diff --git a/internal/tui/turn_viewport.go b/internal/tui/turn_viewport.go
index 3c18f1c..7dd7b56 100644
--- a/internal/tui/turn_viewport.go
+++ b/internal/tui/turn_viewport.go
@@ -236,6 +236,11 @@ func (m turnViewportModel) updateKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 		m.cursor = 0
 	case tea.KeyEnd:
 		m.cursor = len(m.text)
+	case tea.KeySpace:
+		m.text = append(m.text, 0)
+		copy(m.text[m.cursor+1:], m.text[m.cursor:])
+		m.text[m.cursor] = ' '
+		m.cursor++
 	case tea.KeyRunes:
 		if msg.Alt && len(msg.Runes) == 1 {
 			switch msg.Runes[0] {
diff --git a/internal/tui/turn_viewport_test.go b/internal/tui/turn_viewport_test.go
index 0035559..0c6f421 100644
--- a/internal/tui/turn_viewport_test.go
+++ b/internal/tui/turn_viewport_test.go
@@ -93,6 +93,18 @@ func TestTurnViewportEditingMatchesMainInput(t *testing.T) {
 	}
 }
 
+func TestTurnViewportInsertsSpaceKey(t *testing.T) {
+	m := newTurnViewportModel("qmax > ", nil, nil)
+	m.text = []rune("hello")
+	m.cursor = len(m.text)
+	m, _ = updateTurnViewport(t, m, tea.KeyMsg{Type: tea.KeySpace})
+	m, _ = updateTurnViewport(t, m, tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune("world")})
+
+	if got, want := string(m.text), "hello world"; got != want {
+		t.Fatalf("text = %q, want %q (space key was dropped)", got, want)
+	}
+}
+
 func TestTurnViewportPreservesDraftWhenTurnFinishes(t *testing.T) {
 	m := newTurnViewportModel("qmax > ", nil, nil)
 	m, _ = updateTurnViewport(t, m, tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune("follow up")})