I took Tilda with me, setting her on some grass near the foot of the ladder. We chatted for a bit while DH did his stuff. Then it started to rain.
I mentioned the rain to DH, just in case he hadn't realised. He growled a bit. Tilda looked at me for a few seconds, then shuffled to the open door. She waited, presumably expecting the magic lift to occur. Of course it didn't, as I was on the ladder.
I wondered, idly as you do, how heavy the rain would have to be for me to abandon my post to save the hen. (Standing on the bottom rung of the ladder staring at brickwork is rather dull, so my mind does have a tendency to wander).
Fortunately, Tilda took matters into her own wings. She did that head bobbing thing that chooks do when they are evaluating the jump required and, amid a tremendous flurry of wing activity, she managed or get herself over the door threshold.
She watched me from the dryness of the kitchen. I'm sure she thinks I'm a little odd.