Fix: Accept Signed FROST Transactions as Input

mina-tx/src/transactions.rs

@@ -2,7 +2,7 @@
 
 use crate::{
     errors::MinaTxError,
-    signatures::Sig,
+    signatures::{Sig, TransactionSignature},
     transactions::{
         legacy_tx::LegacyTransaction,
         network_id::NetworkIdEnvelope,
@@ -89,6 +89,13 @@ impl TransactionEnvelope {
     pub fn from_str_network(s: &str, network_id: NetworkIdEnvelope) -> Result<Self, MinaTxError> {
         let s = s.trim();
 
+        // Try parsing as a TransactionSignature first (output from a previous signing session).
+        // This enables chained multi-group signing where the output of one session is fed as
+        // input to the next. The inner payload already has the previous signature injected.
+        if let Ok(signed) = serde_json::from_str::<TransactionSignature>(s) {
+            return Ok(signed.payload);
+        }
+
         // Try parsing as ZkApp transaction first, then Legacy.
         // IMPORTANT: Do NOT silently swallow parse errors here. If both fail, the caller
         // needs to see the actual serde errors to diagnose the problem — not a generic
@@ -360,6 +367,26 @@ mod tests {
         );
     }
 
+    /// A TransactionSignature (output from a previous FROST signing session) should be
+    /// parseable as input for a subsequent signing session, enabling chained multi-group
+    /// signing of the same transaction.
+    #[cfg(not(feature = "mesa-hardfork"))]
+    #[test]
+    fn test_parse_signed_transaction_as_input() {
+        let json = include_str!("../tests/data/deploy-v0.0.6-admin-signed.json");
+        let result = TransactionEnvelope::from_str_network(
+            json,
+            NetworkIdEnvelope::from(NetworkId::Testnet),
+        );
+        assert!(
+            result.is_ok(),
+            "Signed transaction should be parseable as input: {:?}",
+            result.unwrap_err()
+        );
+        let envelope = result.unwrap();
+        assert!(!envelope.is_legacy());
+    }
+
     #[test]
     fn test_from_str_network_invalid_json() {
         let result = TransactionEnvelope::from_str_network(