Updates/fixes to selectedMessage handling in chat TUI view

pkg/tui/views/chat/update.go

@@ -78,6 +78,12 @@ func (m *Model) Update(msg tea.Msg) (shared.ViewModel, tea.Cmd) {
 		if m.App.Conversation.ID > 0 {
 			// (re)load conversation contents
 			cmds = append(cmds, m.loadConversationMessages())
+		} else {
+			if len(m.App.Messages) > 0 && m.showDetails {
+				m.selectedMessage = 0
+			} else {
+				m.selectedMessage = -1
+			}
 		}
 	case tuiutil.MsgTempfileEditorClosed:
 		contents := string(msg)
@@ -97,11 +103,7 @@ func (m *Model) Update(msg tea.Msg) (shared.ViewModel, tea.Cmd) {
 		}
 	case msgConversationMessagesLoaded:
 		m.App.Messages = msg.messages
-		if m.selectedMessage == -1 {
-			m.selectedMessage = len(msg.messages) - 1
-		} else {
-			m.selectedMessage = min(m.selectedMessage, len(m.App.Messages))
-		}
+		m.selectedMessage = len(msg.messages) - 1
 		m.rebuildMessageCache()
 		m.updateContent()
 	case msgChatResponseChunk: