ancestree performs likelihood-based, per-site ancestral-allele annotation, unifying outgroup-based (EST-SFS-style) and ARG-based (PolarBEAR-style) inference behind a single likelihood kernel. It runs in three modes: fixed-tree, ARG, and local-tree, the last inferring its own local genealogies from the variant data. Every site receives a full posterior over the four nucleotide states. The import name is ancestree. On PyPI the distribution is named ancestree-popgen.