Known-answer tests for every part of the protocol that produces bytes: key
derivation, sealed envelopes with their intermediate values, accept tokens,
session and registration frames, rotation certificates, frontmatter parsing,
and the inputs a conformant implementation must refuse.
vectors.py derives every value by calling smolmail.py, so the vectors cannot
drift from the code, and verifies each one from the opposite side before
emitting it. --check regenerates and diffs against the committed files.
Verified independently: a checker written against SPEC.md and libsodium alone,
without importing the reference, reproduces all 81 values.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
