Version an existing JSON array with an explicit sentinel

When a JSON array must gain richer configuration without an immediate database migration, add one explicit version sentinel and keep the legacy parser separate from the versioned parser. New writes include the sentinel plus the complete explicit state; legacy rows continue to derive their historical defaults. Preserve any existing containment-query tokens needed by selectors, validate every stored element, and never expose the sentinel through the public API. This works for small bounded vocabularies; use a proper versioned object or schema migration when configuration becomes nested or independently queryable.

Applies when: an existing JSON array needs backward-compatible explicit configuration while old rows and containment queries must keep working. Keywords: JSONB array version sentinel legacy parser migration compatibility containment