A rewrite replaces a file only when the runtime's own reader opens it. C#
drops ReadStoreHeader (a second, header-only verdict that let a flush replace
files the reader refuses) and asks DeserializeSnapshot from open, flush and
commit; the reader now requires exactly one array, so C# refuses bytes after
the store on read as TS and Python do. A zero-byte file is an empty store for
all three paths. CultMesh.WriteSingleFileDocument reads the file it replaces
through the Mesh reader before writing. Rust reads and rewrites through one
classification (trailing bytes refused on read; a non-store first slot must be a
legacy envelope array the reader accepts). TypeScript checks a legacy array with
pullAll's own decoder before replacing it. Python already conformed.
Shared byte vectors and per-runtime verdicts live in
tests/vectors/document-variants-c2a/readability; every runtime's test reads
them. Holds gains second-dictionary-value and second-list-item cases. The
persistence format contract now marks v3 by content and states the readability
rule.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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