How does Nocturne's ability to be cast when seen interact with Promising Future's resolution?

Ruling: When you see Nocturne while resolving an effect like Promising Future, you fully resolve that effect first (including any spells from Promising Future). Then Nocturne's trigger allows you to cast it, and it goes on the chain as a permanent (which cannot be reacted to).

Sequence:

• Fully resolve the effect that allowed you to look at cards (including Promising Future spells)
• Nocturne's trigger occurs
• You may cast Nocturne for one power (only on empty chain)
• If you don't cast it, it stays where it was in your library

Nuances:

• The trigger happens when you see Nocturne, but it's unclear if you need to reveal it to your opponent
• There's ambiguity about whether opponents can know if you're missing the trigger to conceal information
• The exact timing relative to other similar effects (like new Teemo) remains unclear under current rules