test(#502): add regression test for TTL extended on creator state after sell

creator-keys/tests/ttl_extended_on_sell.rs

@@ -0,0 +1,41 @@
+//! Regression test: TTL must be extended after sell, not only after buy.
+
+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 ttl_extended_after_sell() {
+    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 to establish initial state
+    let buy_price = compute_expected_buy_price(0, 100i128);
+    client.buy_key(&creator, &buyer, &buy_price, &None);
+
+    // Record TTL after buy
+    let ttl_after_buy = client.get_creator_ttl_remaining(&creator);
+    assert!(ttl_after_buy > 0, "TTL must be positive after buy");
+
+    // Advance ledger to consume some TTL
+    env.ledger().with_mut(|li| { li.sequence_number += 1000; });
+
+    // Sell the key
+    let sell_proceeds = client.get_sell_quote(&creator, &1i128);
+    client.sell_key(&creator, &buyer, &1i128, &sell_proceeds);
+
+    // TTL must be extended after sell
+    let ttl_after_sell = client.get_creator_ttl_remaining(&creator);
+    assert!(
+        ttl_after_sell > ttl_after_buy - 1000,
+        "TTL must be extended after sell: ttl_after_sell={} ttl_after_buy={}",
+        ttl_after_sell, ttl_after_buy
+    );
+}