fade out competed tool calls in collpased reasoning blocks

also adds some "bottom slack" to the scrolling of messages so the UI doesn't jump up and down if tool calls in reasoning blocks appear and then get removed at the very bottom of the viewport

Signed-off-by: Christopher Petito <[email protected]>

Author: krissetto

pkg/tui/components/messages/messages.go

@@ -81,6 +81,7 @@ type model struct {
 
 	// Height tracking system fields
 	scrollOffset  int                  // Current scroll position in lines
+	bottomSlack   int                  // Extra blank lines added after content shrinks
 	rendered      string               // Complete rendered content string
 	renderedItems map[int]renderedItem // Cache of rendered items with positions
 	totalHeight   int                  // Total height of all content in lines
@@ -185,6 +186,9 @@ func (m *model) Update(msg tea.Msg) (layout.Model, tea.Cmd) {
 		m.invalidateAllItems()
 		return m, nil
 
+	case reasoningblock.BlockMsg:
+		return m.forwardToReasoningBlock(msg.GetBlockID(), msg)
+
 	case tea.KeyPressMsg:
 		return m.handleKeyPress(msg)
 	}
@@ -216,6 +220,7 @@ func (m *model) handleMouseClick(msg tea.MouseClickMsg) (layout.Model, tea.Cmd)
 			if block.IsToggleLine(localLine) {
 				block.Toggle()
 				m.userHasScrolled = true // Prevent auto-scroll jump
+				m.bottomSlack = 0
 				m.invalidateItem(msgIdx)
 				return m, nil
 			}
@@ -306,12 +311,14 @@ func (m *model) handleMouseWheel(msg tea.MouseWheelMsg) (layout.Model, tea.Cmd)
 	case "wheelup":
 		if m.scrollOffset > 0 {
 			m.userHasScrolled = true
+			m.bottomSlack = 0
 			for range mouseScrollAmount {
 				m.setScrollOffset(m.scrollOffset - defaultScrollAmount)
 			}
 		}
 	case "wheeldown":
 		m.userHasScrolled = true
+		m.bottomSlack = 0
 		for range mouseScrollAmount {
 			m.setScrollOffset(m.scrollOffset + defaultScrollAmount)
 		}
@@ -370,23 +377,39 @@ func (m *model) View() string {
 	}
 
 	prevTotalHeight := m.totalHeight
+	prevScrollableHeight := m.totalHeight + m.bottomSlack
 	m.ensureAllItemsRendered()
 
 	if m.totalHeight == 0 {
 		return ""
 	}
 
-	// Calculate viewport bounds
-	maxScrollOffset := max(0, m.totalHeight-m.height)
+	if m.userHasScrolled {
+		m.bottomSlack = 0
+	} else {
+		delta := m.totalHeight - prevTotalHeight
+		if delta < 0 {
+			m.bottomSlack += -delta
+		} else if delta > 0 && m.bottomSlack > 0 {
+			consume := min(delta, m.bottomSlack)
+			m.bottomSlack -= consume
+		}
+	}
+
+	scrollableHeight := m.totalHeight + m.bottomSlack
+	maxScrollOffset := max(0, scrollableHeight-m.height)
 
-	// Auto-scroll if content grew and user hasn't manually scrolled
-	if !m.userHasScrolled && m.totalHeight > prevTotalHeight {
+	// Auto-scroll when content grows beyond any slack.
+	if !m.userHasScrolled && scrollableHeight > prevScrollableHeight {
 		m.scrollOffset = maxScrollOffset
 	} else {
 		m.scrollOffset = max(0, min(m.scrollOffset, maxScrollOffset))
 	}
 
 	lines := strings.Split(m.rendered, "\n")
+	if m.bottomSlack > 0 {
+		lines = append(lines, make([]string, m.bottomSlack)...)
+	}
 	if len(lines) == 0 {
 		return ""
 	}
@@ -515,12 +538,14 @@ const defaultScrollAmount = 1
 func (m *model) scrollUp() {
 	if m.scrollOffset > 0 {
 		m.userHasScrolled = true
+		m.bottomSlack = 0
 		m.setScrollOffset(max(0, m.scrollOffset-defaultScrollAmount))
 	}
 }
 
 func (m *model) scrollDown() {
 	m.userHasScrolled = true
+	m.bottomSlack = 0
 	m.setScrollOffset(m.scrollOffset + defaultScrollAmount)
 	if m.isAtBottom() {
 		m.userHasScrolled = false
@@ -529,11 +554,13 @@ func (m *model) scrollDown() {
 
 func (m *model) scrollPageUp() {
 	m.userHasScrolled = true
+	m.bottomSlack = 0
 	m.setScrollOffset(max(0, m.scrollOffset-m.height))
 }
 
 func (m *model) scrollPageDown() {
 	m.userHasScrolled = true
+	m.bottomSlack = 0
 	m.setScrollOffset(m.scrollOffset + m.height)
 	if m.isAtBottom() {
 		m.userHasScrolled = false
@@ -542,6 +569,7 @@ func (m *model) scrollPageDown() {
 
 func (m *model) scrollToTop() {
 	m.userHasScrolled = true
+	m.bottomSlack = 0
 	m.setScrollOffset(0)
 }
 
@@ -551,7 +579,7 @@ func (m *model) scrollToBottom() {
 }
 
 func (m *model) setScrollOffset(offset int) {
-	maxOffset := max(0, m.totalHeight-m.height)
+	maxOffset := max(0, m.totalScrollableHeight()-m.height)
 	m.scrollOffset = max(0, min(offset, maxOffset))
 	m.scrollbar.SetScrollOffset(m.scrollOffset)
 }
@@ -560,7 +588,7 @@ func (m *model) isAtBottom() bool {
 	if len(m.messages) == 0 {
 		return true
 	}
-	maxScrollOffset := max(0, m.totalHeight-m.height)
+	maxScrollOffset := max(0, m.totalScrollableHeight()-m.height)
 	return m.scrollOffset >= maxScrollOffset
 }
 
@@ -653,9 +681,11 @@ func (m *model) scrollToSelectedMessage() {
 	// Scroll to make the selected message visible
 	if startLine < m.scrollOffset {
 		m.userHasScrolled = true
+		m.bottomSlack = 0
 		m.setScrollOffset(startLine)
 	} else if endLine > m.scrollOffset+m.height {
 		m.userHasScrolled = true
+		m.bottomSlack = 0
 		m.setScrollOffset(endLine - m.height)
 	}
 }
@@ -778,6 +808,21 @@ func (m *model) invalidateAllItems() {
 	m.renderDirty = true
 }
 
+// forwardToReasoningBlock finds the reasoning block with the given ID and forwards the message to it.
+func (m *model) forwardToReasoningBlock(blockID string, msg tea.Msg) (layout.Model, tea.Cmd) {
+	for i, tuiMsg := range m.messages {
+		if tuiMsg.Type == types.MessageTypeAssistantReasoningBlock {
+			if block, ok := m.views[i].(*reasoningblock.Model); ok && block.ID() == blockID {
+				updatedView, cmd := m.views[i].Update(msg)
+				m.views[i] = updatedView
+				m.invalidateItem(i)
+				return m, cmd
+			}
+		}
+	}
+	return m, nil
+}
+
 // Message management methods
 func (m *model) AddUserMessage(content string) tea.Cmd {
 	return m.addMessage(types.User(content))
@@ -909,6 +954,7 @@ func (m *model) LoadFromSession(sess *session.Session) tea.Cmd {
 	m.rendered = ""
 	m.scrollOffset = 0
 	m.totalHeight = 0
+	m.bottomSlack = 0
 	m.selectedMessageIndex = -1
 
 	var cmds []tea.Cmd
@@ -1185,6 +1231,10 @@ func (m *model) contentWidth() int {
 	return m.width - 2
 }
 
+func (m *model) totalScrollableHeight() int {
+	return m.totalHeight + m.bottomSlack
+}
+
 // Helper methods
 func (m *model) createToolCallView(msg *types.Message) layout.Model {
 	view := tool.New(msg, m.sessionState)
@@ -1254,6 +1304,8 @@ func (m *model) isMouseOnScrollbar(x, y int) bool {
 func (m *model) handleScrollbarUpdate(msg tea.Msg) (layout.Model, tea.Cmd) {
 	sb, cmd := m.scrollbar.Update(msg)
 	m.scrollbar = sb
+	m.userHasScrolled = true
+	m.bottomSlack = 0
 	m.scrollOffset = m.scrollbar.GetScrollOffset()
 	return m, cmd
 }