Make simple transfers always satisfy app contracts

charms-data/src/lib.rs

@@ -497,6 +497,15 @@ pub const TOKEN: char = 't';
 /// Special `App.tag` value for non-fungible tokens (NFTs). See [`App`] for more details.
 pub const NFT: char = 'n';
 
+/// Check if the transaction is a simple transfer of assets specified by `app`.
+pub fn is_simple_transfer(app: &App, tx: &Transaction) -> bool {
+    match app.tag {
+        TOKEN => token_amounts_balanced(app, tx) && nft_state_preserved(app, tx),
+        NFT => nft_state_preserved(app, tx),
+        _ => false,
+    }
+}
+
 /// Check if the provided app's token amounts are balanced in the transaction. This means that the
 /// sum of the token amounts in the `tx` inputs is equal to the sum of the token amounts in the `tx`
 /// outputs.

charms-sdk/src/lib.rs

@@ -5,7 +5,7 @@ pub use sp1_zkvm;
 macro_rules! main {
     ($path:path) => {
         fn main() {
-            use charms_sdk::data::{util, App, Data, Transaction};
+            use charms_sdk::data::{is_simple_transfer, util, App, Data, Transaction};
 
             fn read_input() -> (App, Transaction, Data, Data) {
                 let buf = charms_sdk::sp1_zkvm::io::read_vec();
@@ -20,7 +20,7 @@ macro_rules! main {
             }
 
             let (app, tx, x, w): (App, Transaction, Data, Data) = read_input();
-            assert!($path(&app, &tx, &x, &w));
+            assert!(is_simple_transfer(&app, &tx) || $path(&app, &tx, &x, &w));
             commit(app, tx, x);
         }
 

examples/toad-token/src/lib.rs

@@ -1,7 +1,4 @@
-use charms_sdk::data::{
-    check, nft_state_preserved, sum_token_amount, token_amounts_balanced, App, Data, Transaction,
-    UtxoId, B32, NFT, TOKEN,
-};
+use charms_sdk::data::{check, sum_token_amount, App, Data, Transaction, UtxoId, B32, NFT, TOKEN};
 use sha2::{Digest, Sha256};
 
 pub fn app_contract(app: &App, tx: &Transaction, x: &Data, w: &Data) -> bool {
@@ -25,9 +22,7 @@ fn nft_contract_satisfied(app: &App, tx: &Transaction, w: &Data) -> bool {
         identity: app.identity.clone(),
         vk: app.vk.clone(),
     };
-    check!(
-        nft_state_preserved(app, tx) || can_mint_nft(app, tx, w) || can_mint_token(&token_app, tx)
-    );
+    check!(can_mint_nft(app, tx, w) || can_mint_token(&token_app, tx));
     true
 }
 
@@ -58,7 +53,7 @@ pub(crate) fn hash(data: &str) -> B32 {
 }
 
 fn token_contract_satisfied(token_app: &App, tx: &Transaction) -> bool {
-    check!(token_amounts_balanced(token_app, tx) || can_mint_token(token_app, tx));
+    check!(can_mint_token(token_app, tx));
     true
 }