Fix: Clamp side pane titles to pane width

internal/tui/tui.go

@@ -710,15 +710,15 @@ func (m model) View() string {
 		}
 	}
 	oursPane := oursStyle.Render(
-		titleStyle.Render(oursTitle) + "\n" +
+		renderPaneTitle(oursTitle, m.viewportOurs.Width, titleStyle) + "\n" +
 			m.viewportOurs.View(),
 	)
 
 	resultStyle := resultUnresolvedPaneStyle
 	if allResolved(m.doc, m.manualResolved) {
 		resultStyle = resultResolvedPaneStyle
 	}
-	resultTitle := resultTitleStyle.Render("RESULT " + statusStyle.Render("("+statusText+")"))
+	resultTitle := renderResultPaneTitle(statusText, m.viewportResult.Width, resultTitleStyle, statusStyle)
 	resultPane := resultStyle.Render(
 		resultTitle + "\n" +
 			m.viewportResult.View(),
@@ -735,7 +735,7 @@ func (m model) View() string {
 		}
 	}
 	theirsPane := theirsStyle.Render(
-		titleStyle.Render(theirsTitle) + "\n" +
+		renderPaneTitle(theirsTitle, m.viewportTheirs.Width, titleStyle) + "\n" +
 			m.viewportTheirs.View(),
 	)
 
@@ -1233,6 +1233,83 @@ func formatLabel(label string) string {
 	return label
 }
 
+func renderPaneTitle(title string, paneWidth int, style lipgloss.Style) string {
+	if paneWidth <= 0 {
+		return ""
+	}
+
+	frameWidth := style.GetHorizontalFrameSize()
+	if paneWidth <= frameWidth {
+		return truncateDisplayWidth(title, paneWidth)
+	}
+
+	trimmed := truncateDisplayWidth(title, paneWidth-frameWidth)
+	return style.Render(trimmed)
+}
+
+func renderResultPaneTitle(statusText string, paneWidth int, titleStyle lipgloss.Style, statusStyle lipgloss.Style) string {
+	const prefix = "RESULT "
+	statusSegment := "(" + statusText + ")"
+	rawTitle := prefix + statusSegment
+
+	if paneWidth <= 0 {
+		return ""
+	}
+
+	frameWidth := titleStyle.GetHorizontalFrameSize()
+	if paneWidth <= frameWidth {
+		return truncateDisplayWidth(rawTitle, paneWidth)
+	}
+
+	trimmed := truncateDisplayWidth(rawTitle, paneWidth-frameWidth)
+	if !strings.HasPrefix(trimmed, prefix) {
+		return titleStyle.Render(trimmed)
+	}
+
+	trimmedStatus := strings.TrimPrefix(trimmed, prefix)
+	if trimmedStatus == "" {
+		return titleStyle.Render(prefix)
+	}
+
+	return titleStyle.Render(prefix + statusStyle.Render(trimmedStatus))
+}
+
+func truncateDisplayWidth(value string, maxWidth int) string {
+	if maxWidth <= 0 {
+		return ""
+	}
+	if lipgloss.Width(value) <= maxWidth {
+		return value
+	}
+
+	const ellipsis = "..."
+	ellipsisWidth := lipgloss.Width(ellipsis)
+	if maxWidth <= ellipsisWidth {
+		return trimDisplayWidth(value, maxWidth)
+	}
+
+	return trimDisplayWidth(value, maxWidth-ellipsisWidth) + ellipsis
+}
+
+func trimDisplayWidth(value string, maxWidth int) string {
+	if maxWidth <= 0 {
+		return ""
+	}
+
+	var b strings.Builder
+	currentWidth := 0
+	for _, r := range value {
+		runeWidth := lipgloss.Width(string(r))
+		if currentWidth+runeWidth > maxWidth {
+			break
+		}
+		b.WriteRune(r)
+		currentWidth += runeWidth
+	}
+
+	return b.String()
+}
+
 func firstHexRun(label string) (int, int) {
 	start := -1
 	for i, r := range label {

internal/tui/tui_test.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/charmbracelet/bubbles/viewport"
 	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
 	"github.com/chojs23/ec/internal/cli"
 	"github.com/chojs23/ec/internal/engine"
 	"github.com/chojs23/ec/internal/gitmerge"
@@ -412,6 +413,43 @@ func TestFormatLabel(t *testing.T) {
 	}
 }
 
+func TestRenderPaneTitleFitsPaneWidth(t *testing.T) {
+	title := "OURS (/var/folders/n5/10r8gvt52mq58dpz62c7_jt00000gn/T/ec-local-766054358)"
+	paneWidth := 34
+
+	got := renderPaneTitle(title, paneWidth, titleStyle)
+	if lipgloss.Width(got) > paneWidth {
+		t.Fatalf("renderPaneTitle width = %d, want <= %d", lipgloss.Width(got), paneWidth)
+	}
+	if !strings.Contains(got, "...") {
+		t.Fatalf("expected truncated title with ellipsis, got %q", got)
+	}
+}
+
+func TestRenderPaneTitleHandlesVeryNarrowPane(t *testing.T) {
+	got := renderPaneTitle("OURS (HEAD)", 1, titleStyle)
+	if lipgloss.Width(got) > 1 {
+		t.Fatalf("renderPaneTitle width = %d, want <= 1", lipgloss.Width(got))
+	}
+}
+
+func TestRenderResultPaneTitleFitsPaneWidth(t *testing.T) {
+	got := renderResultPaneTitle("Resolved (manual)", 18, resultTitleStyle, statusResolvedStyle)
+	if lipgloss.Width(got) > 18 {
+		t.Fatalf("renderResultPaneTitle width = %d, want <= 18", lipgloss.Width(got))
+	}
+	if !strings.Contains(got, "...") {
+		t.Fatalf("expected truncated title with ellipsis, got %q", got)
+	}
+}
+
+func TestRenderResultPaneTitleKeepsStatusWhenWide(t *testing.T) {
+	got := renderResultPaneTitle("Unresolved", 50, resultTitleStyle, statusUnresolvedStyle)
+	if !strings.Contains(got, "RESULT (Unresolved)") {
+		t.Fatalf("expected full result status title, got %q", got)
+	}
+}
+
 func TestFirstHexRun(t *testing.T) {
 	start, end := firstHexRun("x1234567y")
 	if start != 1 || end != 8 {
@@ -496,9 +534,9 @@ func TestModelViewReady(t *testing.T) {
 		currentConflict: 0,
 		selectedSide:    selectedOurs,
 		manualResolved:  map[int][]byte{},
-		viewportOurs:    viewport.New(10, 5),
-		viewportResult:  viewport.New(10, 5),
-		viewportTheirs:  viewport.New(10, 5),
+		viewportOurs:    viewport.New(40, 5),
+		viewportResult:  viewport.New(40, 5),
+		viewportTheirs:  viewport.New(40, 5),
 		width:           80,
 		height:          20,
 	}
@@ -530,9 +568,9 @@ func TestModelViewShowsBranchLabels(t *testing.T) {
 			{OursLabel: "HEAD", TheirsLabel: "feature/add-auth"},
 		},
 		manualResolved: map[int][]byte{},
-		viewportOurs:   viewport.New(10, 5),
-		viewportResult: viewport.New(10, 5),
-		viewportTheirs: viewport.New(10, 5),
+		viewportOurs:   viewport.New(40, 5),
+		viewportResult: viewport.New(40, 5),
+		viewportTheirs: viewport.New(40, 5),
 		width:          120,
 		height:         20,
 	}
@@ -547,6 +585,41 @@ func TestModelViewShowsBranchLabels(t *testing.T) {
 	}
 }
 
+func TestModelViewTruncatesLongBranchLabels(t *testing.T) {
+	doc := parseSingleConflictDoc(t)
+	state, err := engine.NewState(doc)
+	if err != nil {
+		t.Fatalf("NewState error = %v", err)
+	}
+	longLabel := "/var/folders/n5/10r8gvt52mq58dpz62c7_jt00000gn/T/ec-local-766054358"
+	m := model{
+		ready:           true,
+		opts:            cliOptionsWithMergedPath("merged.txt"),
+		state:           state,
+		doc:             doc,
+		currentConflict: 0,
+		selectedSide:    selectedOurs,
+		mergedLabels: []conflictLabels{
+			{OursLabel: longLabel, TheirsLabel: longLabel},
+		},
+		manualResolved: map[int][]byte{},
+		viewportOurs:   viewport.New(10, 5),
+		viewportResult: viewport.New(10, 5),
+		viewportTheirs: viewport.New(10, 5),
+		width:          90,
+		height:         20,
+	}
+	m.updateViewports()
+
+	view := m.View()
+	if strings.Contains(view, longLabel) {
+		t.Fatalf("expected long labels to be truncated, got:\n%s", view)
+	}
+	if !strings.Contains(view, "...") {
+		t.Fatalf("expected truncated labels with ellipsis, got:\n%s", view)
+	}
+}
+
 func TestModelViewNoLabelsWithoutMergedLabels(t *testing.T) {
 	doc := parseSingleConflictDoc(t)
 	state, err := engine.NewState(doc)