fix: sluggish mouse scroll

tui.go

@@ -34,6 +34,8 @@ const (
 type tickMsg time.Time
 type pathTickMsg time.Time
 
+const mouseWheelScrollStep = 3
+
 type writeMode int
 
 const (
@@ -703,6 +705,9 @@ func (m App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	if tick, ok := msg.(diffletTickMsg); ok {
 		return m, m.difflet.update(tick)
 	}
+	if mouse, ok := msg.(tea.MouseMsg); ok && m.handleMouseWheel(mouse) {
+		return m, nil
+	}
 	if m.aiMode != aiNone {
 		if updated, command, handled := m.updateAI(msg); handled {
 			return updated, command
@@ -1887,6 +1892,49 @@ func (m *App) page(direction int) {
 	m.move(direction * max(3, m.height/2))
 }
 
+func (m *App) handleMouseWheel(message tea.MouseMsg) bool {
+	if message.Action != tea.MouseActionPress {
+		return false
+	}
+	direction := 0
+	switch message.Button {
+	case tea.MouseButtonWheelUp:
+		direction = -1
+	case tea.MouseButtonWheelDown:
+		direction = 1
+	default:
+		return false
+	}
+	delta := direction * mouseWheelScrollStep
+	if m.helpVisible {
+		m.helpScroll = clamp(m.helpScroll+delta, 0, m.helpMaxScroll())
+		return true
+	}
+	if m.aiMode == aiConfirm {
+		m.aiPreviewScroll = max(0, m.aiPreviewScroll+delta)
+		return true
+	}
+	if m.aiMode != aiNone && m.aiMode != aiDiscussion {
+		return true
+	}
+	switch m.screen {
+	case dashboardScreen:
+		m.scrollDashboard(delta)
+	case healthScreen:
+		m.healthScroll = clamp(m.healthScroll+delta, 0, m.healthMaxScroll())
+	case threadScreen:
+		if m.focus == threadDetailPane || m.writeMode == writeReply ||
+			m.aiMode == aiDiscussion {
+			m.scrollDetail(delta)
+		} else {
+			m.move(delta)
+		}
+	case prScreen:
+		m.move(delta)
+	}
+	return true
+}
+
 func (m *App) scrollDetail(delta int) {
 	m.scroll = clamp(m.scroll+delta, 0, m.detailMaxScroll())
 	m.acknowledgeVisibleUnread()