On sinks and mirrors
Homological mirror symmetry between Fock-Goncharov pairs of Langlands-dual cluster varieties has long been conjectured. A central obstacle is the 'deep locus' outside the cluster charts, which compact real tori in those charts cannot probe.
A new descent result for partially wrapped Fukaya categories (Sylvan-Orlov-Viterbo descent) is proved via a categorical pullback criterion for spherical functors. Sink covers and freezings of cluster algebras are combined with good Liouville structures on cluster varieties. These are matched with a B-side computation using blowups and coherent sheaves on a stacky dual cluster X variety. The skeleton calculation in an appendix is formalized in Lean 4 with Mathlib.
For any full rank sink-recurrent cluster A variety, the wrapped Fukaya category is equivalent to coherent sheaves on a stacky version of the dual Fock-Goncharov X variety. Consequences include mirror symmetry between braid varieties of Langlands-dual groups, and between the SL(2) and PGL(2) Fock-Goncharov moduli for suitable marked surfaces.
