feat(airdrop): add admin-gated sweep_unclaimed to recover unclaimed TLEND

contracts/tlend_airdrop/src/lib.rs

@@ -116,6 +116,31 @@ impl TlendAirdropContract {
         );
     }
 
+    /// Recover unclaimed TLEND from the pool to `to`. Admin only; intended for
+    /// use once an airdrop round has closed or expired, so tokens allocated to
+    /// addresses that never claimed are not trapped in the contract.
+    pub fn sweep_unclaimed(env: Env, caller: Address, to: Address, amount: i128) {
+        caller.require_auth();
+        let admin = Self::get_admin(env.clone());
+        if caller != admin {
+            panic!("Unauthorised caller: not admin");
+        }
+        if amount <= 0 {
+            panic!("amount must be positive");
+        }
+        let token_addr = Self::get_token(env.clone());
+        let token_client = token::Client::new(&env, &token_addr);
+        if token_client.balance(&env.current_contract_address()) < amount {
+            panic!("Insufficient airdrop balance");
+        }
+        token_client.transfer(&env.current_contract_address(), &to, &amount);
+
+        env.events().publish(
+            (symbol_short!("airdrop"), symbol_short!("sweep")),
+            (to, amount),
+        );
+    }
+
     // ── Queries ──────────────────────────────────────────────────────────────
 
     pub fn get_admin(env: Env) -> Address {

contracts/tlend_airdrop/src/test.rs

@@ -168,3 +168,48 @@ fn test_non_admin_cannot_set_root() {
     let attacker = Address::generate(&w.env);
     w.airdrop.set_merkle_root(&attacker, &w.root);
 }
+
+#[test]
+fn test_admin_sweeps_unclaimed_tokens() {
+    let w = setup();
+    w.airdrop.claim(&w.c0, &AMOUNTS[0], &w.proof0);
+
+    let treasury = Address::generate(&w.env);
+    let remaining = w.token.balance(&w.airdrop.address);
+    assert_eq!(remaining, 900);
+
+    w.airdrop.sweep_unclaimed(&w.admin, &treasury, &remaining);
+    assert_eq!(w.token.balance(&treasury), 900);
+    assert_eq!(w.token.balance(&w.airdrop.address), 0);
+}
+
+#[test]
+fn test_admin_can_partially_sweep() {
+    let w = setup();
+    let treasury = Address::generate(&w.env);
+    w.airdrop.sweep_unclaimed(&w.admin, &treasury, &250);
+    assert_eq!(w.token.balance(&treasury), 250);
+    assert_eq!(w.token.balance(&w.airdrop.address), 750);
+}
+
+#[test]
+#[should_panic(expected = "not admin")]
+fn test_non_admin_cannot_sweep() {
+    let w = setup();
+    let attacker = Address::generate(&w.env);
+    w.airdrop.sweep_unclaimed(&attacker, &attacker, &100);
+}
+
+#[test]
+#[should_panic(expected = "amount must be positive")]
+fn test_sweep_rejects_non_positive_amount() {
+    let w = setup();
+    w.airdrop.sweep_unclaimed(&w.admin, &w.admin, &0);
+}
+
+#[test]
+#[should_panic(expected = "Insufficient airdrop balance")]
+fn test_sweep_rejects_amount_above_balance() {
+    let w = setup();
+    w.airdrop.sweep_unclaimed(&w.admin, &w.admin, &1_001);
+}