Function decode_strict_json_envelope 

pub fn decode_strict_json_envelope<T: DeserializeOwned>(
    bytes: &[u8],
    supported_version: u32,
    classify_kind: impl FnOnce(&str) -> Result<(), EnvelopeCodecError>,
) -> Result<DecodedJsonEnvelope<T>, EnvelopeCodecError>

Immutable envelope families tolerate unknown fields, while mutable control-object envelopes reject them. A tolerant read followed by rewrite would erase fields the current binary does not understand.