fix: gate issue_carbon_credits behind carbon-oracle auth (Closes #312)

investment_vault/src/events.rs

@@ -415,6 +415,15 @@ pub struct CarbonCreditsTransferred {
     pub amount: i128,
 }
 
+#[contractevent]
+pub struct CarbonCreditsIssued {
+    #[topic]
+    pub to: Address,
+    #[topic]
+    pub project_id: u32,
+    pub credits: i128,
+}
+
 pub fn carbon_oracle_set(env: &Env, oracle: &Address) {
     CarbonOracleSet {
         oracle: oracle.clone(),
@@ -444,6 +453,15 @@ pub fn carbon_credits_transferred(env: &Env, from: &Address, to: &Address, amoun
     .publish(env);
 }
 
+pub fn carbon_credits_issued(env: &Env, to: &Address, project_id: u32, credits: i128) {
+    CarbonCreditsIssued {
+        to: to.clone(),
+        project_id,
+        credits,
+    }
+    .publish(env);
+}
+
 // ── Compliance / regulatory events ───────────────────────────────────────
 
 #[contractevent]

investment_vault/src/lib.rs

@@ -1552,8 +1552,20 @@ impl InvestmentVault {
     }
 
     /// Issue carbon credits to a specified recipient (#184).
+    ///
+    /// Only the carbon credit oracle may mint credits (#312): this closes the
+    /// hole where any caller could credit an arbitrary address with freely
+    /// transferable carbon-credit balances. The authorization gate mirrors
+    /// `set_carbon_credit_price`.
     pub fn issue_carbon_credits(env: Env, to: Address, project_id: u32, amount: i128) -> i128 {
         require_current_state(&env);
+        let oracle: Address = env
+            .storage()
+            .instance()
+            .get(&VaultKey::CarbonOracle)
+            .expect("carbon oracle not set");
+        oracle.require_auth();
+
         let calc = Self::calculate_carbon_credits(env.clone(), project_id, amount);
 
         if calc.credits <= 0 {
@@ -1570,6 +1582,8 @@ impl InvestmentVault {
             &(prev + calc.credits),
         );
 
+        events::carbon_credits_issued(&env, &to, project_id, calc.credits);
+
         calc.credits
     }
 

investment_vault/src/test.rs

@@ -2733,3 +2733,30 @@ fn test_flash_loan_fails_without_repayment() {
         &soroban_sdk::Bytes::new(&s.env),
     );
 }
+
+
+#[test]
+fn test_issue_carbon_credits_rejects_non_oracle_caller() {
+    let s = setup();
+    let oracle = Address::generate(&s.env);
+    s.vault_client.set_carbon_oracle(&oracle);
+
+    let stranger = Address::generate(&s.env);
+    s.env.mock_auths(&[soroban_sdk::testutils::MockAuth {
+        address: &stranger,
+        invoke: &soroban_sdk::testutils::MockAuthInvoke {
+            contract: &s.vault_address,
+            fn_name: "issue_carbon_credits",
+            args: soroban_sdk::vec![&s.env, stranger.clone(), 1u32, 1_000_0000000i128],
+            sub_invokes: &[],
+        },
+    }]);
+
+    let res = s
+        .vault_client
+        .try_issue_carbon_credits(&stranger, &1u32, &1_000_0000000i128);
+    assert!(
+        res.is_err(),
+        "a non-oracle caller must not be able to mint carbon credits"
+    );
+}