test(#500): add regression test for slippage protection on sell at exact min_proceeds boundary

creator-keys/tests/slippage_sell_boundary.rs

@@ -0,0 +1,49 @@
+//! Regression: sell with min_proceeds == exact quote must succeed (not revert).
+
+mod contract_test_env;
+use contract_test_env::{
+    register_creator_keys, register_test_creator, test_env_with_auths,
+    set_key_price_for_tests, set_protocol_fee_bps, compute_expected_buy_price,
+};
+use soroban_sdk::{testutils::Address as _, Address};
+
+#[test]
+fn sell_succeeds_when_proceeds_equal_min_proceeds_exactly() {
+    let env = test_env_with_auths();
+    let (client, _) = register_creator_keys(&env);
+    set_key_price_for_tests(&env, &client, 100i128);
+    set_protocol_fee_bps(&env, &client, 9000u32, 1000u32);
+    let creator = register_test_creator(&env, &client);
+    let buyer = Address::generate(&env);
+
+    // Buy a key first
+    let buy_price = compute_expected_buy_price(0, 100i128);
+    client.buy_key(&creator, &buyer, &buy_price, &None);
+
+    // Get exact sell quote
+    let exact_proceeds = client.get_sell_quote(&creator, &1i128);
+
+    // Sell with min_proceeds == exact quote: must NOT revert
+    let result = client.try_sell_key(&creator, &buyer, &1i128, &exact_proceeds);
+    assert!(
+        result.is_ok(),
+        "Sell must succeed when min_proceeds equals exact proceeds, got: {:?}", result
+    );
+}
+
+#[test]
+fn sell_reverts_when_proceeds_below_min() {
+    let env = test_env_with_auths();
+    let (client, _) = register_creator_keys(&env);
+    set_key_price_for_tests(&env, &client, 100i128);
+    set_protocol_fee_bps(&env, &client, 9000u32, 1000u32);
+    let creator = register_test_creator(&env, &client);
+    let buyer = Address::generate(&env);
+    let buy_price = compute_expected_buy_price(0, 100i128);
+    client.buy_key(&creator, &buyer, &buy_price, &None);
+    let exact_proceeds = client.get_sell_quote(&creator, &1i128);
+
+    // min_proceeds = exact + 1: must revert (proceeds < min)
+    let result = client.try_sell_key(&creator, &buyer, &1i128, &(exact_proceeds + 1));
+    assert!(result.is_err(), "Sell must revert when min_proceeds exceeds actual proceeds");
+}