I had been stuck on the same bug since Thursday. By Sunday I had the screen-staring equivalent of snow blindness, reading the same forty lines over and over and seeing nothing. So I gave up, put on too many layers for a February morning, and went for a ride.
It was cold and grey and the kind of damp that gets into your gloves within the first mile. I was not thinking about the bug. I was thinking about whether my fingers would survive the descent, which is its own form of problem solving. And then, somewhere near the top of a climb I always underestimate, with my heart rate doing the talking, the answer just arrived. Not the whole answer, but the shape of it, the bit I had been refusing to consider because it implied I had been wrong about something for two days.
I am wary of dressing this up as some productivity hack, because it is not. I did not ride in order to solve the bug. The point is the opposite: you have to actually stop, properly, with no laptop and no nagging tab open in the back of your head, before the quiet part of your brain gets a turn. Staring harder never once worked. Leaving the room has worked more times than I can count.
I got home, peeled off the wet kit, made a coffee, and wrote the fix in about ten minutes. The fix had been there the whole time. I just needed to be somewhere a bicycle could find it.