Function TestPromptShrinksAfterSubmit

internal/tui/tui_test.go:2413–2430

TestPromptShrinksAfterSubmit: after Enter submits a multi-line prompt the textarea resets to empty and the height snaps back to 1 line.

(t *testing.T)

// newlines, and clamps to height - minViewport - 2 - popover, so big pastes use
// most of the screen while chat keeps its floor.
func TestPromptAutoGrowsWithContent(t *testing.T) {
	m := newTestModel(t, func(http.ResponseWriter, *http.Request) {})
	if m.ta.Height() != 1 {
		t.Fatalf("empty prompt should be 1 line, got %d", m.ta.Height())
	}

	m.ta.SetValue("line1\nline2\nline3\nline4")
	m.recomputeLayout()
	if got := m.ta.Height(); got != 4 {
		t.Fatalf("4 lines in textarea should produce height 4, got %d", got)
	}

	// Far past the cap, height must clamp to leave room for chat. With
	// newTestModel's 30-row terminal, cap = 30 - 5 - 2 - 0 = 23.
	m.ta.SetValue(strings.Repeat("x\n", 40) + "end")
	m.recomputeLayout()
	want := m.height - minViewport - 2
	if got := m.ta.Height(); got != want {
		t.Fatalf("height should clamp to %d (h=%d - minViewport=%d - chrome=2), got %d",
			want, m.height, minViewport, got)
	}