Triangular face edge: L
Circumradius of face: r_min = L/√3
A wavepacket at face centre with λ_c = L/√3
simultaneously resolves all 3 vertices.
Further compression forbidden by topology.

m_soft = ℏ/(Lc) ≈ 11.8 µg
λ_c = L — lattice onset

m_hard = √3 · m_soft ≈ 20.5 µg
λ_c = L/√3 — topological cutoff

Ratio: m_hard/m_soft = √3 (exact)

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