Building tau: a time-series database where time is modelled
as a sequence of half-open intervals [start, end) with algebraically precise semantics.
Corrections append as new layers; the newest layer wins at query time. Compaction normalises any stack of layers into a single canonical layer, every query result is identical before and after. The invariants are not asserted by hand: they are verified by property-based tests and a deterministic simulation tester that drives every configuration combination against a reference oracle.