diff --git a/tui/component_chat_stream.go b/tui/component_chat_stream.go
index c5c02f44..2029965e 100644
--- a/tui/component_chat_stream.go
+++ b/tui/component_chat_stream.go
@@ -46,6 +46,9 @@ func (m *model) appendAssistantDelta(delta string) {
 			delta = m.suppressedAssistantDelta + delta
 			m.suppressedAssistantDelta = ""
 		}
+		if m.deltaDuplicatesFinalAssistant(delta) {
+			return
+		}
 	}
 	if m.streamingIndex >= 0 && m.streamingIndex < len(m.chatItems) {
 		current := m.chatItems[m.streamingIndex].Body
@@ -132,6 +135,7 @@ func (m *model) finishAssistantMessage(content string) {
 		}
 	}
 
+	m.removeLatestOpenAssistantInCurrentTurn()
 	m.chatItems = append(m.chatItems, chatEntry{
 		Kind:   "assistant",
 		Title:  assistantLabel,
@@ -140,6 +144,73 @@ func (m *model) finishAssistantMessage(content string) {
 	})
 }
 
+func (m *model) removeLatestOpenAssistantInCurrentTurn() {
+	for i := len(m.chatItems) - 1; i >= 0; i-- {
+		item := m.chatItems[i]
+		if item.Kind == "user" {
+			return
+		}
+		if item.Kind != "assistant" {
+			continue
+		}
+		switch strings.TrimSpace(strings.ToLower(item.Status)) {
+		case "pending", "thinking", "streaming", "settling":
+			m.chatItems = append(m.chatItems[:i], m.chatItems[i+1:]...)
+			if m.streamingIndex == i {
+				m.streamingIndex = -1
+			} else if m.streamingIndex > i {
+				m.streamingIndex--
+			}
+			return
+		}
+	}
+}
+
+func (m *model) removeDuplicateOpenAssistantPreviews() {
+	for i := 0; i < len(m.chatItems); i++ {
+		item := m.chatItems[i]
+		if item.Kind != "assistant" || !isOpenAssistantStatus(item.Status) {
+			continue
+		}
+		if normalizeAssistantFinalBody(item.Body) == "" {
+			continue
+		}
+		for j := i + 1; j < len(m.chatItems); j++ {
+			next := m.chatItems[j]
+			if next.Kind == "user" {
+				break
+			}
+			if next.Kind == "assistant" && isFinalAssistantStatus(next.Status) && sameAssistantFinalBody(item.Body, next.Body) {
+				m.chatItems = append(m.chatItems[:i], m.chatItems[i+1:]...)
+				if m.streamingIndex == i {
+					m.streamingIndex = -1
+				} else if m.streamingIndex > i {
+					m.streamingIndex--
+				}
+				i--
+				break
+			}
+		}
+	}
+}
+
+func (m model) deltaDuplicatesFinalAssistant(delta string) bool {
+	delta = normalizeAssistantFinalBody(delta)
+	if delta == "" {
+		return false
+	}
+	for i := len(m.chatItems) - 1; i >= 0; i-- {
+		item := m.chatItems[i]
+		if item.Kind == "user" {
+			return false
+		}
+		if item.Kind == "assistant" && isFinalAssistantStatus(item.Status) {
+			return normalizeAssistantFinalBody(item.Body) == delta
+		}
+	}
+	return false
+}
+
 func (m model) latestTailOpenAssistantIndex() int {
 	if len(m.chatItems) == 0 {
 		return -1
@@ -157,6 +228,19 @@ func (m model) latestTailOpenAssistantIndex() int {
 	}
 }
 
+func isOpenAssistantStatus(status string) bool {
+	switch strings.TrimSpace(strings.ToLower(status)) {
+	case "pending", "thinking", "streaming", "settling":
+		return true
+	default:
+		return false
+	}
+}
+
+func isFinalAssistantStatus(status string) bool {
+	return strings.TrimSpace(strings.ToLower(status)) == "final"
+}
+
 func sameAssistantFinalBody(a, b string) bool {
 	return normalizeAssistantFinalBody(a) == normalizeAssistantFinalBody(b)
 }
diff --git a/tui/component_chat_stream_test.go b/tui/component_chat_stream_test.go
index 74f6242f..02153e31 100644
--- a/tui/component_chat_stream_test.go
+++ b/tui/component_chat_stream_test.go
@@ -776,6 +776,86 @@ func TestHandleAgentEventDeltaAppendsToStream(t *testing.T) {
 	}
 }
 
+func TestFinalAssistantMessageReplacesFullStreamingDeltaAfterRunFinished(t *testing.T) {
+	content := strings.Join([]string{
+		"你说的情况我理解了--你在 UI 里看到我先输出了一段短文本。",
+		"",
+		"1. 第一段是 generating。",
+		"2. 第二段是 answer。",
+	}, "\n")
+	m := model{
+		async: make(chan tea.Msg, 1),
+		busy:  true,
+		chatItems: []chatEntry{
+			{Kind: "user", Title: "You", Body: "为什么输出两遍", Status: "final"},
+		},
+		streamingIndex: -1,
+	}
+
+	m.handleAgentEvent(Event{Type: EventAssistantDelta, Content: content})
+	got, _ := m.Update(runFinishedMsg{})
+	updated := got.(model)
+	updated.handleAgentEvent(Event{Type: EventRunFinished, Content: content})
+	updated.handleAgentEvent(Event{Type: EventAssistantMessage, Content: content})
+
+	assistantCount := 0
+	for _, item := range updated.chatItems {
+		if item.Kind == "assistant" {
+			assistantCount++
+			if item.Status != "final" {
+				t.Fatalf("expected only final assistant item, got %+v", item)
+			}
+		}
+	}
+	if assistantCount != 1 {
+		t.Fatalf("expected final message to replace streaming delta, got %d assistant items: %+v", assistantCount, updated.chatItems)
+	}
+}
+
+func TestRunFinishedRemovesDuplicateOpenAssistantPreview(t *testing.T) {
+	m := model{
+		async: make(chan tea.Msg, 1),
+		chatItems: []chatEntry{
+			{Kind: "user", Title: "You", Body: "hello", Status: "final"},
+			{Kind: "assistant", Title: assistantLabel, Body: "same answer", Status: "streaming"},
+			{Kind: "assistant", Title: assistantLabel, Body: "same answer\n\nProcessed for 1s", Status: "final"},
+		},
+		streamingIndex: 1,
+	}
+
+	got, _ := m.Update(runFinishedMsg{})
+	updated := got.(model)
+
+	if len(updated.chatItems) != 2 {
+		t.Fatalf("expected duplicate streaming preview to be removed, got %+v", updated.chatItems)
+	}
+	if updated.chatItems[1].Status != "final" || !strings.Contains(updated.chatItems[1].Body, "same answer") {
+		t.Fatalf("expected final answer to remain, got %+v", updated.chatItems[1])
+	}
+	if updated.streamingIndex != -1 {
+		t.Fatalf("expected streaming index to be cleared, got %d", updated.streamingIndex)
+	}
+}
+
+func TestAppendAssistantDeltaIgnoresLateDuplicateAfterFinalAnswer(t *testing.T) {
+	m := model{
+		chatItems: []chatEntry{
+			{Kind: "user", Title: "You", Body: "hello", Status: "final"},
+			{Kind: "assistant", Title: assistantLabel, Body: "same answer\n\nProcessed for 1s", Status: "final"},
+		},
+		streamingIndex: -1,
+	}
+
+	m.appendAssistantDelta("same answer")
+
+	if len(m.chatItems) != 2 {
+		t.Fatalf("expected late duplicate delta to be ignored, got %+v", m.chatItems)
+	}
+	if m.streamingIndex != -1 {
+		t.Fatalf("expected streaming index to stay cleared, got %d", m.streamingIndex)
+	}
+}
+
 func TestHandleAgentEventToolCallStartedAppendsToolCard(t *testing.T) {
 	m := model{
 		chatItems: []chatEntry{
diff --git a/tui/component_viewport_layout.go b/tui/component_viewport_layout.go
index 6ba4f960..4d774f28 100644
--- a/tui/component_viewport_layout.go
+++ b/tui/component_viewport_layout.go
@@ -76,8 +76,10 @@ func (m *model) syncViewportSize() {
 	if bodyHeight < 6 {
 		bodyHeight = 6
 	}
-	statusHeight := lipgloss.Height(m.renderStatusBar())
-	panelInnerHeight := max(4, bodyHeight-panelStyle.GetVerticalFrameSize()-statusHeight-1)
+	width := max(24, m.chatPanelInnerWidth())
+	statusHeight := lipgloss.Height(m.renderStatusBarWithWidth(width))
+	topRightHeight := m.mainPanelTopRightHeight(width)
+	panelInnerHeight := max(4, bodyHeight-panelStyle.GetVerticalFrameSize()-statusHeight-topRightHeight-1)
 	m.planView.Width = 0
 	m.planView.Height = 0
 	contentHeight := max(3, panelInnerHeight)
@@ -88,6 +90,18 @@ func (m *model) syncViewportSize() {
 	m.syncCopyViewOffset()
 }
 
+func (m model) mainPanelTopRightHeight(width int) int {
+	width = max(1, width)
+	height := 0
+	if badge := strings.TrimSpace(m.renderTopRightCluster(width)); badge != "" {
+		height += lipgloss.Height(lipgloss.PlaceHorizontal(width, lipgloss.Right, badge))
+		if popup := strings.TrimSpace(m.tokenUsage.PopupView()); popup != "" {
+			height += lipgloss.Height(lipgloss.PlaceHorizontal(width, lipgloss.Right, popup))
+		}
+	}
+	return height
+}
+
 func (m *model) syncCopyViewOffset() {
 	if m == nil {
 		return
diff --git a/tui/model.go b/tui/model.go
index 3a90b739..cb6a9643 100644
--- a/tui/model.go
+++ b/tui/model.go
@@ -809,6 +809,7 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		return m, cmd
 	case agentEventMsg:
 		m.handleAgentEvent(msg.Event)
+		m.removeDuplicateOpenAssistantPreviews()
 		m.refreshViewport()
 		return m, waitForAsync(m.async)
 	case runFinishedMsg:
@@ -905,6 +906,7 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		}
 		m.stalled = false
 		m.lastTokenReceivedAt = time.Time{}
+		m.removeDuplicateOpenAssistantPreviews()
 		m.refreshViewport()
 		return m, tea.Batch(waitForAsync(m.async), m.loadSessionsCmd())
 	case approvalRequestMsg:
diff --git a/tui/model_layout_viewport.go b/tui/model_layout_viewport.go
index 13c81091..bf54ab24 100644
--- a/tui/model_layout_viewport.go
+++ b/tui/model_layout_viewport.go
@@ -145,12 +145,6 @@ func (m model) conversationViewportBoundsByLayout() (left, right, top, bottom in
 func (m model) conversationViewportOffsetInMainPanel() int {
 	width := max(24, m.chatPanelInnerWidth())
 	offset := lipgloss.Height(m.renderStatusBar())
-	badge := strings.TrimSpace(m.renderTopRightCluster(width))
-	if badge != "" {
-		offset += lipgloss.Height(lipgloss.PlaceHorizontal(width, lipgloss.Right, badge))
-		if popup := strings.TrimSpace(m.tokenUsage.PopupView()); popup != "" {
-			offset += lipgloss.Height(lipgloss.PlaceHorizontal(width, lipgloss.Right, popup))
-		}
-	}
+	offset += m.mainPanelTopRightHeight(width)
 	return offset + 1
 }
diff --git a/tui/model_layout_viewport_test.go b/tui/model_layout_viewport_test.go
index a2d92911..92bbd37c 100644
--- a/tui/model_layout_viewport_test.go
+++ b/tui/model_layout_viewport_test.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/charmbracelet/bubbles/textarea"
 	"github.com/charmbracelet/bubbles/viewport"
+	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
 	xansi "github.com/charmbracelet/x/ansi"
 )
@@ -361,3 +362,41 @@ func TestConversationViewportBoundsByLayoutStartsAtPanelLeft(t *testing.T) {
 		t.Fatalf("expected viewport width %d from bounds, got %d", m.viewport.Width, right-left+1)
 	}
 }
+
+func TestChatViewHeightStaysWithinWindowWithTopRightClusterAfterScroll(t *testing.T) {
+	input := textarea.New()
+	input.Focus()
+	m := model{
+		screen:     screenChat,
+		width:      120,
+		height:     30,
+		input:      input,
+		viewport:   viewport.New(0, 0),
+		planView:   viewport.New(0, 0),
+		tokenUsage: newTokenUsageComponent(),
+		workspace:  `D:\happycoding\lzy1\bytemind`,
+	}
+	_ = m.tokenUsage.SetUsage(2345, 5000)
+	for i := 0; i < 24; i++ {
+		m.chatItems = append(m.chatItems, chatEntry{
+			Kind:   "assistant",
+			Title:  assistantLabel,
+			Body:   strings.Repeat("message ", 12),
+			Status: "final",
+		})
+	}
+
+	m.resize()
+	if got := lipgloss.Height(m.View()); got > m.height {
+		t.Fatalf("expected initial chat view height <= %d, got %d", m.height, got)
+	}
+
+	got, _ := m.handleMouse(tea.MouseMsg{
+		Button: tea.MouseButtonWheelUp,
+		Action: tea.MouseActionPress,
+	})
+	scrolled := got.(model)
+	if got := lipgloss.Height(scrolled.View()); got > scrolled.height {
+		t.Fatalf("expected scrolled chat view height <= %d, got %d", scrolled.height, got)
+	}
+}
diff --git a/tui/model_test.go b/tui/model_test.go
index e3d56fd3..bbbf0039 100644
--- a/tui/model_test.go
+++ b/tui/model_test.go
@@ -7997,7 +7997,7 @@ func TestFinishAssistantMessageFinalizesStreamingCardAfterPendingPlaceholder(t *
 	}
 }
 
-func TestFinishAssistantMessageDoesNotMoveFinalAnswerBeforeToolTail(t *testing.T) {
+func TestFinishAssistantMessageRemovesStaleStreamingBeforeToolTail(t *testing.T) {
 	m := model{
 		chatItems: []chatEntry{
 			{Kind: "assistant", Title: assistantLabel, Body: "old streamed text", Status: "streaming"},
@@ -8008,8 +8008,11 @@ func TestFinishAssistantMessageDoesNotMoveFinalAnswerBeforeToolTail(t *testing.T
 
 	m.finishAssistantMessage("final answer after tool")
 
-	if len(m.chatItems) != 3 {
-		t.Fatalf("expected final message after tool tail, got %d items", len(m.chatItems))
+	if len(m.chatItems) != 2 {
+		t.Fatalf("expected stale streaming card to be removed before appending final answer, got %d items", len(m.chatItems))
+	}
+	if m.chatItems[0].Kind != "tool" || m.chatItems[0].Status != "done" {
+		t.Fatalf("expected tool tail to remain before final answer, got %+v", m.chatItems[0])
 	}
 	last := m.chatItems[len(m.chatItems)-1]
 	if last.Kind != "assistant" || last.Status != "final" || last.Body != "final answer after tool" {