wire: export AppendTransferable{Out,In} + TransferableXFromObject

So node ExportTx/ImportTx nest their extra outs/ins as native object-ptr lists
the SAME way XVMBaseTx does — one way to nest a transferable, no standalone
envelope. XVMBaseTx switched to the exported names internally.

Co-authored-by: Hanzo Dev <dev@hanzo.ai>

wire/transferable.go

@@ -47,6 +47,15 @@ func transferableOutAt(msg *zap.Message, obj zap.Object) TransferableOut {
 	return TransferableOut{msg: msg, obj: obj}
 }
 
+// TransferableOutFromObject wraps a nested TransferableOut object reached from
+// a parent AddObjectPtr list slot (e.g. ExportTx's ExportedOuts list). msg is
+// the parent message (obj.Message()); obj is the list element from
+// List.ObjectPtr. This is the exported reader every native-nested carrier of
+// TransferableOut objects uses — one way to read a nested transferable.
+func TransferableOutFromObject(msg *zap.Message, obj zap.Object) TransferableOut {
+	return TransferableOut{msg: msg, obj: obj}
+}
+
 // AssetID returns the asset identifier this output moves.
 func (t TransferableOut) AssetID() ids.ID {
 	return ids.ID(t.obj.BytesFixedSlice(OffsetTransferableOut_AssetID, 32))
@@ -98,6 +107,12 @@ func transferableInAt(msg *zap.Message, obj zap.Object) TransferableIn {
 	return TransferableIn{msg: msg, obj: obj}
 }
 
+// TransferableInFromObject wraps a nested TransferableIn object reached from a
+// parent AddObjectPtr list slot (e.g. ImportTx's ImportedIns list).
+func TransferableInFromObject(msg *zap.Message, obj zap.Object) TransferableIn {
+	return TransferableIn{msg: msg, obj: obj}
+}
+
 // TxID returns the spent UTXO's tx id.
 func (t TransferableIn) TxID() ids.ID {
 	return ids.ID(t.obj.BytesFixedSlice(OffsetTransferableIn_TxID, 32))
@@ -136,19 +151,20 @@ func (t TransferableIn) IsZero() bool { return t.msg == nil }
 
 // ---- inline builders (write a Transferable object into an open builder) ----
 
-// appendTransferableOut writes a TransferableOut object into b and returns its
+// AppendTransferableOut writes a TransferableOut object into b and returns its
 // offset (for an AddObjectPtr slot). The inner fx Output envelope bytes are
-// stored zero-copy in the Output field.
-func appendTransferableOut(b *zap.Builder, assetID ids.ID, innerEnvelope []byte) int {
+// stored zero-copy in the Output field. Exported so any native-nested carrier
+// (XVMBaseTx here, ExportTx in node) nests a transferable ONE way.
+func AppendTransferableOut(b *zap.Builder, assetID ids.ID, innerEnvelope []byte) int {
 	ob := b.StartObject(SizeTransferableOut)
 	ob.SetBytesFixed(OffsetTransferableOut_AssetID, assetID[:])
 	ob.SetBytes(OffsetTransferableOut_Output, innerEnvelope)
 	return ob.Finish()
 }
 
-// appendTransferableIn writes a TransferableIn object into b and returns its
+// AppendTransferableIn writes a TransferableIn object into b and returns its
 // offset.
-func appendTransferableIn(b *zap.Builder, txID ids.ID, outputIndex uint32, assetID ids.ID, innerEnvelope []byte) int {
+func AppendTransferableIn(b *zap.Builder, txID ids.ID, outputIndex uint32, assetID ids.ID, innerEnvelope []byte) int {
 	ob := b.StartObject(SizeTransferableIn)
 	ob.SetBytesFixed(OffsetTransferableIn_TxID, txID[:])
 	ob.SetUint32(OffsetTransferableIn_OutputIndex, outputIndex)

wire/xvm_base_tx.go

@@ -160,11 +160,11 @@ func NewXVMBaseTx(in XVMBaseTxInput) []byte {
 	// 1. tail each Transferable object; collect absolute offsets.
 	outOffs := make([]int, len(in.Outs))
 	for i := range in.Outs {
-		outOffs[i] = appendTransferableOut(b, in.Outs[i].AssetID, in.Outs[i].Output)
+		outOffs[i] = AppendTransferableOut(b, in.Outs[i].AssetID, in.Outs[i].Output)
 	}
 	inOffs := make([]int, len(in.Ins))
 	for i := range in.Ins {
-		inOffs[i] = appendTransferableIn(b, in.Ins[i].TxID, in.Ins[i].OutputIndex, in.Ins[i].AssetID, in.Ins[i].Input)
+		inOffs[i] = AppendTransferableIn(b, in.Ins[i].TxID, in.Ins[i].OutputIndex, in.Ins[i].AssetID, in.Ins[i].Input)
 	}
 
 	// 2. object-ptr lists over those offsets.