fix persistent history when used with teaser message

Author: kwinto

src/webchat/store/reducer.ts

@@ -52,15 +52,17 @@ export type SetPrevStateAction = ReturnType<typeof setPrevState>;
 
 export const reducer = (state = rootReducer(undefined, { type: "" }), action) => {
 	switch (action.type) {
+		// This is actually "Restore persisted history"
 		case "RESET_STATE": {
+			// To avoid duplicate messages in chat history during re-connection, we only restore messages and prepend them if the current message history is empty
+			const isEmptyHistory =
+				state.messages.length === 0 ||
+				(state.messages.length === 1 && state.messages[0].source === "engagement");
+			const messages = isEmptyHistory ? action.state.messages : [];
 			return rootReducer(
 				{
 					...state,
-					messages: [
-						// To avoid duplicate messages in chat history during re-connection, we only restore messages and prepend them if the current message history is empty
-						...(state.messages.length === 0 ? action.state.messages : []),
-						...state.messages,
-					],
+					messages: [...messages, ...state.messages],
 					rating: {
 						...state.rating,
 						hasGivenRating: action.state.rating.hasGivenRating,