The signs are public. The compass is ours. Anyone can read a sign. The compass is what says which way it points.
Why inflection math
A number tells you how big. An inflection tells you whether it can keep going — and those are different questions with different answers. A company can post a huge quarter on something that exhausts itself, and a small one on something that compounds for a decade.
We measure whether a force can keep pushing, never how loud it was. Borrowed momentum is temporary and runs out. Real mass persists. Magnitude cannot tell those apart; the bend in the curve can.
What the needle actually reads
One reading joins four things: the car (which company), the crossing (which other party, if any), the type of sign, and the date it became knowable. That last one is the honesty: a reading may only use what a person standing on that road, on that day, could actually have known.
And no thumb goes on the scale. Nobody decides in advance what a meaningful sign looks like. A sign earns its meaning by having come before real turns, across thousands of companies and years of history — with every idea we ever tried counted before we tried it, so luck is priced in rather than celebrated. A sign that cannot show its record does not get to speak.