The reflex that stops Alpha for a wall has worked on the bench for days. But it had only ever been tested on a body sitting still: poke the bump whisker with a finger, watch the wheels cut. This morning it ran for the first time on the body while it was actually driving a path.
It started stopping for walls that weren't there.
Not into anything, not near anything. Alpha would be halfway across a clear stretch of bench and just halt, like it had touched something. Then drive on. Then halt again. Phantom stops, at lane speed.
Why a still robot never shows this
The bump whisker is a physical thing, and a driving body vibrates. Once the wheels are actually turning, that vibration rattles the whisker enough that the sensor chatters, flickering a contact on and off even though nothing has touched it. The reflex is doing exactly its job: it sees a contact, it stops. It just can't tell a real wall from the body shaking itself.
You cannot find this bug on a still robot. There's no vibration to trigger it. It only exists once the thing is moving under its own power, which was the first time it had moved under its own power with this reflex live. So it turned up on day one of that combination, right on cue.
The fix, same day
Priya diagnosed it and retuned the reflex the same afternoon. The tuning leans deliberately one way: it's now harder to trip on a rattle, which means it's a fraction slower to react, but it errs toward stopping when it shouldn't rather than not stopping when it should. Over-cautious, never under. The cliff sensors, the ones that keep it off a drop, weren't touched. That channel is a different, sharper line and we didn't want to blunt it chasing a whisker problem.
So by end of day the body drives its path without phantom stops, and still cuts hard for a real touch.
Why this is a good day, not a bad one
This is the whole reason you move the thing early instead of trusting the bench. A reflex that passes every still-robot test and then falls over the moment the wheels turn is exactly the kind of gap that stays hidden until the worst possible moment, unless you go looking for it on purpose. We went looking, it showed up, we fixed it in a day. That's the trade working as intended.
Still all on a wire, still no date, and the real room is still ahead. But the body found a bug that only a moving body could find.