The projection-cache writer preserves lossless JSON, including own keys named
__proto__. The z.json reader rebuilds objects and drops those keys, so opening
the same stored checkpoint can produce state different from Session replay.
This affects embedded result metadata and opaque extension payloads as well
as other projection state.
Validate with the existing isJsonValue predicate used by the writer's
snapshotJsonValue rules. It rejects non-JSON and lossy values without
rebuilding valid borrowed records. Keep the stored representation and domain
version unchanged: this is a reader correction, not a new cache format.
Exercise a fixture captured through the actual pre-fix writer with a real
StorageDomain open, rewrite, close and reopen. Preserve nested prototype-named
keys and retain negative coverage for invalid JSON values. Document why this
validation matches the storage-domain immutable borrowed-value contract.
Use neutral arbitrary JSON in the new opaque-state fixture so this reader
regression stays independent of Session message representation. Its own
prototype-named keys and nested arrays are unchanged in purpose. Confirm
the fixture matches the pre-fix StorageDomain writer output and that the
old z.json reader fails its key-preservation assertion. No released Session
recordings or historical cache fixtures are edited.
Tianyi Cui
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