packages/session-types mirrors the Rust crate: canonical JSON (RFC 8785), strict parsing,
canonical digests, readers with a validate step for every payload of ipc-v1, workers-v1,
state-media-v1 and publishing-v1, the trace comparator, seed derivation and the FLYSESS1
envelope. It loads the crate fixtures/ directory rather than keeping a copy.
43 tests with node test runner, as in packages/feed. Both languages assert the same recorded
canonical bytes and digests, so agreement is checked rather than assumed; the envelope test
goes further and requires the bytes this package writes to equal the fixture the Rust crate
wrote.
Also narrows the canonical number rule to a value-based one (finite, and within the exact
integer range when integral), because JSON.parse cannot tell 1e21 from the same digits
written out, and two implementations that disagree about one number agree about no digest.
