diff --git a/deno-runtime/lib/accessors/builders/BlockBuilder.ts b/deno-runtime/lib/accessors/builders/BlockBuilder.ts
new file mode 100644
index 000000000..d643792fa
--- /dev/null
+++ b/deno-runtime/lib/accessors/builders/BlockBuilder.ts
@@ -0,0 +1,208 @@
+import { v1 as uuid } from 'uuid';
+
+import {
+    BlockType,
+    IActionsBlock,
+    IBlock,
+    IConditionalBlock,
+    IConditionalBlockFilters,
+    IContextBlock,
+    IImageBlock,
+    IInputBlock,
+    ISectionBlock,
+} from "@rocket.chat/apps-engine/definition/uikit/blocks/Blocks.ts";
+import type {
+    IBlockElement,
+    IButtonElement,
+    IImageElement,
+    IInputElement,
+    IInteractiveElement,
+    IMultiStaticSelectElement,
+    IOverflowMenuElement,
+    IPlainTextInputElement,
+    ISelectElement,
+    IStaticSelectElement,
+} from '@rocket.chat/apps-engine/definition/uikit/blocks/Elements.ts';
+import { BlockElementType } from '@rocket.chat/apps-engine/definition/uikit/blocks/Elements.ts';
+import type { ITextObject } from '@rocket.chat/apps-engine/definition/uikit/blocks/Objects.ts';
+import { TextObjectType } from '@rocket.chat/apps-engine/definition/uikit/blocks/Objects.ts';
+import { AppObjectRegistry } from "../../../AppObjectRegistry.ts";
+
+type BlockFunctionParameter<T extends IBlock> = Omit<T, 'type'>;
+type ElementFunctionParameter<T extends IBlockElement> = T extends IInteractiveElement
+    ? Omit<T, 'type' | 'actionId'> | Partial<Pick<T, 'actionId'>>
+    : Omit<T, 'type'>;
+
+type SectionBlockParam = BlockFunctionParameter<ISectionBlock>;
+type ImageBlockParam = BlockFunctionParameter<IImageBlock>;
+type ActionsBlockParam = BlockFunctionParameter<IActionsBlock>;
+type ContextBlockParam = BlockFunctionParameter<IContextBlock>;
+type InputBlockParam = BlockFunctionParameter<IInputBlock>;
+
+type ButtonElementParam = ElementFunctionParameter<IButtonElement>;
+type ImageElementParam = ElementFunctionParameter<IImageElement>;
+type OverflowMenuElementParam = ElementFunctionParameter<IOverflowMenuElement>;
+type PlainTextInputElementParam = ElementFunctionParameter<IPlainTextInputElement>;
+type StaticSelectElementParam = ElementFunctionParameter<IStaticSelectElement>;
+type MultiStaticSelectElementParam = ElementFunctionParameter<IMultiStaticSelectElement>;
+
+/**
+ * @deprecated please prefer the rocket.chat/ui-kit components
+ */
+export class BlockBuilder {
+    private readonly blocks: Array<IBlock>;
+    private readonly appId: string;
+
+    constructor() {
+        this.blocks = [];
+        this.appId = String(AppObjectRegistry.get('appId'));
+    }
+
+    public addSectionBlock(block: SectionBlockParam): BlockBuilder {
+        this.addBlock({ type: BlockType.SECTION, ...block } as ISectionBlock);
+
+        return this;
+    }
+
+    public addImageBlock(block: ImageBlockParam): BlockBuilder {
+        this.addBlock({ type: BlockType.IMAGE, ...block } as IImageBlock);
+
+        return this;
+    }
+
+    public addDividerBlock(): BlockBuilder {
+        this.addBlock({ type: BlockType.DIVIDER });
+
+        return this;
+    }
+
+    public addActionsBlock(block: ActionsBlockParam): BlockBuilder {
+        this.addBlock({ type: BlockType.ACTIONS, ...block } as IActionsBlock);
+
+        return this;
+    }
+
+    public addContextBlock(block: ContextBlockParam): BlockBuilder {
+        this.addBlock({ type: BlockType.CONTEXT, ...block } as IContextBlock);
+
+        return this;
+    }
+
+    public addInputBlock(block: InputBlockParam): BlockBuilder {
+        this.addBlock({ type: BlockType.INPUT, ...block } as IInputBlock);
+
+        return this;
+    }
+
+    public addConditionalBlock(innerBlocks: BlockBuilder | Array<IBlock>, condition?: IConditionalBlockFilters): BlockBuilder {
+        const render = innerBlocks instanceof BlockBuilder ? innerBlocks.getBlocks() : innerBlocks;
+
+        this.addBlock({ type: BlockType.CONDITIONAL, render, when: condition } as IConditionalBlock);
+
+        return this;
+    }
+
+    public getBlocks() {
+        return this.blocks;
+    }
+
+    public newPlainTextObject(text: string, emoji = false): ITextObject {
+        return {
+            type: TextObjectType.PLAINTEXT,
+            text,
+            emoji,
+        };
+    }
+
+    public newMarkdownTextObject(text: string): ITextObject {
+        return {
+            type: TextObjectType.MARKDOWN,
+            text,
+        };
+    }
+
+    public newButtonElement(info: ButtonElementParam): IButtonElement {
+        return this.newInteractiveElement({
+            type: BlockElementType.BUTTON,
+            ...info,
+        } as IButtonElement);
+    }
+
+    public newImageElement(info: ImageElementParam): IImageElement {
+        return {
+            type: BlockElementType.IMAGE,
+            ...info,
+        };
+    }
+
+    public newOverflowMenuElement(info: OverflowMenuElementParam): IOverflowMenuElement {
+        return this.newInteractiveElement({
+            type: BlockElementType.OVERFLOW_MENU,
+            ...info,
+        } as IOverflowMenuElement);
+    }
+
+    public newPlainTextInputElement(info: PlainTextInputElementParam): IPlainTextInputElement {
+        return this.newInputElement({
+            type: BlockElementType.PLAIN_TEXT_INPUT,
+            ...info,
+        } as IPlainTextInputElement);
+    }
+
+    public newStaticSelectElement(info: StaticSelectElementParam): IStaticSelectElement {
+        return this.newSelectElement({
+            type: BlockElementType.STATIC_SELECT,
+            ...info,
+        } as IStaticSelectElement);
+    }
+
+    public newMultiStaticElement(info: MultiStaticSelectElementParam): IMultiStaticSelectElement {
+        return this.newSelectElement({
+            type: BlockElementType.MULTI_STATIC_SELECT,
+            ...info,
+        } as IMultiStaticSelectElement);
+    }
+
+    private newInteractiveElement<T extends IInteractiveElement>(element: T): T {
+        if (!element.actionId) {
+            element.actionId = this.generateActionId();
+        }
+
+        return element;
+    }
+
+    private newInputElement<T extends IInputElement>(element: T): T {
+        if (!element.actionId) {
+            element.actionId = this.generateActionId();
+        }
+
+        return element;
+    }
+
+    private newSelectElement<T extends ISelectElement>(element: T): T {
+        if (!element.actionId) {
+            element.actionId = this.generateActionId();
+        }
+
+        return element;
+    }
+
+    private addBlock(block: IBlock): void {
+        if (!block.blockId) {
+            block.blockId = this.generateBlockId();
+        }
+
+        block.appId = this.appId;
+
+        this.blocks.push(block);
+    }
+
+    private generateBlockId(): string {
+        return uuid();
+    }
+
+    private generateActionId(): string {
+        return uuid();
+    }
+
+}
diff --git a/deno-runtime/lib/accessors/builders/DiscussionBuilder.ts b/deno-runtime/lib/accessors/builders/DiscussionBuilder.ts
new file mode 100644
index 000000000..b69142eff
--- /dev/null
+++ b/deno-runtime/lib/accessors/builders/DiscussionBuilder.ts
@@ -0,0 +1,53 @@
+import type { IDiscussionBuilder as _IDiscussionBuilder } from "@rocket.chat/apps-engine/definition/accessors/IDiscussionBuilder.ts";
+import type { IMessage } from "@rocket.chat/apps-engine/definition/messages/IMessage.ts";
+import type { IRoom } from "@rocket.chat/apps-engine/definition/rooms/IRoom.ts";
+import type { IRoomBuilder } from "@rocket.chat/apps-engine/definition/accessors/IRoomBuilder.ts";
+
+import { RocketChatAssociationModel } from "@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts";
+import { RoomType } from "@rocket.chat/apps-engine/definition/rooms/RoomType.ts";
+
+import { RoomBuilder } from "./RoomBuilder.ts";
+
+export interface IDiscussionBuilder extends _IDiscussionBuilder, IRoomBuilder {}
+
+export class DiscussionBuilder extends RoomBuilder implements IDiscussionBuilder {
+    public kind: RocketChatAssociationModel.DISCUSSION;
+
+    private reply?: string;
+
+    private parentMessage?: IMessage;
+
+    constructor(data?: Partial<IRoom>) {
+        super(data);
+        this.kind = RocketChatAssociationModel.DISCUSSION;
+        this.room.type = RoomType.PRIVATE_GROUP;
+    }
+
+    public setParentRoom(parentRoom: IRoom): IDiscussionBuilder {
+        this.room.parentRoom = parentRoom;
+        return this;
+    }
+
+    public getParentRoom(): IRoom {
+        return this.room.parentRoom!;
+    }
+
+    public setReply(reply: string): IDiscussionBuilder {
+        this.reply = reply;
+        return this;
+    }
+
+    public getReply(): string {
+        return this.reply!;
+    }
+
+    public setParentMessage(parentMessage: IMessage): IDiscussionBuilder {
+        this.parentMessage = parentMessage;
+        return this;
+    }
+
+    public getParentMessage(): IMessage {
+        return this.parentMessage!;
+    }
+}
+
diff --git a/deno-runtime/lib/accessors/builders/LivechatMessageBuilder.ts b/deno-runtime/lib/accessors/builders/LivechatMessageBuilder.ts
new file mode 100644
index 000000000..b90081e23
--- /dev/null
+++ b/deno-runtime/lib/accessors/builders/LivechatMessageBuilder.ts
@@ -0,0 +1,198 @@
+import { RocketChatAssociationModel } from "@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts";
+import { RoomType } from "@rocket.chat/apps-engine/definition/rooms/RoomType.ts";
+
+import type { ILivechatMessageBuilder } from "@rocket.chat/apps-engine/definition/accessors/ILivechatMessageBuilder.ts";
+import type { IMessage } from '@rocket.chat/apps-engine/definition/messages/IMessage.ts';
+import type { IMessageAttachment } from '@rocket.chat/apps-engine/definition/messages/IMessageAttachment.ts';
+import type { IRoom } from '@rocket.chat/apps-engine/definition/rooms/IRoom.ts';
+import type { IUser } from '@rocket.chat/apps-engine/definition/users/IUser.ts';
+import type { ILivechatMessage as EngineLivechatMessage } from '@rocket.chat/apps-engine/definition/livechat/ILivechatMessage.ts';
+import type { IVisitor } from "@rocket.chat/apps-engine/definition/livechat/IVisitor.ts";
+import type { IMessageBuilder } from "@rocket.chat/apps-engine/definition/accessors/IMessageBuilder.ts";
+
+import { MessageBuilder } from "./MessageBuilder.ts";
+
+export interface ILivechatMessage extends EngineLivechatMessage, IMessage {}
+
+export class LivechatMessageBuilder implements ILivechatMessageBuilder {
+    public kind: RocketChatAssociationModel.LIVECHAT_MESSAGE;
+
+    private msg: ILivechatMessage;
+
+    constructor(message?: ILivechatMessage) {
+        this.kind = RocketChatAssociationModel.LIVECHAT_MESSAGE;
+        this.msg = message || ({} as ILivechatMessage);
+    }
+
+    public setData(data: ILivechatMessage): ILivechatMessageBuilder {
+        delete data.id;
+        this.msg = data;
+
+        return this;
+    }
+
+    public setRoom(room: IRoom): ILivechatMessageBuilder {
+        this.msg.room = room;
+        return this;
+    }
+
+    public getRoom(): IRoom {
+        return this.msg.room;
+    }
+
+    public setSender(sender: IUser): ILivechatMessageBuilder {
+        this.msg.sender = sender;
+        delete this.msg.visitor;
+
+        return this;
+    }
+
+    public getSender(): IUser {
+        return this.msg.sender;
+    }
+
+    public setText(text: string): ILivechatMessageBuilder {
+        this.msg.text = text;
+        return this;
+    }
+
+    public getText(): string {
+        return this.msg.text!;
+    }
+
+    public setEmojiAvatar(emoji: string): ILivechatMessageBuilder {
+        this.msg.emoji = emoji;
+        return this;
+    }
+
+    public getEmojiAvatar(): string {
+        return this.msg.emoji!;
+    }
+
+    public setAvatarUrl(avatarUrl: string): ILivechatMessageBuilder {
+        this.msg.avatarUrl = avatarUrl;
+        return this;
+    }
+
+    public getAvatarUrl(): string {
+        return this.msg.avatarUrl!;
+    }
+
+    public setUsernameAlias(alias: string): ILivechatMessageBuilder {
+        this.msg.alias = alias;
+        return this;
+    }
+
+    public getUsernameAlias(): string {
+        return this.msg.alias!;
+    }
+
+    public addAttachment(attachment: IMessageAttachment): ILivechatMessageBuilder {
+        if (!this.msg.attachments) {
+            this.msg.attachments = [];
+        }
+
+        this.msg.attachments.push(attachment);
+        return this;
+    }
+
+    public setAttachments(attachments: Array<IMessageAttachment>): ILivechatMessageBuilder {
+        this.msg.attachments = attachments;
+        return this;
+    }
+
+    public getAttachments(): Array<IMessageAttachment> {
+        return this.msg.attachments!;
+    }
+
+    public replaceAttachment(position: number, attachment: IMessageAttachment): ILivechatMessageBuilder {
+        if (!this.msg.attachments) {
+            this.msg.attachments = [];
+        }
+
+        if (!this.msg.attachments[position]) {
+            throw new Error(`No attachment found at the index of "${position}" to replace.`);
+        }
+
+        this.msg.attachments[position] = attachment;
+        return this;
+    }
+
+    public removeAttachment(position: number): ILivechatMessageBuilder {
+        if (!this.msg.attachments) {
+            this.msg.attachments = [];
+        }
+
+        if (!this.msg.attachments[position]) {
+            throw new Error(`No attachment found at the index of "${position}" to remove.`);
+        }
+
+        this.msg.attachments.splice(position, 1);
+
+        return this;
+    }
+
+    public setEditor(user: IUser): ILivechatMessageBuilder {
+        this.msg.editor = user;
+        return this;
+    }
+
+    public getEditor(): IUser {
+        return this.msg.editor;
+    }
+
+    public setGroupable(groupable: boolean): ILivechatMessageBuilder {
+        this.msg.groupable = groupable;
+        return this;
+    }
+
+    public getGroupable(): boolean {
+        return this.msg.groupable!;
+    }
+
+    public setParseUrls(parseUrls: boolean): ILivechatMessageBuilder {
+        this.msg.parseUrls = parseUrls;
+        return this;
+    }
+
+    public getParseUrls(): boolean {
+        return this.msg.parseUrls!;
+    }
+
+    public setToken(token: string): ILivechatMessageBuilder {
+        this.msg.token = token;
+        return this;
+    }
+
+    public getToken(): string {
+        return this.msg.token!;
+    }
+
+    public setVisitor(visitor: IVisitor): ILivechatMessageBuilder {
+        this.msg.visitor = visitor;
+        delete this.msg.sender;
+
+        return this;
+    }
+
+    public getVisitor(): IVisitor {
+        return this.msg.visitor;
+    }
+
+    public getMessage(): ILivechatMessage {
+        if (!this.msg.room) {
+            throw new Error('The "room" property is required.');
+        }
+
+        if (this.msg.room.type !== RoomType.LIVE_CHAT) {
+            throw new Error('The room is not a Livechat room');
+        }
+
+        return this.msg;
+    }
+
+    public getMessageBuilder(): IMessageBuilder {
+        return new MessageBuilder(this.msg as IMessage);
+    }
+}
+
diff --git a/deno-runtime/lib/accessors/builders/MessageBuilder.ts b/deno-runtime/lib/accessors/builders/MessageBuilder.ts
new file mode 100644
index 000000000..f8bebbcc4
--- /dev/null
+++ b/deno-runtime/lib/accessors/builders/MessageBuilder.ts
@@ -0,0 +1,226 @@
+import { Block } from '@rocket.chat/ui-kit';
+
+import { IMessageBuilder } from '@rocket.chat/apps-engine/definition/accessors/IMessageBuilder.ts';
+import { RocketChatAssociationModel } from '@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts';
+import { IMessage } from '@rocket.chat/apps-engine/definition/messages/IMessage.ts';
+import { IMessageAttachment } from '@rocket.chat/apps-engine/definition/messages/IMessageAttachment.ts';
+import { IUser } from '@rocket.chat/apps-engine/definition/users/IUser.ts';
+import { IRoom } from '@rocket.chat/apps-engine/definition/rooms/IRoom.ts';
+import { IBlock } from '@rocket.chat/apps-engine/definition/uikit/blocks/Blocks.ts';
+import { BlockBuilder } from "./BlockBuilder.ts";
+
+export class MessageBuilder implements IMessageBuilder {
+    public kind: RocketChatAssociationModel.MESSAGE;
+
+    private msg: IMessage;
+
+    constructor(message?: IMessage) {
+        this.kind = RocketChatAssociationModel.MESSAGE;
+        this.msg = message || ({} as IMessage);
+    }
+
+    public setData(data: IMessage): IMessageBuilder {
+        delete data.id;
+        this.msg = data;
+
+        return this as IMessageBuilder;
+    }
+
+    public setUpdateData(data: IMessage, editor: IUser): IMessageBuilder {
+        this.msg = data;
+        this.msg.editor = editor;
+        this.msg.editedAt = new Date();
+
+        return this as IMessageBuilder;
+    }
+
+    public setThreadId(threadId: string): IMessageBuilder {
+        this.msg.threadId = threadId;
+
+        return this as IMessageBuilder;
+    }
+
+    public getThreadId(): string {
+        return this.msg.threadId!;
+    }
+
+    public setRoom(room: IRoom): IMessageBuilder {
+        this.msg.room = room;
+        return this as IMessageBuilder;
+    }
+
+    public getRoom(): IRoom {
+        return this.msg.room;
+    }
+
+    public setSender(sender: IUser): IMessageBuilder {
+        this.msg.sender = sender;
+        return this as IMessageBuilder;
+    }
+
+    public getSender(): IUser {
+        return this.msg.sender;
+    }
+
+    public setText(text: string): IMessageBuilder {
+        this.msg.text = text;
+        return this as IMessageBuilder;
+    }
+
+    public getText(): string {
+        return this.msg.text!;
+    }
+
+    public setEmojiAvatar(emoji: string): IMessageBuilder {
+        this.msg.emoji = emoji;
+        return this as IMessageBuilder;
+    }
+
+    public getEmojiAvatar(): string {
+        return this.msg.emoji!;
+    }
+
+    public setAvatarUrl(avatarUrl: string): IMessageBuilder {
+        this.msg.avatarUrl = avatarUrl;
+        return this as IMessageBuilder;
+    }
+
+    public getAvatarUrl(): string {
+        return this.msg.avatarUrl!;
+    }
+
+    public setUsernameAlias(alias: string): IMessageBuilder {
+        this.msg.alias = alias;
+        return this as IMessageBuilder;
+    }
+
+    public getUsernameAlias(): string {
+        return this.msg.alias!;
+    }
+
+    public addAttachment(attachment: IMessageAttachment): IMessageBuilder {
+        if (!this.msg.attachments) {
+            this.msg.attachments = [];
+        }
+
+        this.msg.attachments.push(attachment);
+        return this as IMessageBuilder;
+    }
+
+    public setAttachments(attachments: Array<IMessageAttachment>): IMessageBuilder {
+        this.msg.attachments = attachments;
+        return this as IMessageBuilder;
+    }
+
+    public getAttachments(): Array<IMessageAttachment> {
+        return this.msg.attachments!;
+    }
+
+    public replaceAttachment(position: number, attachment: IMessageAttachment): IMessageBuilder {
+        if (!this.msg.attachments) {
+            this.msg.attachments = [];
+        }
+
+        if (!this.msg.attachments[position]) {
+            throw new Error(`No attachment found at the index of "${position}" to replace.`);
+        }
+
+        this.msg.attachments[position] = attachment;
+        return this as IMessageBuilder;
+    }
+
+    public removeAttachment(position: number): IMessageBuilder {
+        if (!this.msg.attachments) {
+            this.msg.attachments = [];
+        }
+
+        if (!this.msg.attachments[position]) {
+            throw new Error(`No attachment found at the index of "${position}" to remove.`);
+        }
+
+        this.msg.attachments.splice(position, 1);
+
+        return this as IMessageBuilder;
+    }
+
+    public setEditor(user: IUser): IMessageBuilder {
+        this.msg.editor = user;
+        return this as IMessageBuilder;
+    }
+
+    public getEditor(): IUser {
+        return this.msg.editor;
+    }
+
+    public setGroupable(groupable: boolean): IMessageBuilder {
+        this.msg.groupable = groupable;
+        return this as IMessageBuilder;
+    }
+
+    public getGroupable(): boolean {
+        return this.msg.groupable!;
+    }
+
+    public setParseUrls(parseUrls: boolean): IMessageBuilder {
+        this.msg.parseUrls = parseUrls;
+        return this as IMessageBuilder;
+    }
+
+    public getParseUrls(): boolean {
+        return this.msg.parseUrls!;
+    }
+
+    public getMessage(): IMessage {
+        if (!this.msg.room) {
+            throw new Error('The "room" property is required.');
+        }
+
+        return this.msg;
+    }
+
+    public addBlocks(blocks: BlockBuilder | Array<IBlock | Block>) {
+        if (!Array.isArray(this.msg.blocks)) {
+            this.msg.blocks = [];
+        }
+
+        if (blocks instanceof BlockBuilder) {
+            this.msg.blocks.push(...blocks.getBlocks());
+        } else {
+            this.msg.blocks.push(...blocks);
+        }
+
+        return this as IMessageBuilder;
+    }
+
+    public setBlocks(blocks: BlockBuilder | Array<IBlock | Block>) {
+        if (blocks instanceof BlockBuilder) {
+            this.msg.blocks = blocks.getBlocks();
+        } else {
+            this.msg.blocks = blocks;
+        }
+
+        return this as IMessageBuilder;
+    }
+
+    public getBlocks() {
+        return this.msg.blocks!;
+    }
+
+    public addCustomField(key: string, value: unknown): IMessageBuilder {
+        if (!this.msg.customFields) {
+            this.msg.customFields = {};
+        }
+
+        if (this.msg.customFields[key]) {
+            throw new Error(`The message already contains a custom field by the key: ${key}`);
+        }
+
+        if (key.includes('.')) {
+            throw new Error(`The given key contains a period, which is not allowed. Key: ${key}`);
+        }
+
+        this.msg.customFields[key] = value;
+
+        return this as IMessageBuilder;
+    }
+}
diff --git a/deno-runtime/lib/accessors/builders/RoomBuilder.ts b/deno-runtime/lib/accessors/builders/RoomBuilder.ts
new file mode 100644
index 000000000..19b634b37
--- /dev/null
+++ b/deno-runtime/lib/accessors/builders/RoomBuilder.ts
@@ -0,0 +1,157 @@
+import { IRoomBuilder } from "@rocket.chat/apps-engine/definition/accessors/IRoomBuilder.ts";
+import { RocketChatAssociationModel } from "@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts";
+import { IRoom } from "@rocket.chat/apps-engine/definition/rooms/IRoom.ts";
+import { RoomType } from "@rocket.chat/apps-engine/definition/rooms/RoomType.ts";
+import { IUser } from "@rocket.chat/apps-engine/definition/users/IUser.ts";
+
+export class RoomBuilder implements IRoomBuilder {
+    public kind: RocketChatAssociationModel.ROOM | RocketChatAssociationModel.DISCUSSION;
+
+    protected room: IRoom;
+
+    private members: Array<string>;
+
+    constructor(data?: Partial<IRoom>) {
+        this.kind = RocketChatAssociationModel.ROOM;
+        this.room = (data || { customFields: {} }) as IRoom;
+        this.members = [];
+    }
+
+    public setData(data: Partial<IRoom>): IRoomBuilder {
+        delete data.id;
+        this.room = data as IRoom;
+
+        return this;
+    }
+
+    public setDisplayName(name: string): IRoomBuilder {
+        this.room.displayName = name;
+        return this;
+    }
+
+    public getDisplayName(): string {
+        return this.room.displayName!;
+    }
+
+    public setSlugifiedName(name: string): IRoomBuilder {
+        this.room.slugifiedName = name;
+        return this;
+    }
+
+    public getSlugifiedName(): string {
+        return this.room.slugifiedName;
+    }
+
+    public setType(type: RoomType): IRoomBuilder {
+        this.room.type = type;
+        return this;
+    }
+
+    public getType(): RoomType {
+        return this.room.type;
+    }
+
+    public setCreator(creator: IUser): IRoomBuilder {
+        this.room.creator = creator;
+        return this;
+    }
+
+    public getCreator(): IUser {
+        return this.room.creator;
+    }
+
+    /**
+     * @deprecated
+     */
+    public addUsername(username: string): IRoomBuilder {
+        this.addMemberToBeAddedByUsername(username);
+        return this;
+    }
+
+    /**
+     * @deprecated
+     */
+    public setUsernames(usernames: Array<string>): IRoomBuilder {
+        this.setMembersToBeAddedByUsernames(usernames);
+        return this;
+    }
+
+    /**
+     * @deprecated
+     */
+    public getUsernames(): Array<string> {
+        const usernames = this.getMembersToBeAddedUsernames();
+        if (usernames && usernames.length > 0) {
+            return usernames;
+        }
+        return this.room.usernames || [];
+    }
+
+    public addMemberToBeAddedByUsername(username: string): IRoomBuilder {
+        this.members.push(username);
+        return this;
+    }
+
+    public setMembersToBeAddedByUsernames(usernames: Array<string>): IRoomBuilder {
+        this.members = usernames;
+        return this;
+    }
+
+    public getMembersToBeAddedUsernames(): Array<string> {
+        return this.members;
+    }
+
+    public setDefault(isDefault: boolean): IRoomBuilder {
+        this.room.isDefault = isDefault;
+        return this;
+    }
+
+    public getIsDefault(): boolean {
+        return this.room.isDefault!;
+    }
+
+    public setReadOnly(isReadOnly: boolean): IRoomBuilder {
+        this.room.isReadOnly = isReadOnly;
+        return this;
+    }
+
+    public getIsReadOnly(): boolean {
+        return this.room.isReadOnly!;
+    }
+
+    public setDisplayingOfSystemMessages(displaySystemMessages: boolean): IRoomBuilder {
+        this.room.displaySystemMessages = displaySystemMessages;
+        return this;
+    }
+
+    public getDisplayingOfSystemMessages(): boolean {
+        return this.room.displaySystemMessages!;
+    }
+
+    public addCustomField(key: string, value: object): IRoomBuilder {
+        if (typeof this.room.customFields !== 'object') {
+            this.room.customFields = {};
+        }
+
+        this.room.customFields[key] = value;
+        return this;
+    }
+
+    public setCustomFields(fields: { [key: string]: object }): IRoomBuilder {
+        this.room.customFields = fields;
+        return this;
+    }
+
+    public getCustomFields(): { [key: string]: object } {
+        return this.room.customFields!;
+    }
+
+    public getUserIds(): Array<string> {
+        return this.room.userIds!;
+    }
+
+    public getRoom(): IRoom {
+        return this.room;
+    }
+}
+
diff --git a/deno-runtime/lib/accessors/builders/UserBuilder.ts b/deno-runtime/lib/accessors/builders/UserBuilder.ts
new file mode 100644
index 000000000..05fcc3d1f
--- /dev/null
+++ b/deno-runtime/lib/accessors/builders/UserBuilder.ts
@@ -0,0 +1,75 @@
+import { IUserBuilder } from '@rocket.chat/apps-engine/definition/accessors/IUserBuilder.ts';
+import { RocketChatAssociationModel } from '@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts';
+import { IUser } from '@rocket.chat/apps-engine/definition/users/IUser.ts';
+import { IUserSettings } from '@rocket.chat/apps-engine/definition/users/IUserSettings.ts';
+import { IUserEmail } from '@rocket.chat/apps-engine/definition/users/IUserEmail.ts';
+
+export class UserBuilder implements IUserBuilder {
+    public kind: RocketChatAssociationModel.USER;
+
+    private user: Partial<IUser>;
+
+    constructor(user?: Partial<IUser>) {
+        this.kind = RocketChatAssociationModel.USER;
+        this.user = user || ({} as Partial<IUser>);
+    }
+
+    public setData(data: Partial<IUser>): IUserBuilder {
+        delete data.id;
+        this.user = data;
+
+        return this;
+    }
+
+    public setEmails(emails: Array<IUserEmail>): IUserBuilder {
+        this.user.emails = emails;
+        return this;
+    }
+
+    public getEmails(): Array<IUserEmail> {
+        return this.user.emails!;
+    }
+
+    public setDisplayName(name: string): IUserBuilder {
+        this.user.name = name;
+        return this;
+    }
+
+    public getDisplayName(): string {
+        return this.user.name!;
+    }
+
+    public setUsername(username: string): IUserBuilder {
+        this.user.username = username;
+        return this;
+    }
+
+    public getUsername(): string {
+        return this.user.username!;
+    }
+
+    public setRoles(roles: Array<string>): IUserBuilder {
+        this.user.roles = roles;
+        return this;
+    }
+
+    public getRoles(): Array<string> {
+        return this.user.roles!;
+    }
+
+    public getSettings(): Partial<IUserSettings> {
+        return this.user.settings;
+    }
+
+    public getUser(): Partial<IUser> {
+        if (!this.user.username) {
+            throw new Error('The "username" property is required.');
+        }
+
+        if (!this.user.name) {
+            throw new Error('The "name" property is required.');
+        }
+
+        return this.user;
+    }
+}
diff --git a/deno-runtime/lib/accessors/builders/VideoConferenceBuilder.ts b/deno-runtime/lib/accessors/builders/VideoConferenceBuilder.ts
new file mode 100644
index 000000000..fad79aa3f
--- /dev/null
+++ b/deno-runtime/lib/accessors/builders/VideoConferenceBuilder.ts
@@ -0,0 +1,78 @@
+import { IVideoConferenceBuilder } from "@rocket.chat/apps-engine/definition/accessors/IVideoConferenceBuilder.ts";
+import { RocketChatAssociationModel } from "@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts";
+import type { IGroupVideoConference } from "@rocket.chat/apps-engine/definition/videoConferences/IVideoConference.ts";
+
+export type AppVideoConference = Pick<IGroupVideoConference, 'rid' | 'providerName' | 'providerData' | 'title'> & {
+    createdBy: IGroupVideoConference['createdBy']['_id'];
+};
+
+export class VideoConferenceBuilder implements IVideoConferenceBuilder {
+    public kind: RocketChatAssociationModel.VIDEO_CONFERENCE = RocketChatAssociationModel.VIDEO_CONFERENCE;
+
+    protected call: AppVideoConference;
+
+    constructor(data?: Partial<AppVideoConference>) {
+        this.call = (data || {}) as AppVideoConference;
+    }
+
+    public setData(data: Partial<AppVideoConference>): IVideoConferenceBuilder {
+        this.call = {
+            rid: data.rid!,
+            createdBy: data.createdBy,
+            providerName: data.providerName!,
+            title: data.title!,
+        };
+
+        return this;
+    }
+
+    public setRoomId(rid: string): IVideoConferenceBuilder {
+        this.call.rid = rid;
+        return this;
+    }
+
+    public getRoomId(): string {
+        return this.call.rid;
+    }
+
+    public setCreatedBy(userId: string): IVideoConferenceBuilder {
+        this.call.createdBy = userId;
+        return this;
+    }
+
+    public getCreatedBy(): string {
+        return this.call.createdBy;
+    }
+
+    public setProviderName(userId: string): IVideoConferenceBuilder {
+        this.call.providerName = userId;
+        return this;
+    }
+
+    public getProviderName(): string {
+        return this.call.providerName;
+    }
+
+    public setProviderData(data: Record<string, unknown> | undefined): IVideoConferenceBuilder {
+        this.call.providerData = data;
+        return this;
+    }
+
+    public getProviderData(): Record<string, unknown> {
+        return this.call.providerData!;
+    }
+
+    public setTitle(userId: string): IVideoConferenceBuilder {
+        this.call.title = userId;
+        return this;
+    }
+
+    public getTitle(): string {
+        return this.call.title;
+    }
+
+    public getVideoConference(): AppVideoConference {
+        return this.call;
+    }
+}
+
diff --git a/deno-runtime/lib/accessors/extenders/MessageExtender.ts b/deno-runtime/lib/accessors/extenders/MessageExtender.ts
new file mode 100644
index 000000000..12eae78df
--- /dev/null
+++ b/deno-runtime/lib/accessors/extenders/MessageExtender.ts
@@ -0,0 +1,60 @@
+import { IMessageExtender } from '@rocket.chat/apps-engine/definition/accessors/IMessageExtender.ts';
+import { RocketChatAssociationModel } from '@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts';
+import { IMessage } from '@rocket.chat/apps-engine/definition/messages/IMessage.ts';
+import { IMessageAttachment } from '@rocket.chat/apps-engine/definition/messages/IMessageAttachment.ts';
+
+export class MessageExtender implements IMessageExtender {
+    public readonly kind: RocketChatAssociationModel.MESSAGE;
+
+    constructor(private msg: IMessage) {
+        this.kind = RocketChatAssociationModel.MESSAGE;
+
+        if (!Array.isArray(msg.attachments)) {
+            this.msg.attachments = [];
+        }
+    }
+
+    public addCustomField(key: string, value: unknown): IMessageExtender {
+        if (!this.msg.customFields) {
+            this.msg.customFields = {};
+        }
+
+        if (this.msg.customFields[key]) {
+            throw new Error(`The message already contains a custom field by the key: ${key}`);
+        }
+
+        if (key.includes('.')) {
+            throw new Error(`The given key contains a period, which is not allowed. Key: ${key}`);
+        }
+
+        this.msg.customFields[key] = value;
+
+        return this;
+    }
+
+    public addAttachment(attachment: IMessageAttachment): IMessageExtender {
+        this.ensureAttachment();
+
+        this.msg.attachments!.push(attachment);
+
+        return this;
+    }
+
+    public addAttachments(attachments: Array<IMessageAttachment>): IMessageExtender {
+        this.ensureAttachment();
+
+        this.msg.attachments = this.msg.attachments!.concat(attachments);
+
+        return this;
+    }
+
+    public getMessage(): IMessage {
+        return structuredClone(this.msg);
+    }
+
+    private ensureAttachment(): void {
+        if (!Array.isArray(this.msg.attachments)) {
+            this.msg.attachments = [];
+        }
+    }
+}
diff --git a/deno-runtime/lib/accessors/extenders/RoomExtender.ts b/deno-runtime/lib/accessors/extenders/RoomExtender.ts
new file mode 100644
index 000000000..7063bf90e
--- /dev/null
+++ b/deno-runtime/lib/accessors/extenders/RoomExtender.ts
@@ -0,0 +1,55 @@
+import { IRoomExtender } from "@rocket.chat/apps-engine/definition/accessors/IRoomExtender.ts";
+import { RocketChatAssociationModel } from "@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts";
+import { IRoom } from "@rocket.chat/apps-engine/definition/rooms/IRoom.ts";
+import { IUser } from "@rocket.chat/apps-engine/definition/users/IUser.ts";
+
+export class RoomExtender implements IRoomExtender {
+    public kind: RocketChatAssociationModel.ROOM;
+
+    private members: Array<IUser>;
+
+    constructor(private room: IRoom) {
+        this.kind = RocketChatAssociationModel.ROOM;
+        this.members = [];
+    }
+
+    public addCustomField(key: string, value: unknown): IRoomExtender {
+        if (!this.room.customFields) {
+            this.room.customFields = {};
+        }
+
+        if (this.room.customFields[key]) {
+            throw new Error(`The room already contains a custom field by the key: ${key}`);
+        }
+
+        if (key.includes('.')) {
+            throw new Error(`The given key contains a period, which is not allowed. Key: ${key}`);
+        }
+
+        this.room.customFields[key] = value;
+
+        return this;
+    }
+
+    public addMember(user: IUser): IRoomExtender {
+        if (this.members.find((u) => u.username === user.username)) {
+            throw new Error('The user is already in the room.');
+        }
+
+        this.members.push(user);
+
+        return this;
+    }
+
+    public getMembersBeingAdded(): Array<IUser> {
+        return this.members;
+    }
+
+    public getUsernamesOfMembersBeingAdded(): Array<string> {
+        return this.members.map((u) => u.username);
+    }
+
+    public getRoom(): IRoom {
+        return structuredClone(this.room);
+    }
+}
diff --git a/deno-runtime/lib/accessors/extenders/VideoConferenceExtend.ts b/deno-runtime/lib/accessors/extenders/VideoConferenceExtend.ts
new file mode 100644
index 000000000..5e1027541
--- /dev/null
+++ b/deno-runtime/lib/accessors/extenders/VideoConferenceExtend.ts
@@ -0,0 +1,57 @@
+import type { IVideoConferenceExtender } from "@rocket.chat/apps-engine/definition/accessors/IVideoConferenceExtend.ts";
+import type { VideoConference, VideoConferenceMember } from "@rocket.chat/apps-engine/definition/videoConferences/IVideoConference.ts";
+import type { IVideoConferenceUser } from "@rocket.chat/apps-engine/definition/videoConferences/IVideoConferenceUser.ts";
+import { RocketChatAssociationModel } from "@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts";
+
+export class VideoConferenceExtender implements IVideoConferenceExtender {
+    public kind: RocketChatAssociationModel.VIDEO_CONFERENCE;
+
+    constructor(private videoConference: VideoConference) {
+        this.kind = RocketChatAssociationModel.VIDEO_CONFERENCE;
+    }
+
+    public setProviderData(value: Record<string, unknown>): IVideoConferenceExtender {
+        this.videoConference.providerData = value;
+
+        return this;
+    }
+
+    public setStatus(value: VideoConference['status']): IVideoConferenceExtender {
+        this.videoConference.status = value;
+
+        return this;
+    }
+
+    public setEndedBy(value: IVideoConferenceUser['_id']): IVideoConferenceExtender {
+        this.videoConference.endedBy = {
+            _id: value,
+            // Name and username will be loaded automatically by the bridge
+            username: '',
+            name: '',
+        };
+
+        return this;
+    }
+
+    public setEndedAt(value: VideoConference['endedAt']): IVideoConferenceExtender {
+        this.videoConference.endedAt = value;
+
+        return this;
+    }
+
+    public addUser(userId: VideoConferenceMember['_id'], ts?: VideoConferenceMember['ts']): IVideoConferenceExtender {
+        this.videoConference.users.push({
+            _id: userId,
+            ts,
+            // Name and username will be loaded automatically by the bridge
+            username: '',
+            name: '',
+        });
+
+        return this;
+    }
+
+    public getVideoConference(): VideoConference {
+        return structuredClone(this.videoConference);
+    }
+}
diff --git a/deno-runtime/lib/accessors/mod.ts b/deno-runtime/lib/accessors/mod.ts
index 5418e776f..95ac7f7d6 100644
--- a/deno-runtime/lib/accessors/mod.ts
+++ b/deno-runtime/lib/accessors/mod.ts
@@ -16,6 +16,7 @@ import * as Messenger from '../messenger.ts';
 import { AppObjectRegistry } from '../../AppObjectRegistry.ts';
 import { ModifyCreator } from "./modify/ModifyCreator.ts";
 import { ModifyUpdater } from "./modify/ModifyUpdater.ts";
+import { ModifyExtender } from "./modify/ModifyExtender.ts";
 
 const httpMethods = ['get', 'post', 'put', 'delete', 'head', 'options', 'patch'] as const;
 
@@ -31,6 +32,7 @@ export class AppAccessors {
     private http?: IHttp;
     private creator?: ModifyCreator;
     private updater?: ModifyUpdater;
+    private extender?: ModifyExtender;
 
     private proxify: <T>(namespace: string) => T;
 
@@ -198,8 +200,8 @@ export class AppAccessors {
             this.modifier = {
                 getCreator: this.getCreator.bind(this),
                 getUpdater: this.getUpdater.bind(this),
+                getExtender: this.getExtender.bind(this),
                 getDeleter: () => this.proxify('getModifier:getDeleter'),
-                getExtender: () => this.proxify('getModifier:getExtender'), // can't be proxy
                 getNotifier: () => this.proxify('getModifier:getNotifier'),
                 getUiController: () => this.proxify('getModifier:getUiController'),
                 getScheduler: () => this.proxify('getModifier:getScheduler'),
@@ -242,6 +244,14 @@ export class AppAccessors {
 
         return this.updater;
     }
+
+    private getExtender() {
+        if (!this.extender) {
+            this.extender = new ModifyExtender(this.senderFn);
+        }
+
+        return this.extender;
+    }
 }
 
 export const AppAccessorsInstance = new AppAccessors(Messenger.sendRequest);
diff --git a/deno-runtime/lib/accessors/modify/ModifyCreator.ts b/deno-runtime/lib/accessors/modify/ModifyCreator.ts
index 42614f228..69f909327 100644
--- a/deno-runtime/lib/accessors/modify/ModifyCreator.ts
+++ b/deno-runtime/lib/accessors/modify/ModifyCreator.ts
@@ -16,14 +16,15 @@ import { IVideoConferenceBuilder } from '@rocket.chat/apps-engine/definition/acc
 import { RoomType } from '@rocket.chat/apps-engine/definition/rooms/RoomType.ts';
 import { ILivechatMessageBuilder } from '@rocket.chat/apps-engine/definition/accessors/ILivechatMessageBuilder.ts';
 
-import { BlockBuilder } from '../BlockBuilder.ts';
-import { MessageBuilder } from '../MessageBuilder.ts';
-import { DiscussionBuilder, IDiscussionBuilder } from '../DiscussionBuilder.ts';
-import { ILivechatMessage, LivechatMessageBuilder } from '../LivechatMessageBuilder.ts';
-import { RoomBuilder } from '../RoomBuilder.ts';
-import { UserBuilder } from '../UserBuilder.ts';
-import { AppVideoConference, VideoConferenceBuilder } from '../VideoConferenceBuilder.ts';
 import * as Messenger from '../../messenger.ts';
+
+import { BlockBuilder } from '../builders/BlockBuilder.ts';
+import { MessageBuilder } from '../builders/MessageBuilder.ts';
+import { DiscussionBuilder, IDiscussionBuilder } from '../builders/DiscussionBuilder.ts';
+import { ILivechatMessage, LivechatMessageBuilder } from '../builders/LivechatMessageBuilder.ts';
+import { RoomBuilder } from '../builders/RoomBuilder.ts';
+import { UserBuilder } from '../builders/UserBuilder.ts';
+import { AppVideoConference, VideoConferenceBuilder } from '../builders/VideoConferenceBuilder.ts';
 import { AppObjectRegistry } from '../../../AppObjectRegistry.ts';
 
 const require = createRequire(import.meta.url);
diff --git a/deno-runtime/lib/accessors/modify/ModifyExtender.ts b/deno-runtime/lib/accessors/modify/ModifyExtender.ts
new file mode 100644
index 000000000..e380b53e5
--- /dev/null
+++ b/deno-runtime/lib/accessors/modify/ModifyExtender.ts
@@ -0,0 +1,84 @@
+import type { IModifyExtender } from '@rocket.chat/apps-engine/definition/accessors/IModifyExtender.ts';
+import type { IMessage } from '@rocket.chat/apps-engine/definition/messages/IMessage.ts';
+import type { IMessageExtender } from "@rocket.chat/apps-engine/definition/accessors/IMessageExtender.ts";
+import type { IRoomExtender } from "@rocket.chat/apps-engine/definition/accessors/IRoomExtender.ts";
+import type { IVideoConferenceExtender } from "@rocket.chat/apps-engine/definition/accessors/IVideoConferenceExtend.ts";
+import type { IUser } from "@rocket.chat/apps-engine/definition/users/IUser.ts";
+import type { VideoConference } from "@rocket.chat/apps-engine/definition/videoConferences/IVideoConference.ts";
+import type { IRoom } from "@rocket.chat/apps-engine/definition/rooms/IRoom.ts";
+import { RocketChatAssociationModel } from "@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts";
+
+import * as Messenger from '../../messenger.ts';
+import { AppObjectRegistry } from "../../../AppObjectRegistry.ts";
+import { MessageExtender } from "../extenders/MessageExtender.ts";
+import { RoomExtender } from "../extenders/RoomExtender.ts";
+import { VideoConferenceExtender } from "../extenders/VideoConferenceExtend.ts";
+
+export class ModifyExtender implements IModifyExtender {
+    constructor(private readonly senderFn: typeof Messenger.sendRequest) {}
+
+    public async extendMessage(messageId: string, updater: IUser): Promise<IMessageExtender> {
+        const result = await this.senderFn({
+            method: 'bridges:getMessageBridge:doGetById',
+            params: [messageId, AppObjectRegistry.get('appId')],
+        });
+
+        const msg = result.result as IMessage;
+
+        msg.editor = updater;
+        msg.editedAt = new Date();
+
+        return new MessageExtender(msg);
+    }
+
+    public async extendRoom(roomId: string, _updater: IUser): Promise<IRoomExtender> {
+        const result = await this.senderFn({
+            method: 'bridges:getRoomBridge:doGetById',
+            params: [roomId, AppObjectRegistry.get('appId')],
+        });
+
+        const room = result.result as IRoom;
+
+        room.updatedAt = new Date();
+
+        return new RoomExtender(room);
+    }
+
+    public async extendVideoConference(id: string): Promise<IVideoConferenceExtender> {
+        const result = await this.senderFn({
+            method: 'bridges:getVideoConferenceBridge:doGetById',
+            params: [id, AppObjectRegistry.get('appId')],
+        });
+
+        const call = result.result as VideoConference;
+
+        call._updatedAt = new Date();
+
+        return new VideoConferenceExtender(call);
+    }
+
+    public async finish(extender: IMessageExtender | IRoomExtender | IVideoConferenceExtender): Promise<void> {
+        switch (extender.kind) {
+            case RocketChatAssociationModel.MESSAGE:
+                await this.senderFn({
+                  method: 'bridges:getMessageBridge:doUpdate',
+                  params: [(extender as IMessageExtender).getMessage(), AppObjectRegistry.get('appId')],
+                });
+                break;
+            case RocketChatAssociationModel.ROOM:
+                await this.senderFn({
+                  method: 'bridges:getRoomBridge:doUpdate',
+                  params: [(extender as IRoomExtender).getRoom(), (extender as IRoomExtender).getUsernamesOfMembersBeingAdded(), AppObjectRegistry.get('appId')],
+                });
+                break;
+            case RocketChatAssociationModel.VIDEO_CONFERENCE:
+                await this.senderFn({
+                  method: 'bridges:getVideoConferenceBridge:doUpdate',
+                  params: [(extender as IVideoConferenceExtender).getVideoConference(), AppObjectRegistry.get('appId')],
+                });
+                break;
+            default:
+                throw new Error('Invalid extender passed to the ModifyExtender.finish function.');
+        }
+    }
+}
diff --git a/deno-runtime/lib/accessors/modify/ModifyUpdater.ts b/deno-runtime/lib/accessors/modify/ModifyUpdater.ts
index 5cd23d86d..11188a673 100644
--- a/deno-runtime/lib/accessors/modify/ModifyUpdater.ts
+++ b/deno-runtime/lib/accessors/modify/ModifyUpdater.ts
@@ -13,8 +13,9 @@ import { RoomType } from '@rocket.chat/apps-engine/definition/rooms/RoomType.ts'
 import { RocketChatAssociationModel } from '@rocket.chat/apps-engine/definition/metadata/RocketChatAssociations.ts';
 
 import * as Messenger from '../../messenger.ts';
-import { MessageBuilder } from '../MessageBuilder.ts';
-import { RoomBuilder } from '../RoomBuilder.ts';
+
+import { MessageBuilder } from '../builders/MessageBuilder.ts';
+import { RoomBuilder } from '../builders/RoomBuilder.ts';
 import { AppObjectRegistry } from '../../../AppObjectRegistry.ts';
 
 const require = createRequire(import.meta.url);
diff --git a/deno-runtime/lib/accessors/tests/ModifyExtender.test.ts b/deno-runtime/lib/accessors/tests/ModifyExtender.test.ts
new file mode 100644
index 000000000..c318b9f33
--- /dev/null
+++ b/deno-runtime/lib/accessors/tests/ModifyExtender.test.ts
@@ -0,0 +1,120 @@
+// deno-lint-ignore-file no-explicit-any
+import { afterAll, beforeEach, describe, it } from 'https://deno.land/std@0.203.0/testing/bdd.ts';
+import { assertSpyCall, spy } from 'https://deno.land/std@0.203.0/testing/mock.ts';
+
+import { AppObjectRegistry } from '../../../AppObjectRegistry.ts';
+import { ModifyExtender } from '../modify/ModifyExtender.ts';
+
+describe('ModifyExtender', () => {
+    let extender: ModifyExtender;
+
+    const senderFn = (r: any) =>
+        Promise.resolve({
+            id: Math.random().toString(36).substring(2),
+            jsonrpc: '2.0',
+            result: structuredClone(r),
+            serialize() {
+                return JSON.stringify(this);
+            },
+        });
+
+    beforeEach(() => {
+        AppObjectRegistry.clear();
+        AppObjectRegistry.set('appId', 'deno-test');
+        extender = new ModifyExtender(senderFn);
+    });
+
+    afterAll(() => {
+        AppObjectRegistry.clear();
+    });
+
+    it('correctly formats requests for the extend message requests', async () => {
+        const _spy = spy(extender, 'senderFn' as keyof ModifyExtender);
+
+        const messageExtender = await extender.extendMessage('message-id', { _id: 'user-id' } as any);
+
+        assertSpyCall(_spy, 0, {
+            args: [
+                {
+                    method: 'bridges:getMessageBridge:doGetById',
+                    params: ['message-id', 'deno-test'],
+                },
+            ],
+        });
+
+        messageExtender.addCustomField('key', 'value');
+
+        await extender.finish(messageExtender);
+
+        assertSpyCall(_spy, 1, {
+            args: [
+                {
+                    method: 'bridges:getMessageBridge:doUpdate',
+                    params: [messageExtender.getMessage(), 'deno-test'],
+                },
+            ],
+        });
+
+        _spy.restore();
+    });
+
+    it('correctly formats requests for the extend room requests', async () => {
+        const _spy = spy(extender, 'senderFn' as keyof ModifyExtender);
+
+        const roomExtender = await extender.extendRoom('room-id', { _id: 'user-id' } as any);
+
+        assertSpyCall(_spy, 0, {
+            args: [
+                {
+                    method: 'bridges:getRoomBridge:doGetById',
+                    params: ['room-id', 'deno-test'],
+                },
+            ],
+        });
+
+        roomExtender.addCustomField('key', 'value');
+
+        await extender.finish(roomExtender);
+
+        assertSpyCall(_spy, 1, {
+            args: [
+                {
+                    method: 'bridges:getRoomBridge:doUpdate',
+                    params: [roomExtender.getRoom(), [], 'deno-test'],
+                },
+            ],
+        });
+
+        _spy.restore();
+    });
+
+    it('correctly formats requests for the extend video conference requests', async () => {
+        const _spy = spy(extender, 'senderFn' as keyof ModifyExtender);
+
+        const videoConferenceExtender = await extender.extendVideoConference('video-conference-id');
+
+        assertSpyCall(_spy, 0, {
+            args: [
+                {
+                    method: 'bridges:getVideoConferenceBridge:doGetById',
+                    params: ['video-conference-id', 'deno-test'],
+                },
+            ],
+        });
+
+        videoConferenceExtender.setStatus(4);
+
+        await extender.finish(videoConferenceExtender);
+
+        assertSpyCall(_spy, 1, {
+            args: [
+                {
+                    method: 'bridges:getVideoConferenceBridge:doUpdate',
+                    params: [videoConferenceExtender.getVideoConference(), 'deno-test'],
+                },
+            ],
+        });
+
+        _spy.restore();
+    });
+});
diff --git a/deno-runtime/lib/accessors/tests/ModifyUpdater.test.ts b/deno-runtime/lib/accessors/tests/ModifyUpdater.test.ts
index 99ef7e556..712b9cb8f 100644
--- a/deno-runtime/lib/accessors/tests/ModifyUpdater.test.ts
+++ b/deno-runtime/lib/accessors/tests/ModifyUpdater.test.ts
@@ -13,7 +13,7 @@ describe('ModifyUpdater', () => {
         Promise.resolve({
             id: Math.random().toString(36).substring(2),
             jsonrpc: '2.0',
-            result: r,
+            result: structuredClone(r),
             serialize() {
                 return JSON.stringify(this);
             },