We find and propose an explanation for a large variety of modularity-related symmetries in problems of 3-manifold topology and physics of 3d $mathcal{N}=2$ theories where such structures a priori are not manifest. These modular structures include: mock modular forms, $SL(2,mathbb{Z})$ Weil representations, quantum modular forms, non-semisimple modular tensor categories, and chiral algebras of logarithmic CFTs.
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