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fix(tbtcpg): size FROST wallet fees as P2TR #4153

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Merged
mswilkison merged 1 commit into from
Jul 13, 2026
+295 −48
Merged

fix(tbtcpg): size FROST wallet fees as P2TR #4153

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116 changes: 103 additions & 13 deletions pkg/tbtcpg/moved_funds_sweep.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -332,14 +332,50 @@ func (mfst *MovedFundsSweepTask) ProposeMovedFundsSweep(
)
}

estimatedFee, err := EstimateMovedFundsSweepFee(
movedFundsOutputScript, err := movedFundsSweepOutputScript(
mfst.btcChain,
movingFundsTxHash,
movingFundsTxOutputIndex,
)
if err != nil {
return nil, fmt.Errorf(
"cannot resolve moved funds output script: [%w]",
err,
)
}

walletData, err := mfst.chain.GetWallet(walletPublicKeyHash)
if err != nil {
return nil, fmt.Errorf(
"cannot get wallet chain data: [%w]",
err,
)
}
if walletData == nil {
return nil, fmt.Errorf("wallet chain data is nil")
}

walletOutputScript, err := tbtc.WalletOutputScript(
walletPublicKeyHash,
walletData.WalletID,
)
if err != nil {
return nil, fmt.Errorf(
"cannot compute wallet output script: [%w]",
err,
)
}

estimatedFee, err := EstimateMovedFundsSweepFeeForScripts(
mfst.btcChain,
movedFundsOutputScript,
walletOutputScript,
hasMainUtxo,
sweepTxMaxTotalFee,
)
if err != nil {
return nil, fmt.Errorf(
"cannot estimate moving funds transaction fee: [%w]",
"cannot estimate moved funds sweep transaction fee: [%w]",
err,
)
}
Expand Down Expand Up @@ -372,25 +408,79 @@ func (mfst *MovedFundsSweepTask) ProposeMovedFundsSweep(
return proposal, nil
}

// EstimateMovedFundsSweepFee estimates fee for the moved funds sweep transaction
// that merges the received main UTXO from the source wallets with the current
// wallet's main UTXO.
func movedFundsSweepOutputScript(
btcChain bitcoin.Chain,
movingFundsTxHash bitcoin.Hash,
movingFundsTxOutputIndex uint32,
) (bitcoin.Script, error) {
transaction, err := btcChain.GetTransaction(movingFundsTxHash)
if err != nil {
return nil, fmt.Errorf("cannot get moving funds transaction: [%w]", err)
}
if transaction == nil {
return nil, fmt.Errorf("moving funds transaction is nil")
}

if movingFundsTxOutputIndex >= uint32(len(transaction.Outputs)) {
return nil, fmt.Errorf(
"moving funds output index [%d] out of range for transaction with [%d] outputs",
movingFundsTxOutputIndex,
len(transaction.Outputs),
)
}

output := transaction.Outputs[movingFundsTxOutputIndex]
if output == nil {
return nil, fmt.Errorf(
"moving funds transaction output [%d] is nil",
movingFundsTxOutputIndex,
)
}

return output.PublicKeyScript, nil
}

// EstimateMovedFundsSweepFee estimates a legacy P2WPKH moved-funds sweep fee.
// Call EstimateMovedFundsSweepFeeForScripts when either the moved-funds output
// or the wallet output may use another script type.
func EstimateMovedFundsSweepFee(
btcChain bitcoin.Chain,
hasMainUtxo bool,
sweepTxMaxTotalFee uint64,
) (int64, error) {
// The transaction always has an input coming from the moved funds
// transferred by the source wallet. Additionally, it may have the second
// input which is the wallet main UTXO.
inputCount := 1
if hasMainUtxo {
inputCount++
legacyWalletOutputScript, err := bitcoin.PayToWitnessPublicKeyHash([20]byte{})
if err != nil {
return 0, fmt.Errorf("cannot construct legacy wallet output script: [%v]", err)
}

return EstimateMovedFundsSweepFeeForScripts(
btcChain,
legacyWalletOutputScript,
legacyWalletOutputScript,
hasMainUtxo,
sweepTxMaxTotalFee,
)
}

// EstimateMovedFundsSweepFeeForScripts estimates fee for a moved-funds sweep
// transaction using the resolved moved-funds input and wallet output scripts.
func EstimateMovedFundsSweepFeeForScripts(
btcChain bitcoin.Chain,
movedFundsOutputScript bitcoin.Script,
walletOutputScript bitcoin.Script,
hasMainUtxo bool,
sweepTxMaxTotalFee uint64,
) (int64, error) {
sizeEstimator := bitcoin.NewTransactionSizeEstimator().
AddPublicKeyHashInputs(inputCount, true).
AddPublicKeyHashOutputs(1, true)
AddPublicKeyScriptInput(movedFundsOutputScript)

// The transaction may have a second input spending the wallet's main UTXO.
// That UTXO is locked using the same script as the new wallet output.
if hasMainUtxo {
sizeEstimator.AddPublicKeyScriptInput(walletOutputScript)
}

sizeEstimator.AddOutputScript(walletOutputScript)

transactionSize, err := sizeEstimator.VirtualSize()
if err != nil {
Expand Down
136 changes: 108 additions & 28 deletions pkg/tbtcpg/moved_funds_sweep_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -346,28 +346,40 @@ func TestMovedFundsSweepAction_ProposeMovedFundsSweep(t *testing.T) {

movingFundsTxOutputIndex := uint32(1)

hasMainUtxo := true

var tests = map[string]struct {
fee int64
walletID [32]byte
hasMainUtxo bool
expectedProposal *tbtc.MovedFundsSweepProposal
}{
"fee provided": {
fee: 10000,
fee: 10000,
hasMainUtxo: true,
expectedProposal: &tbtc.MovedFundsSweepProposal{
MovingFundsTxHash: movingFundsTxHash,
MovingFundsTxOutputIndex: movingFundsTxOutputIndex,
SweepTxFee: big.NewInt(10000),
},
},
"fee estimated": {
fee: 0, // trigger fee estimation
"legacy fee estimated": {
fee: 0, // trigger fee estimation
hasMainUtxo: true,
expectedProposal: &tbtc.MovedFundsSweepProposal{
MovingFundsTxHash: movingFundsTxHash,
MovingFundsTxOutputIndex: movingFundsTxOutputIndex,
SweepTxFee: big.NewInt(4450),
},
},
"fresh FROST wallet fee estimated": {
fee: 0, // trigger fee estimation
walletID: [32]byte{0x01},
hasMainUtxo: false,
expectedProposal: &tbtc.MovedFundsSweepProposal{
MovingFundsTxHash: movingFundsTxHash,
MovingFundsTxOutputIndex: movingFundsTxOutputIndex,
SweepTxFee: big.NewInt(2775),
},
},
}

for testName, test := range tests {
Expand All @@ -391,7 +403,28 @@ func TestMovedFundsSweepAction_ProposeMovedFundsSweep(t *testing.T) {
0,
)

err := tbtcChain.SetMovedFundsSweepProposalValidationResult(
walletOutputScript, err := tbtc.WalletOutputScript(
walletPublicKeyHash,
test.walletID,
)
if err != nil {
t.Fatal(err)
}

tbtcChain.SetWallet(
walletPublicKeyHash,
&tbtc.WalletChainData{WalletID: test.walletID},
)
movingFundsTxOutputs := make([]*bitcoin.TransactionOutput, 2)
movingFundsTxOutputs[movingFundsTxOutputIndex] = &bitcoin.TransactionOutput{
PublicKeyScript: walletOutputScript,
}
btcChain.SetTransaction(
movingFundsTxHash,
&bitcoin.Transaction{Outputs: movingFundsTxOutputs},
)

err = tbtcChain.SetMovedFundsSweepProposalValidationResult(
walletPublicKeyHash,
test.expectedProposal,
true,
Expand All @@ -407,7 +440,7 @@ func TestMovedFundsSweepAction_ProposeMovedFundsSweep(t *testing.T) {
walletPublicKeyHash,
movingFundsTxHash,
movingFundsTxOutputIndex,
hasMainUtxo,
test.hasMainUtxo,
test.fee,
)
if err != nil {
Expand All @@ -421,30 +454,63 @@ func TestMovedFundsSweepAction_ProposeMovedFundsSweep(t *testing.T) {
}
}

func TestEstimateMovedFundsSweepFee(t *testing.T) {
func TestEstimateMovedFundsSweepFeeForScripts(t *testing.T) {
legacyWalletScript, err := bitcoin.PayToWitnessPublicKeyHash([20]byte{0x01})
if err != nil {
t.Fatal(err)
}
taprootWalletScript, err := bitcoin.PayToTaproot([32]byte{0x02})
if err != nil {
t.Fatal(err)
}

var tests = map[string]struct {
sweepTxMaxTotalFee uint64
hasMainUtxo bool
expectedFee uint64
expectedError error
movedFundsOutputScript bitcoin.Script
walletOutputScript bitcoin.Script
sweepTxMaxTotalFee uint64
hasMainUtxo bool
expectedFee uint64
expectedError error
}{
"estimated fee correct, one input": {
sweepTxMaxTotalFee: 3000,
hasMainUtxo: false,
expectedFee: 1760,
expectedError: nil,
"legacy scripts, one input": {
movedFundsOutputScript: legacyWalletScript,
walletOutputScript: legacyWalletScript,
sweepTxMaxTotalFee: 3000,
hasMainUtxo: false,
expectedFee: 1760,
expectedError: nil,
},
"legacy scripts, two inputs": {
movedFundsOutputScript: legacyWalletScript,
walletOutputScript: legacyWalletScript,
sweepTxMaxTotalFee: 3000,
hasMainUtxo: true,
expectedFee: 2848,
expectedError: nil,
},
"estimated fee correct, two inputs": {
sweepTxMaxTotalFee: 3000,
hasMainUtxo: true,
expectedFee: 2848,
expectedError: nil,
"Taproot scripts, one input": {
movedFundsOutputScript: taprootWalletScript,
walletOutputScript: taprootWalletScript,
sweepTxMaxTotalFee: 3000,
hasMainUtxo: false,
expectedFee: 1776,
expectedError: nil,
},
"estimated fee too high": {
sweepTxMaxTotalFee: 2500,
hasMainUtxo: true,
expectedFee: 0,
expectedError: tbtcpg.ErrSweepTxFeeTooHigh,
"Taproot scripts, two inputs": {
movedFundsOutputScript: taprootWalletScript,
walletOutputScript: taprootWalletScript,
sweepTxMaxTotalFee: 3000,
hasMainUtxo: true,
expectedFee: 2704,
expectedError: nil,
},
"estimated Taproot fee too high": {
movedFundsOutputScript: taprootWalletScript,
walletOutputScript: taprootWalletScript,
sweepTxMaxTotalFee: 2700,
hasMainUtxo: true,
expectedFee: 0,
expectedError: tbtcpg.ErrSweepTxFeeTooHigh,
},
}

Expand All @@ -453,8 +519,10 @@ func TestEstimateMovedFundsSweepFee(t *testing.T) {
btcChain := tbtcpg.NewLocalBitcoinChain()
btcChain.SetEstimateSatPerVByteFee(1, 16)

actualFee, err := tbtcpg.EstimateMovedFundsSweepFee(
actualFee, err := tbtcpg.EstimateMovedFundsSweepFeeForScripts(
btcChain,
test.movedFundsOutputScript,
test.walletOutputScript,
test.hasMainUtxo,
test.sweepTxMaxTotalFee,
)
Expand All @@ -475,6 +543,18 @@ func TestEstimateMovedFundsSweepFee(t *testing.T) {
}
}

func TestEstimateMovedFundsSweepFee(t *testing.T) {
btcChain := tbtcpg.NewLocalBitcoinChain()
btcChain.SetEstimateSatPerVByteFee(1, 16)

actualFee, err := tbtcpg.EstimateMovedFundsSweepFee(btcChain, true, 3000)
if err != nil {
t.Fatal(err)
}

testutils.AssertUintsEqual(t, "fee", 2848, uint64(actualFee))
}

func hashFromString(str string) bitcoin.Hash {
hash, err := bitcoin.NewHashFromString(
str,
Expand Down
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