garbage collect zero-value UTXOs

asset/asset.go

@@ -1803,6 +1803,16 @@ func (a *Asset) IsBurn() bool {
 	return IsBurnKey(a.ScriptKey.PubKey, a.PrevWitnesses[0])
 }
 
+// IsTombstone returns true if an asset uses the NUMS script key and has zero
+// value.
+func (a *Asset) IsTombstone() bool {
+	if a.ScriptKey.PubKey == nil {
+		return false
+	}
+
+	return a.Amount == 0 && a.ScriptKey.PubKey.IsEqual(NUMSPubKey)
+}
+
 // PrimaryPrevID returns the primary prev ID of an asset. This is the prev ID of
 // the first witness, unless the first witness is a split-commitment witness,
 // in which case it is the prev ID of the first witness of the root asset.

config.go

@@ -190,6 +190,10 @@ type Config struct {
 
 	ChainPorter tapfreighter.Porter
 
+	// SweepOrphanUtxos toggles sweeping orphaned UTXOs into anchor
+	// transactions for sends and burns.
+	SweepOrphanUtxos bool
+
 	// FsmDaemonAdapters is a set of adapters that allow a state machine to
 	// interact with external daemons.
 	FsmDaemonAdapters *lndservices.LndFsmDaemonAdapters

docs/release-notes/release-notes-0.8.0.md

@@ -37,6 +37,12 @@
 
 ## Functional Updates
 
+- [Garbage collection of orphaned UTXOs](https://github.com/lightninglabs/taproot-assets/pull/1832)
+  by sweeping tombstones and burn outputs when executing onchain transactions.
+  Garbage collection will be executed on every burn, transfer or call to
+  `AnchorVirtualPsbts`. A new configuration is available to control the sweeping 
+  via the flag `wallet.sweep-orphan-utxos`.
+
 ## RPC Updates
 
 - [PR#1841](https://github.com/lightninglabs/taproot-assets/pull/1841): Remove

itest/assertions.go

@@ -1276,10 +1276,6 @@ func AssertAssetOutboundTransferWithOutputs(t *testing.T,
 		scripts[string(o.ScriptKey)] = struct{}{}
 	}
 
-	sendRespJSON, err := formatProtoJSON(transfer)
-	require.NoError(t, err)
-	t.Logf("Got response from sending assets: %v", sendRespJSON)
-
 	// Mine a block to force the send event to complete (confirm on-chain).
 	var newBlock *wire.MsgBlock
 	if confirm {
@@ -1325,16 +1321,6 @@ func AssertAssetOutboundTransferWithOutputs(t *testing.T,
 				return slices.Contains(actualInputAssetIDs, id)
 			})
 	}, defaultTimeout, wait.PollInterval)
-	require.NoError(t, err)
-
-	transferResp, err := sender.ListTransfers(
-		ctxb, &taprpc.ListTransfersRequest{},
-	)
-	require.NoError(t, err)
-
-	transferRespJSON, err := formatProtoJSON(transferResp)
-	require.NoError(t, err)
-	t.Logf("Got response from list transfers: %v", transferRespJSON)
 
 	return newBlock
 }
@@ -2414,7 +2400,7 @@ func AssertBalances(t *testing.T, client taprpc.TaprootAssetsClient,
 			actualBalance := balanceSum(resp, false)
 			if balance != actualBalance {
 				return fmt.Errorf("asset balance, wanted %d, "+
-					"got: %v", balance, toJSON(t, resp))
+					"got: %v", balance, actualBalance)
 			}
 
 			// If we query for grouped asset balances too, it means
@@ -2532,7 +2518,7 @@ func AssertBalances(t *testing.T, client taprpc.TaprootAssetsClient,
 		}
 		if balance != totalBalance {
 			return fmt.Errorf("ListAssets balance, wanted %d, "+
-				"got: %v", balance, toJSON(t, resp))
+				"got: %v", balance, totalBalance)
 		}
 
 		// The number of UTXOs means asset outputs in this case. We
@@ -2609,7 +2595,7 @@ func AssertBalances(t *testing.T, client taprpc.TaprootAssetsClient,
 
 		if balance != totalBalance {
 			return fmt.Errorf("ListUtxos balance, wanted %d, "+
-				"got: %v", balance, toJSON(t, resp))
+				"got: %v", balance, totalBalance)
 		}
 
 		if config.numAnchorUtxos > 0 {

itest/burn_test.go

@@ -246,11 +246,6 @@ func testBurnAssets(t *harnessTest) {
 		WithScriptKeyType(asset.ScriptKeyBurn),
 	)
 
-	_, err = t.tapd.ListAssets(ctxt, &taprpc.ListAssetRequest{
-		IncludeSpent: true,
-	})
-	require.NoError(t.t, err)
-
 	// Test case 4: Burn some units of a grouped asset. We start by making
 	// sure we still have the full balance before burning.
 	AssertBalanceByID(

itest/tapd_harness.go

@@ -145,6 +145,10 @@ type harnessOpts struct {
 	// verification should only occur for commitments submitted by peers,
 	// not via on-chain spend detection.
 	disableSupplyVerifierChainWatch bool
+
+	// sweepOrphanUtxos indicates whether orphaned anchor UTXOs should be
+	// swept into anchor transactions.
+	sweepOrphanUtxos bool
 }
 
 type harnessOption func(*harnessOpts)
@@ -256,6 +260,10 @@ func newTapdHarness(t *testing.T, ht *harnessTest, cfg tapdConfig,
 	// nolint: lll
 	tapCfg.Universe.DisableSupplyVerifierChainWatch = opts.disableSupplyVerifierChainWatch
 
+	// Pass through the sweep orphan UTXOs flag. If the option was not set,
+	// this will be false, which is the default.
+	tapCfg.Wallet.SweepOrphanUtxos = opts.sweepOrphanUtxos
+
 	switch {
 	case len(opts.oracleServerAddress) > 0:
 		tapCfg.Experimental.Rfq.PriceOracleAddress =

itest/test_harness.go

@@ -372,6 +372,10 @@ type tapdHarnessParams struct {
 	// sendPriceHint indicates whether the tapd should send price hints from
 	// the local oracle to the counterparty when requesting a quote.
 	sendPriceHint bool
+
+	// sweepOrphanUtxos indicates whether orphaned UTXOs should be swept
+	// into anchor transactions.
+	sweepOrphanUtxos bool
 }
 
 // Option is a tapd harness option.
@@ -400,6 +404,14 @@ func WithSendPriceHint() Option {
 	}
 }
 
+// WithSweepOrphanUtxos enables sweeping zero-value anchor UTXOs for
+// the tapd harness created with this option.
+func WithSweepOrphanUtxos() Option {
+	return func(th *tapdHarnessParams) {
+		th.sweepOrphanUtxos = true
+	}
+}
+
 // setupTapdHarness creates a new tapd that connects to the given lnd node
 // and to the given universe server.
 func setupTapdHarness(t *testing.T, ht *harnessTest,
@@ -434,6 +446,7 @@ func setupTapdHarness(t *testing.T, ht *harnessTest,
 		ho.disableSyncCache = params.disableSyncCache
 		ho.oracleServerAddress = params.oracleServerAddress
 		ho.sendPriceHint = params.sendPriceHint
+		ho.sweepOrphanUtxos = params.sweepOrphanUtxos
 	}
 
 	tapdCfg := tapdConfig{

itest/test_list_on_test.go

@@ -101,6 +101,14 @@ var allTestCases = []*testCase{
 		name: "min relay fee bump",
 		test: testMinRelayFeeBump,
 	},
+	{
+		name: "zero value anchor sweep",
+		test: testZeroValueAnchorSweep,
+	},
+	{
+		name: "zero value anchor accumulation",
+		test: testZeroValueAnchorAccumulation,
+	},
 	{
 		name: "restart receiver check balance",
 		test: testRestartReceiverCheckBalance,