Cross frame API safety (#491)

* Require error type

* Add TODOs

* Fix init

* Updates

* More type safety

* Fix incorrect API map

* Update type safety

* Updates

* Add API

* Update types

* Update types

* Updates

* Remove unused

* Restore types

* Update frame ancestry handler

* Simplify names

* Fix

* Remove old message handlers

12 files changed, 217 insertions, 317 deletions

diff --git a/ext/js/app/frontend.js b/ext/js/app/frontend.js
index e386bf64..9dafde7a 100644
--- a/ext/js/app/frontend.js
+++ b/ext/js/app/frontend.js
@@ -178,11 +178,11 @@ export class Frontend {
 
         /* eslint-disable no-multi-spaces */
         yomitan.crossFrame.registerHandlers([
-            ['Frontend.closePopup',       this._onApiClosePopup.bind(this)],
-            ['Frontend.copySelection',    this._onApiCopySelection.bind(this)],
-            ['Frontend.getSelectionText', this._onApiGetSelectionText.bind(this)],
-            ['Frontend.getPopupInfo',     this._onApiGetPopupInfo.bind(this)],
-            ['Frontend.getPageInfo',      this._onApiGetPageInfo.bind(this)]
+            ['frontendClosePopup',       this._onApiClosePopup.bind(this)],
+            ['frontendCopySelection',    this._onApiCopySelection.bind(this)],
+            ['frontendGetSelectionText', this._onApiGetSelectionText.bind(this)],
+            ['frontendGetPopupInfo',     this._onApiGetPopupInfo.bind(this)],
+            ['frontendGetPageInfo',      this._onApiGetPageInfo.bind(this)]
         ]);
         /* eslint-enable no-multi-spaces */
 
@@ -263,48 +263,31 @@ export class Frontend {
 
     // API message handlers
 
-    /**
-     * @returns {string}
-     */
-    _onApiGetUrl() {
-        return window.location.href;
-    }
-
-    /**
-     * @returns {void}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'frontendClosePopup'>} */
     _onApiClosePopup() {
         this._clearSelection(false);
     }
 
-    /**
-     * @returns {void}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'frontendCopySelection'>} */
     _onApiCopySelection() {
         // This will not work on Firefox if a popup has focus, which is usually the case when this function is called.
         document.execCommand('copy');
     }
 
-    /**
-     * @returns {string}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'frontendGetSelectionText'>} */
     _onApiGetSelectionText() {
         const selection = document.getSelection();
         return selection !== null ? selection.toString() : '';
     }
 
-    /**
-     * @returns {import('frontend').GetPopupInfoResult}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'frontendGetPopupInfo'>} */
     _onApiGetPopupInfo() {
         return {
             popupId: (this._popup !== null ? this._popup.id : null)
         };
     }
 
-    /**
-     * @returns {{url: string, documentTitle: string}}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'frontendGetPageInfo'>} */
     _onApiGetPageInfo() {
         return {
             url: window.location.href,
@@ -620,8 +603,7 @@ export class Frontend {
             return await this._getDefaultPopup();
         }
 
-        /** @type {import('frontend').GetPopupInfoResult} */
-        const {popupId} = await yomitan.crossFrame.invoke(targetFrameId, 'Frontend.getPopupInfo', {});
+        const {popupId} = await yomitan.crossFrame.invoke(targetFrameId, 'frontendGetPopupInfo', void 0);
         if (popupId === null) {
             return null;
         }
@@ -905,7 +887,7 @@ export class Frontend {
         let documentTitle = document.title;
         if (this._useProxyPopup && this._parentFrameId !== null) {
             try {
-                ({url, documentTitle} = await yomitan.crossFrame.invoke(this._parentFrameId, 'Frontend.getPageInfo', {}));
+                ({url, documentTitle} = await yomitan.crossFrame.invoke(this._parentFrameId, 'frontendGetPageInfo', void 0));
             } catch (e) {
                 // NOP
             }
diff --git a/ext/js/app/popup-factory.js b/ext/js/app/popup-factory.js
index 184a55ca..0d8cabd4 100644
--- a/ext/js/app/popup-factory.js
+++ b/ext/js/app/popup-factory.js
@@ -49,21 +49,21 @@ export class PopupFactory {
         this._frameOffsetForwarder.prepare();
         /* eslint-disable no-multi-spaces */
         yomitan.crossFrame.registerHandlers([
-            ['PopupFactory.getOrCreatePopup',     this._onApiGetOrCreatePopup.bind(this)],
-            ['PopupFactory.setOptionsContext',    this._onApiSetOptionsContext.bind(this)],
-            ['PopupFactory.hide',                 this._onApiHide.bind(this)],
-            ['PopupFactory.isVisible',            this._onApiIsVisibleAsync.bind(this)],
-            ['PopupFactory.setVisibleOverride',   this._onApiSetVisibleOverride.bind(this)],
-            ['PopupFactory.clearVisibleOverride', this._onApiClearVisibleOverride.bind(this)],
-            ['PopupFactory.containsPoint',        this._onApiContainsPoint.bind(this)],
-            ['PopupFactory.showContent',          this._onApiShowContent.bind(this)],
-            ['PopupFactory.setCustomCss',         this._onApiSetCustomCss.bind(this)],
-            ['PopupFactory.clearAutoPlayTimer',   this._onApiClearAutoPlayTimer.bind(this)],
-            ['PopupFactory.setContentScale',      this._onApiSetContentScale.bind(this)],
-            ['PopupFactory.updateTheme',          this._onApiUpdateTheme.bind(this)],
-            ['PopupFactory.setCustomOuterCss',    this._onApiSetCustomOuterCss.bind(this)],
-            ['PopupFactory.getFrameSize',         this._onApiGetFrameSize.bind(this)],
-            ['PopupFactory.setFrameSize',         this._onApiSetFrameSize.bind(this)]
+            ['popupFactoryGetOrCreatePopup',     this._onApiGetOrCreatePopup.bind(this)],
+            ['popupFactorySetOptionsContext',    this._onApiSetOptionsContext.bind(this)],
+            ['popupFactoryHide',                 this._onApiHide.bind(this)],
+            ['popupFactoryIsVisible',            this._onApiIsVisibleAsync.bind(this)],
+            ['popupFactorySetVisibleOverride',   this._onApiSetVisibleOverride.bind(this)],
+            ['popupFactoryClearVisibleOverride', this._onApiClearVisibleOverride.bind(this)],
+            ['popupFactoryContainsPoint',        this._onApiContainsPoint.bind(this)],
+            ['popupFactoryShowContent',          this._onApiShowContent.bind(this)],
+            ['popupFactorySetCustomCss',         this._onApiSetCustomCss.bind(this)],
+            ['popupFactoryClearAutoPlayTimer',   this._onApiClearAutoPlayTimer.bind(this)],
+            ['popupFactorySetContentScale',      this._onApiSetContentScale.bind(this)],
+            ['popupFactoryUpdateTheme',          this._onApiUpdateTheme.bind(this)],
+            ['popupFactorySetCustomOuterCss',    this._onApiSetCustomOuterCss.bind(this)],
+            ['popupFactoryGetFrameSize',         this._onApiGetFrameSize.bind(this)],
+            ['popupFactorySetFrameSize',         this._onApiSetFrameSize.bind(this)]
         ]);
         /* eslint-enable no-multi-spaces */
     }
@@ -152,7 +152,7 @@ export class PopupFactory {
             }
             const useFrameOffsetForwarder = (parentPopupId === null);
             /** @type {{id: string, depth: number, frameId: number}} */
-            const info = await yomitan.crossFrame.invoke(frameId, 'PopupFactory.getOrCreatePopup', /** @type {import('popup-factory').GetOrCreatePopupDetails} */ ({
+            const info = await yomitan.crossFrame.invoke(frameId, 'popupFactoryGetOrCreatePopup', /** @type {import('popup-factory').GetOrCreatePopupDetails} */ ({
                 id,
                 parentPopupId,
                 frameId,
@@ -239,10 +239,7 @@ export class PopupFactory {
 
     // API message handlers
 
-    /**
-     * @param {import('popup-factory').GetOrCreatePopupDetails} details
-     * @returns {Promise<{id: string, depth: number, frameId: number}>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryGetOrCreatePopup'>} */
     async _onApiGetOrCreatePopup(details) {
         const popup = await this.getOrCreatePopup(details);
         return {
@@ -252,53 +249,37 @@ export class PopupFactory {
         };
     }
 
-    /**
-     * @param {{id: string, optionsContext: import('settings').OptionsContext}} params
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactorySetOptionsContext'>} */
     async _onApiSetOptionsContext({id, optionsContext}) {
         const popup = this._getPopup(id);
         await popup.setOptionsContext(optionsContext);
     }
 
-    /**
-     * @param {{id: string, changeFocus: boolean}} params
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryHide'>} */
     async _onApiHide({id, changeFocus}) {
         const popup = this._getPopup(id);
         await popup.hide(changeFocus);
     }
 
-    /**
-     * @param {{id: string}} params
-     * @returns {Promise<boolean>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryIsVisible'>} */
     async _onApiIsVisibleAsync({id}) {
         const popup = this._getPopup(id);
         return await popup.isVisible();
     }
 
-    /**
-     * @param {{id: string, value: boolean, priority: number}} params
-     * @returns {Promise<?import('core').TokenString>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactorySetVisibleOverride'>} */
     async _onApiSetVisibleOverride({id, value, priority}) {
         const popup = this._getPopup(id);
         return await popup.setVisibleOverride(value, priority);
     }
 
-    /**
-     * @param {{id: string, token: import('core').TokenString}} params
-     * @returns {Promise<boolean>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryClearVisibleOverride'>} */
     async _onApiClearVisibleOverride({id, token}) {
         const popup = this._getPopup(id);
         return await popup.clearVisibleOverride(token);
     }
 
-    /**
-     * @param {{id: string, x: number, y: number}} params
-     * @returns {Promise<boolean>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryContainsPoint'>} */
     async _onApiContainsPoint({id, x, y}) {
         const popup = this._getPopup(id);
         const offset = this._getPopupOffset(popup);
@@ -307,10 +288,7 @@ export class PopupFactory {
         return await popup.containsPoint(x, y);
     }
 
-    /**
-     * @param {{id: string, details: import('popup').ContentDetails, displayDetails: ?import('display').ContentDetails}} params
-     * @returns {Promise<void>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryShowContent'>} */
     async _onApiShowContent({id, details, displayDetails}) {
         const popup = this._getPopup(id);
         if (!this._popupCanShow(popup)) { return; }
@@ -327,64 +305,43 @@ export class PopupFactory {
         return await popup.showContent(details, displayDetails);
     }
 
-    /**
-     * @param {{id: string, css: string}} params
-     * @returns {Promise<void>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactorySetCustomCss'>} */
     async _onApiSetCustomCss({id, css}) {
         const popup = this._getPopup(id);
         await popup.setCustomCss(css);
     }
 
-    /**
-     * @param {{id: string}} params
-     * @returns {Promise<void>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryClearAutoPlayTimer'>} */
     async _onApiClearAutoPlayTimer({id}) {
         const popup = this._getPopup(id);
         await popup.clearAutoPlayTimer();
     }
 
-    /**
-     * @param {{id: string, scale: number}} params
-     * @returns {Promise<void>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactorySetContentScale'>} */
     async _onApiSetContentScale({id, scale}) {
         const popup = this._getPopup(id);
         await popup.setContentScale(scale);
     }
 
-    /**
-     * @param {{id: string}} params
-     * @returns {Promise<void>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryUpdateTheme'>} */
     async _onApiUpdateTheme({id}) {
         const popup = this._getPopup(id);
         await popup.updateTheme();
     }
 
-    /**
-     * @param {{id: string, css: string, useWebExtensionApi: boolean}} params
-     * @returns {Promise<void>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactorySetCustomOuterCss'>} */
     async _onApiSetCustomOuterCss({id, css, useWebExtensionApi}) {
         const popup = this._getPopup(id);
         await popup.setCustomOuterCss(css, useWebExtensionApi);
     }
 
-    /**
-     * @param {{id: string}} params
-     * @returns {Promise<import('popup').ValidSize>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactoryGetFrameSize'>} */
     async _onApiGetFrameSize({id}) {
         const popup = this._getPopup(id);
         return await popup.getFrameSize();
     }
 
-    /**
-     * @param {{id: string, width: number, height: number}} params
-     * @returns {Promise<boolean>}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'popupFactorySetFrameSize'>} */
     async _onApiSetFrameSize({id, width, height}) {
         const popup = this._getPopup(id);
         return await popup.setFrameSize(width, height);
diff --git a/ext/js/app/popup-proxy.js b/ext/js/app/popup-proxy.js
index 2821d774..e581be82 100644
--- a/ext/js/app/popup-proxy.js
+++ b/ext/js/app/popup-proxy.js
@@ -140,7 +140,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async setOptionsContext(optionsContext) {
-        await this._invokeSafe('PopupFactory.setOptionsContext', {id: this._id, optionsContext}, void 0);
+        await this._invokeSafe('popupFactorySetOptionsContext', {id: this._id, optionsContext}, void 0);
     }
 
     /**
@@ -149,7 +149,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async hide(changeFocus) {
-        await this._invokeSafe('PopupFactory.hide', {id: this._id, changeFocus}, void 0);
+        await this._invokeSafe('popupFactoryHide', {id: this._id, changeFocus}, void 0);
     }
 
     /**
@@ -157,7 +157,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<boolean>} `true` if the popup is visible, `false` otherwise.
      */
     isVisible() {
-        return this._invokeSafe('PopupFactory.isVisible', {id: this._id}, false);
+        return this._invokeSafe('popupFactoryIsVisible', {id: this._id}, false);
     }
 
     /**
@@ -168,7 +168,7 @@ export class PopupProxy extends EventDispatcher {
      *   or null if the override wasn't assigned.
      */
     setVisibleOverride(value, priority) {
-        return this._invokeSafe('PopupFactory.setVisibleOverride', {id: this._id, value, priority}, null);
+        return this._invokeSafe('popupFactorySetVisibleOverride', {id: this._id, value, priority}, null);
     }
 
     /**
@@ -177,7 +177,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<boolean>} `true` if the override existed and was removed, `false` otherwise.
      */
     clearVisibleOverride(token) {
-        return this._invokeSafe('PopupFactory.clearVisibleOverride', {id: this._id, token}, false);
+        return this._invokeSafe('popupFactoryClearVisibleOverride', {id: this._id, token}, false);
     }
 
     /**
@@ -192,7 +192,7 @@ export class PopupProxy extends EventDispatcher {
             x += this._frameOffsetX;
             y += this._frameOffsetY;
         }
-        return await this._invokeSafe('PopupFactory.containsPoint', {id: this._id, x, y}, false);
+        return await this._invokeSafe('popupFactoryContainsPoint', {id: this._id, x, y}, false);
     }
 
     /**
@@ -212,7 +212,7 @@ export class PopupProxy extends EventDispatcher {
                 sourceRect.bottom += this._frameOffsetY;
             }
         }
-        await this._invokeSafe('PopupFactory.showContent', {id: this._id, details, displayDetails}, void 0);
+        await this._invokeSafe('popupFactoryShowContent', {id: this._id, details, displayDetails}, void 0);
     }
 
     /**
@@ -221,7 +221,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async setCustomCss(css) {
-        await this._invokeSafe('PopupFactory.setCustomCss', {id: this._id, css}, void 0);
+        await this._invokeSafe('popupFactorySetCustomCss', {id: this._id, css}, void 0);
     }
 
     /**
@@ -229,7 +229,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async clearAutoPlayTimer() {
-        await this._invokeSafe('PopupFactory.clearAutoPlayTimer', {id: this._id}, void 0);
+        await this._invokeSafe('popupFactoryClearAutoPlayTimer', {id: this._id}, void 0);
     }
 
     /**
@@ -238,7 +238,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async setContentScale(scale) {
-        await this._invokeSafe('PopupFactory.setContentScale', {id: this._id, scale}, void 0);
+        await this._invokeSafe('popupFactorySetContentScale', {id: this._id, scale}, void 0);
     }
 
     /**
@@ -254,7 +254,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async updateTheme() {
-        await this._invokeSafe('PopupFactory.updateTheme', {id: this._id}, void 0);
+        await this._invokeSafe('popupFactoryUpdateTheme', {id: this._id}, void 0);
     }
 
     /**
@@ -265,7 +265,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async setCustomOuterCss(css, useWebExtensionApi) {
-        await this._invokeSafe('PopupFactory.setCustomOuterCss', {id: this._id, css, useWebExtensionApi}, void 0);
+        await this._invokeSafe('popupFactorySetCustomOuterCss', {id: this._id, css, useWebExtensionApi}, void 0);
     }
 
     /**
@@ -282,7 +282,7 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<import('popup').ValidSize>} The size and whether or not it is valid.
      */
     getFrameSize() {
-        return this._invokeSafe('PopupFactory.getFrameSize', {id: this._id}, {width: 0, height: 0, valid: false});
+        return this._invokeSafe('popupFactoryGetFrameSize', {id: this._id}, {width: 0, height: 0, valid: false});
     }
 
     /**
@@ -292,32 +292,28 @@ export class PopupProxy extends EventDispatcher {
      * @returns {Promise<boolean>} `true` if the size assignment was successful, `false` otherwise.
      */
     setFrameSize(width, height) {
-        return this._invokeSafe('PopupFactory.setFrameSize', {id: this._id, width, height}, false);
+        return this._invokeSafe('popupFactorySetFrameSize', {id: this._id, width, height}, false);
     }
 
     // Private
 
-    // TODO : Type safety
     /**
-     * @template {import('core').SerializableObject} TParams
-     * @template [TReturn=unknown]
-     * @param {string} action
-     * @param {TParams} params
-     * @returns {Promise<TReturn>}
+     * @template {import('cross-frame-api').ApiNames} TName
+     * @param {TName} action
+     * @param {import('cross-frame-api').ApiParams<TName>} params
+     * @returns {Promise<import('cross-frame-api').ApiReturn<TName>>}
      */
     _invoke(action, params) {
         return yomitan.crossFrame.invoke(this._frameId, action, params);
     }
 
-    // TODO : Type safety
     /**
-     * @template {import('core').SerializableObject} TParams
-     * @template [TReturn=unknown]
+     * @template {import('cross-frame-api').ApiNames} TName
      * @template [TReturnDefault=unknown]
-     * @param {string} action
-     * @param {TParams} params
+     * @param {TName} action
+     * @param {import('cross-frame-api').ApiParams<TName>} params
      * @param {TReturnDefault} defaultReturnValue
-     * @returns {Promise<TReturn|TReturnDefault>}
+     * @returns {Promise<import('cross-frame-api').ApiReturn<TName>|TReturnDefault>}
      */
     async _invokeSafe(action, params, defaultReturnValue) {
         try {
diff --git a/ext/js/app/popup-window.js b/ext/js/app/popup-window.js
index 801afb3f..a696885a 100644
--- a/ext/js/app/popup-window.js
+++ b/ext/js/app/popup-window.js
@@ -126,7 +126,7 @@ export class PopupWindow extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async setOptionsContext(optionsContext) {
-        await this._invoke(false, 'displaySetOptionsContext', {id: this._id, optionsContext});
+        await this._invoke(false, 'displaySetOptionsContext', {optionsContext});
     }
 
     /**
@@ -183,7 +183,7 @@ export class PopupWindow extends EventDispatcher {
      */
     async showContent(_details, displayDetails) {
         if (displayDetails === null) { return; }
-        await this._invoke(true, 'displaySetContent', {id: this._id, details: displayDetails});
+        await this._invoke(true, 'displaySetContent', {details: displayDetails});
     }
 
     /**
@@ -192,7 +192,7 @@ export class PopupWindow extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async setCustomCss(css) {
-        await this._invoke(false, 'displaySetCustomCss', {id: this._id, css});
+        await this._invoke(false, 'displaySetCustomCss', {css});
     }
 
     /**
@@ -200,7 +200,7 @@ export class PopupWindow extends EventDispatcher {
      * @returns {Promise<void>}
      */
     async clearAutoPlayTimer() {
-        await this._invoke(false, 'displayAudioClearAutoPlayTimer', {id: this._id});
+        await this._invoke(false, 'displayAudioClearAutoPlayTimer', void 0);
     }
 
     /**
@@ -266,24 +266,29 @@ export class PopupWindow extends EventDispatcher {
 
     // Private
 
-    // TODO : Type safety
     /**
-     * @template {import('core').SerializableObject} TParams
-     * @template [TReturn=unknown]
+     * @template {import('display').DirectApiNames} TName
      * @param {boolean} open
-     * @param {string} action
-     * @param {TParams} params
-     * @returns {Promise<TReturn|undefined>}
+     * @param {TName} action
+     * @param {import('display').DirectApiParams<TName>} params
+     * @returns {Promise<import('display').DirectApiReturn<TName>|undefined>}
      */
     async _invoke(open, action, params) {
         if (yomitan.isExtensionUnloaded) {
             return void 0;
         }
 
+        const message = /** @type {import('display').DirectApiMessageAny} */ ({action, params});
+
         const frameId = 0;
         if (this._popupTabId !== null) {
             try {
-                return await yomitan.crossFrame.invokeTab(this._popupTabId, frameId, 'popupMessage', {action, params});
+                return /** @type {import('display').DirectApiReturn<TName>} */ (await yomitan.crossFrame.invokeTab(
+                    this._popupTabId,
+                    frameId,
+                    'displayPopupMessage2',
+                    message
+                ));
             } catch (e) {
                 if (yomitan.isExtensionUnloaded) {
                     open = false;
@@ -299,6 +304,11 @@ export class PopupWindow extends EventDispatcher {
         const {tabId} = await yomitan.api.getOrCreateSearchPopup({focus: 'ifCreated'});
         this._popupTabId = tabId;
 
-        return await yomitan.crossFrame.invokeTab(this._popupTabId, frameId, 'popupMessage', {action, params});
+        return /** @type {import('display').DirectApiReturn<TName>} */ (await yomitan.crossFrame.invokeTab(
+            this._popupTabId,
+            frameId,
+            'displayPopupMessage2',
+            message
+        ));
     }
 }
diff --git a/ext/js/app/popup.js b/ext/js/app/popup.js
index a8cdf1a6..0f7fbd87 100644
--- a/ext/js/app/popup.js
+++ b/ext/js/app/popup.js
@@ -316,7 +316,7 @@ export class Popup extends EventDispatcher {
      */
     async clearAutoPlayTimer() {
         if (this._frameConnected) {
-            await this._invokeSafe('displayAudioClearAutoPlayTimer', {});
+            await this._invokeSafe('displayAudioClearAutoPlayTimer', void 0);
         }
     }
 
@@ -679,13 +679,11 @@ export class Popup extends EventDispatcher {
         }
     }
 
-    // TODO : Type safety
     /**
-     * @template {import('core').SerializableObject} TParams
-     * @template [TReturn=unknown]
-     * @param {string} action
-     * @param {TParams} params
-     * @returns {Promise<TReturn>}
+     * @template {import('display').DirectApiNames} TName
+     * @param {TName} action
+     * @param {import('display').DirectApiParams<TName>} params
+     * @returns {Promise<import('display').DirectApiReturn<TName>>}
      */
     async _invoke(action, params) {
         const contentWindow = this._frame.contentWindow;
@@ -693,17 +691,21 @@ export class Popup extends EventDispatcher {
             throw new Error(`Failed to invoke action ${action}: frame state invalid`);
         }
 
-        const message = this._frameClient.createMessage({action, params});
-        return await yomitan.crossFrame.invoke(this._frameClient.frameId, 'popupMessage', message);
+        /** @type {import('display').DirectApiMessage<TName>} */
+        const message = {action, params};
+        const wrappedMessage = this._frameClient.createMessage(message);
+        return /** @type {import('display').DirectApiReturn<TName>} */ (await yomitan.crossFrame.invoke(
+            this._frameClient.frameId,
+            'displayPopupMessage1',
+            /** @type {import('display').DirectApiFrameClientMessageAny} */ (wrappedMessage)
+        ));
     }
 
-    // TODO : Type safety
     /**
-     * @template {import('core').SerializableObject} TParams
-     * @template [TReturn=unknown]
-     * @param {string} action
-     * @param {TParams} params
-     * @returns {Promise<TReturn|undefined>}
+     * @template {import('display').DirectApiNames} TName
+     * @param {TName} action
+     * @param {import('display').DirectApiParams<TName>} params
+     * @returns {Promise<import('display').DirectApiReturn<TName>|undefined>}
      */
     async _invokeSafe(action, params) {
         try {
diff --git a/ext/js/comm/cross-frame-api.js b/ext/js/comm/cross-frame-api.js
index 14e410a8..3569c037 100644
--- a/ext/js/comm/cross-frame-api.js
+++ b/ext/js/comm/cross-frame-api.js
@@ -16,7 +16,8 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import {EventDispatcher, EventListenerCollection, invokeMessageHandler, log} from '../core.js';
+import {EventDispatcher, EventListenerCollection, log} from '../core.js';
+import {extendApiMap, invokeApiMapHandler} from '../core/api-map.js';
 import {ExtensionError} from '../core/extension-error.js';
 import {parseJson} from '../core/json.js';
 import {yomitan} from '../yomitan.js';
@@ -29,9 +30,9 @@ export class CrossFrameAPIPort extends EventDispatcher {
      * @param {number} otherTabId
      * @param {number} otherFrameId
      * @param {chrome.runtime.Port} port
-     * @param {import('core').MessageHandlerMap} messageHandlers
+     * @param {import('cross-frame-api').ApiMap} apiMap
      */
-    constructor(otherTabId, otherFrameId, port, messageHandlers) {
+    constructor(otherTabId, otherFrameId, port, apiMap) {
         super();
         /** @type {number} */
         this._otherTabId = otherTabId;
@@ -39,8 +40,8 @@ export class CrossFrameAPIPort extends EventDispatcher {
         this._otherFrameId = otherFrameId;
         /** @type {?chrome.runtime.Port} */
         this._port = port;
-        /** @type {import('core').MessageHandlerMap} */
-        this._messageHandlers = messageHandlers;
+        /** @type {import('cross-frame-api').ApiMap} */
+        this._apiMap = apiMap;
         /** @type {Map<number, import('cross-frame-api').Invocation>} */
         this._activeInvocations = new Map();
         /** @type {number} */
@@ -69,13 +70,12 @@ export class CrossFrameAPIPort extends EventDispatcher {
     }
 
     /**
-     * @template [TParams=import('core').SerializableObject]
-     * @template [TReturn=unknown]
-     * @param {string} action
-     * @param {TParams} params
+     * @template {import('cross-frame-api').ApiNames} TName
+     * @param {TName} action
+     * @param {import('cross-frame-api').ApiParams<TName>} params
      * @param {number} ackTimeout
      * @param {number} responseTimeout
-     * @returns {Promise<TReturn>}
+     * @returns {Promise<import('cross-frame-api').ApiReturn<TName>>}
      */
     invoke(action, params, ackTimeout, responseTimeout) {
         return new Promise((resolve, reject) => {
@@ -186,7 +186,7 @@ export class CrossFrameAPIPort extends EventDispatcher {
 
     /**
      * @param {number} id
-     * @param {import('core').Response<unknown>} data
+     * @param {import('core').Response<import('cross-frame-api').ApiReturnAny>} data
      */
     _onResult(id, data) {
         const invocation = this._activeInvocations.get(id);
@@ -217,15 +217,13 @@ export class CrossFrameAPIPort extends EventDispatcher {
 
     /**
      * @param {number} id
-     * @param {unknown} error
+     * @param {unknown} errorOrMessage
      */
-    _onError(id, error) {
+    _onError(id, errorOrMessage) {
         const invocation = this._activeInvocations.get(id);
         if (typeof invocation === 'undefined') { return; }
 
-        if (!(error instanceof Error)) {
-            error = new Error(`${error} (${invocation.action})`);
-        }
+        const error = errorOrMessage instanceof Error ? errorOrMessage : new Error(`${errorOrMessage} (${invocation.action})`);
 
         this._activeInvocations.delete(id);
         if (invocation.timer !== null) {
@@ -239,23 +237,18 @@ export class CrossFrameAPIPort extends EventDispatcher {
 
     /**
      * @param {number} id
-     * @param {import('cross-frame-api').InvocationData} details
-     * @returns {boolean}
+     * @param {import('cross-frame-api').ApiMessageAny} details
      */
     _onInvoke(id, {action, params}) {
-        const messageHandler = this._messageHandlers.get(action);
         this._sendAck(id);
-        if (typeof messageHandler === 'undefined') {
-            this._sendError(id, new Error(`Unknown action: ${action}`));
-            return false;
-        }
-
-        /**
-         * @param {import('core').Response<unknown>} data
-         * @returns {void}
-         */
-        const callback = (data) => this._sendResult(id, data);
-        return invokeMessageHandler(messageHandler, params, callback);
+        invokeApiMapHandler(
+            this._apiMap,
+            action,
+            params,
+            [],
+            (data) => this._sendResult(id, data),
+            () => this._sendError(id, new Error(`Unknown action: ${action}`))
+        );
     }
 
     /**
@@ -279,7 +272,7 @@ export class CrossFrameAPIPort extends EventDispatcher {
 
     /**
      * @param {number} id
-     * @param {import('core').Response<unknown>} data
+     * @param {import('core').Response<import('cross-frame-api').ApiReturnAny>} data
      */
     _sendResult(id, data) {
         this._sendResponse({type: 'result', id, data});
@@ -302,8 +295,8 @@ export class CrossFrameAPI {
         this._responseTimeout = 10000; // 10 seconds
         /** @type {Map<number, Map<number, CrossFrameAPIPort>>} */
         this._commPorts = new Map();
-        /** @type {import('core').MessageHandlerMap} */
-        this._messageHandlers = new Map();
+        /** @type {import('cross-frame-api').ApiMap} */
+        this._apiMap = new Map();
         /** @type {(port: CrossFrameAPIPort) => void} */
         this._onDisconnectBind = this._onDisconnect.bind(this);
         /** @type {?number} */
@@ -319,25 +312,23 @@ export class CrossFrameAPI {
     }
 
     /**
-     * @template [TParams=import('core').SerializableObject]
-     * @template [TReturn=unknown]
+     * @template {import('cross-frame-api').ApiNames} TName
      * @param {number} targetFrameId
-     * @param {string} action
-     * @param {TParams} params
-     * @returns {Promise<TReturn>}
+     * @param {TName} action
+     * @param {import('cross-frame-api').ApiParams<TName>} params
+     * @returns {Promise<import('cross-frame-api').ApiReturn<TName>>}
      */
     invoke(targetFrameId, action, params) {
         return this.invokeTab(null, targetFrameId, action, params);
     }
 
     /**
-     * @template [TParams=import('core').SerializableObject]
-     * @template [TReturn=unknown]
+     * @template {import('cross-frame-api').ApiNames} TName
      * @param {?number} targetTabId
      * @param {number} targetFrameId
-     * @param {string} action
-     * @param {TParams} params
-     * @returns {Promise<TReturn>}
+     * @param {TName} action
+     * @param {import('cross-frame-api').ApiParams<TName>} params
+     * @returns {Promise<import('cross-frame-api').ApiReturn<TName>>}
      */
     async invokeTab(targetTabId, targetFrameId, action, params) {
         if (typeof targetTabId !== 'number') {
@@ -351,24 +342,10 @@ export class CrossFrameAPI {
     }
 
     /**
-     * @param {import('core').MessageHandlerMapInit} messageHandlers
-     * @throws {Error}
-     */
-    registerHandlers(messageHandlers) {
-        for (const [key, value] of messageHandlers) {
-            if (this._messageHandlers.has(key)) {
-                throw new Error(`Handler ${key} is already registered`);
-            }
-            this._messageHandlers.set(key, value);
-        }
-    }
-
-    /**
-     * @param {string} key
-     * @returns {boolean}
+     * @param {import('cross-frame-api').ApiMapInit} handlers
      */
-    unregisterHandler(key) {
-        return this._messageHandlers.delete(key);
+    registerHandlers(handlers) {
+        extendApiMap(this._apiMap, handlers);
     }
 
     // Private
@@ -451,7 +428,7 @@ export class CrossFrameAPI {
      * @returns {CrossFrameAPIPort}
      */
     _setupCommPort(otherTabId, otherFrameId, port) {
-        const commPort = new CrossFrameAPIPort(otherTabId, otherFrameId, port, this._messageHandlers);
+        const commPort = new CrossFrameAPIPort(otherTabId, otherFrameId, port, this._apiMap);
         let tabPorts = this._commPorts.get(otherTabId);
         if (typeof tabPorts === 'undefined') {
             tabPorts = new Map();
diff --git a/ext/js/comm/frame-ancestry-handler.js b/ext/js/comm/frame-ancestry-handler.js
index 261ea943..e715cedc 100644
--- a/ext/js/comm/frame-ancestry-handler.js
+++ b/ext/js/comm/frame-ancestry-handler.js
@@ -37,12 +37,12 @@ export class FrameAncestryHandler {
         this._isPrepared = false;
         /** @type {string} */
         this._requestMessageId = 'FrameAncestryHandler.requestFrameInfo';
-        /** @type {string} */
-        this._responseMessageIdBase = `${this._requestMessageId}.response.`;
         /** @type {?Promise<number[]>} */
         this._getFrameAncestryInfoPromise = null;
         /** @type {Map<number, {window: Window, frameElement: ?(undefined|Element)}>} */
         this._childFrameMap = new Map();
+        /** @type {Map<string, import('frame-ancestry-handler').ResponseHandler>} */
+        this._responseHandlers = new Map();
     }
 
     /**
@@ -59,6 +59,9 @@ export class FrameAncestryHandler {
     prepare() {
         if (this._isPrepared) { return; }
         window.addEventListener('message', this._onWindowMessage.bind(this), false);
+        yomitan.crossFrame.registerHandlers([
+            ['frameAncestryHandlerRequestFrameInfoResponse', this._onFrameAncestryHandlerRequestFrameInfoResponse.bind(this)]
+        ]);
         this._isPrepared = true;
     }
 
@@ -119,7 +122,6 @@ export class FrameAncestryHandler {
 
             const uniqueId = generateId(16);
             let nonce = generateId(16);
-            const responseMessageId = `${this._responseMessageIdBase}${uniqueId}`;
             /** @type {number[]} */
             const results = [];
             /** @type {?import('core').Timeout} */
@@ -130,12 +132,9 @@ export class FrameAncestryHandler {
                     clearTimeout(timer);
                     timer = null;
                 }
-                yomitan.crossFrame.unregisterHandler(responseMessageId);
+                this._removeResponseHandler(uniqueId);
             };
-            /**
-             * @param {import('frame-ancestry-handler').RequestFrameInfoResponseParams} params
-             * @returns {?import('frame-ancestry-handler').RequestFrameInfoResponseReturn}
-             */
+            /** @type {import('frame-ancestry-handler').ResponseHandler} */
             const onMessage = (params) => {
                 if (params.nonce !== nonce) { return null; }
 
@@ -164,9 +163,7 @@ export class FrameAncestryHandler {
             };
 
             // Start
-            yomitan.crossFrame.registerHandlers([
-                [responseMessageId, onMessage]
-            ]);
+            this._addResponseHandler(uniqueId, onMessage);
             resetTimeout();
             const frameId = this._frameId;
             this._requestFrameInfo(targetWindow, frameId, frameId, uniqueId, nonce);
@@ -212,13 +209,9 @@ export class FrameAncestryHandler {
             const frameId = this._frameId;
             const {parent} = window;
             const more = (window !== parent);
-            /** @type {import('frame-ancestry-handler').RequestFrameInfoResponseParams} */
-            const responseParams = {frameId, nonce, more};
-            const responseMessageId = `${this._responseMessageIdBase}${uniqueId}`;
 
             try {
-                /** @type {?import('frame-ancestry-handler').RequestFrameInfoResponseReturn} */
-                const response = await yomitan.crossFrame.invoke(originFrameId, responseMessageId, responseParams);
+                const response = await yomitan.crossFrame.invoke(originFrameId, 'frameAncestryHandlerRequestFrameInfoResponse', {uniqueId, frameId, nonce, more});
                 if (response === null) { return; }
                 const nonce2 = response.nonce;
                 if (typeof nonce2 !== 'string') { return; }
@@ -317,4 +310,27 @@ export class FrameAncestryHandler {
         // Not found
         return null;
     }
+
+    /**
+     * @param {string} id
+     * @param {import('frame-ancestry-handler').ResponseHandler} handler
+     * @throws {Error}
+     */
+    _addResponseHandler(id, handler) {
+        if (this._responseHandlers.has(id)) { throw new Error('Identifier already used'); }
+        this._responseHandlers.set(id, handler);
+    }
+
+    /**
+     * @param {string} id
+     */
+    _removeResponseHandler(id) {
+        this._responseHandlers.delete(id);
+    }
+
+    /** @type {import('cross-frame-api').ApiHandler<'frameAncestryHandlerRequestFrameInfoResponse'>} */
+    _onFrameAncestryHandlerRequestFrameInfoResponse(params) {
+        const handler = this._responseHandlers.get(params.uniqueId);
+        return typeof handler !== 'undefined' ? handler(params) : null;
+    }
 }
diff --git a/ext/js/comm/frame-offset-forwarder.js b/ext/js/comm/frame-offset-forwarder.js
index afa6a5e6..570f3e88 100644
--- a/ext/js/comm/frame-offset-forwarder.js
+++ b/ext/js/comm/frame-offset-forwarder.js
@@ -36,7 +36,7 @@ export class FrameOffsetForwarder {
     prepare() {
         this._frameAncestryHandler.prepare();
         yomitan.crossFrame.registerHandlers([
-            ['FrameOffsetForwarder.getChildFrameRect', this._onMessageGetChildFrameRect.bind(this)]
+            ['frameOffsetForwarderGetChildFrameRect', this._onMessageGetChildFrameRect.bind(this)]
         ]);
     }
 
@@ -55,7 +55,7 @@ export class FrameOffsetForwarder {
             /** @type {Promise<?import('frame-offset-forwarder').ChildFrameRect>[]} */
             const promises = [];
             for (const frameId of ancestorFrameIds) {
-                promises.push(yomitan.crossFrame.invoke(frameId, 'FrameOffsetForwarder.getChildFrameRect', {frameId: childFrameId}));
+                promises.push(yomitan.crossFrame.invoke(frameId, 'frameOffsetForwarderGetChildFrameRect', {frameId: childFrameId}));
                 childFrameId = frameId;
             }
 
@@ -76,10 +76,7 @@ export class FrameOffsetForwarder {
 
     // Private
 
-    /**
-     * @param {{frameId: number}} event
-     * @returns {?import('frame-offset-forwarder').ChildFrameRect}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'frameOffsetForwarderGetChildFrameRect'>} */
     _onMessageGetChildFrameRect({frameId}) {
         const frameElement = this._frameAncestryHandler.getChildFrameElement(frameId);
         if (frameElement === null) { return null; }
diff --git a/ext/js/core.js b/ext/js/core.js
index c9c989ac..726b037c 100644
--- a/ext/js/core.js
+++ b/ext/js/core.js
@@ -321,38 +321,6 @@ export function promiseAnimationFrame(timeout) {
 }
 
 /**
- * Invokes a standard message handler. This function is used to react and respond
- * to communication messages within the extension.
- * @template {import('core').SafeAny} TParams
- * @param {import('core').MessageHandler} handler The message handler function.
- * @param {TParams} params Information which was passed with the original message.
- * @param {(response: import('core').Response) => void} callback A callback function which is invoked after the handler has completed. The value passed
- *   to the function is in the format:
- *   - `{result: unknown}` if the handler invoked successfully.
- *   - `{error: object}` if the handler thew an error. The error is serialized.
- * @param {...*} extraArgs Additional arguments which are passed to the `handler` function.
- * @returns {boolean} `true` if the function is invoked asynchronously, `false` otherwise.
- */
-export function invokeMessageHandler(handler, params, callback, ...extraArgs) {
-    try {
-        const promiseOrResult = handler(params, ...extraArgs);
-        if (promiseOrResult instanceof Promise) {
-            /** @type {Promise<any>} */ (promiseOrResult).then(
-                (result) => { callback({result}); },
-                (error) => { callback({error: ExtensionError.serialize(error)}); }
-            );
-            return true;
-        } else {
-            callback({result: promiseOrResult});
-            return false;
-        }
-    } catch (error) {
-        callback({error: ExtensionError.serialize(error)});
-        return false;
-    }
-}
-
-/**
  * The following typedef is required because the JSDoc `implements` tag doesn't work with `import()`.
  * https://github.com/microsoft/TypeScript/issues/49905
  * @typedef {import('core').EventDispatcherOffGeneric} EventDispatcherOffGeneric
diff --git a/ext/js/display/display-resizer.js b/ext/js/display/display-resizer.js
index 794398b8..8245e0bb 100644
--- a/ext/js/display/display-resizer.js
+++ b/ext/js/display/display-resizer.js
@@ -174,7 +174,7 @@ export class DisplayResizer {
         if (parentPopupId === null) { return; }
 
         /** @type {import('popup').ValidSize} */
-        const size = await this._display.invokeParentFrame('PopupFactory.getFrameSize', {id: parentPopupId});
+        const size = await this._display.invokeParentFrame('popupFactoryGetFrameSize', {id: parentPopupId});
         if (this._token !== token) { return; }
         const {width, height} = size;
         this._startSize = {width, height};
@@ -210,7 +210,7 @@ export class DisplayResizer {
         height += y - this._startOffset.y;
         width = Math.max(Math.max(0, handleSize.width), width);
         height = Math.max(Math.max(0, handleSize.height), height);
-        await this._display.invokeParentFrame('PopupFactory.setFrameSize', {id: parentPopupId, width, height});
+        await this._display.invokeParentFrame('popupFactorySetFrameSize', {id: parentPopupId, width, height});
     }
 
     /**
diff --git a/ext/js/display/display.js b/ext/js/display/display.js
index e3c92ee2..cae394f8 100644
--- a/ext/js/display/display.js
+++ b/ext/js/display/display.js
@@ -19,7 +19,7 @@
 import {ThemeController} from '../app/theme-controller.js';
 import {FrameEndpoint} from '../comm/frame-endpoint.js';
 import {DynamicProperty, EventDispatcher, EventListenerCollection, clone, deepEqual, log, promiseTimeout} from '../core.js';
-import {invokeApiMapHandler} from '../core/api-map.js';
+import {extendApiMap, invokeApiMapHandler} from '../core/api-map.js';
 import {ExtensionError} from '../core/extension-error.js';
 import {PopupMenu} from '../dom/popup-menu.js';
 import {querySelectorNotNull} from '../dom/query-selector.js';
@@ -91,7 +91,7 @@ export class Display extends EventDispatcher {
         });
         /** @type {import('display').DirectApiMap} */
         this._directApiMap = new Map();
-        /** @type {import('display').WindowApiMap} */
+        /** @type {import('api-map').ApiMap<import('display').WindowApiSurface>} */ // import('display').WindowApiMap
         this._windowApiMap = new Map();
         /** @type {DisplayHistory} */
         this._history = new DisplayHistory({clearable: true, useBrowserHistory: false});
@@ -328,7 +328,8 @@ export class Display extends EventDispatcher {
         this._progressIndicatorVisible.on('change', this._onProgressIndicatorVisibleChanged.bind(this));
         yomitan.on('extensionUnloaded', this._onExtensionUnloaded.bind(this));
         yomitan.crossFrame.registerHandlers([
-            ['popupMessage', this._onDirectMessage.bind(this)]
+            ['displayPopupMessage1', this._onDisplayPopupMessage1.bind(this)],
+            ['displayPopupMessage2', this._onDisplayPopupMessage2.bind(this)]
         ]);
         window.addEventListener('message', this._onWindowMessage.bind(this), false);
 
@@ -507,25 +508,21 @@ export class Display extends EventDispatcher {
      * @param {import('display').DirectApiMapInit} handlers
      */
     registerDirectMessageHandlers(handlers) {
-        for (const [name, handlerInfo] of handlers) {
-            this._directApiMap.set(name, handlerInfo);
-        }
+        extendApiMap(this._directApiMap, handlers);
     }
 
     /**
      * @param {import('display').WindowApiMapInit} handlers
      */
     registerWindowMessageHandlers(handlers) {
-        for (const [name, handlerInfo] of handlers) {
-            this._windowApiMap.set(name, handlerInfo);
-        }
+        extendApiMap(this._windowApiMap, handlers);
     }
 
     /** */
     close() {
         switch (this._pageType) {
             case 'popup':
-                this.invokeContentOrigin('Frontend.closePopup');
+                this.invokeContentOrigin('frontendClosePopup', void 0);
                 break;
             case 'search':
                 this._closeTab();
@@ -578,12 +575,12 @@ export class Display extends EventDispatcher {
     }
 
     /**
-     * @template [TReturn=unknown]
-     * @param {string} action
-     * @param {import('core').SerializableObject} [params]
-     * @returns {Promise<TReturn>}
+     * @template {import('cross-frame-api').ApiNames} TName
+     * @param {TName} action
+     * @param {import('cross-frame-api').ApiParams<TName>} params
+     * @returns {Promise<import('cross-frame-api').ApiReturn<TName>>}
      */
-    async invokeContentOrigin(action, params = {}) {
+    async invokeContentOrigin(action, params) {
         if (this._contentOriginTabId === this._tabId && this._contentOriginFrameId === this._frameId) {
             throw new Error('Content origin is same page');
         }
@@ -594,12 +591,12 @@ export class Display extends EventDispatcher {
     }
 
     /**
-     * @template [TReturn=unknown]
-     * @param {string} action
-     * @param {import('core').SerializableObject} [params]
-     * @returns {Promise<TReturn>}
+     * @template {import('cross-frame-api').ApiNames} TName
+     * @param {TName} action
+     * @param {import('cross-frame-api').ApiParams<TName>} params
+     * @returns {Promise<import('cross-frame-api').ApiReturn<TName>>}
      */
-    async invokeParentFrame(action, params = {}) {
+    async invokeParentFrame(action, params) {
         if (this._parentFrameId === null || this._parentFrameId === this._frameId) {
             throw new Error('Invalid parent frame');
         }
@@ -634,14 +631,17 @@ export class Display extends EventDispatcher {
 
     // Message handlers
 
-    /**
-     * @param {import('frame-client').Message<import('display').DirectApiMessageAny>} data
-     * @returns {Promise<import('display').DirectApiReturnAny>}
-     * @throws {Error}
-     */
-    _onDirectMessage(data) {
+    /** @type {import('cross-frame-api').ApiHandler<'displayPopupMessage1'>} */
+    async _onDisplayPopupMessage1(message) {
+        /** @type {import('display').DirectApiMessageAny} */
+        const messageInner = this._authenticateMessageData(message);
+        return await this._onDisplayPopupMessage2(messageInner);
+    }
+
+    /** @type {import('cross-frame-api').ApiHandler<'displayPopupMessage2'>} */
+    _onDisplayPopupMessage2(message) {
         return new Promise((resolve, reject) => {
-            const {action, params} = this._authenticateMessageData(data);
+            const {action, params} = message;
             invokeApiMapHandler(
                 this._directApiMap,
                 action,
@@ -663,9 +663,10 @@ export class Display extends EventDispatcher {
     }
 
     /**
-     * @param {MessageEvent<import('frame-client').Message<import('display').WindowApiMessageAny>>} details
+     * @param {MessageEvent<import('display').WindowApiFrameClientMessageAny>} details
      */
     _onWindowMessage({data}) {
+        /** @type {import('display').WindowApiMessageAny} */
         let data2;
         try {
             data2 = this._authenticateMessageData(data);
@@ -676,7 +677,7 @@ export class Display extends EventDispatcher {
         try {
             const {action, params} = data2;
             const callback = () => {}; // NOP
-            invokeApiMapHandler(this._directApiMap, action, params, [], callback);
+            invokeApiMapHandler(this._windowApiMap, action, params, [], callback);
         } catch (e) {
             // NOP
         }
@@ -729,18 +730,15 @@ export class Display extends EventDispatcher {
 
     /**
      * @template [T=unknown]
-     * @param {T|import('frame-client').Message<T>} data
+     * @param {import('frame-client').Message<unknown>} message
      * @returns {T}
      * @throws {Error}
      */
-    _authenticateMessageData(data) {
-        if (this._frameEndpoint === null) {
-            return /** @type {T} */ (data);
-        }
-        if (!this._frameEndpoint.authenticate(data)) {
+    _authenticateMessageData(message) {
+        if (this._frameEndpoint !== null && !this._frameEndpoint.authenticate(message)) {
             throw new Error('Invalid authentication');
         }
-        return /** @type {import('frame-client').Message<T>} */ (data).data;
+        return /** @type {import('frame-client').Message<T>} */ (message).data;
     }
 
     /** */
@@ -1767,7 +1765,7 @@ export class Display extends EventDispatcher {
                     /** @type {string} */
                     let text;
                     try {
-                        text = await this.invokeContentOrigin('Frontend.getSelectionText');
+                        text = await this.invokeContentOrigin('frontendGetSelectionText', void 0);
                     } catch (e) {
                         break;
                     }
@@ -1775,7 +1773,7 @@ export class Display extends EventDispatcher {
                 }
                 break;
             default:
-                await this.invokeContentOrigin('Frontend.copySelection');
+                await this.invokeContentOrigin('frontendCopySelection', void 0);
                 break;
         }
     }
diff --git a/ext/js/input/hotkey-handler.js b/ext/js/input/hotkey-handler.js
index 48c2de57..5969af05 100644
--- a/ext/js/input/hotkey-handler.js
+++ b/ext/js/input/hotkey-handler.js
@@ -51,7 +51,7 @@ export class HotkeyHandler extends EventDispatcher {
         this._isPrepared = true;
         this._updateEventHandlers();
         yomitan.crossFrame.registerHandlers([
-            ['HotkeyHandler.forwardHotkey', this._onMessageForwardHotkey.bind(this)]
+            ['hotkeyHandlerForwardHotkey', this._onMessageForwardHotkey.bind(this)]
         ]);
     }
 
@@ -159,10 +159,7 @@ export class HotkeyHandler extends EventDispatcher {
 
     // Message handlers
 
-    /**
-     * @param {{key: string, modifiers: import('input').ModifierKey[]}} details
-     * @returns {boolean}
-     */
+    /** @type {import('cross-frame-api').ApiHandler<'hotkeyHandlerForwardHotkey'>} */
     _onMessageForwardHotkey({key, modifiers}) {
         return this.simulate(key, modifiers);
     }