Queue UI output and status updates

uiterm/ui_regression_test.go

@@ -4,6 +4,24 @@ import "testing"
 
 // Regression: Close sent to a bounded channel and could block or enqueue
 // duplicate shutdowns when called more than once.
+// Regression: network callbacks modified terminal state directly. Post gives
+// them a bounded handoff to the UI-owning Run goroutine instead of blocking.
+func TestPostIsBoundedAndRejectsClosedUI(t *testing.T) {
+	ui := New(nil)
+	for i := 0; i < cap(ui.events); i++ {
+		if !ui.Post(func() {}) {
+			t.Fatal("queue filled too early")
+		}
+	}
+	if ui.Post(func() {}) {
+		t.Fatal("Post accepted work past queue capacity")
+	}
+	ui.Close()
+	if ui.Post(func() {}) {
+		t.Fatal("Post accepted work after close")
+	}
+}
+
 func TestCloseIsNonblockingAndIdempotent(t *testing.T) {
 	ui := New(nil)
 	ui.Close()