Arrow interchange and compatibility

VOIAGE uses Apache Arrow as its in-memory interchange contract and compressed Parquet or Arrow IPC files at durable boundaries. Perspective-result tables carry the method contract version, estimand, and interchange name in schema metadata.

The versioned golden artifacts are under specs/frontier/perspective/v1/interchange/. Regenerate and verify them with:

uv run python scripts/perspective_interchange_manifest.py --write
uv run python scripts/perspective_interchange_manifest.py --check

The manifest fingerprints the serialized Arrow schema. Text-source hashes are computed after UTF-8 decoding and LF normalization; binary Parquet and IPC files are hashed as raw bytes. This keeps evidence hashes stable across Windows and Linux while retaining byte-exact binary verification.

CI verifies PyArrow-to-Polars round trips, fresh-process reads, the current and previous fixture version, and relative serialization performance against JSON Lines. Python 3.12–3.14 is the supported runtime range. Python 3.14t is observed in a non-blocking job while its ecosystem support remains beta.