diff --git a/app/components/thread/MessageList.tsx b/app/components/thread/MessageList.tsx
index 757ccd1..fe3690e 100644
--- a/app/components/thread/MessageList.tsx
+++ b/app/components/thread/MessageList.tsx
@@ -23,6 +23,7 @@ const MessageList = forwardRef(
       isFetching,
       userId,
       teamUserIds,
+      viewerIsStore = false,
       onReply,
       onDelete,
       onScroll,
@@ -32,10 +33,13 @@ const MessageList = forwardRef(
       isLoading: boolean;
       isFetching: boolean;
       userId: string | undefined;
-      // When present, any message sender in this set is treated as "our side"
-      // (right-aligned, blue). Lets staff see coworkers' messages on the team
-      // side of the store inbox instead of confusing them with customer messages.
+      // Senders on the store team. Only treated as "our side" when the VIEWER
+      // is store-side (viewerIsStore) — otherwise a customer would wrongly see
+      // the store's staff messages on their own (right) side.
       teamUserIds?: readonly string[];
+      // True when the current viewer is on this thread's store team. Gates all
+      // team-grouping so the customer view stays "my messages right, store left".
+      viewerIsStore?: boolean;
       onReply: (message: MessageListType) => void;
       onDelete?: (messageId: string) => void;
       onScroll?: (event: React.UIEvent<HTMLDivElement>) => void;
@@ -170,9 +174,12 @@ const MessageList = forwardRef(
               message={message}
               isCurrentUser={
                 message.sender === userId ||
-                (!!message.sender && !!teamUserIds?.includes(message.sender))
+                (viewerIsStore &&
+                  !!message.sender &&
+                  !!teamUserIds?.includes(message.sender))
               }
               isCoworker={
+                viewerIsStore &&
                 message.sender !== userId &&
                 !!message.sender &&
                 !!teamUserIds?.includes(message.sender)
diff --git a/app/components/thread/ThreadChatPage.tsx b/app/components/thread/ThreadChatPage.tsx
index d7162d2..95171d0 100644
--- a/app/components/thread/ThreadChatPage.tsx
+++ b/app/components/thread/ThreadChatPage.tsx
@@ -286,6 +286,7 @@ export default function ThreadChatPage({ threadId }: ThreadChatPageProps) {
               isFetching={isFetchingNextPage}
               userId={user?.id}
               teamUserIds={threadDetails?.teamUserIds}
+              viewerIsStore={threadDetails?.viewerIsStore}
               onReply={handleReplyClick}
               onDelete={handleDeleteMessage}
               onScroll={handleScroll}
diff --git a/src/api/types/models/index.ts b/src/api/types/models/index.ts
index aa772d0..db92628 100644
--- a/src/api/types/models/index.ts
+++ b/src/api/types/models/index.ts
@@ -6587,6 +6587,12 @@ export interface ThreadDetail {
      * @memberof ThreadDetail
      */
     readonly teamUserIds?: Array<string>;
+    /**
+     * True when the viewer is on this thread's store team (owner/staff).
+     * @type {boolean}
+     * @memberof ThreadDetail
+     */
+    readonly viewerIsStore?: boolean;
 }
 /**
  *