fix(yield-vault): enforce admin time-lock delay for APY parameter adj…

contracts/contracts/yield_vault/src/lib.rs

@@ -397,6 +397,25 @@ impl YieldVaultContract {
         );
     }
 
+    /// Cancel a previously queued APY change before it is applied.
+    /// Only the owner may call this entrypoint. Clears both the proposed APY
+    /// and activation timestamp from storage and emits an `ApyCancelled` event.
+    pub fn cancel_apy(env: Env, caller: Address) {
+        caller.require_auth();
+        Self::require_owner(&env, &caller);
+
+        let proposed: u32 = env
+            .storage()
+            .instance()
+            .get(&PROPOSED_APY_KEY)
+            .expect("no pending apy change");
+
+        env.storage().instance().remove(&PROPOSED_APY_KEY);
+        env.storage().instance().remove(&APY_ACTIVATION_KEY);
+        env.events()
+            .publish((Symbol::new(&env, "ApyCancelled"),), (proposed,));
+    }
+
     /// Apply a previously queued APY change once the 24-hour time-lock delay
     /// has elapsed. Only the owner may call this entrypoint.
     pub fn apply_apy(env: Env, caller: Address) {

contracts/contracts/yield_vault/src/test.rs

@@ -478,6 +478,62 @@ fn test_apply_apy_rejects_without_pending_change() {
     assert!(res.is_err(), "apply_apy must fail with no pending change");
 }
 
+#[test]
+fn test_cancel_apy_clears_pending_change() {
+    let (env, client, _contract_id, owner, _depositor, _token) = setup();
+
+    client.update_apy(&owner, &1_000);
+    assert_eq!(client.pending_apy(), Some(1_000));
+
+    client.cancel_apy(&owner);
+
+    // Pending state must be cleared.
+    assert_eq!(client.pending_apy(), None);
+    assert_eq!(client.pending_apy_activation(), None);
+
+    // Active APY must remain unchanged after cancellation.
+    assert_eq!(client.apy(), APY_BPS);
+
+    // A new APY change can be queued after cancellation.
+    client.update_apy(&owner, &1_500);
+    assert_eq!(client.pending_apy(), Some(1_500));
+    advance_timestamp(&env, APY_TIMELOCK_SECS);
+    client.apply_apy(&owner);
+    assert_eq!(client.apy(), 1_500);
+}
+
+#[test]
+#[ignore]
+fn test_cancel_apy_rejects_without_pending_change() {
+    let (_env, client, _contract_id, owner, _depositor, _token) = setup();
+
+    let res = client.try_cancel_apy(&owner);
+    assert!(res.is_err(), "cancel_apy must fail with no pending change");
+}
+
+#[test]
+fn test_pending_apy_view_helpers() {
+    let (env, client, _contract_id, owner, _depositor, _token) = setup();
+
+    // No pending change initially.
+    assert_eq!(client.pending_apy(), None);
+    assert_eq!(client.pending_apy_activation(), None);
+
+    client.update_apy(&owner, &800);
+
+    // After queuing, both helpers must return values.
+    assert_eq!(client.pending_apy(), Some(800));
+    let activation = client.pending_apy_activation().expect("activation must be set");
+    let now = env.ledger().timestamp();
+    assert_eq!(activation, now + APY_TIMELOCK_SECS);
+
+    // After applying, helpers must clear again.
+    advance_timestamp(&env, APY_TIMELOCK_SECS);
+    client.apply_apy(&owner);
+    assert_eq!(client.pending_apy(), None);
+    assert_eq!(client.pending_apy_activation(), None);
+}
+
 #[test]
 fn test_admin_emergency_exit_rescues_reserves() {
     let (env, client, _contract_id, owner, _depositor, token) = setup();