tapsend: copy sort to before creating virtual packets

This fixes a bug where the order of the inputs in a virtual packet
wasn't deterministic, because we only sorted the proofs _after_ already
assigning them as inputs to the packet.

Author: guggero

tapsend/allocation.go

@@ -504,6 +504,14 @@ func DistributeCoins(inputs []*proof.Proof, allocations []*Allocation,
 			},
 		)
 
+		// Before creating the virtual packet, sort the proofs by
+		// amount (in reverse order) then by script key. This ensures
+		// deterministic ordering before assigning them to the virtual
+		// packet inputs.
+		slices.SortFunc(proofsByID, func(i, j *proof.Proof) int {
+			return AssetSortForInputs(i.Asset, j.Asset)
+		})
+
 		pkt, err := tappsbt.FromProofs(
 			proofsByID, chainParams, vPktVersion,
 		)

tapsend/allocation_test.go

@@ -410,8 +410,8 @@ func TestDistributeCoins(t *testing.T) {
 			vPktVersion: tappsbt.V1,
 			expectedInputs: map[asset.ID][]asset.ScriptKey{
 				assetID2.ID(): {
-					assetID2Tranche1.ScriptKey,
 					assetID2Tranche2.ScriptKey,
+					assetID2Tranche1.ScriptKey,
 				},
 			},
 			expectedOutputs: map[asset.ID][]*tappsbt.VOutput{
@@ -452,8 +452,8 @@ func TestDistributeCoins(t *testing.T) {
 			},
 			expectedInputs: map[asset.ID][]asset.ScriptKey{
 				assetID2.ID(): {
-					assetID2Tranche1.ScriptKey,
 					assetID2Tranche2.ScriptKey,
+					assetID2Tranche1.ScriptKey,
 				},
 			},
 			expectedOutputs: map[asset.ID][]*tappsbt.VOutput{
@@ -613,19 +613,19 @@ func TestDistributeCoins(t *testing.T) {
 			},
 			expectedInputs: map[asset.ID][]asset.ScriptKey{
 				assetID1.ID(): {
-					assetID1Tranche1.ScriptKey,
-					assetID1Tranche2.ScriptKey,
 					assetID1Tranche3.ScriptKey,
+					assetID1Tranche2.ScriptKey,
+					assetID1Tranche1.ScriptKey,
 				},
 				assetID2.ID(): {
-					assetID2Tranche1.ScriptKey,
-					assetID2Tranche2.ScriptKey,
 					assetID2Tranche3.ScriptKey,
+					assetID2Tranche2.ScriptKey,
+					assetID2Tranche1.ScriptKey,
 				},
 				assetID3.ID(): {
-					assetID3Tranche1.ScriptKey,
-					assetID3Tranche2.ScriptKey,
 					assetID3Tranche3.ScriptKey,
+					assetID3Tranche2.ScriptKey,
+					assetID3Tranche1.ScriptKey,
 				},
 			},
 			expectedOutputs: map[asset.ID][]*tappsbt.VOutput{
@@ -689,19 +689,19 @@ func TestDistributeCoins(t *testing.T) {
 			},
 			expectedInputs: map[asset.ID][]asset.ScriptKey{
 				assetID1.ID(): {
-					assetID1Tranche1.ScriptKey,
-					assetID1Tranche2.ScriptKey,
 					assetID1Tranche3.ScriptKey,
+					assetID1Tranche2.ScriptKey,
+					assetID1Tranche1.ScriptKey,
 				},
 				assetID2.ID(): {
-					assetID2Tranche1.ScriptKey,
-					assetID2Tranche2.ScriptKey,
 					assetID2Tranche3.ScriptKey,
+					assetID2Tranche2.ScriptKey,
+					assetID2Tranche1.ScriptKey,
 				},
 				assetID3.ID(): {
-					assetID3Tranche1.ScriptKey,
-					assetID3Tranche2.ScriptKey,
 					assetID3Tranche3.ScriptKey,
+					assetID3Tranche2.ScriptKey,
+					assetID3Tranche1.ScriptKey,
 				},
 			},
 			expectedOutputs: map[asset.ID][]*tappsbt.VOutput{
@@ -770,19 +770,19 @@ func TestDistributeCoins(t *testing.T) {
 			},
 			expectedInputs: map[asset.ID][]asset.ScriptKey{
 				assetID1.ID(): {
-					assetID1Tranche1.ScriptKey,
-					assetID1Tranche2.ScriptKey,
 					assetID1Tranche3.ScriptKey,
+					assetID1Tranche2.ScriptKey,
+					assetID1Tranche1.ScriptKey,
 				},
 				assetID2.ID(): {
-					assetID2Tranche1.ScriptKey,
-					assetID2Tranche2.ScriptKey,
 					assetID2Tranche3.ScriptKey,
+					assetID2Tranche2.ScriptKey,
+					assetID2Tranche1.ScriptKey,
 				},
 				assetID3.ID(): {
-					assetID3Tranche1.ScriptKey,
-					assetID3Tranche2.ScriptKey,
 					assetID3Tranche3.ScriptKey,
+					assetID3Tranche2.ScriptKey,
+					assetID3Tranche1.ScriptKey,
 				},
 			},
 			expectedOutputs: map[asset.ID][]*tappsbt.VOutput{