itest: update SealBatch RPC call to accept a signed PSBT

This commit updates the SealBatch RPC endpoint call to pass a
complete signed PSBT directly, instead of extracting the witness
and passing it as a separate argument.

itest/mint_fund_seal_test.go

@@ -4,11 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/base64"
-	"encoding/binary"
 	"encoding/hex"
-	"errors"
-	"fmt"
-	"log"
 	"math"
 	"testing"
 
@@ -571,25 +567,16 @@ func testMintExternalGroupKeyChantools(t *harnessTest) {
 	var genesisAssetID asset.ID
 	copy(genesisAssetID[:], genesisAssetIDBytes)
 
-	// Extract witness from signed PSBT.
-	witnessStack, err := DeserializeWitnessStack(
-		signedPsbt.Inputs[0].FinalScriptWitness,
-	)
-	if err != nil {
-		log.Fatalf("Failed to deserialize witness stack: %v", err)
-	}
-
-	groupWitness := taprpc.GroupWitness{
-		GenesisId: genesisAssetID[:],
-		Witness:   witnessStack,
-	}
-
 	ctxt, cancel = context.WithTimeout(ctxb, defaultWaitTimeout)
 	defer cancel()
 
+	// Encode the signed PSBT as a string.
+	signedPsbtStr, err := signedPsbt.B64Encode()
+	require.NoError(t.t, err)
+
 	sealReq := mintrpc.SealBatchRequest{
-		GroupWitnesses: []*taprpc.GroupWitness{
-			&groupWitness,
+		SignedGroupVirtualPsbts: []string{
+			signedPsbtStr,
 		},
 	}
 	sealResp, err := t.tapd.SealBatch(ctxt, &sealReq)
@@ -619,74 +606,6 @@ func testMintExternalGroupKeyChantools(t *harnessTest) {
 	t.Logf("Batch assets: %v", batchAssets)
 }
 
-// DeserializeWitnessStack deserializes a serialized witness stack into a
-// [][]byte.
-func DeserializeWitnessStack(serialized []byte) ([][]byte, error) {
-	var stack [][]byte
-	reader := bytes.NewReader(serialized)
-
-	// Read the number of witness elements (compact size integer)
-	count, err := readCompactSize(reader)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read witness count: %w", err)
-	}
-
-	// Read each witness element
-	for i := uint64(0); i < count; i++ {
-		elementSize, err := readCompactSize(reader)
-		if err != nil {
-			return nil, fmt.Errorf("failed to read witness "+
-				"element size: %w", err)
-		}
-
-		// Read the witness element data
-		element := make([]byte, elementSize)
-		if _, err := reader.Read(element); err != nil {
-			return nil, fmt.Errorf("failed to read witness "+
-				"element data: %w", err)
-		}
-		stack = append(stack, element)
-	}
-
-	return stack, nil
-}
-
-// readCompactSize reads a compact size integer from the given reader.
-func readCompactSize(r *bytes.Reader) (uint64, error) {
-	if r.Len() == 0 {
-		return 0, errors.New("unexpected EOF")
-	}
-
-	prefix, _ := r.ReadByte()
-	switch {
-	case prefix < 253:
-		return uint64(prefix), nil
-	case prefix == 253:
-		var value uint16
-		err := binary.Read(r, binary.LittleEndian, &value)
-		if err != nil {
-			return 0, err
-		}
-		return uint64(value), nil
-	case prefix == 254:
-		var value uint32
-		err := binary.Read(r, binary.LittleEndian, &value)
-		if err != nil {
-			return 0, err
-		}
-		return uint64(value), nil
-	case prefix == 255:
-		var value uint64
-		err := binary.Read(r, binary.LittleEndian, &value)
-		if err != nil {
-			return 0, err
-		}
-		return value, nil
-	default:
-		return 0, errors.New("invalid compact size prefix")
-	}
-}
-
 // Derive a random key on an LND node, with a key family not matching the
 // Taproot Assets key family.
 func deriveRandomKey(t *testing.T, ctxt context.Context,