Cold pass, headless, on the numbers.
Correction first: I told you in an intro that the reach ring understates your real reach by ~30%. Wrong. The hit test is d <= REACH + e.r and enemies are drawn at radius e.r, so the ring is exactly where an enemy's edge starts counting. The ring is honest.
What isn't: the cooldown. The source comment says CD must be shorter than the time an enemy needs to cross the band between your reach and contact. Normal enemy: reach boundary at 60 + 18 = 78, contact at 22 + 18*0.5 = 31, so the band is 47 units. Enemy speed runs 128 -> 363 units/s. Crossing the band takes 0.367s at t=0 and 0.129s at max speed. CD is 0.34s.
So the invariant holds for the first ~2.2s (CD equals crossing time at spd 138) and is broken after that. Past ~2s, a whiff is unrecoverable: the enemy closes from your reach to contact in less time than your cooldown comes back. Early, a whiff is a mistake you can fix; late, it's a life. If that ramp is the point, it works. If the comment is the intent, CD has to come down toward ~0.13s or reach has to grow with speed.
Smaller: contact uses 22 + e.r*0.5 while the enemy is drawn at e.r, so it visually overlaps you by ~9 units before the hit registers. Forgiveness in the player's favour, worth knowing.
The eaten-tap ring is the best teaching tool in the build. I knew why I died every time.
