Fix backward compatibility when building Bundle

src/builder.rs

@@ -969,7 +969,28 @@ fn build_bundle<B, R: RngCore>(
         // as we can estimate the vector size beforehand.
         let mut indexed_spends_outputs = Vec::with_capacity(num_actions);
 
-        let spends_outputs_by_asset = partition_by_asset(&spends, &outputs);
+        let mut spends_outputs_by_asset = partition_by_asset(&spends, &outputs);
+
+        // For zatoshi-only bundles, pad spends and outputs to num_actions
+        // before per-asset processing, so that dummies are created before the shuffle —
+        // matching vanilla Orchard RNG consumption order.
+        if spends_outputs_by_asset
+            .keys()
+            .all(|asset| asset == &AssetBase::zatoshi())
+        {
+            let (asset_spends, asset_outputs) = spends_outputs_by_asset
+                .entry(AssetBase::zatoshi())
+                .or_insert_with(|| (vec![], vec![]));
+            asset_spends.extend(
+                iter::repeat_with(|| (SpendInfo::dummy(AssetBase::zatoshi(), &mut rng), None))
+                    .take(num_actions.saturating_sub(asset_spends.len())),
+            );
+            asset_outputs.extend(
+                iter::repeat_with(|| (OutputInfo::dummy(&mut rng, AssetBase::zatoshi()), None))
+                    .take(num_actions.saturating_sub(asset_outputs.len())),
+            );
+        }
+        let asset_count = spends_outputs_by_asset.len();
 
         indexed_spends_outputs.extend(spends_outputs_by_asset.into_iter().flat_map(
             |(asset, (spends, outputs))| {
@@ -1009,6 +1030,9 @@ fn build_bundle<B, R: RngCore>(
             },
         ));
 
+        // Pad total actions to num_actions.
+        // This covers the edge case of a single non-zatoshi asset with fewer than
+        // MIN_ACTIONS spends/outputs (e.g. a bundle that only burns a custom asset).
         indexed_spends_outputs.extend(
             iter::repeat_with(|| {
                 (
@@ -1021,7 +1045,9 @@ fn build_bundle<B, R: RngCore>(
 
         // We shuffled the spends and outputs within each `AssetBase` above; now we
         // shuffle the actions to achieve a similar property across `AssetBase`s.
-        indexed_spends_outputs.shuffle(&mut rng);
+        if asset_count > 1 {
+            indexed_spends_outputs.shuffle(&mut rng);
+        }
 
         let mut bundle_meta = BundleMetadata::new(num_requested_spends, num_requested_outputs);
         let pre_actions = indexed_spends_outputs

src/bundle/commitments.rs

@@ -168,7 +168,9 @@ mod tests {
         let sighash = hash_bundle_txid_data(&bundle);
         assert_eq!(
             sighash.to_hex().as_str(),
-            "f3ea89ea2b1e17b3313a6f2f9e4e47c21eec1574902f5ea6961227e1eaed2327"
+            // Bundle hash for Orchard (vanilla) generated using
+            // Zcash/Orchard commit: 9d89b504
+            "0ac1e319f6761a8561b7bd3fc0907a5c73ed5590a6c210c4d39ffae1d5741875"
         );
     }
 
@@ -184,7 +186,7 @@ mod tests {
         let sighash = hash_bundle_txid_data(&bundle);
         assert_eq!(
             sighash.to_hex().as_str(),
-            "a0d843b7278788e3b47dc9fe1e1da227a94898b7111d76514a87df486d32773c"
+            "f84871d872081fa7744cbaf575e342cf81951a9b17818264170243d1551a99ea"
         );
     }
 
@@ -213,7 +215,9 @@ mod tests {
         let orchard_auth_digest = hash_bundle_auth_data(&bundle, test_sighash_info_for_kind);
         assert_eq!(
             orchard_auth_digest.to_hex().as_str(),
-            "c99aa5a33fd4e7b78de0ee846397e2eb0da3a5d176e6df57d0401c49f51d7295"
+            // Bundle hash for Orchard (vanilla) generated using
+            // Zcash/Orchard commit: 9d89b504
+            "5f3bcf759cddf19170ec47a882a470b5767d66c95fc72ffc360f31324474a06b"
         );
     }
 
@@ -230,7 +234,7 @@ mod tests {
         let orchard_auth_digest = hash_bundle_auth_data(&bundle, test_sighash_info_for_kind);
         assert_eq!(
             orchard_auth_digest.to_hex().as_str(),
-            "9d47819082f2323b30ceabe0fea993b39541cc0e62a8be6e1bc2a19840b0d9ab"
+            "0c29408a07863016f5b4c5c0ccc5b944f24c686d06035945c5514f8b8c195a99"
         );
     }
 

tests/builder.rs

@@ -213,16 +213,16 @@ fn bundle_chain_vanilla() {
         orchard_digest_1,
         // Locks the `orchard_digest` for OrchardVanilla
         [
-            25, 143, 25, 148, 146, 133, 196, 243, 163, 122, 136, 217, 179, 122, 70, 233, 4, 4, 26,
-            170, 152, 243, 177, 199, 226, 241, 63, 143, 104, 77, 149, 254
+            165, 242, 106, 135, 168, 224, 110, 252, 175, 110, 63, 29, 78, 243, 33, 14, 152, 202,
+            209, 47, 68, 32, 138, 96, 79, 213, 218, 93, 45, 87, 221, 174
         ]
     );
     assert_eq!(
         orchard_digest_2,
         // Locks the `orchard_digest` for OrchardVanilla
         [
-            164, 197, 26, 212, 108, 232, 219, 47, 64, 35, 3, 171, 77, 191, 253, 173, 173, 0, 148,
-            119, 98, 210, 134, 196, 201, 205, 117, 10, 37, 72, 234, 3
+            74, 174, 42, 41, 68, 92, 171, 110, 10, 148, 217, 61, 68, 50, 49, 1, 1, 180, 221, 210,
+            97, 237, 25, 198, 195, 77, 19, 160, 186, 172, 8, 26
         ]
     );
 }
@@ -234,16 +234,16 @@ fn bundle_chain_zsa() {
         orchard_digest_1,
         // Locks the `orchard_digest` for OrchardZSA
         [
-            47, 247, 30, 9, 58, 47, 181, 208, 48, 162, 133, 51, 186, 54, 13, 82, 207, 227, 33, 48,
-            223, 31, 90, 129, 96, 166, 247, 156, 122, 125, 100, 190
+            176, 24, 152, 89, 60, 222, 215, 240, 176, 197, 147, 81, 4, 84, 61, 189, 163, 117, 43,
+            201, 63, 140, 116, 211, 133, 186, 54, 58, 171, 124, 192, 215
         ]
     );
     assert_eq!(
         orchard_digest_2,
         // Locks the `orchard_digest` for OrchardZSA
         [
-            40, 249, 161, 168, 11, 100, 205, 146, 11, 203, 210, 239, 51, 73, 208, 236, 47, 110, 49,
-            18, 132, 199, 179, 63, 140, 28, 106, 34, 155, 93, 111, 254
+            161, 158, 107, 122, 89, 77, 236, 178, 130, 85, 148, 101, 237, 1, 67, 119, 76, 126, 233,
+            123, 94, 240, 183, 227, 9, 245, 74, 51, 16, 12, 157, 60
         ]
     );
 }