fix(ui): remove double-render of expandedCellView in View()

Bugfix task (UUID d04dccbd): expandedCellView() was called once
unconditionally in the base JoinVertical and again inside the
cellExpanded guard, producing a duplicate expanded-cell line
whenever the user toggled cell expansion.

Fix: remove the unconditional call; expand only when cellExpanded is true.

Also corrected updateTableHeight() which still reserved an extra row
for the now-removed base expanded line (windowHeight-3 → windowHeight-2).

Added regression test TestExpandedCellViewNoDoubleRender that verifies
the expanded content is absent when cellExpanded is false and appears
exactly once when true.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

2 files changed, 48 insertions, 2 deletions

diff --git a/internal/ui/table.go b/internal/ui/table.go
index 7348dab..2cc2b3d 100644
--- a/internal/ui/table.go
+++ b/internal/ui/table.go
@@ -625,10 +625,12 @@ func (m Model) View() string {
 	if m.showTaskDetail {
 		return m.renderTaskDetail()
 	}
+	// expandedCellView is only appended when the user has toggled the
+	// expanded-cell panel open; including it unconditionally caused a
+	// double-render whenever cellExpanded was true.
 	view := lipgloss.JoinVertical(lipgloss.Left,
 		m.topStatusLine(),
 		m.tbl.View(),
-		m.expandedCellView(),
 		m.statusLine(),
 	)
 	if m.cellExpanded {
@@ -1208,7 +1210,7 @@ func (m *Model) updateTableHeight() {
 	if m.windowHeight == 0 {
 		return
 	}
-	h := m.windowHeight - 3 // space for two status bars and base expanded line
+	h := m.windowHeight - 2 // space for top and bottom status bars
 	if m.cellExpanded {
 		h--
 	}
diff --git a/internal/ui/table_test.go b/internal/ui/table_test.go
index 4e52842..63e1cf7 100644
--- a/internal/ui/table_test.go
+++ b/internal/ui/table_test.go
@@ -644,6 +644,50 @@ func TestEscClosesHelp(t *testing.T) {
 	}
 }
 
+// TestExpandedCellViewNoDoubleRender is a regression test for a bug where
+// expandedCellView() was appended to the layout unconditionally AND again
+// inside the cellExpanded guard, producing a duplicate line when expanded.
+// It verifies that:
+//   - when cellExpanded is false, expandedCellView content is absent from View()
+//   - when cellExpanded is true, expandedCellView content appears exactly once
+//   - the expanded content does not appear when expandedCellView returns ""
+func TestExpandedCellViewNoDoubleRender(t *testing.T) {
+	tmp := t.TempDir()
+	taskPath := setupBasicTask(t, tmp)
+	setupEnv(t, taskPath)
+
+	m, err := New(nil, "firefox")
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	// Give the model a non-zero window size so View() renders real content.
+	m.windowHeight = 24
+	mv, _ := (&m).Update(tea.WindowSizeMsg{Width: 120, Height: 24})
+	m = *mv.(*Model)
+
+	// Determine what expandedCellView() currently returns so we know what to
+	// search for in the full View() output.
+	expanded := m.expandedCellView()
+	if expanded == "" {
+		t.Skip("expandedCellView returned empty string; cannot test placement")
+	}
+
+	// With cellExpanded false (the default), the expanded content must be absent.
+	m.cellExpanded = false
+	viewCollapsed := m.View()
+	if strings.Contains(viewCollapsed, expanded) {
+		t.Fatalf("cellExpanded=false: expandedCellView content unexpectedly present in View()")
+	}
+
+	// With cellExpanded true, the expanded content must appear exactly once.
+	m.cellExpanded = true
+	viewExpanded := m.View()
+	count := strings.Count(viewExpanded, expanded)
+	if count != 1 {
+		t.Fatalf("cellExpanded=true: expandedCellView content appears %d times in View(), want exactly 1", count)
+	}
+}
+
 func TestSearchExitHotkeys(t *testing.T) {
 	tmp := t.TempDir()
 	taskPath := setupBasicTask(t, tmp)