baselineFieldsCoercible

Whether, in the baseline (old) snapshot, every field that decodes this enum is a defaulted direct property — the precondition for coerceInputValues to rescue an unknown value in the forward direction (old code reading new data). coerceInputValues only coerces an unknown enum to a field's default, so a required field, a nested (List/Map) usage, or a top-level decode still throws. The classifier downgrades the forward BREAK to a WARN only when this is true and the reader coerces; otherwise it stays a BREAK (#129).