diff --git a/surfsense_web/contracts/types/chat-session-state.types.ts b/surfsense_web/contracts/types/chat-session-state.types.ts
new file mode 100644
index 000000000..cf73859e6
--- /dev/null
+++ b/surfsense_web/contracts/types/chat-session-state.types.ts
@@ -0,0 +1,24 @@
+import { z } from "zod";
+
+/**
+ * Chat session state for live collaboration.
+ * Tracks which user the AI is currently responding to.
+ */
+export const chatSessionState = z.object({
+	id: z.number(),
+	thread_id: z.number(),
+	ai_responding_to_user_id: z.string().uuid().nullable(),
+	updated_at: z.string(),
+});
+
+/**
+ * User currently being responded to by the AI.
+ */
+export const respondingUser = z.object({
+	id: z.string().uuid(),
+	display_name: z.string().nullable(),
+	email: z.string(),
+});
+
+export type ChatSessionState = z.infer<typeof chatSessionState>;
+export type RespondingUser = z.infer<typeof respondingUser>;