v1: Constraint fill (≥5 = LIKELY)
v2: Candidates (≤2 = LIKELY)
LIKELY → Find the shape:
● Lock — forced single
◐ Signal — knight elimination
═ Beam — knight chain
◈ Resonance — knight-box
⟶ Vision — trial chain
Mistake Budget:
Easy: 10 | Med: 8 | Hard: 7 | Expert: 7