v1: Filled in row+col+cage (≥N = LIKELY)
v2: Candidates (≤2 = LIKELY)
LIKELY → Find the shape:
● Lock — 1 candidate forced
◐ Signal — cage combos agree
═ Beam — row/col forces digit
◈ Resonance — multi-cage
⟶ Vision — trial arithmetic
Mistake Budget:
Easy: 4 | Med: 3 | Hard: 2 | Expert: 2