fix(dashboard): don't mark agent inbox messages read when user views them

When the dashboard user browses another agent's mailbox (e.g. the CEO's
inbox), opening a message no longer triggers POST /messages/:id/read.
The previous behavior silently consumed the agent's unread state, so the
agent's heartbeat never surfaced the message and fn_read_messages (which
defaults to unread_only=true) returned nothing. Auto-mark-read now only
fires on the dashboard user's own inbox tab. Adds regression tests in
MailboxView.test.tsx and MailboxModal.test.tsx.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.changeset/agent-mailbox-no-mark-read.md

@@ -0,0 +1,12 @@
+---
+"@runfusion/fusion": patch
+---
+
+Stop the dashboard from auto-marking another agent's messages as read when
+the user opens them while browsing that agent's mailbox. Previously, viewing
+a message in an agent's inbox (e.g. the CEO's mailbox) would call
+`POST /messages/:id/read`, which silently consumed the agent's unread state.
+The agent's heartbeat would then never see the message as pending, and the
+agent's `fn_read_messages` tool (which defaults to `unread_only: true`)
+returned nothing. The mark-as-read call now only fires for the dashboard
+user's own inbox tab.

packages/dashboard/app/components/MailboxModal.tsx

@@ -207,8 +207,10 @@ export function MailboxModal({
 
   const handleOpenMessage = useCallback(async (message: Message) => {
     setSelectedMessage(message);
-    // Mark as read if unread
-    if (!message.read) {
+    // Only auto-mark as read when viewing the dashboard user's own inbox.
+    // Browsing another agent's mailbox must not consume their unread messages
+    // out from under them — the agent's heartbeat is the one that reads + acks.
+    if (!message.read && activeTab === "inbox") {
       try {
         const updated = await markMessageRead(message.id, projectId);
         // Update inbox state
@@ -233,7 +235,7 @@ export function MailboxModal({
     } catch {
       setConversationMessages([message]);
     }
-  }, [projectId]);
+  }, [projectId, activeTab]);
 
   const handleCloseMessage = useCallback(() => {
     setSelectedMessage(null);

packages/dashboard/app/components/MailboxView.tsx

@@ -291,8 +291,10 @@ export function MailboxView({
 
   const handleOpenMessage = useCallback(async (message: Message) => {
     setSelectedMessage(message);
-    // Mark as read if unread
-    if (!message.read) {
+    // Only auto-mark as read when viewing the dashboard user's own inbox.
+    // Browsing another agent's mailbox must not consume their unread messages
+    // out from under them — the agent's heartbeat is the one that reads + acks.
+    if (!message.read && activeTab === "inbox") {
       try {
         const updated = await markMessageRead(message.id, projectId);
         // Update inbox state
@@ -321,7 +323,7 @@ export function MailboxView({
     } catch {
       setConversationMessages([message]);
     }
-  }, [projectId, unreadCount, onUnreadCountChange]);
+  }, [projectId, unreadCount, onUnreadCountChange, activeTab]);
 
   const handleCloseMessage = useCallback(() => {
     setSelectedMessage(null);

packages/dashboard/app/components/__tests__/MailboxModal.test.tsx

@@ -285,6 +285,53 @@ describe("MailboxModal", () => {
     });
   });
 
+  it("does not mark agent inbox messages as read when the dashboard user opens them", async () => {
+    const agentInboxMessage: Message = {
+      id: "msg-agent-unread",
+      fromId: "user-001",
+      fromType: "user",
+      toId: "agent-001",
+      toType: "agent",
+      content: "Important — please reply",
+      type: "user-to-agent",
+      read: false,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+    };
+    mockFetchAgentMailbox.mockResolvedValue({
+      ownerId: "agent-001",
+      ownerType: "agent",
+      unreadCount: 1,
+      messages: [agentInboxMessage],
+      inbox: [agentInboxMessage],
+      outbox: [],
+    });
+    mockFetchConversation.mockResolvedValue([agentInboxMessage]);
+
+    render(<MailboxModal {...defaultProps} />);
+    fireEvent.click(screen.getByTestId("mailbox-tab-agents"));
+    await waitFor(() => {
+      expect(screen.getByTestId("mailbox-agent-select")).toBeDefined();
+    });
+    fireEvent.change(screen.getByTestId("mailbox-agent-select"), { target: { value: "agent-001" } });
+    await waitFor(() => {
+      expect(screen.getByTestId("mailbox-item-msg-agent-unread")).toBeDefined();
+    });
+
+    await act(async () => {
+      fireEvent.click(screen.getByTestId("mailbox-item-msg-agent-unread"));
+    });
+
+    await waitFor(() => {
+      expect(screen.getByTestId("mailbox-message-detail")).toBeDefined();
+    });
+
+    // Critical: the dashboard user browsing an agent's mailbox MUST NOT
+    // consume the agent's unread state — the agent's heartbeat is the
+    // authoritative reader.
+    expect(mockMarkMessageRead).not.toHaveBeenCalled();
+  });
+
   it("shows back button in message detail", async () => {
     render(<MailboxModal {...defaultProps} />);
     await waitFor(() => {

packages/dashboard/app/components/__tests__/MailboxView.test.tsx

@@ -974,6 +974,58 @@ describe("MailboxView", () => {
       });
     });
 
+    it("does not mark agent inbox messages as read when the dashboard user opens them", async () => {
+      const agentInboxMessage: Message = {
+        id: "msg-agent-unread",
+        fromId: "user-001",
+        fromType: "user",
+        toId: "agent-001",
+        toType: "agent",
+        content: "Important — please reply",
+        type: "user-to-agent",
+        read: false,
+        createdAt: new Date().toISOString(),
+        updatedAt: new Date().toISOString(),
+      };
+
+      mockFetchInbox.mockResolvedValue({ messages: [], unreadCount: 0, total: 0 });
+      mockFetchAgentMailbox.mockResolvedValue({
+        ownerId: "agent-001",
+        ownerType: "agent",
+        unreadCount: 1,
+        messages: [agentInboxMessage],
+        inbox: [agentInboxMessage],
+        outbox: [],
+      });
+      mockFetchConversation.mockResolvedValue([agentInboxMessage]);
+
+      render(<MailboxView {...defaultProps} />);
+
+      const agentsTab = screen.getByTestId("mailbox-tab-agents");
+      await act(async () => {
+        fireEvent.click(agentsTab);
+      });
+
+      fireEvent.change(screen.getByTestId("mailbox-agent-select"), { target: { value: "agent-001" } });
+
+      await waitFor(() => {
+        expect(screen.getByTestId("mailbox-item-msg-agent-unread")).toBeDefined();
+      });
+
+      await act(async () => {
+        fireEvent.click(screen.getByTestId("mailbox-item-msg-agent-unread"));
+      });
+
+      await waitFor(() => {
+        expect(screen.getByTestId("mailbox-message-detail")).toBeDefined();
+      });
+
+      // Critical: the dashboard user browsing an agent's mailbox MUST NOT
+      // consume the agent's unread state — the agent's heartbeat is the
+      // authoritative reader.
+      expect(mockMarkMessageRead).not.toHaveBeenCalled();
+    });
+
     it("switches to outbox view when clicking outbox sub-tab", async () => {
       mockFetchInbox.mockResolvedValue({
         messages: [],