handler: this._prepareDatabaseHandler.bind(this)}],
+            ['getDictionaryInfoOffscreen',   {async: true,  handler: this._getDictionaryInfoHandler.bind(this)}],
+            ['databasePurgeOffscreen',       {async: true,  handler: this._purgeDatabaseHandler.bind(this)}],
+            ['databaseGetMediaOffscreen',    {async: true,  handler: this._getMediaHandler.bind(this)}],
+            ['translatorPrepareOffscreen',   {async: false, handler: this._prepareTranslatorHandler.bind(this)}],
+            ['findKanjiOffscreen',           {async: true,  handler: this._findKanjiHandler.bind(this)}],
+            ['findTermsOffscreen',           {async: true,  handler: this._findTermsHandler.bind(this)}],
+            ['getTermFrequenciesOffscreen',  {async: true,  handler: this._getTermFrequenciesHandler.bind(this)}],
+            ['clearDatabaseCachesOffscreen', {async: false, handler: this._clearDatabaseCachesHandler.bind(this)}]
         ]);
 
         const onMessage = this._onMessage.bind(this);
         chrome.runtime.onMessage.addListener(onMessage);
 
+        /** @type {?Promise<void>} */
         this._prepareDatabasePromise = null;
     }
 
-    _getTextHandler({useRichText}) {
-        return this._clipboardReader.getText(useRichText);
+    /** @type {import('offscreen').MessageHandler<'clipboardGetTextOffscreen', true>} */
+    async _getTextHandler({useRichText}) {
+        return await this._clipboardReader.getText(useRichText);
     }
 
-    _getImageHandler() {
-        return this._clipboardReader.getImage();
+    /** @type {import('offscreen').MessageHandler<'clipboardGetImageOffscreen', true>} */
+    async _getImageHandler() {
+        return await this._clipboardReader.getImage();
     }
 
-    /**
-     * @param {{value: import('environment').Browser}} details
-     */
+    /** @type {import('offscreen').MessageHandler<'clipboardSetBrowserOffscreen', false>} */
     _setClipboardBrowser({value}) {
         this._clipboardReader.browser = value;
     }
 
+    /** @type {import('offscreen').MessageHandler<'databasePrepareOffscreen', true>} */
     _prepareDatabaseHandler() {
         if (this._prepareDatabasePromise !== null) {
             return this._prepareDatabasePromise;
@@ -91,70 +97,79 @@ export class Offscreen {
         return this._prepareDatabasePromise;
     }
 
-    _getDictionaryInfoHandler() {
-        return this._dictionaryDatabase.getDictionaryInfo();
+    /** @type {import('offscreen').MessageHandler<'getDictionaryInfoOffscreen', true>} */
+    async _getDictionaryInfoHandler() {
+        return await this._dictionaryDatabase.getDictionaryInfo();
     }
 
-    _purgeDatabaseHandler() {
-        return this._dictionaryDatabase.purge();
+    /** @type {import('offscreen').MessageHandler<'databasePurgeOffscreen', true>} */
+    async _purgeDatabaseHandler() {
+        return await this._dictionaryDatabase.purge();
     }
 
+    /** @type {import('offscreen').MessageHandler<'databaseGetMediaOffscreen', true>} */
     async _getMediaHandler({targets}) {
         const media = await this._dictionaryDatabase.getMedia(targets);
         const serializedMedia = media.map((m) => ({...m, content: ArrayBufferUtil.arrayBufferToBase64(m.content)}));
         return serializedMedia;
     }
 
+    /** @type {import('offscreen').MessageHandler<'translatorPrepareOffscreen', false>} */
     _prepareTranslatorHandler({deinflectionReasons}) {
-        return this._translator.prepare(deinflectionReasons);
+        this._translator.prepare(deinflectionReasons);
     }
 
-    _findKanjiHandler({text, findKanjiOptions}) {
-        findKanjiOptions.enabledDictionaryMap = new Map(findKanjiOptions.enabledDictionaryMap);
-        return this._translator.findKanji(text, findKanjiOptions);
+    /** @type {import('offscreen').MessageHandler<'findKanjiOffscreen', true>} */
+    async _findKanjiHandler({text, options}) {
+        /** @type {import('translation').FindKanjiOptions} */
+        const modifiedOptions = {
+            ...options,
+            enabledDictionaryMap: new Map(options.enabledDictionaryMap)
+        };
+        return await this._translator.findKanji(text, modifiedOptions);
     }
 
-    _findTermsHandler({mode, text, findTermsOptions}) {
-        findTermsOptions.enabledDictionaryMap = new Map(findTermsOptions.enabledDictionaryMap);
-        if (findTermsOptions.excludeDictionaryDefinitions) {
-            findTermsOptions.excludeDictionaryDefinitions = new Set(findTermsOptions.excludeDictionaryDefinitions);
-        }
-        findTermsOptions.textReplacements = findTermsOptions.textReplacements.map((group) => {
-            if (!group) {
-                return group;
-            }
+    /** @type {import('offscreen').MessageHandler<'findTermsOffscreen', true>} */
+    _findTermsHandler({mode, text, options}) {
+        const enabledDictionaryMap = new Map(options.enabledDictionaryMap);
+        const excludeDictionaryDefinitions = (
+            options.excludeDictionaryDefinitions !== null ?
+            new Set(options.excludeDictionaryDefinitions) :
+            null
+        );
+        const textReplacements = options.textReplacements.map((group) => {
+            if (group === null) { return null; }
             return group.map((opt) => {
-                const [, pattern, flags] = opt.pattern.match(/\/(.*?)\/([a-z]*)?$/i); // https://stackoverflow.com/a/33642463
+                // https://stackoverflow.com/a/33642463
+                const match = opt.pattern.match(/\/(.*?)\/([a-z]*)?$/i);
+                const [, pattern, flags] = match !== null ? match : ['', '', ''];
                 return {...opt, pattern: new RegExp(pattern, flags ?? '')};
             });
         });
-        return this._translator.findTerms(mode, text, findTermsOptions);
+        /** @type {import('translation').FindTermsOptions} */
+        const modifiedOptions = {
+            ...options,
+            enabledDictionaryMap,
+            excludeDictionaryDefinitions,
+            textReplacements
+        };
+        return this._translator.findTerms(mode, text, modifiedOptions);
     }
 
+    /** @type {import('offscreen').MessageHandler<'getTermFrequenciesOffscreen', true>} */
     _getTermFrequenciesHandler({termReadingList, dictionaries}) {
         return this._translator.getTermFrequencies(termReadingList, dictionaries);
     }
 
+    /** @type {import('offscreen').MessageHandler<'clearDatabaseCachesOffscreen', false>} */
     _clearDatabaseCachesHandler() {
-        return this._translator.clearDatabaseCaches();
+        this._translator.clearDatabaseCaches();
     }
 
+    /** @type {import('extension').ChromeRuntimeOnMessageCallback} */
     _onMessage({action, params}, sender, callback) {
         const messageHandler = this._messageHandlers.get(action);
         if (typeof messageHandler === 'undefined') { return false; }
-        this._validatePrivilegedMessageSender(sender);
-
         return invokeMessageHandler(messageHandler, params, callback, sender);
     }
-
-    _validatePrivilegedMessageSender(sender) {
-        let {url} = sender;
-        if (typeof url === 'string' && yomitan.isExtensionUrl(url)) { return; }
-        const {tab} = url;
-        if (typeof tab === 'object' && tab !== null) {
-            ({url} = tab);
-            if (typeof url === 'string' && yomitan.isExtensionUrl(url)) { return; }
-        }
-        throw new Error('Invalid message sender');
-    }
 }
diff --git a/ext/js/language/translator.js b/ext/js/language/translator.js
index c21b16b1..aa1b71dd 100644
--- a/ext/js/language/translator.js
+++ b/ext/js/language/translator.js
@@ -157,7 +157,7 @@ export class Translator {
     /**
      * Gets a list of frequency information for a given list of term-reading pairs
      * and a list of dictionaries.
-     * @param {{term: string, reading: string|null}[]} termReadingList An array of `{term, reading}` pairs. If reading is null,
+     * @param {import('translator').TermReadingList} termReadingList An array of `{term, reading}` pairs. If reading is null,
      *   the reading won't be compared.
      * @param {string[]} dictionaries An array of dictionary names.
      * @returns {Promise<import('translator').TermFrequencySimple[]>} An array of term frequencies.
@@ -203,7 +203,7 @@ export class Translator {
      * @param {Map<string, import('translation').FindTermDictionary>} enabledDictionaryMap
      * @param {import('translation').FindTermsOptions} options
      * @param {TranslatorTagAggregator} tagAggregator
-     * @returns {Promise<{dictionaryEntries: import('dictionary').TermDictionaryEntry[], originalTextLength: number}>}
+     * @returns {Promise<import('translator').FindTermsResult>}
      */
     async _findTermsInternal(text, enabledDictionaryMap, options, tagAggregator) {
         if (options.removeNonJapaneseCharacters) {
diff --git a/types/ext/dictionary-database.d.ts b/types/ext/dictionary-database.d.ts
index 2e0f854b..06a246e8 100644
--- a/types/ext/dictionary-database.d.ts
+++ b/types/ext/dictionary-database.d.ts
@@ -35,7 +35,7 @@ export interface MediaDataBase<TContentType = unknown> {
 export interface MediaDataArrayBufferContent extends MediaDataBase<ArrayBuffer> {}
 export interface MediaDataStringContent extends MediaDataBase<string> {}
 
-export type Media = {index: number} & MediaDataBase<ArrayBuffer>;
+export type Media<T extends (ArrayBuffer | string) = ArrayBuffer> = {index: number} & MediaDataBase<T>;
 
 export type DatabaseTermEntry = {
     expression: string;
diff --git a/types/ext/offscreen.d.ts b/types/ext/offscreen.d.ts
new file mode 100644
index 00000000..7dd64d1e
--- /dev/null
+++ b/types/ext/offscreen.d.ts
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2023  Yomitan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import type * as Core from './core';
+import type * as Deinflector from './deinflector';
+import type * as Dictionary from './dictionary';
+import type * as DictionaryDatabase from './dictionary-database';
+import type * as DictionaryImporter from './dictionary-importer';
+import type * as Environment from './environment';
+import type * as Translation from './translation';
+import type * as Translator from './translator';
+
+export type MessageAny2 = Message<keyof MessageDetailsMap>;
+
+export type Message<T extends MessageType> = (
+    MessageDetailsMap[T] extends undefined ?
+        {action: T} :
+        {action: T, params: MessageDetailsMap[T]}
+);
+
+export type MessageReturn<T extends MessageType> = MessageReturnMap[T];
+
+type MessageDetailsMap = {
+    databasePrepareOffscreen: undefined;
+    getDictionaryInfoOffscreen: undefined;
+    databasePurgeOffscreen: undefined;
+    databaseGetMediaOffscreen: {
+        targets: DictionaryDatabase.MediaRequest[];
+    };
+    translatorPrepareOffscreen: {
+        deinflectionReasons: Deinflector.ReasonsRaw;
+    };
+    findKanjiOffscreen: {
+        text: string;
+        options: FindKanjiOptionsOffscreen;
+    };
+    findTermsOffscreen: {
+        mode: Translator.FindTermsMode;
+        text: string;
+        options: FindTermsOptionsOffscreen;
+    };
+    getTermFrequenciesOffscreen: {
+        termReadingList: Translator.TermReadingList;
+        dictionaries: string[];
+    };
+    clearDatabaseCachesOffscreen: undefined;
+    clipboardSetBrowserOffscreen: {
+        value: Environment.Browser | null;
+    };
+    clipboardGetTextOffscreen: {
+        useRichText: boolean;
+    };
+    clipboardGetImageOffscreen: undefined;
+};
+
+type MessageReturnMap = {
+    databasePrepareOffscreen: void;
+    getDictionaryInfoOffscreen: DictionaryImporter.Summary[];
+    databasePurgeOffscreen: boolean;
+    databaseGetMediaOffscreen: DictionaryDatabase.Media<string>[];
+    translatorPrepareOffscreen: void;
+    findKanjiOffscreen: Dictionary.KanjiDictionaryEntry[];
+    findTermsOffscreen: Translator.FindTermsResult;
+    getTermFrequenciesOffscreen: Translator.TermFrequencySimple[];
+    clearDatabaseCachesOffscreen: void;
+    clipboardSetBrowserOffscreen: void;
+    clipboardGetTextOffscreen: string;
+    clipboardGetImageOffscreen: string | null;
+};
+
+export type MessageType = keyof MessageDetailsMap;
+
+export type FindKanjiOptionsOffscreen = Omit<Translation.FindKanjiOptions, 'enabledDictionaryMap'> & {
+    enabledDictionaryMap: [
+        key: string,
+        options: Translation.FindKanjiDictionary,
+    ][];
+};
+
+
+export type FindTermsOptionsOffscreen = Omit<Translation.FindTermsOptions, 'enabledDictionaryMap' | 'excludeDictionaryDefinitions' | 'textReplacements'> & {
+    enabledDictionaryMap: [
+        key: string,
+        options: Translation.FindTermDictionary,
+    ][];
+    excludeDictionaryDefinitions: string[] | null;
+    textReplacements: (FindTermsTextReplacementOffscreen[] | null)[];
+};
+
+export type FindTermsTextReplacementOffscreen = Omit<Translation.FindTermsTextReplacement, 'pattern'> & {
+    pattern: string;
+};
+
+export type MessageHandler<
+    TMessage extends MessageType,
+    TIsAsync extends boolean,
+> = (
+    details: MessageDetailsMap[TMessage],
+) => (TIsAsync extends true ? Promise<MessageReturn<TMessage>> : MessageReturn<TMessage>);
+
+export type MessageHandlerMap = Map<MessageType, Core.MessageHandlerDetails>;
diff --git a/types/ext/translator.d.ts b/types/ext/translator.d.ts
index f17b3bf6..e7d45295 100644
--- a/types/ext/translator.d.ts
+++ b/types/ext/translator.d.ts
@@ -81,3 +81,15 @@ export type SequenceQuery = {
 };
 
 export type FindTermsMode = 'simple' | 'group' | 'merge' | 'split';
+
+export type TermReadingItem = {
+    term: string;
+    reading: string | null;
+};
+
+export type TermReadingList = TermReadingItem[];
+
+export type FindTermsResult = {
+    dictionaryEntries: Dictionary.TermDictionaryEntry[];
+    originalTextLength: number;
+};