The PoiStore trait abstracts read-only access to points of interest via
bounding-box queries.[^7] Implementations must accept rectangles in longitude,
latitude order (WGS84) and treat boundary points as contained. The default
store is SqlitePoiStore, which is available when the store-sqlite feature
is enabled. It opens two artefacts: a read-only SQLite database and a
serialized R*-tree. The loader verifies both files by reading a WSPI magic
header, checking the format version (2), and ensuring that every indexed
point exists in the database. Failing checks raise SqlitePoiStoreError,
covering problems such as missing records, malformed JSON tag payloads, and I/O
or SQLite errors.[^8]