Are tops AND bottoms both getting steeper — or flattening?
Confirmed ATR-k swings only (the last open pivot is ignored).
ACCEL_UP iff the last 2–3 high-to-high legs and the last 2–3 low-to-low legs
are both strictly steepening, all slopes positive. ACCEL_DOWN is both dumping steeper.
One side only = NONE, and the tile names which side failed. Orange dateline = first
confirmation of the current verdict (earlier than a human naming a parabola). Never predicts.