Serializable cross-plane request envelope.
@type t() :: %GroundPlane.Boundary.Envelope{ id: String.t(), issued_at: String.t() | nil, metadata: map(), operation: String.t(), origin: String.t(), payload: map() | nil, payload_ref: String.t() | nil, schema_version: String.t(), target: String.t(), tenant_id: String.t(), trace: map() }
@spec digest(t()) :: String.t()
@spec encode!(t()) :: String.t()
@spec new(map() | keyword()) :: {:ok, t()} | {:error, term()}
@spec new!(map() | keyword()) :: t()
@spec to_map(t()) :: map()