  We present the first direct $N_f=2$ lattice QCD computation of two- and
three-$\pi^+$ scattering quantities that includes an ensemble at the physical
point. We study the quark mass dependence of the two-pion phase shift, and the
three-particle interaction parameters. We also compare to phenomenology and
chiral perturbation theory (ChPT). In the two-particle sector, we observe good
agreement to the phenomenological fits in $s$- and $d$-wave, and obtain $M_\pi
a_0 = -0.0481(86)$ at the physical point from a direct computation. In the
three-particle sector, we observe reasonable agreement at threshold to the
leading order chiral expansion, i.e.\@ a mildly attractive three-particle
contact term. In contrast, we observe that the energy-dependent part of the
three-particle quasilocal scattering quantity is not well described by leading
order ChPT.
