fix: clear ValidatorTrust/ValidatorPermit on neuron replace

pallets/subtensor/src/subnets/uids.rs

@@ -46,6 +46,8 @@ impl<T: Config> Pallet<T> {
         }
         Dividends::<T>::mutate(netuid, |v| Self::set_element_at(v, neuron_index, 0));
         StakeWeight::<T>::mutate(netuid, |v| Self::set_element_at(v, neuron_index, 0));
+        ValidatorTrust::<T>::mutate(netuid, |v| Self::set_element_at(v, neuron_index, 0));
+        ValidatorPermit::<T>::mutate(netuid, |v| Self::set_element_at(v, neuron_index, false));
     }
 
     /// Replace the neuron under this uid.

pallets/subtensor/src/tests/uids.rs

@@ -225,6 +225,52 @@ fn test_replace_neuron_resets_last_update() {
     });
 }
 
+#[test]
+fn test_replace_neuron_clears_validator_trust_and_permit() {
+    new_test_ext(1).execute_with(|| {
+        let registration_block: u64 = 0;
+        let replacement_block: u64 = 123;
+        let netuid = NetUid::from(1);
+        let tempo: u16 = 13;
+        let hotkey_account_id = U256::from(1);
+        let coldkey_account_id = U256::from(1234);
+        let new_hotkey_account_id = U256::from(2);
+
+        System::set_block_number(registration_block);
+        add_network(netuid, tempo, 0);
+        register_ok_neuron(netuid, hotkey_account_id, coldkey_account_id, 0);
+
+        let neuron_uid =
+            SubtensorModule::get_uid_for_net_and_hotkey(netuid, &hotkey_account_id).unwrap();
+        let idx = neuron_uid as usize;
+
+        // Simulate the previous occupant having earned a validator_permit and trust score.
+        ValidatorTrust::<Test>::mutate(netuid, |v| {
+            if v.len() <= idx {
+                v.resize(idx + 1, 0);
+            }
+            v[idx] = 42;
+        });
+        ValidatorPermit::<Test>::mutate(netuid, |v| {
+            if v.len() <= idx {
+                v.resize(idx + 1, false);
+            }
+            v[idx] = true;
+        });
+
+        SubtensorModule::replace_neuron(
+            netuid,
+            neuron_uid,
+            &new_hotkey_account_id,
+            replacement_block,
+        );
+
+        // The replaced neuron must not inherit the previous occupant's validator state.
+        assert_eq!(ValidatorTrust::<Test>::get(netuid)[idx], 0);
+        assert!(!ValidatorPermit::<Test>::get(netuid)[idx]);
+    });
+}
+
 #[test]
 fn test_replace_neuron_multiple_subnets() {
     new_test_ext(1).execute_with(|| {