diff --git a/packages/sdk/src/plugins/user-chat/plugin.ts b/packages/sdk/src/plugins/user-chat/plugin.ts
index 069bdee..55c86ae 100644
--- a/packages/sdk/src/plugins/user-chat/plugin.ts
+++ b/packages/sdk/src/plugins/user-chat/plugin.ts
@@ -600,6 +600,7 @@ export const userChatPlugin = definePlugin("user-chat")
 	.notification("agentMessage", {
 		schema: z.object({
 			sessionId: sessionIdSchema,
+			messageId: chatMessageIdSchema,
 			content: z.string(),
 			format: z.enum(["text", "markdown"]),
 			timestamp: z.number(),
@@ -671,6 +672,7 @@ export const userChatPlugin = definePlugin("user-chat")
 			);
 			ctx.notify("agentMessage", {
 				sessionId: ctx.sessionId,
+				messageId,
 				content: input.message,
 				format: input.format,
 				timestamp,
@@ -849,6 +851,7 @@ export const userChatPlugin = definePlugin("user-chat")
 			);
 			ctx.notify("agentMessage", {
 				sessionId: ctx.sessionId,
+				messageId: chatMessageId,
 				content,
 				format: "text",
 				timestamp: Date.now(),
diff --git a/packages/sdk/src/plugins/user-chat/user-chat.integration.test.ts b/packages/sdk/src/plugins/user-chat/user-chat.integration.test.ts
index cca99fa..ad98564 100644
--- a/packages/sdk/src/plugins/user-chat/user-chat.integration.test.ts
+++ b/packages/sdk/src/plugins/user-chat/user-chat.integration.test.ts
@@ -544,6 +544,11 @@ describe('user-chat plugin', () => {
 			const messages = harness.notifications.getAgentMessages()
 			expect(messages).toHaveLength(1)
 			expect(messages[0].content).toBe('Hello user!')
+			const stored = selectPluginState<UserChatState>(session.state, 'messages')?.messages.filter(message => message.type === 'agent_message') ?? []
+			expect(stored).toHaveLength(1)
+			expect(harness.notifications.getByType('user-chat', 'agentMessage')[0].payload).toMatchObject({
+				messageId: stored[0].messageId,
+			})
 
 			await harness.shutdown()
 		})
@@ -1135,6 +1140,11 @@ describe('user-chat plugin', () => {
 			const messages = harness.notifications.getAgentMessages()
 			expect(messages).toHaveLength(1)
 			expect(messages[0].content).toBe('Hello from XML!')
+			const stored = selectPluginState<UserChatState>(session.state, 'messages')?.messages.filter(message => message.type === 'agent_message') ?? []
+			expect(stored).toHaveLength(1)
+			expect(harness.notifications.getByType('user-chat', 'agentMessage')[0].payload).toMatchObject({
+				messageId: stored[0].messageId,
+			})
 
 			await harness.shutdown()
 		})