The formatter wrote default(CultRecordRef<T>) as nil but read nil back as
"", so re-upserting a loaded record changed its bytes (0xC0 became 0xA0).
One in-memory unset value: CultRecordKey.Value is never null, so
default(CultRecordRef<T>) equals a ref built from "". One wire form: an
empty key writes nil, and nil or a legacy "" reads back as default.
Load then save is byte-stable; a store holding "" converges to nil on its
next save.
Rust, TypeScript and Python have no reference type: a reference member is a
string in the consumer's own payload, so there is no sibling codec to align.
The store-composition contract now names nil as the one unset wire form.
The new test loads a record with an unset ref through a fresh cache,
re-upserts and flushes, and requires identical payload bytes; it fails on
the old formatter.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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