Given a strongly local Dirichlet space and $$\lambda \geqslant 0$$
λ
⩾
0
, we introduce a new notion of $$\lambda $$
λ
-subharmonicity for $$L^1_\textrm{loc}$$
L
loc
1
-functions, which we call local$$\lambda $$
λ
-shift defectivity, and which turns out to be equivalent to distributional $$\lambda $$
λ
-subharmonicity in the Riemannian case. We study the regularity of these functions on a new class of strongly local Dirichlet, so called locally smoothing spaces, which includes Riemannian manifolds (without any curvature assumptions), finite dimensional RCD spaces, Carnot groups, and Sierpinski gaskets. As a byproduct of this regularity theory, we obtain in this general framework a proof of a conjecture by Braverman, Milatovic, Shubin on the positivity of distributional $$L^q$$
L
q
-solutions of $$\Delta f\leqslant f$$
Δ
f
⩽
f
for complete Riemannian manifolds.