feat: harden fee payment and verification flow

dongle-smartcontract/src/errors.rs

@@ -1,5 +1,4 @@
 use soroban_sdk::contracterror;
-
 /// Error types for the Dongle smart contract
 #[contracterror]
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
@@ -53,7 +52,10 @@ pub enum ContractError {
     InvalidProjectDescriptionFormat = 23,
     /// User has exceeded maximum number of projects allowed
     MaxProjectsExceeded = 24,
+    /// Fee already paid for this project in the current verification cycle
+    FeeAlreadyPaid = 25,
+    /// Token provided does not match the configured payment token
+    InvalidToken = 26,
 }
-
 // Legacy alias to avoid breaking any code that uses `Error` directly
-pub type Error = ContractError;
+pub type Error = ContractError;

dongle-smartcontract/src/fee_manager.rs

@@ -52,8 +52,12 @@ impl FeeManager {
             .get(&StorageKey::Treasury)
             .ok_or(ContractError::TreasuryNotSet)?;
 
+        if Self::is_fee_paid(env, project_id) {
+            return Err(ContractError::FeeAlreadyPaid);
+        }
+
         if config.token != token {
-            return Err(ContractError::InvalidProjectData);
+            return Err(ContractError::InvalidToken);
         }
 
         let amount = config.verification_fee;

dongle-smartcontract/src/tests/fixtures.rs

@@ -11,7 +11,7 @@ use soroban_sdk::{testutils::Address as _, Address, Env, String, Vec};
 ///
 /// This is the most basic setup function used by most tests.
 pub fn setup_contract(env: &Env) -> (DongleContractClient<'_>, Address) {
-    let contract_id = env.register(DongleContract, ());
+    let contract_id = env.register_contract(None, DongleContract);
     let client = DongleContractClient::new(env, &contract_id);
 
     let admin = Address::generate(env);
@@ -87,4 +87,4 @@ pub fn assert_project_state(
     assert_eq!(project.name, String::from_str(env, expected_name));
     assert_eq!(project.owner, *expected_owner);
     assert_eq!(project.verification_status, expected_status);
-}
+}