Incomplete checkpoint, preserved after the implementing session hit a
capacity limit partway through mutation verification. NOT reviewed and NOT
gate-clean: make fmt has not been run, so fmt-check currently fails on
ARCHITECTURE.md and TODO.md.
Work still outstanding before this is fit for review:
- run make fmt and fold the result in
- finish mutation-proving each of the three behaviors
- verify every message string byte-for-byte against the C sources
- confirm TestSeedCompatItemTables passes with its golden untouched
Refs #13.