diff --git a/src/features/modules/chat/modules/closed/store/__tests__/closed.spec.js b/src/features/modules/chat/modules/closed/store/__tests__/closed.spec.js
new file mode 100644
index 000000000..ac9b56c53
--- /dev/null
+++ b/src/features/modules/chat/modules/closed/store/__tests__/closed.spec.js
@@ -0,0 +1,266 @@
+import { Conversation } from 'webitel-sdk';
+
+import closedModule from '../closed';
+
+describe('features/chat/closed store: actions', () => {
+	let context;
+
+	beforeEach(() => {
+		context = {
+			rootState: {
+				features: {
+					chat: {
+						chatHistory: {
+							next: false,
+						},
+					},
+				},
+			},
+			dispatch: vi.fn().mockResolvedValue(undefined),
+			commit: vi.fn(),
+		};
+	});
+
+	describe('OPEN_CLOSED_CHAT', () => {
+		it('dispatches LOAD_CLOSED_CHAT for a REST stub without an identified contact', async () => {
+			const chat = {
+				id: '1',
+				closedAt: Date.now(),
+			};
+			await closedModule.actions.OPEN_CLOSED_CHAT(context, chat);
+			expect(context.dispatch).toHaveBeenCalledWith('LOAD_CLOSED_CHAT', chat);
+		});
+
+		it('dispatches SET_WORKSPACE directly for a REST stub with an identified contact', async () => {
+			const chat = {
+				id: '1',
+				closedAt: Date.now(),
+				contact: {
+					id: 'contact-1',
+				},
+			};
+			await closedModule.actions.OPEN_CLOSED_CHAT(context, chat);
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'features/chat/SET_WORKSPACE',
+				chat,
+				{
+					root: true,
+				},
+			);
+			expect(context.dispatch).not.toHaveBeenCalledWith(
+				'LOAD_CLOSED_CHAT',
+				expect.anything(),
+			);
+		});
+
+		it('dispatches SET_WORKSPACE for a live SDK Conversation even when contact.id is unset (post-processing) [WTEL-9955]', async () => {
+			// a live SDK Conversation instance, not a plain REST object;
+			// `id` is a getter derived from `channelId`, so set that instead
+			const chat = Object.assign(new Conversation(), {
+				channelId: 'channel-1',
+				closedAt: Date.now(),
+				contact: {
+					id: null,
+				},
+			});
+
+			await closedModule.actions.OPEN_CLOSED_CHAT(context, chat);
+
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'features/chat/SET_WORKSPACE',
+				chat,
+				{
+					root: true,
+				},
+			);
+			expect(context.dispatch).not.toHaveBeenCalledWith(
+				'LOAD_CLOSED_CHAT',
+				expect.anything(),
+			);
+		});
+	});
+
+	describe('LOAD_CLOSED_CHAT_HISTORY', () => {
+		it('loads history for the given contactId (not chat.contact.id) and searches for the target chat', async () => {
+			const chat = {
+				id: 'channel-1',
+				conversationId: 'conv-1',
+				// chat.contact.id is null here on purpose: the action must rely on
+				// the passed-in contactId instead, see WTEL-9955
+				contact: {
+					id: null,
+				},
+			};
+			const contactId = 'contact-1';
+
+			await closedModule.actions.LOAD_CLOSED_CHAT_HISTORY(context, {
+				chat,
+				contactId,
+			});
+
+			expect(context.dispatch).toHaveBeenCalledWith('RESET_CLOSED_CHAT');
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'features/chat/chatHistory/LOAD_CHAT_HISTORY',
+				contactId,
+				{
+					root: true,
+				},
+			);
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'FIND_TARGET_CHAT_IN_HISTORY',
+				{
+					chat,
+					contactId,
+				},
+			);
+			expect(context.commit).toHaveBeenCalledWith(
+				'SET_IS_CLOSED_CHAT_LOADED',
+				true,
+			);
+		});
+
+		it('still marks the closed chat as loaded when loading history fails', async () => {
+			const err = new Error('network error');
+			context.dispatch.mockImplementation((action) => {
+				if (action === 'features/chat/chatHistory/LOAD_CHAT_HISTORY') {
+					return Promise.reject(err);
+				}
+				return Promise.resolve();
+			});
+
+			await expect(
+				closedModule.actions.LOAD_CLOSED_CHAT_HISTORY(context, {
+					chat: {
+						id: 'channel-1',
+					},
+					contactId: 'contact-1',
+				}),
+			).rejects.toBeTruthy();
+
+			expect(context.commit).toHaveBeenCalledWith(
+				'SET_IS_CLOSED_CHAT_LOADED',
+				true,
+			);
+		});
+	});
+
+	describe('FIND_TARGET_CHAT_IN_HISTORY', () => {
+		it('returns early without dispatching anything when there is no next history page', async () => {
+			context.rootState.features.chat.chatHistory.next = false;
+			const chat = {
+				id: 'channel-1',
+				conversationId: 'conv-1',
+			};
+
+			await closedModule.actions.FIND_TARGET_CHAT_IN_HISTORY(context, {
+				chat,
+				contactId: 'contact-1',
+			});
+
+			expect(context.dispatch).not.toHaveBeenCalled();
+		});
+
+		it('looks up the target message by conversationId, not by the live chat.id [WTEL-9955]', async () => {
+			context.rootState.features.chat.chatHistory.next = true;
+			// chat.id is the live channelId, which never appears as message.chat.id
+			// in chatHistory data — conversationId does (see ContactChatMessagesAPI)
+			const chat = {
+				id: 'channel-1',
+				conversationId: 'conv-1',
+			};
+
+			await closedModule.actions.FIND_TARGET_CHAT_IN_HISTORY(context, {
+				chat,
+				contactId: 'contact-1',
+			});
+
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'FIND_TARGET_CHAT_FIRST_MESSAGE',
+				'conv-1',
+			);
+		});
+
+		it('falls back to chat.id when conversationId is missing', async () => {
+			context.rootState.features.chat.chatHistory.next = true;
+			const chat = {
+				id: 'channel-1',
+			};
+
+			await closedModule.actions.FIND_TARGET_CHAT_IN_HISTORY(context, {
+				chat,
+				contactId: 'contact-1',
+			});
+
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'FIND_TARGET_CHAT_FIRST_MESSAGE',
+				'channel-1',
+			);
+		});
+
+		it('commits the found message id and does not load another history page once the target chat is found', async () => {
+			context.rootState.features.chat.chatHistory.next = true;
+			const foundMessage = {
+				id: 'message-1',
+			};
+			context.dispatch.mockImplementation((action) => {
+				if (action === 'FIND_TARGET_CHAT_FIRST_MESSAGE') {
+					return Promise.resolve(foundMessage);
+				}
+				return Promise.resolve();
+			});
+
+			await closedModule.actions.FIND_TARGET_CHAT_IN_HISTORY(context, {
+				chat: {
+					id: 'channel-1',
+					conversationId: 'conv-1',
+				},
+				contactId: 'contact-1',
+			});
+
+			expect(context.commit).toHaveBeenCalledWith(
+				'SET_CLOSED_CHAT_FIRST_MESSAGE_ID',
+				foundMessage.id,
+			);
+			expect(context.dispatch).not.toHaveBeenCalledWith(
+				'features/chat/chatHistory/LOAD_NEXT',
+				expect.anything(),
+				expect.anything(),
+			);
+		});
+
+		it('loads the next history page and recurses with the same contactId when the target chat is not found yet', async () => {
+			context.rootState.features.chat.chatHistory.next = true;
+			context.dispatch.mockImplementation((action) => {
+				if (action === 'FIND_TARGET_CHAT_FIRST_MESSAGE') {
+					return Promise.resolve(undefined);
+				}
+				return Promise.resolve();
+			});
+			const chat = {
+				id: 'channel-1',
+				conversationId: 'conv-1',
+			};
+			const contactId = 'contact-1';
+
+			await closedModule.actions.FIND_TARGET_CHAT_IN_HISTORY(context, {
+				chat,
+				contactId,
+			});
+
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'features/chat/chatHistory/LOAD_NEXT',
+				contactId,
+				{
+					root: true,
+				},
+			);
+			expect(context.dispatch).toHaveBeenCalledWith(
+				'FIND_TARGET_CHAT_IN_HISTORY',
+				{
+					chat,
+					contactId,
+				},
+			);
+		});
+	});
+});
diff --git a/src/features/modules/chat/modules/closed/store/closed.js b/src/features/modules/chat/modules/closed/store/closed.js
index f5ba9f0f4..41521214f 100644
--- a/src/features/modules/chat/modules/closed/store/closed.js
+++ b/src/features/modules/chat/modules/closed/store/closed.js
@@ -1,6 +1,7 @@
 import applyTransform, {
 	notify,
 } from '@webitel/ui-sdk/src/api/transformers/index';
+import { Conversation } from 'webitel-sdk';
 
 import AgentChatsAPI from '../../../../../../app/api/agent-workspace/endpoints/agent-info/agent-chats';
 import CatalogAPI from '../../../../../../app/api/agent-workspace/endpoints/catalog/CatalogAPIRepository';
@@ -138,7 +139,16 @@ const actions = {
 		}
 	},
 	OPEN_CLOSED_CHAT: async (context, chat) => {
-		if (!chat.contact?.id) {
+		/**
+		 * @author @OleksandrPalonnyi
+		 *
+		 * [WTEL-9955](https://webitel.atlassian.net/browse/WTEL-9955)
+		 *
+		 * see OPEN_CHAT in features/chat/store/chat.js — same reasoning for
+		 * distinguishing a REST closed-chat stub from a live SDK instance.
+		 */
+		const isChatFromRestApi = !(chat instanceof Conversation);
+		if (isChatFromRestApi && !chat.contact?.id) {
 			await context.dispatch('LOAD_CLOSED_CHAT', chat);
 		} else {
 			context.commit('SET_CLOSED_CHAT_FIRST_MESSAGE_ID', null);
@@ -148,10 +158,18 @@ const actions = {
 			});
 		}
 	},
-	LOAD_CLOSED_CHAT_HISTORY: async (context, chat) => {
-		const contactId = chat.contact.id;
-		const targetChatId = chat.id;
-
+	/**
+	 * @author @OleksandrPalonnyi
+	 *
+	 * [WTEL-9955](https://webitel.atlassian.net/browse/WTEL-9955)
+	 *
+	 * chat here comes from the CHAT_ON_WORKSPACE getter, which can hold either
+	 * a chat or a task during the closing/post-processing lifecycle, so its id
+	 * and contact are unreliable and can go missing between renders. contactId
+	 * is captured from the contact prop when history loading starts and passed
+	 * through explicitly instead of being re-read off chat later.
+	 */
+	LOAD_CLOSED_CHAT_HISTORY: async (context, { chat, contactId }) => {
 		try {
 			context.dispatch('RESET_CLOSED_CHAT');
 			await context.dispatch(
@@ -162,7 +180,10 @@ const actions = {
 				},
 			);
 
-			await context.dispatch('FIND_TARGET_CHAT_IN_HISTORY', chat);
+			await context.dispatch('FIND_TARGET_CHAT_IN_HISTORY', {
+				chat,
+				contactId,
+			});
 		} catch (err) {
 			throw applyTransform(err, [
 				notify,
@@ -172,10 +193,9 @@ const actions = {
 		}
 	},
 
-	FIND_TARGET_CHAT_IN_HISTORY: async (context, chat) => {
+	FIND_TARGET_CHAT_IN_HISTORY: async (context, { chat, contactId }) => {
 		// recursive function
-		const contactId = chat.contact.id;
-		const targetChatId = chat.id;
+		const targetChatId = chat.conversationId || chat.id;
 		const next = context.rootState.features.chat.chatHistory.next;
 
 		if (!next) return;
@@ -196,7 +216,10 @@ const actions = {
 		await context.dispatch('features/chat/chatHistory/LOAD_NEXT', contactId, {
 			root: true,
 		});
-		await context.dispatch('FIND_TARGET_CHAT_IN_HISTORY', chat); // call itself until find target chat
+		await context.dispatch('FIND_TARGET_CHAT_IN_HISTORY', {
+			chat,
+			contactId,
+		}); // call itself until find target chat
 	},
 	FIND_TARGET_CHAT_FIRST_MESSAGE: async (context, targetChatId) => {
 		// try to find first message of needed chat
diff --git a/src/features/modules/chat/store/chat.js b/src/features/modules/chat/store/chat.js
index 85cb77b62..8694b9c91 100644
--- a/src/features/modules/chat/store/chat.js
+++ b/src/features/modules/chat/store/chat.js
@@ -1,5 +1,5 @@
 import { applyTransform, notify } from '@webitel/api-services/api/transformers';
-import { ConversationState } from 'webitel-sdk';
+import { Conversation, ConversationState } from 'webitel-sdk';
 
 import i18n from '../../../../app/locale/i18n';
 import WorkspaceStates from '../../../../ui/enums/WorkspaceState.enum';
@@ -143,7 +143,23 @@ const actions = {
 	},
 
 	OPEN_CHAT: async (context, chat) => {
-		const isUnidentifiedClosedChat = !chat.contact?.id && chat.closedAt;
+		/**
+		 * @author @OleksandrPalonnyi
+		 *
+		 * [WTEL-9955](https://webitel.atlassian.net/browse/WTEL-9955)
+		 *
+		 * A live SDK `Conversation` can have `contact.id` unset too (e.g. during
+		 * post-processing), so `!chat.contact?.id` alone can't tell a REST closed-chat
+		 * stub from a live instance. `chat instanceof Conversation` checks directly
+		 * against the only place a live instance is ever built
+		 * (buildConversationFromDialog.js) instead of inferring it from the shape of
+		 * a plain object. Only a REST stub needs the LOAD_CLOSED_CHAT reload —
+		 * spreading a live Conversation into a plain object drops its prototype
+		 * getters (`id`, `allowReporting`, …).
+		 */
+		const isChatFromRestApi = !(chat instanceof Conversation);
+		const isUnidentifiedClosedChat =
+			isChatFromRestApi && !chat.contact?.id && chat.closedAt;
 
 		if (isUnidentifiedClosedChat) {
 			await context.dispatch('features/chat/closed/LOAD_CLOSED_CHAT', chat, {
diff --git a/src/ui/modules/work-section/modules/chat/chat-messaging/chat-history/the-chat-history.vue b/src/ui/modules/work-section/modules/chat/chat-messaging/chat-history/the-chat-history.vue
index e94c246e2..a444b74d5 100644
--- a/src/ui/modules/work-section/modules/chat/chat-messaging/chat-history/the-chat-history.vue
+++ b/src/ui/modules/work-section/modules/chat/chat-messaging/chat-history/the-chat-history.vue
@@ -189,10 +189,10 @@ const { startObserve: startObserveClosedChat } = useObserveHeightUntilStable(
 const loadHistory = async () =>
 	await store.dispatch(`${namespace}/LOAD_CHAT_HISTORY`, props.contact?.id);
 const loadClosedChatHistory = async () =>
-	await store.dispatch(
-		`features/chat/closed/LOAD_CLOSED_CHAT_HISTORY`,
-		chat.value,
-	);
+	await store.dispatch(`features/chat/closed/LOAD_CLOSED_CHAT_HISTORY`, {
+		chat: chat.value,
+		contactId: props.contact?.id,
+	});
 const resetHistory = () => store.dispatch(`${namespace}/RESET_CHAT_HISTORY`);
 
 const attachPlayer = (player) =>