narration

How long after focus lands to speak an opening announcement, in seconds: the one piece of narration timing that cannot be event-driven. Every dialog and screen that announces itself on opening uses this; keep it the only copy.

Established on-device, one behavior at a time:

• The platform announces the focused button only when focus first enters the dialog. Moving between buttons afterwards is silent (TextButton extends Group, not Roku's Button, so the "text of button is spoken only if focused" rule never applies). Those moves are ours alone, and need no timing.
• That one initial announcement FLUSHES ours. Speaking from the focus observer, which is as early as any event lets us react, still loses: the platform speaks after us and we are cut off. Speaking before focus loses the same way. To survive we must speak AFTER the platform's announcement, and SceneGraph exposes no event for "the platform has finished dispatching speech". The only observable speech events are for utterances the app itself starts. So the opening announcement is the one place a delay is unavoidable.

Keep it short: long enough to land second, short enough to flush the platform's word before it is audible. At 0.6s the clipped word was clearly audible. Changing this needs an ear, not reasoning: there is no test that can catch it.