diff --git a/src/vs/workbench/contrib/chat/common/chatAgents.ts b/src/vs/workbench/contrib/chat/common/chatAgents.ts
index 83530ec46c7..89beecd07bb 100644
--- a/src/vs/workbench/contrib/chat/common/chatAgents.ts
+++ b/src/vs/workbench/contrib/chat/common/chatAgents.ts
@@ -16,9 +16,12 @@ import { IChatRequestVariableValue } from 'vs/workbench/contrib/chat/common/chat
 
 //#region agent service, commands etc
 
-export interface IChatAgent {
+export interface IChatAgentData {
 	id: string;
 	metadata: IChatAgentMetadata;
+}
+
+export interface IChatAgent extends IChatAgentData {
 	invoke(request: IChatAgentRequest, progress: (part: IChatProgress) => void, history: IChatMessage[], token: CancellationToken): Promise<IChatAgentResult>;
 	provideFollowups?(sessionId: string, token: CancellationToken): Promise<IChatFollowup[]>;
 	provideSlashCommands(token: CancellationToken): Promise<IChatAgentCommand[]>;
diff --git a/src/vs/workbench/contrib/chat/common/chatModel.ts b/src/vs/workbench/contrib/chat/common/chatModel.ts
index e1cc5cce29e..353420a7274 100644
--- a/src/vs/workbench/contrib/chat/common/chatModel.ts
+++ b/src/vs/workbench/contrib/chat/common/chatModel.ts
@@ -8,12 +8,13 @@ import { DeferredPromise } from 'vs/base/common/async';
 import { Emitter, Event } from 'vs/base/common/event';
 import { IMarkdownString, MarkdownString, isMarkdownString } from 'vs/base/common/htmlContent';
 import { Disposable } from 'vs/base/common/lifecycle';
+import { revive } from 'vs/base/common/marshalling';
 import { basename } from 'vs/base/common/resources';
-import { URI, UriComponents } from 'vs/base/common/uri';
+import { URI, UriComponents, UriDto } from 'vs/base/common/uri';
 import { generateUuid } from 'vs/base/common/uuid';
 import { OffsetRange } from 'vs/editor/common/core/offsetRange';
 import { ILogService } from 'vs/platform/log/common/log';
-import { IChatAgent, IChatAgentService } from 'vs/workbench/contrib/chat/common/chatAgents';
+import { IChatAgentData } from 'vs/workbench/contrib/chat/common/chatAgents';
 import { ChatRequestTextPart, IParsedChatRequest, reviveParsedChatRequest } from 'vs/workbench/contrib/chat/common/chatParserTypes';
 import { IChat, IChatContentInlineReference, IChatContentReference, IChatFollowup, IChatProgress, IChatReplyFollowup, IChatResponse, IChatResponseErrorDetails, IChatResponseProgressFileTreeData, IUsedContext, InteractiveSessionVoteDirection, isIUsedContext } from 'vs/workbench/contrib/chat/common/chatService';
 
@@ -57,7 +58,7 @@ export interface IChatResponseModel {
 	readonly username: string;
 	readonly avatarIconUri?: URI;
 	readonly session: IChatModel;
-	readonly agent?: IChatAgent;
+	readonly agent?: IChatAgentData;
 	readonly response: IResponse;
 	readonly isComplete: boolean;
 	readonly isCanceled: boolean;
@@ -294,7 +295,7 @@ export class ChatResponseModel extends Disposable implements IChatResponseModel
 	constructor(
 		_response: IMarkdownString | ReadonlyArray<IMarkdownString | IChatResponseProgressFileTreeData | IChatContentInlineReference>,
 		public readonly session: ChatModel,
-		public readonly agent: IChatAgent | undefined,
+		public readonly agent: IChatAgentData | undefined,
 		public readonly requestId: string,
 		private _isComplete: boolean = false,
 		private _isCanceled = false,
@@ -364,12 +365,7 @@ export interface ISerializableChatsData {
 	[sessionId: string]: ISerializableChatData;
 }
 
-export interface ISerializableChatAgentData {
-	id: string;
-	description?: string;
-	fullName?: string;
-	icon?: UriComponents;
-}
+export type ISerializableChatAgentData = UriDto<IChatAgentData>;
 
 export interface ISerializableChatRequestData {
 	providerRequestId: string | undefined;
@@ -532,7 +528,6 @@ export class ChatModel extends Disposable implements IChatModel {
 		public readonly providerId: string,
 		private readonly initialData: ISerializableChatData | IExportableChatData | undefined,
 		@ILogService private readonly logService: ILogService,
-		@IChatAgentService private readonly chatAgentService: IChatAgentService,
 	) {
 		super();
 
@@ -566,7 +561,8 @@ export class ChatModel extends Disposable implements IChatModel {
 						: reviveParsedChatRequest(raw.message);
 				const request = new ChatRequestModel(this, parsedRequest, raw.providerRequestId);
 				if (raw.response || raw.responseErrorDetails) {
-					const agent = raw.agent && this.chatAgentService.getAgents().find(a => a.id === raw.agent!.id); // TODO do something reasonable if this agent has disappeared since the last session
+					const agent = (raw.agent && 'metadata' in raw.agent) ? // Check for the new format, ignore entries in the old format
+						revive<ISerializableChatAgentData>(raw.agent) : undefined;
 					request.response = new ChatResponseModel(raw.response ?? [new MarkdownString(raw.response)], this, agent, request.id, true, raw.isCanceled, raw.vote, raw.providerRequestId, raw.responseErrorDetails, raw.followups);
 					if (raw.usedContext) { // @ulugbekna: if this's a new vscode sessions, doc versions are incorrect anyway?
 						request.response.updateContent(raw.usedContext);
@@ -648,7 +644,7 @@ export class ChatModel extends Disposable implements IChatModel {
 		return this._requests;
 	}
 
-	addRequest(message: IParsedChatRequest, chatAgent?: IChatAgent): ChatRequestModel {
+	addRequest(message: IParsedChatRequest, chatAgent?: IChatAgentData): ChatRequestModel {
 		if (!this._session) {
 			throw new Error('addRequest: No session');
 		}
@@ -762,12 +758,7 @@ export class ChatModel extends Disposable implements IChatModel {
 					followups: r.response?.followups,
 					isCanceled: r.response?.isCanceled,
 					vote: r.response?.vote,
-					agent: r.response?.agent ? {
-						id: r.response.agent.id,
-						description: r.response.agent.metadata.description,
-						fullName: r.response.agent.metadata.fullName,
-						icon: r.response.agent.metadata.icon
-					} : undefined,
+					agent: r.response?.agent,
 					usedContext: r.response?.response.usedContext,
 					contentReferences: r.response?.response.contentReferences
 				};
diff --git a/src/vs/workbench/contrib/chat/common/chatViewModel.ts b/src/vs/workbench/contrib/chat/common/chatViewModel.ts
index 7043b5a54a8..81cd931f203 100644
--- a/src/vs/workbench/contrib/chat/common/chatViewModel.ts
+++ b/src/vs/workbench/contrib/chat/common/chatViewModel.ts
@@ -8,7 +8,7 @@ import { Disposable } from 'vs/base/common/lifecycle';
 import { URI } from 'vs/base/common/uri';
 import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
 import { ILogService } from 'vs/platform/log/common/log';
-import { IChatAgent } from 'vs/workbench/contrib/chat/common/chatAgents';
+import { IChatAgentData } from 'vs/workbench/contrib/chat/common/chatAgents';
 import { ChatModelInitState, IChatModel, IChatRequestModel, IChatResponseModel, IChatWelcomeMessageContent, IResponse } from 'vs/workbench/contrib/chat/common/chatModel';
 import { IParsedChatRequest } from 'vs/workbench/contrib/chat/common/chatParserTypes';
 import { IChatReplyFollowup, IChatResponseCommandFollowup, IChatResponseErrorDetails, IChatResponseProgressFileTreeData, InteractiveSessionVoteDirection } from 'vs/workbench/contrib/chat/common/chatService';
@@ -89,7 +89,7 @@ export interface IChatResponseViewModel {
 	readonly requestId: string;
 	readonly username: string;
 	readonly avatarIconUri?: URI;
-	readonly agent?: IChatAgent;
+	readonly agent?: IChatAgentData;
 	readonly response: IResponse;
 	readonly isComplete: boolean;
 	readonly isCanceled: boolean;