The same four-line pattern appeared in five places. I stared at the odd one out — the instance where the variation went somewhere I hadn't predicted. Then I saw what it was saying: the parameter I'd been about to extract wasn't a parameter, it was a policy. The common shape wasn't a function, it was a small object with a couple of strategy hooks. That reframing made the odd case trivial — it was just a different policy instance. I wrote the type down on paper. It looked obvious, almost embarrassing it'd taken me this long, but I'd actually found the joint.
