fix(tui): blank row under panel headers; no panel controls when Agents is the only panel

Every sidebar panel gets a header with a click-to-collapse chevron and a
click-to-zoom glyph; a one-row chip on the viewer line hides the whole
sidebar and brings it back from a narrow rail. Tab skips collapsed and
hidden panels, scrollbar hit zones follow the rendered bars, and
fillBackground also repaints after the bare ESC[m reset so no cell shows
the terminal background.

strix/interface/tui/internal/app/agents.go

@@ -209,8 +209,7 @@ func (m *Model) ensureAgentVisible() {
 		m.agentOffset = 0
 		return
 	}
-	_, _, _, agentHeight := m.sidebarHeights()
-	rows := max(1, agentHeight-4)
+	rows := m.agentPageSize()
 	row := selectedAgentRow(entries, m.selectedAgent)
 	if row < m.agentOffset {
 		m.agentOffset = row

strix/interface/tui/internal/app/mcp_test.go

@@ -27,11 +27,14 @@ func mcpModel(t *testing.T) Model {
 func TestMcpPanelShowsHealthyAndOffline(t *testing.T) {
 	m := mcpModel(t)
 	out := ansi.Strip(m.mcpConnectionsView(40, 6))
-	for _, want := range []string{"MCP Connections (2)", "supabase", "3 tools", "vercel", "offline"} {
+	for _, want := range []string{"supabase", "3 tools", "vercel", "offline"} {
 		if !strings.Contains(out, want) {
 			t.Fatalf("panel missing %q:\n%s", want, out)
 		}
 	}
+	if sidebar := ansi.Strip(m.sidebarView(26, 40)); !strings.Contains(sidebar, "MCP (2)") {
+		t.Fatalf("sidebar header did not carry the connection count:\n%s", sidebar)
+	}
 }
 
 // A roster longer than the panel height shows a window of rows rather than every
@@ -46,9 +49,8 @@ func TestMcpPanelWindowsLargeRosterAndCountsAll(t *testing.T) {
 	}
 	m.snapshot.Connections = conns
 
-	// rows = 6 → one header line + five roster rows.
 	out := ansi.Strip(m.mcpConnectionsView(40, 6))
-	if !strings.Contains(out, "MCP Connections (12)") {
+	if !strings.Contains(ansi.Strip(m.sidebarView(26, 40)), "MCP (12)") {
 		t.Fatalf("header did not carry the full connection count:\n%s", out)
 	}
 	if !strings.Contains(out, "conn-00") {
@@ -58,14 +60,13 @@ func TestMcpPanelWindowsLargeRosterAndCountsAll(t *testing.T) {
 		t.Fatalf("a roster past the panel height should be windowed, not fully drawn:\n%s", out)
 	}
 	if got := strings.Count(out, "\n") + 1; got != 6 {
-		t.Fatalf("panel rendered %d lines, want 6 (header + five rows)", got)
+		t.Fatalf("panel rendered %d lines, want 6", got)
 	}
 
-	// Scrolling the roster brings the tail into view while the header count holds.
-	m.mcpOffset = 7
+	m.mcpOffset = 6
 	scrolled := ansi.Strip(m.mcpConnectionsView(40, 6))
-	if !strings.Contains(scrolled, "conn-11") || !strings.Contains(scrolled, "MCP Connections (12)") {
-		t.Fatalf("scrolled window did not reveal the tail with the count intact:\n%s", scrolled)
+	if !strings.Contains(scrolled, "conn-11") {
+		t.Fatalf("scrolled window did not reveal the tail:\n%s", scrolled)
 	}
 }
 

strix/interface/tui/internal/app/model.go

@@ -100,6 +100,9 @@ type Model struct {
 	filtered               []string
 	cursor                 int
 	collapsedAgents        map[string]bool
+	collapsedPanels        map[sidebarPanel]bool
+	zoomedPanel            sidebarPanel
+	sidebarHidden          bool
 	expandedEvents         map[string]bool
 	blockCache             map[string]renderedBlock
 	eventSpans             []eventSpan
@@ -278,7 +281,7 @@ func New(client *Client) Model {
 	input.Focus()
 	return Model{
 		client: client, input: input, viewport: viewport.New(80, 20), vulnViewport: viewport.New(80, 20),
-		collapsedAgents: map[string]bool{}, expandedEvents: map[string]bool{}, blockCache: map[string]renderedBlock{}, showSplash: true, splashStarted: time.Now(), followOutput: true,
+		collapsedAgents: map[string]bool{}, collapsedPanels: map[sidebarPanel]bool{}, zoomedPanel: panelNone, expandedEvents: map[string]bool{}, blockCache: map[string]renderedBlock{}, showSplash: true, splashStarted: time.Now(), followOutput: true,
 		collectionRevisions: map[string]int{}, collectionAssemblies: map[string]*collectionAssembly{}, resyncRequested: map[string]bool{}, resyncRequests: map[string]string{},
 		seenMessages: map[string]bool{},
 	}

strix/interface/tui/internal/app/model_test.go

@@ -959,6 +959,17 @@ func TestFillBackgroundRestoresBaseForegroundAfterReset(t *testing.T) {
 	}
 }
 
+func TestFillBackgroundRestoresBaseColorsAfterBareReset(t *testing.T) {
+	view := "\x1b[38;2;115;115;115mModel\x1b[m   padding\x1b[0m"
+	filled := fillBackground(view)
+	if !strings.Contains(filled, "\x1b[m"+baseFrameColors+"   padding") {
+		t.Fatalf("base colors not restored after bare reset: %q", filled)
+	}
+	if strings.Contains(filled, "\x1b[m   ") {
+		t.Fatalf("cells after a bare reset show the terminal background: %q", filled)
+	}
+}
+
 func TestMainTraceTreeAndFindingsRenderScrollbars(t *testing.T) {
 	model := New(nil)
 	model.width, model.height = 150, 35

strix/interface/tui/internal/app/panels.go

@@ -0,0 +1,311 @@
+package app
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+type sidebarPanel int
+
+const (
+	panelNone sidebarPanel = iota - 1
+	panelAgents
+	panelFindings
+	panelMcp
+	panelStats
+)
+
+const (
+	panelOpenGlyph      = "▾"
+	panelCollapsedGlyph = "▸"
+	panelZoomGlyph      = "⤢"
+	panelUnzoomGlyph    = "⤡"
+	sidebarHideGlyph    = "»"
+	sidebarShowGlyph    = "«"
+	panelGlyphZone      = 3
+)
+
+type panelRect struct {
+	panel  sidebarPanel
+	top    int
+	height int
+}
+
+func (m Model) panelControls() bool {
+	return len(m.snapshot.Vulnerabilities) > 0 || len(m.snapshot.Connections) > 0
+}
+
+func (m Model) panelShrunk(panel sidebarPanel) bool {
+	if panel == panelStats || !m.panelControls() {
+		return false
+	}
+	return m.collapsedPanels[panel] || (m.zoomedPanel != panelNone && m.zoomedPanel != panel)
+}
+
+func (m Model) panelHeight(panel sidebarPanel, open int) int {
+	if m.panelShrunk(panel) {
+		return 1
+	}
+	return open
+}
+
+func panelFocus(panel sidebarPanel) (focusMode, bool) {
+	switch panel {
+	case panelAgents:
+		return focusAgents, true
+	case panelFindings:
+		return focusVulnerabilities, true
+	case panelMcp:
+		return focusMcp, true
+	default:
+		return focusInput, false
+	}
+}
+
+func (m Model) sidebarPanels() []panelRect {
+	statsHeight, vulnHeight, mcpHeight, agentHeight := m.sidebarHeights()
+	top := m.viewerHeight()
+	rects := []panelRect{{panelAgents, top, agentHeight}}
+	top += agentHeight
+	if vulnHeight > 0 {
+		rects = append(rects, panelRect{panelFindings, top, vulnHeight})
+		top += vulnHeight
+	}
+	if mcpHeight > 0 {
+		rects = append(rects, panelRect{panelMcp, top, mcpHeight})
+		top += mcpHeight
+	}
+	top += m.sidebarGap()
+	return append(rects, panelRect{panelStats, top, statsHeight})
+}
+
+func (m Model) sidebarGap() int {
+	statsHeight, vulnHeight, mcpHeight, agentHeight := m.sidebarHeights()
+	return max(0, m.height-m.viewerHeight()-agentHeight-vulnHeight-mcpHeight-statsHeight)
+}
+
+func (m Model) panelAt(y int) (panelRect, bool) {
+	for _, rect := range m.sidebarPanels() {
+		if y >= rect.top && y < rect.top+rect.height {
+			return rect, true
+		}
+	}
+	return panelRect{}, false
+}
+
+func (m Model) panelTop(panel sidebarPanel) int {
+	for _, rect := range m.sidebarPanels() {
+		if rect.panel == panel {
+			return rect.top
+		}
+	}
+	return 0
+}
+
+func (m Model) panelTitle(panel sidebarPanel) string {
+	switch panel {
+	case panelAgents:
+		return fmt.Sprintf("Agents (%d)", len(m.snapshot.Agents))
+	case panelFindings:
+		return fmt.Sprintf("Findings (%d)", len(m.snapshot.Vulnerabilities))
+	case panelMcp:
+		return fmt.Sprintf("MCP (%d)", len(m.snapshot.Connections))
+	default:
+		return m.snapshot.Model
+	}
+}
+
+func (m Model) panelHeader(panel sidebarPanel, width int) string {
+	style := lipgloss.NewStyle().Foreground(dim)
+	if !m.panelControls() {
+		return truncate(style.Render(m.panelTitle(panel)), max(1, width))
+	}
+	glyph := panelZoomGlyph
+	if m.zoomedPanel == panel {
+		glyph = panelUnzoomGlyph
+	}
+	label := truncate(style.Render(panelOpenGlyph+" "+m.panelTitle(panel)), max(1, width-2))
+	gap := max(1, width-lipgloss.Width(label)-1)
+	return label + strings.Repeat(" ", gap) + style.Render(glyph)
+}
+
+func (m Model) collapsedPanelRow(panel sidebarPanel, width int) string {
+	title := m.panelTitle(panel)
+	if panel != panelStats {
+		title = panelCollapsedGlyph + " " + title
+	}
+	label := lipgloss.NewStyle().Foreground(dim).Render(title)
+	return " " + truncate(label, max(1, width-1))
+}
+
+func (m Model) panelBox(panel sidebarPanel, body string, width, height int, focused bool) string {
+	if height <= 1 {
+		return m.collapsedPanelRow(panel, width)
+	}
+	border := dark
+	if focused {
+		border = green
+	}
+	content := body
+	if panel != panelStats {
+		content = m.panelHeader(panel, width-4)
+		if body != "" {
+			content += "\n\n" + body
+		}
+	}
+	return lipgloss.NewStyle().Width(width-2).Height(height-2).Border(lipgloss.RoundedBorder()).
+		BorderForeground(border).Padding(0, 1).Render(content)
+}
+
+const (
+	toggleButtonWidth = 3
+	railButtonWidth   = 5
+	railButtonHeight  = 3
+	sidebarRailWidth  = railButtonWidth + 1
+)
+
+var toggleButtonFill = lipgloss.Color("#262626")
+
+func sidebarToggleButton(glyph string) string {
+	return lipgloss.NewStyle().
+		Background(toggleButtonFill).
+		Foreground(brightWhite).
+		Bold(true).
+		Width(toggleButtonWidth).
+		Align(lipgloss.Center).
+		Render(glyph)
+}
+
+func (m Model) railVisible() bool {
+	return m.sidebarHidden && m.width >= 120
+}
+
+func (m Model) sidebarRail(height int) string {
+	button := lipgloss.NewStyle().
+		Background(toggleButtonFill).
+		Foreground(brightWhite).
+		Bold(true).
+		Width(railButtonWidth).
+		Height(railButtonHeight).
+		Align(lipgloss.Center, lipgloss.Center).
+		Render(sidebarShowGlyph)
+	return lipgloss.NewStyle().
+		Width(sidebarRailWidth).
+		Height(height).
+		Align(lipgloss.Right).
+		Render(button)
+}
+
+func (m Model) toggleButtonHit(x, y int) bool {
+	if m.railVisible() {
+		return y < railButtonHeight && x >= m.width-railButtonWidth
+	}
+	return y == 1 && x >= m.width-2-toggleButtonWidth && x < m.width-2
+}
+
+func (m Model) viewerBox(width int) string {
+	textWidth := max(1, width-toggleButtonWidth-1)
+	text := m.viewerView(textWidth)
+	rows := strings.Count(text, "\n") + 1
+	return lipgloss.JoinHorizontal(
+		lipgloss.Top,
+		fixedPanelBody(text, textWidth, rows),
+		" ",
+		sidebarToggleButton(sidebarHideGlyph),
+	)
+}
+
+func (m *Model) toggleSidebar() {
+	m.sidebarHidden = !m.sidebarHidden
+	m.resizeViewport()
+	m.panelsChanged()
+}
+
+func (m *Model) togglePanelCollapsed(panel sidebarPanel) {
+	if m.collapsedPanels[panel] {
+		delete(m.collapsedPanels, panel)
+	} else {
+		m.collapsedPanels[panel] = true
+		if m.zoomedPanel == panel {
+			m.zoomedPanel = panelNone
+		}
+	}
+	m.panelsChanged()
+}
+
+func (m *Model) togglePanelZoom(panel sidebarPanel) {
+	if m.zoomedPanel == panel {
+		m.zoomedPanel = panelNone
+	} else {
+		m.zoomedPanel = panel
+		delete(m.collapsedPanels, panel)
+	}
+	m.panelsChanged()
+}
+
+func (m *Model) revealPanel(panel sidebarPanel) {
+	delete(m.collapsedPanels, panel)
+	m.zoomedPanel = panelNone
+	m.panelsChanged()
+}
+
+func (m *Model) clickPanel(rect panelRect, x, y int) bool {
+	switch {
+	case rect.panel == panelStats || !m.panelControls():
+		return false
+	case rect.height <= 1 && !m.panelShrunk(rect.panel):
+		m.togglePanelZoom(rect.panel)
+	case rect.height <= 1:
+		m.revealPanel(rect.panel)
+	case y-rect.top != 1:
+		return false
+	case x >= m.width-2-panelGlyphZone:
+		m.togglePanelZoom(rect.panel)
+	default:
+		m.togglePanelCollapsed(rect.panel)
+	}
+	if focus, ok := panelFocus(rect.panel); ok && !m.panelShrunk(rect.panel) {
+		m.focus = focus
+		m.input.Blur()
+	}
+	return true
+}
+
+func (m *Model) panelsChanged() {
+	showSidebar, _, _, _ := m.layout()
+	for _, rect := range m.sidebarPanels() {
+		if focus, ok := panelFocus(rect.panel); ok && m.focus == focus && (!showSidebar || rect.height <= 1) {
+			m.focus = focusInput
+			m.input.Focus()
+		}
+	}
+	m.ensureAgentVisible()
+	totalRows, _ := m.vulnerabilityScrollRows()
+	m.vulnOffset = clampVulnerabilityOffset(m.vulnOffset, totalRows, m.vulnerabilityPageSize())
+	m.mcpOffset = m.clampMcpOffset(m.mcpOffset)
+}
+
+func (m *Model) scrollPanel(panel sidebarPanel, delta int) {
+	switch panel {
+	case panelAgents:
+		m.focus = focusAgents
+		m.input.Blur()
+		rows := m.agentPageSize()
+		total := len(agentTreeEntries(m.snapshot.Agents, m.collapsedAgents))
+		m.agentOffset = min(max(0, total-rows), max(0, m.agentOffset+delta))
+		m.keepAgentSelectionInWindow()
+		m.refreshViewport()
+	case panelFindings:
+		m.focus = focusVulnerabilities
+		m.input.Blur()
+		totalRows, _ := m.vulnerabilityScrollRows()
+		m.vulnOffset = min(max(0, totalRows-m.vulnerabilityPageSize()), max(0, m.vulnOffset+delta))
+		m.keepVulnerabilitySelectionInWindow()
+	case panelMcp:
+		m.focus = focusMcp
+		m.input.Blur()
+		m.mcpOffset = m.clampMcpOffset(m.mcpOffset + delta)
+	}
+}

strix/interface/tui/internal/app/panels_test.go

@@ -0,0 +1,357 @@
+package app
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+	"github.com/charmbracelet/x/ansi"
+	"github.com/usestrix/strix/tui/internal/protocol"
+)
+
+func panelsModel(t *testing.T) Model {
+	t.Helper()
+	m := New(nil)
+	m.width, m.height = 130, 40
+	m.showSplash = false
+	m.ready = true
+	root := "root"
+	agents := []protocol.Agent{{ID: root, Name: "Root Agent", Status: "running"}}
+	for i := 0; i < 30; i++ {
+		name := fmt.Sprintf("Worker %02d", i)
+		agents = append(agents, protocol.Agent{ID: name, Name: name, ParentID: &root, Status: "running"})
+	}
+	conns := make([]protocol.Connection, 0, 12)
+	for i := 0; i < 12; i++ {
+		conns = append(conns, protocol.Connection{Name: fmt.Sprintf("conn-%02d", i), ToolCount: 2})
+	}
+	url := "http://127.0.0.1:57388/?token=abc"
+	m.snapshot = protocol.Snapshot{
+		ScanStarted: true, ScanState: "running", Agents: agents, Connections: conns,
+		ViewerStatus: "running", ViewerURL: &url, Model: "openrouter/z-ai/glm-5.3",
+		Vulnerabilities: []map[string]any{{"id": "v1", "title": "Finding one", "severity": "high"}},
+	}
+	m.resizeViewport()
+	return m
+}
+
+func click(t *testing.T, m Model, x, y int) Model {
+	t.Helper()
+	updated, _ := m.updateMouse(tea.MouseMsg{X: x, Y: y, Button: tea.MouseButtonLeft, Action: tea.MouseActionPress})
+	return updated.(Model)
+}
+
+func panelRectOf(t *testing.T, m Model, panel sidebarPanel) panelRect {
+	t.Helper()
+	for _, rect := range m.sidebarPanels() {
+		if rect.panel == panel {
+			return rect
+		}
+	}
+	t.Fatalf("panel %d not in sidebar", panel)
+	return panelRect{}
+}
+
+func TestSidebarPanelsRenderHeadersWithControls(t *testing.T) {
+	m := panelsModel(t)
+	_, sidebarWidth, _, _ := m.layout()
+	view := ansi.Strip(m.sidebarView(sidebarWidth, m.height))
+	for _, want := range []string{"▾ Agents (31)", "▾ Findings (1)", "▾ MCP (12)", "⤢"} {
+		if !strings.Contains(view, want) {
+			t.Fatalf("sidebar missing %q:\n%s", want, view)
+		}
+	}
+	if strings.Contains(view, "⤡") {
+		t.Fatalf("nothing is zoomed, yet a restore glyph is drawn:\n%s", view)
+	}
+}
+
+func TestClickingPanelHeaderCollapsesAndExpands(t *testing.T) {
+	m := panelsModel(t)
+	_, _, chatWidth, _ := m.layout()
+	rect := panelRectOf(t, m, panelFindings)
+	before := panelRectOf(t, m, panelAgents).height
+
+	m = click(t, m, chatWidth+4, rect.top+1)
+	collapsed := panelRectOf(t, m, panelFindings)
+	if collapsed.height != 1 || !m.collapsedPanels[panelFindings] {
+		t.Fatalf("header click did not collapse the panel: %+v", collapsed)
+	}
+	if got := panelRectOf(t, m, panelAgents).height; got <= before {
+		t.Fatalf("agent panel did not grow into the freed rows: %d -> %d", before, got)
+	}
+	_, sidebarWidth, _, _ := m.layout()
+	view := ansi.Strip(m.sidebarView(sidebarWidth, m.height))
+	if !strings.Contains(view, "▸ Findings (1)") || strings.Contains(view, "Finding one") {
+		t.Fatalf("collapsed panel should be a one-line header without its rows:\n%s", view)
+	}
+
+	m = click(t, m, chatWidth+4, collapsed.top)
+	if panelRectOf(t, m, panelFindings).height == 1 || m.collapsedPanels[panelFindings] {
+		t.Fatalf("clicking the collapsed row did not expand the panel")
+	}
+	if m.focus != focusVulnerabilities {
+		t.Fatalf("expanded panel did not take focus: %v", m.focus)
+	}
+}
+
+func TestClickingZoomGlyphGivesPanelTheSidebar(t *testing.T) {
+	m := panelsModel(t)
+	_, sidebarWidth, chatWidth, _ := m.layout()
+	rect := panelRectOf(t, m, panelMcp)
+
+	m = click(t, m, m.width-3, rect.top+1)
+	if m.zoomedPanel != panelMcp {
+		t.Fatalf("zoom glyph click did not zoom the panel: %d", m.zoomedPanel)
+	}
+	for _, other := range []sidebarPanel{panelAgents, panelFindings} {
+		if got := panelRectOf(t, m, other).height; got != 1 {
+			t.Fatalf("panel %d should shrink to its header while another is zoomed, got %d", other, got)
+		}
+	}
+	zoomed := panelRectOf(t, m, panelMcp)
+	rects := m.sidebarPanels()
+	if last := rects[len(rects)-1]; last.top+last.height != m.height || zoomed.height < m.height-12 {
+		t.Fatalf("zoomed panel does not fill the sidebar: %+v screen=%d", rects, m.height)
+	}
+	view := ansi.Strip(m.sidebarView(sidebarWidth, m.height))
+	if !strings.Contains(view, "⤡") || !strings.Contains(view, "conn-11") {
+		t.Fatalf("zoomed roster should show every connection and the restore glyph:\n%s", view)
+	}
+	if m.focus != focusMcp {
+		t.Fatalf("zoomed panel did not take focus: %v", m.focus)
+	}
+
+	m = click(t, m, m.width-3, zoomed.top+1)
+	if m.zoomedPanel != panelNone || panelRectOf(t, m, panelAgents).height == 1 {
+		t.Fatalf("restore glyph did not unzoom")
+	}
+
+	m = click(t, m, m.width-3, panelRectOf(t, m, panelAgents).top+1)
+	m = click(t, m, chatWidth+4, panelRectOf(t, m, panelFindings).top)
+	if m.zoomedPanel != panelNone || m.collapsedPanels[panelFindings] {
+		t.Fatalf("clicking a shrunk row should restore the whole sidebar")
+	}
+}
+
+func TestToggleButtonsHideAndShowSidebar(t *testing.T) {
+	m := panelsModel(t)
+	m.focus = focusAgents
+	showSidebar, sidebarWidth, chatWidth, _ := m.layout()
+	if !showSidebar {
+		t.Fatalf("precondition: sidebar visible")
+	}
+	rows := strings.Split(ansi.Strip(m.sidebarView(sidebarWidth, m.height)), "\n")
+	if !strings.HasSuffix(rows[1], " »  │") || strings.Contains(rows[2], "»") {
+		t.Fatalf("viewer panel lacks the one-row hide button:\n%s", strings.Join(rows[:3], "\n"))
+	}
+	if strings.Contains(ansi.Strip(m.View()), "«") || strings.Contains(ansi.Strip(m.statusView(chatWidth)), "sidebar") {
+		t.Fatalf("show button or text hint drawn while the sidebar is visible")
+	}
+
+	m = click(t, m, m.width-4, 1)
+	if showSidebar, _, width, _ := m.layout(); showSidebar || width != m.width-sidebarRailWidth-1 {
+		t.Fatalf("hide button click did not hide the sidebar: show=%v chatWidth=%d", showSidebar, width)
+	}
+	if m.focus != focusInput {
+		t.Fatalf("focus stayed on a hidden panel: %v", m.focus)
+	}
+	frame := ansi.Strip(m.View())
+	rows = strings.Split(frame, "\n")
+	if !strings.HasSuffix(rows[1], "  «  ") || strings.Contains(rows[0], "«") || strings.Contains(rows[3], "«") || lipgloss.Width(rows[0]) != m.width {
+		t.Fatalf("hidden sidebar should leave a %d-row show button in the rail:\n%s", railButtonHeight, strings.Join(rows[:4], "\n"))
+	}
+	if !m.toggleButtonHit(m.width-railButtonWidth, railButtonHeight-1) || m.toggleButtonHit(m.width-railButtonWidth-1, 0) || m.toggleButtonHit(m.width-1, railButtonHeight) {
+		t.Fatalf("show button hit zone does not match the drawn button")
+	}
+	if strings.Contains(frame, "»") {
+		t.Fatalf("hide button drawn while the sidebar is hidden")
+	}
+
+	m = click(t, m, m.width-3, 2)
+	if showSidebar, _, _, _ := m.layout(); !showSidebar {
+		t.Fatalf("show button click did not bring the sidebar back")
+	}
+}
+
+func TestFocusCyclingSkipsShrunkPanels(t *testing.T) {
+	m := panelsModel(t)
+	m.collapsedPanels[panelFindings] = true
+	seen := map[focusMode]bool{}
+	for range 6 {
+		m.cycleFocus(1)
+		seen[m.focus] = true
+	}
+	if seen[focusVulnerabilities] || !seen[focusAgents] || !seen[focusMcp] {
+		t.Fatalf("tab order wrong with findings collapsed: %v", seen)
+	}
+
+	m.zoomedPanel = panelAgents
+	seen = map[focusMode]bool{}
+	for range 6 {
+		m.cycleFocus(1)
+		seen[m.focus] = true
+	}
+	if seen[focusMcp] || !seen[focusAgents] {
+		t.Fatalf("tab order wrong with agents zoomed: %v", seen)
+	}
+
+	m.sidebarHidden = true
+	seen = map[focusMode]bool{}
+	for range 4 {
+		m.cycleFocus(1)
+		seen[m.focus] = true
+	}
+	if seen[focusAgents] || len(seen) != 2 {
+		t.Fatalf("tab order should stay in the chat column with the sidebar hidden: %v", seen)
+	}
+}
+
+func TestScrollbarHitTestFollowsPanelState(t *testing.T) {
+	m := panelsModel(t)
+	showSidebar, _, chatWidth, chatHeight := m.layout()
+	agents := panelRectOf(t, m, panelAgents)
+	at := func(y int) scrollbarTarget {
+		return m.scrollbarAt(tea.MouseMsg{X: m.width - 3, Y: y}, showSidebar, chatWidth, chatHeight)
+	}
+	if at(agents.top+2) != scrollbarAgents {
+		t.Fatalf("overflowing agent tree should expose its scrollbar")
+	}
+	if at(agents.top+1) != scrollbarNone {
+		t.Fatalf("the header row is a control, not a scrollbar")
+	}
+	findings := panelRectOf(t, m, panelFindings)
+	if at(findings.top+2) != scrollbarNone {
+		t.Fatalf("a findings list that fits has no scrollbar to grab")
+	}
+
+	m.collapsedPanels[panelAgents] = true
+	agents = panelRectOf(t, m, panelAgents)
+	if agents.height != 1 || at(agents.top) != scrollbarNone {
+		t.Fatalf("collapsed panel still reports a scrollbar")
+	}
+}
+
+func TestSidebarFitsShortTerminal(t *testing.T) {
+	m := panelsModel(t)
+	m.height = 19
+	m.snapshot.Connections = m.snapshot.Connections[:1]
+	m.resizeViewport()
+	_, sidebarWidth, _, _ := m.layout()
+	rects := m.sidebarPanels()
+	last := rects[len(rects)-1]
+	if last.top+last.height > m.height {
+		t.Fatalf("panels run past the screen: %+v (height %d)", rects, m.height)
+	}
+	if got := lipgloss.Height(m.sidebarView(sidebarWidth, m.height)); got > m.height {
+		t.Fatalf("sidebar renders %d rows on a %d-row terminal", got, m.height)
+	}
+	squeezed := panelRectOf(t, m, panelMcp)
+	if squeezed.height != 1 {
+		t.Fatalf("expected the MCP panel squeezed to its header, got %+v", squeezed)
+	}
+	if last.panel != panelStats || last.height < 3 {
+		t.Fatalf("Model panel must keep its box on short terminals: %+v", last)
+	}
+	m = click(t, m, m.width-6, squeezed.top)
+	if m.zoomedPanel != panelMcp {
+		t.Fatalf("clicking a squeezed header should zoom it, zoomed=%v", m.zoomedPanel)
+	}
+}
+
+func TestModelPanelHasNoControlsAndNeverShrinks(t *testing.T) {
+	m := panelsModel(t)
+	_, sidebarWidth, _, _ := m.layout()
+	stats := panelRectOf(t, m, panelStats)
+	rows := strings.Split(ansi.Strip(m.sidebarView(sidebarWidth, m.height)), "\n")
+	if first := rows[stats.top+1]; strings.ContainsAny(first, "▾▸⤢⤡") || strings.Contains(first, "Model") || !strings.Contains(first, m.snapshot.Model[:8]) {
+		t.Fatalf("Model panel should start with the model name and carry no controls: %q", first)
+	}
+	before := m.sidebarPanels()
+	m = click(t, m, m.width-3, stats.top+1)
+	m = click(t, m, m.width-10, stats.top+1)
+	if m.zoomedPanel != panelNone || len(m.collapsedPanels) != 0 {
+		t.Fatalf("clicks on the Model header changed panel state: zoom=%v collapsed=%v", m.zoomedPanel, m.collapsedPanels)
+	}
+	m = click(t, m, m.width-3, panelRectOf(t, m, panelAgents).top+1)
+	if m.zoomedPanel != panelAgents {
+		t.Fatalf("precondition: agents zoomed")
+	}
+	after := panelRectOf(t, m, panelStats)
+	if after.height != before[len(before)-1].height {
+		t.Fatalf("Model panel shrank under zoom: %+v -> %+v", before[len(before)-1], after)
+	}
+}
+
+func TestModelPanelSticksToBottom(t *testing.T) {
+	m := panelsModel(t)
+	m = click(t, m, m.width-10, panelRectOf(t, m, panelAgents).top+1)
+	if !m.collapsedPanels[panelAgents] {
+		t.Fatalf("precondition: agents collapsed")
+	}
+	stats := panelRectOf(t, m, panelStats)
+	if stats.top+stats.height != m.height {
+		t.Fatalf("Model panel not at the bottom: %+v (height %d)", stats, m.height)
+	}
+	_, sidebarWidth, _, _ := m.layout()
+	rows := strings.Split(ansi.Strip(m.sidebarView(sidebarWidth, m.height)), "\n")
+	if len(rows) != m.height {
+		t.Fatalf("sidebar renders %d rows, want %d", len(rows), m.height)
+	}
+	if !strings.Contains(rows[stats.top+1], m.snapshot.Model[:8]) {
+		t.Fatalf("Model panel not where its rect says:\n%s", strings.Join(rows[stats.top-2:], "\n"))
+	}
+}
+
+func TestStatsPanelKeepsAssignedHeight(t *testing.T) {
+	m := panelsModel(t)
+	m.snapshot.Model = strings.Repeat("openrouter/some-vendor/a-very-long-model-name ", 12)
+	m.resizeViewport()
+	_, sidebarWidth, _, _ := m.layout()
+	statsHeight, _, _, _ := m.sidebarHeights()
+	if statsHeight != 15 {
+		t.Fatalf("stats panel should hit its cap, got %d", statsHeight)
+	}
+	if got := lipgloss.Height(m.sidebarView(sidebarWidth, m.height)); got != m.height {
+		t.Fatalf("sidebar renders %d rows, want %d", got, m.height)
+	}
+}
+
+func TestHeadersAreFollowedByABlankRow(t *testing.T) {
+	m := panelsModel(t)
+	_, sidebarWidth, _, _ := m.layout()
+	rows := strings.Split(ansi.Strip(m.sidebarView(sidebarWidth, m.height)), "\n")
+	for _, panel := range []sidebarPanel{panelAgents, panelFindings, panelMcp} {
+		rect := panelRectOf(t, m, panel)
+		header, blank, first := rows[rect.top+1], rows[rect.top+2], rows[rect.top+3]
+		if !strings.Contains(header, m.panelTitle(panel)) || strings.TrimSpace(strings.Trim(blank, "│")) != "" || strings.TrimSpace(strings.Trim(first, "│")) == "" {
+			t.Fatalf("panel %d should render header, blank row, content:\n%s", panel, strings.Join(rows[rect.top:rect.top+4], "\n"))
+		}
+	}
+}
+
+func TestLonePanelHasNoControls(t *testing.T) {
+	m := panelsModel(t)
+	m.snapshot.Vulnerabilities = nil
+	m.snapshot.Connections = nil
+	_, sidebarWidth, _, _ := m.layout()
+	view := ansi.Strip(m.sidebarView(sidebarWidth, m.height))
+	if strings.ContainsAny(view, "▾▸⤢⤡") || !strings.Contains(view, "Agents (31)") {
+		t.Fatalf("a lone Agents panel should carry no collapse or zoom controls:\n%s", view)
+	}
+	rect := panelRectOf(t, m, panelAgents)
+	m = click(t, m, m.width-3, rect.top+1)
+	m = click(t, m, m.width-10, rect.top+1)
+	if m.zoomedPanel != panelNone || len(m.collapsedPanels) != 0 || panelRectOf(t, m, panelAgents) != rect {
+		t.Fatalf("header clicks changed a lone panel: zoom=%v collapsed=%v", m.zoomedPanel, m.collapsedPanels)
+	}
+	if m.sidebarGap() != 0 {
+		t.Fatalf("lone Agents panel should take the spare rows, gap=%d", m.sidebarGap())
+	}
+	m.snapshot.Connections = panelsModel(t).snapshot.Connections
+	if !strings.Contains(ansi.Strip(m.sidebarView(sidebarWidth, m.height)), "▾ Agents (31)") {
+		t.Fatalf("controls should return once a second panel exists")
+	}
+}

strix/interface/tui/internal/app/setup.go

@@ -126,11 +126,14 @@ func (m Model) statusVisible() bool {
 }
 
 func (m Model) layout() (showSidebar bool, sidebarWidth, chatWidth, chatHeight int) {
-	showSidebar = m.width >= 120
-	if showSidebar {
+	showSidebar = m.width >= 120 && !m.sidebarHidden
+	switch {
+	case showSidebar:
 		sidebarWidth = max(24, m.width/5)
 		chatWidth = m.width - sidebarWidth - 1
-	} else {
+	case m.railVisible():
+		chatWidth = m.width - sidebarRailWidth - 1
+	default:
 		chatWidth = m.width
 	}
 	statusH := 0

strix/interface/tui/internal/app/update.go

@@ -162,12 +162,8 @@ func (m Model) updateMouse(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
 		return m.updateSetupMouse(msg)
 	}
 	showSidebar, _, chatWidth, chatHeight := m.layout()
-	viewerHeight := m.viewerHeight()
-	_, vulnHeight, mcpHeight, agentHeight := m.sidebarHeights()
 	x, y := msg.X, msg.Y
-	if m.updateMainScrollbarMouse(
-		msg, showSidebar, chatWidth, chatHeight, viewerHeight, agentHeight, vulnHeight, mcpHeight,
-	) {
+	if m.updateMainScrollbarMouse(msg, showSidebar, chatWidth, chatHeight) {
 		return m, nil
 	}
 	if m.selection.dragging {
@@ -198,24 +194,8 @@ func (m Model) updateMouse(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
 	switch msg.Button {
 	case tea.MouseButtonWheelUp:
 		if showSidebar && x >= chatWidth+1 {
-			switch {
-			case y < viewerHeight:
-				return m, nil
-			case y < viewerHeight+agentHeight:
-				m.focus = focusAgents
-				m.input.Blur()
-				m.agentOffset = max(0, m.agentOffset-3)
-				m.keepAgentSelectionInWindow()
-				m.refreshViewport()
-			case vulnHeight > 0 && y < viewerHeight+agentHeight+vulnHeight:
-				m.focus = focusVulnerabilities
-				m.input.Blur()
-				m.vulnOffset = max(0, m.vulnOffset-3)
-				m.keepVulnerabilitySelectionInWindow()
-			case mcpHeight > 0 && y < viewerHeight+agentHeight+vulnHeight+mcpHeight:
-				m.focus = focusMcp
-				m.input.Blur()
-				m.mcpOffset = m.clampMcpOffset(m.mcpOffset - 3)
+			if rect, ok := m.panelAt(y); ok && rect.height > 1 {
+				m.scrollPanel(rect.panel, -3)
 			}
 			return m, nil
 		}
@@ -226,26 +206,8 @@ func (m Model) updateMouse(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
 		return m, nil
 	case tea.MouseButtonWheelDown:
 		if showSidebar && x >= chatWidth+1 {
-			switch {
-			case y < viewerHeight:
-				return m, nil
-			case y < viewerHeight+agentHeight:
-				m.focus = focusAgents
-				m.input.Blur()
-				rows := m.agentPageSize()
-				m.agentOffset = min(max(0, len(agentTreeEntries(m.snapshot.Agents, m.collapsedAgents))-rows), m.agentOffset+3)
-				m.keepAgentSelectionInWindow()
-				m.refreshViewport()
-			case vulnHeight > 0 && y < viewerHeight+agentHeight+vulnHeight:
-				m.focus = focusVulnerabilities
-				m.input.Blur()
-				totalRows, _ := m.vulnerabilityScrollRows()
-				m.vulnOffset = min(max(0, totalRows-m.vulnerabilityPageSize()), m.vulnOffset+3)
-				m.keepVulnerabilitySelectionInWindow()
-			case mcpHeight > 0 && y < viewerHeight+agentHeight+vulnHeight+mcpHeight:
-				m.focus = focusMcp
-				m.input.Blur()
-				m.mcpOffset = m.clampMcpOffset(m.mcpOffset + 3)
+			if rect, ok := m.panelAt(y); ok && rect.height > 1 {
+				m.scrollPanel(rect.panel, 3)
 			}
 			return m, nil
 		}
@@ -288,21 +250,32 @@ func (m Model) updateMouse(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
 		return m, nil
 	}
 
-	if !showSidebar || x < chatWidth+1 {
+	if x < chatWidth+1 {
 		return m, nil
 	}
-	// Sidebar: viewer, agents, vulnerabilities, then stats.
-	switch {
-	case y < viewerHeight:
+	if m.toggleButtonHit(x, y) {
+		m.selection.active = false
+		m.toggleSidebar()
+		return m, nil
+	}
+	if !showSidebar {
+		return m, nil
+	}
+	if y < m.viewerHeight() {
 		return m, send(m.client, "viewer.open", map[string]any{})
-	case y < viewerHeight+agentHeight:
+	}
+	rect, ok := m.panelAt(y)
+	if !ok || m.clickPanel(rect, x, y) {
+		return m, nil
+	}
+	localY := y - rect.top
+	switch rect.panel {
+	case panelAgents:
 		m.focus = focusAgents
 		m.input.Blur()
-		// Content starts after the top border (1) and vertical padding (1).
 		entries := agentTreeEntries(m.snapshot.Agents, m.collapsedAgents)
-		start := windowStart(m.agentOffset, len(entries), max(1, agentHeight-4))
-		localY := y - viewerHeight
-		if row := start + localY - 2; localY >= 2 && localY < agentHeight-2 && row < len(entries) {
+		start := windowStart(m.agentOffset, len(entries), m.agentPageSize())
+		if row := start + localY - 2; localY >= 2 && localY < rect.height-1 && row < len(entries) {
 			m.selectedAgent = entries[row].index
 			agentID := m.snapshot.Agents[m.selectedAgent].ID
 			if hasAgentChildren(agentID, m.snapshot.Agents) {
@@ -311,24 +284,22 @@ func (m Model) updateMouse(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
 			}
 			m.refreshViewport()
 		}
-	case vulnHeight > 0 && y < viewerHeight+agentHeight+vulnHeight:
+	case panelFindings:
 		m.focus = focusVulnerabilities
 		m.input.Blur()
-		// Content starts after the top border (1); clicking a row opens its detail.
-		row := y - viewerHeight - agentHeight - 1
-		if idx := m.vulnerabilityIndexAtRow(row); row >= 0 && row < vulnHeight-2 && idx >= 0 {
+		row := localY - 2
+		if idx := m.vulnerabilityIndexAtRow(row); row >= 0 && row < rect.height-3 && idx >= 0 {
 			m.selectedVuln = idx
 			m.openModal(modalVulnerability)
 		}
+	case panelMcp:
+		m.focus = focusMcp
+		m.input.Blur()
 	}
 	return m, nil
 }
 
-func (m *Model) updateMainScrollbarMouse(
-	msg tea.MouseMsg,
-	showSidebar bool,
-	chatWidth, chatHeight, viewerHeight, agentHeight, vulnHeight, mcpHeight int,
-) bool {
+func (m *Model) updateMainScrollbarMouse(msg tea.MouseMsg, showSidebar bool, chatWidth, chatHeight int) bool {
 	if msg.Action == tea.MouseActionRelease {
 		if m.draggingScrollbar == scrollbarNone {
 			return false
@@ -337,18 +308,18 @@ func (m *Model) updateMainScrollbarMouse(
 		return true
 	}
 	if msg.Action == tea.MouseActionMotion && m.draggingScrollbar != scrollbarNone {
-		m.scrollFromMouse(m.draggingScrollbar, msg.Y, chatHeight, viewerHeight, agentHeight, vulnHeight)
+		m.scrollFromMouse(m.draggingScrollbar, msg.Y, chatHeight)
 		return true
 	}
 	if msg.Action != tea.MouseActionPress || msg.Button != tea.MouseButtonLeft {
 		return false
 	}
-	target := m.scrollbarAt(msg, showSidebar, chatWidth, chatHeight, viewerHeight, agentHeight, vulnHeight, mcpHeight)
+	target := m.scrollbarAt(msg, showSidebar, chatWidth, chatHeight)
 	if target == scrollbarNone {
 		return false
 	}
 	m.draggingScrollbar = target
-	m.scrollFromMouse(target, msg.Y, chatHeight, viewerHeight, agentHeight, vulnHeight)
+	m.scrollFromMouse(target, msg.Y, chatHeight)
 	return true
 }
 
@@ -361,32 +332,28 @@ func nearColumn(x, column int) bool {
 	return x >= column-scrollbarGrab && x <= column+scrollbarGrab
 }
 
-// scrollbarAt reports which scrollbar, if any, the pointer is over.
-func (m Model) scrollbarAt(
-	msg tea.MouseMsg,
-	showSidebar bool,
-	chatWidth, chatHeight, viewerHeight, agentHeight, vulnHeight, mcpHeight int,
-) scrollbarTarget {
-	mcpTop := viewerHeight + agentHeight + vulnHeight
-	switch {
-	case nearColumn(msg.X, chatWidth-2) && msg.Y >= 1 && msg.Y < chatHeight-1 &&
-		m.viewport.TotalLineCount() > m.viewport.VisibleLineCount():
+func (m Model) scrollbarAt(msg tea.MouseMsg, showSidebar bool, chatWidth, chatHeight int) scrollbarTarget {
+	if nearColumn(msg.X, chatWidth-2) && msg.Y >= 1 && msg.Y < chatHeight-1 &&
+		m.viewport.TotalLineCount() > m.viewport.VisibleLineCount() {
 		return scrollbarTrace
-	case showSidebar && nearColumn(msg.X, m.width-3) && msg.Y >= viewerHeight+2 &&
-		msg.Y < viewerHeight+agentHeight-2 &&
-		len(agentTreeEntries(m.snapshot.Agents, m.collapsedAgents)) > m.agentPageSize():
-		return scrollbarAgents
-	case showSidebar && vulnHeight > 0 && nearColumn(msg.X, m.width-3) &&
-		msg.Y >= viewerHeight+agentHeight+1 &&
-		msg.Y < viewerHeight+agentHeight+vulnHeight-1:
-		totalRows, _ := m.vulnerabilityScrollRows()
-		if totalRows > m.vulnerabilityPageSize() {
+	}
+	if !showSidebar || !nearColumn(msg.X, m.width-3) {
+		return scrollbarNone
+	}
+	rect, ok := m.panelAt(msg.Y)
+	if !ok || rect.height <= 1 || msg.Y < rect.top+2 || msg.Y >= rect.top+rect.height-1 {
+		return scrollbarNone
+	}
+	switch rect.panel {
+	case panelAgents:
+		if len(agentTreeEntries(m.snapshot.Agents, m.collapsedAgents)) > m.agentPageSize() {
+			return scrollbarAgents
+		}
+	case panelFindings:
+		if totalRows, _ := m.vulnerabilityScrollRows(); totalRows > m.vulnerabilityPageSize() {
 			return scrollbarFindings
 		}
-	// The roster scrolls below a fixed header, so its bar starts two rows into
-	// the panel (border then header) rather than one.
-	case showSidebar && mcpHeight > 0 && nearColumn(msg.X, m.width-3) &&
-		msg.Y >= mcpTop+2 && msg.Y < mcpTop+mcpHeight-1:
+	case panelMcp:
 		if len(m.snapshot.Connections) > m.mcpPageSize() {
 			return scrollbarMcp
 		}
@@ -394,10 +361,7 @@ func (m Model) scrollbarAt(
 	return scrollbarNone
 }
 
-func (m *Model) scrollFromMouse(
-	target scrollbarTarget,
-	y, chatHeight, viewerHeight, agentHeight, vulnHeight int,
-) {
+func (m *Model) scrollFromMouse(target scrollbarTarget, y, chatHeight int) {
 	switch target {
 	case scrollbarTrace:
 		height := max(1, chatHeight-2)
@@ -411,7 +375,7 @@ func (m *Model) scrollFromMouse(
 		total := len(agentTreeEntries(m.snapshot.Agents, m.collapsedAgents))
 		m.focus = focusAgents
 		m.input.Blur()
-		m.agentOffset = scrollbarOffset(y-viewerHeight-2, height, total, height)
+		m.agentOffset = scrollbarOffset(y-m.panelTop(panelAgents)-2, height, total, height)
 		m.keepAgentSelectionInWindow()
 		m.refreshViewport()
 	case scrollbarFindings:
@@ -420,15 +384,14 @@ func (m *Model) scrollFromMouse(
 		m.focus = focusVulnerabilities
 		m.input.Blur()
 		// The offset is a row, so dragging moves the list continuously.
-		m.vulnOffset = scrollbarOffset(y-viewerHeight-agentHeight-1, height, totalRows, height)
+		m.vulnOffset = scrollbarOffset(y-m.panelTop(panelFindings)-2, height, totalRows, height)
 		m.keepVulnerabilitySelectionInWindow()
 	case scrollbarMcp:
 		height := m.mcpPageSize()
 		total := len(m.snapshot.Connections)
 		m.focus = focusMcp
 		m.input.Blur()
-		// The bar starts two rows into the panel (border then the fixed header).
-		m.mcpOffset = scrollbarOffset(y-viewerHeight-agentHeight-vulnHeight-2, height, total, height)
+		m.mcpOffset = scrollbarOffset(y-m.panelTop(panelMcp)-2, height, total, height)
 	}
 }
 
@@ -579,13 +542,11 @@ func labelHitAt(panel, label string, left, top, x, y int) bool {
 
 func (m *Model) cycleFocus(delta int) {
 	available := []focusMode{focusInput, focusChat}
-	if m.width >= 120 {
-		available = append(available, focusAgents)
-		if len(m.snapshot.Vulnerabilities) > 0 {
-			available = append(available, focusVulnerabilities)
-		}
-		if len(m.snapshot.Connections) > 0 {
-			available = append(available, focusMcp)
+	if showSidebar, _, _, _ := m.layout(); showSidebar {
+		for _, rect := range m.sidebarPanels() {
+			if focus, ok := panelFocus(rect.panel); ok && rect.height > 1 {
+				available = append(available, focus)
+			}
 		}
 	}
 	idx := 0

strix/interface/tui/internal/app/view.go

@@ -387,10 +387,11 @@ const (
 
 // fillBackground paints the whole frame black like Textual's Screen background.
 // Bubble Tea has no screen compositor, so any cell the view does not explicitly
-// color shows the terminal's default background. lipgloss emits a full reset
-// (\x1b[0m) at the end of every styled span, which clears both foreground and
-// background. Reasserting only black made uncolored and faint text inherit the
-// terminal profile's foreground; light profiles therefore rendered that text
+// color shows the terminal's default background. lipgloss emits a reset
+// (\x1b[0m, or the bare \x1b[m that x/ansi uses) at the end of every styled
+// span, which clears both foreground and background. Reasserting only black
+// made uncolored and faint text inherit the terminal profile's foreground;
+// light profiles therefore rendered that text
 // black-on-black. Reapply both base colors after each reset (and at the start).
 // Spans that set their own colors — inline code, selected rows, buttons — keep
 // them, because their color is emitted after the base style.
@@ -398,9 +399,14 @@ func fillBackground(view string) string {
 	if view == "" {
 		return view
 	}
-	return baseFrameColors + strings.ReplaceAll(view, "\x1b[0m", "\x1b[0m"+baseFrameColors)
+	return baseFrameColors + baseColorRestorer.Replace(view)
 }
 
+var baseColorRestorer = strings.NewReplacer(
+	"\x1b[0m", "\x1b[0m"+baseFrameColors,
+	"\x1b[m", "\x1b[m"+baseFrameColors,
+)
+
 func (m Model) splashView() string {
 	shine := "Starting Strix Agent"
 	chars := []rune(shine)
@@ -516,6 +522,8 @@ func (m Model) mainView() string {
 	body := leftColumn
 	if showSidebar {
 		body = lipgloss.JoinHorizontal(lipgloss.Top, leftColumn, " ", m.sidebarView(sidebarWidth, m.height))
+	} else if m.railVisible() {
+		body = lipgloss.JoinHorizontal(lipgloss.Top, leftColumn, " ", m.sidebarRail(m.height))
 	}
 	return lipgloss.NewStyle().Background(black).Foreground(textColor).Render(body)
 }
@@ -526,75 +534,108 @@ func (m Model) mainView() string {
 // and so never applied - honoring it made the outline vanish on the one panel
 // that had just become active.
 func (m Model) sidebarView(width, height int) string {
-	// Stats box height fits its content (auto, max 15); vulns panel max-height 12.
-	statsBody := m.statsView()
 	statsHeight, vulnHeight, mcpHeight, agentHeight := m.sidebarHeights()
-	agentBorder := dark
-	if m.focus == focusAgents {
-		agentBorder = green
-	}
-	// #agents_tree padding: 1 (all sides); interior lines = box - border - v.padding.
-	agentRows := max(1, agentHeight-4)
-	agentEntries := agentTreeEntries(m.snapshot.Agents, m.collapsedAgents)
-	agents := withVerticalScrollbar(
-		m.agentsView(max(1, width-5), agentRows),
-		width-4,
-		agentRows,
-		len(agentEntries),
-		agentRows,
-		m.agentOffset,
-		m.scrollbarThumb(scrollbarAgents),
-	)
-	parts := []string{
-		lipgloss.NewStyle().Width(width-2).Height(m.viewerHeight()-2).Border(lipgloss.RoundedBorder()).BorderForeground(dark).Padding(0, 1).Render(m.viewerView(width - 4)),
-		lipgloss.NewStyle().Width(width-2).Height(agentHeight-2).Border(lipgloss.RoundedBorder()).BorderForeground(agentBorder).Padding(1, 1).Render(agents),
-	}
-	if vulnHeight > 0 {
-		vulnBorder := dark
-		if m.focus == focusVulnerabilities {
-			vulnBorder = green
-		}
-		vulnRows := max(1, vulnHeight-2)
-		totalRows, offsetRows := m.vulnerabilityScrollRows()
-		findings := withVerticalScrollbar(
-			m.vulnerabilitiesView(m.vulnerabilityListWidth(), vulnRows),
+	parts := []string{lipgloss.NewStyle().
+		Width(width-2).
+		Height(m.viewerHeight()-2).
+		Border(lipgloss.RoundedBorder()).
+		BorderForeground(dark).
+		Padding(0, 1).
+		Render(m.viewerBox(width - 4))}
+	agents := ""
+	if agentHeight > 1 {
+		agentRows := max(1, agentHeight-4)
+		agents = withVerticalScrollbar(
+			m.agentsView(max(1, width-5), agentRows),
 			width-4,
-			vulnRows,
-			totalRows,
-			vulnRows,
-			offsetRows,
-			m.scrollbarThumb(scrollbarFindings),
+			agentRows,
+			len(agentTreeEntries(m.snapshot.Agents, m.collapsedAgents)),
+			agentRows,
+			m.agentOffset,
+			m.scrollbarThumb(scrollbarAgents),
 		)
-		parts = append(parts, lipgloss.NewStyle().Width(width-2).Height(vulnRows).Border(lipgloss.RoundedBorder()).BorderForeground(vulnBorder).Padding(0, 1).Render(findings))
+	}
+	parts = append(parts, m.panelBox(panelAgents, agents, width, agentHeight, m.focus == focusAgents))
+	if vulnHeight > 0 {
+		findings := ""
+		if vulnHeight > 1 {
+			vulnRows := max(1, vulnHeight-4)
+			totalRows, offsetRows := m.vulnerabilityScrollRows()
+			findings = withVerticalScrollbar(
+				m.vulnerabilitiesView(m.vulnerabilityListWidth(), vulnRows),
+				width-4,
+				vulnRows,
+				totalRows,
+				vulnRows,
+				offsetRows,
+				m.scrollbarThumb(scrollbarFindings),
+			)
+		}
+		parts = append(parts, m.panelBox(panelFindings, findings, width, vulnHeight, m.focus == focusVulnerabilities))
 	}
 	if mcpHeight > 0 {
-		mcpBorder := dark
-		if m.focus == focusMcp {
-			mcpBorder = green
+		roster := ""
+		if mcpHeight > 1 {
+			roster = m.mcpConnectionsView(width-4, max(1, mcpHeight-4))
 		}
-		mcpRows := max(1, mcpHeight-2)
-		parts = append(parts, lipgloss.NewStyle().Width(width-2).Height(mcpRows).Border(lipgloss.RoundedBorder()).BorderForeground(mcpBorder).Padding(0, 1).Render(m.mcpConnectionsView(width-4, mcpRows)))
+		parts = append(parts, m.panelBox(panelMcp, roster, width, mcpHeight, m.focus == focusMcp))
 	}
-	parts = append(parts, lipgloss.NewStyle().Width(width-2).Height(statsHeight-2).Border(lipgloss.RoundedBorder()).BorderForeground(dark).Padding(0, 1).Render(statsBody))
-	return strings.Join(parts, "\n")
+	if gap := m.sidebarGap(); gap > 0 {
+		parts = append(parts, lipgloss.NewStyle().Width(width).Height(gap).Render(""))
+	}
+	stats := ""
+	if statsHeight > 1 {
+		stats = fixedPanelBody(lipgloss.NewStyle().Width(width-4).Render(m.statsView()), width-4, statsHeight-2)
+	}
+	parts = append(parts, m.panelBox(panelStats, stats, width, statsHeight, false))
+	return lipgloss.JoinVertical(lipgloss.Left, parts...)
 }
 
 func (m Model) sidebarHeights() (statsHeight, vulnHeight, mcpHeight, agentHeight int) {
 	// Measure the stats panel the way its box will render it: a long model name
 	// wraps inside the sidebar, and counting only its newlines would size the
 	// box short and push the whole frame past the bottom of the terminal.
-	statsRows := lipgloss.Height(lipgloss.NewStyle().Width(m.viewerContentWidth()).Render(m.statsView()))
-	statsHeight = min(15, statsRows+2)
+	statsRows := lipgloss.Height(lipgloss.NewStyle().Width(m.sidebarInnerWidth()).Render(m.statsView()))
+	statsHeight = m.panelHeight(panelStats, min(15, statsRows+2))
 	if len(m.snapshot.Vulnerabilities) > 0 {
-		vulnHeight = min(12, len(m.vulnerabilityRows(m.vulnerabilityListWidth()))+2)
+		vulnHeight = m.panelHeight(panelFindings, min(13, len(m.vulnerabilityRows(m.vulnerabilityListWidth()))+4))
 	}
-	// One header line + one line per connection + the box border (2). Capped so a
+	// Header line + one line per connection + the box border (2). Capped so a
 	// long roster cannot crowd out the agent tree; a roster past the cap scrolls
 	// inside the panel. Absent entirely when the run has no MCP connections.
 	if len(m.snapshot.Connections) > 0 {
-		mcpHeight = min(9, len(m.snapshot.Connections)+3)
+		mcpHeight = m.panelHeight(panelMcp, min(10, len(m.snapshot.Connections)+4))
+	}
+	agentHeight = m.panelHeight(panelAgents, 5)
+	for _, p := range []struct {
+		h     *int
+		floor int
+	}{{&statsHeight, 4}, {&mcpHeight, 5}, {&vulnHeight, 5}} {
+		over := m.viewerHeight() + statsHeight + vulnHeight + mcpHeight + agentHeight - m.height
+		if over <= 0 {
+			break
+		}
+		if *p.h > p.floor {
+			*p.h -= min(over, *p.h-p.floor)
+		}
+	}
+	for _, h := range []*int{&mcpHeight, &vulnHeight, &statsHeight} {
+		if m.viewerHeight()+statsHeight+vulnHeight+mcpHeight+agentHeight <= m.height {
+			break
+		}
+		if *h > 1 {
+			*h = 1
+		}
+	}
+	spare := max(0, m.height-m.viewerHeight()-statsHeight-vulnHeight-mcpHeight-agentHeight)
+	switch {
+	case m.zoomedPanel == panelFindings && vulnHeight > 1:
+		vulnHeight += spare
+	case m.zoomedPanel == panelMcp && mcpHeight > 1:
+		mcpHeight += spare
+	case agentHeight > 1:
+		agentHeight += spare
 	}
-	agentHeight = max(3, m.height-m.viewerHeight()-statsHeight-vulnHeight-mcpHeight)
 	return
 }
 
@@ -602,7 +643,7 @@ func (m Model) viewerHeight() int {
 	return strings.Count(m.viewerView(m.viewerContentWidth()), "\n") + 3
 }
 
-func (m Model) viewerContentWidth() int {
+func (m Model) sidebarInnerWidth() int {
 	_, sidebarWidth, _, _ := m.layout()
 	if sidebarWidth == 0 {
 		sidebarWidth = 24
@@ -610,6 +651,10 @@ func (m Model) viewerContentWidth() int {
 	return max(1, sidebarWidth-4)
 }
 
+func (m Model) viewerContentWidth() int {
+	return max(1, m.sidebarInnerWidth()-toggleButtonWidth-1)
+}
+
 func (m Model) viewerView(width int) string {
 	switch m.snapshot.ViewerStatus {
 	case "running":
@@ -662,29 +707,22 @@ func (m Model) statsView() string {
 	return b.String()
 }
 
-// mcpConnectionsView renders the sidebar MCP panel: a header carrying the total
-// connection count, then one row per connection with a status glyph and its tool
-// count (or "offline").
+// mcpConnectionsView renders the sidebar MCP roster: one row per connection with
+// a status glyph and its tool count (or "offline").
 //   - a solid green dot marks an attached, idle connection;
 //   - a green cycling quarter-circle (◐ ◓ ◑ ◒) marks a call running against it;
 //   - a red dot plus "offline" marks a connection whose live session has died.
 //
-// The header stays fixed while the roster below it scrolls: when there are more
-// connections than the panel can show, the visible window is chosen by
-// m.mcpOffset and withVerticalScrollbar draws a thumb in the reserved last
-// column, exactly as the agent tree and findings list scroll.
+// When there are more connections than the panel can show, the visible window
+// is chosen by m.mcpOffset and withVerticalScrollbar draws a thumb in the
+// reserved last column, exactly as the agent tree and findings list scroll.
 //
 // "In use" is derived from the connection-tagged tool-call events in the stream,
 // not carried on the connection roster, so a call in flight shows motion without
 // any extra backend signal. The quarter-circle rides the shared sweepFrame tick.
 func (m Model) mcpConnectionsView(width, rows int) string {
 	conns := m.snapshot.Connections
-	header := truncate(lipgloss.NewStyle().Foreground(dim).Render(
-		fmt.Sprintf("MCP Connections (%d)", len(conns))), width)
-	bodyRows := max(0, rows-1)
-	if bodyRows == 0 {
-		return header
-	}
+	bodyRows := max(1, rows)
 	inUse := m.mcpInUse()
 	frames := []rune{'◐', '◓', '◑', '◒'}
 	// Reserve the scrollbar column whether or not the bar is showing, so the
@@ -721,7 +759,7 @@ func (m Model) mcpConnectionsView(width, rows int) string {
 		m.mcpOffset,
 		m.scrollbarThumb(scrollbarMcp),
 	)
-	return header + "\n" + roster
+	return roster
 }
 
 // mcpPageSize is how many connection rows the roster shows at once, below its

strix/interface/tui/internal/app/vulnerabilities.go

@@ -135,7 +135,7 @@ func clampVulnerabilityOffset(offset, total, height int) int {
 
 func (m Model) vulnerabilityPageSize() int {
 	_, vulnHeight, _, _ := m.sidebarHeights()
-	return max(1, vulnHeight-2)
+	return max(1, vulnHeight-4)
 }
 
 // vulnerabilityPageItems is how many findings a page step should move by: the
@@ -192,7 +192,7 @@ func (m Model) modalView() string {
 	switch m.modal {
 	case modalHelp:
 		title := lipgloss.NewStyle().Bold(true).Foreground(green).Width(34).Align(lipgloss.Center).Render("Strix Help")
-		body := lipgloss.NewStyle().Foreground(textColor).Render("F1        Help\nCtrl+O    Open viewer\nCtrl+Q/C  Quit\nESC       Stop Agent\nEnter     Send / expand node\nCtrl+J    Newline in message\nTab       Switch panels\n↑/↓       Navigate tree\nDrag      Select & copy text\nClick     Expand/collapse tool")
+		body := lipgloss.NewStyle().Foreground(textColor).Render("F1        Help\nCtrl+O    Open viewer\nCtrl+Q/C  Quit\nESC       Stop Agent\nEnter     Send / expand node\nCtrl+J    Newline in message\nTab       Switch panels\n↑/↓       Navigate tree\nDrag      Select & copy text\nClick     Expand/collapse tool\nClick ▾/⤢ Collapse / zoom panel\nClick »/« Hide / show sidebar")
 		content := title + "\n\n" + body
 		return lipgloss.NewStyle().Width(38).Border(lipgloss.RoundedBorder()).BorderForeground(green).Background(black).Padding(1, 2).Render(content)
 	case modalQuit: