feat(subtensor): add migration to clear orphan subnet identities

pallets/subtensor/src/macros/hooks.rs

@@ -179,7 +179,9 @@ mod hooks {
                 // Fix lock state left behind by subnet-scoped hotkey swaps.
                 .saturating_add(migrations::migrate_fix_subnet_hotkey_lock_swaps::migrate_fix_subnet_hotkey_lock_swaps::<T>())
                 // Populate reverse lookup index for EVM address associations.
-                .saturating_add(migrations::migrate_associated_evm_address_index::migrate_associated_evm_address_index::<T>());
+                .saturating_add(migrations::migrate_associated_evm_address_index::migrate_associated_evm_address_index::<T>())
+                // Remove orphan SubnetIdentitiesV3 entries left for recycled netuids.
+                .saturating_add(migrations::migrate_clear_orphan_subnet_identities_v3::migrate_clear_orphan_subnet_identities_v3::<T>());
             weight
         }
 

pallets/subtensor/src/migrations/migrate_clear_orphan_subnet_identities_v3.rs

@@ -0,0 +1,63 @@
+use crate::{Config, Event, HasMigrationRun, NetworksAdded, Pallet, SubnetIdentitiesV3, Weight};
+use frame_support::traits::Get;
+use scale_info::prelude::string::String;
+use sp_std::vec::Vec;
+use subtensor_runtime_common::NetUid;
+
+/// Remove `SubnetIdentitiesV3` entries that belong to netuids which are no
+/// longer registered networks (`!NetworksAdded`).
+///
+/// Such orphan identities accumulate when a subnet slot is recycled: a new
+/// owner registers a subnet in a previously-used netuid without supplying an
+/// identity, and the stale identity from the prior owner is left in place,
+/// misleading participants about what the subnet is. The registration path
+/// (`set_new_network_state`) only writes on `Some(identity)` and never clears a
+/// pre-existing entry, and the historical `migrate_subnet_identities_to_v3`
+/// migration copied V2 entries unconditionally.
+///
+/// This mirrors the identity-clear in `do_dissolve_network` as a one-shot
+/// upgrade migration: orphan entries are removed and a `SubnetIdentityRemoved`
+/// event is emitted for each; identities of live subnets are untouched.
+pub fn migrate_clear_orphan_subnet_identities_v3<T: Config>() -> Weight {
+    let migration_name = b"migrate_clear_orphan_subnet_identities_v3".to_vec();
+    let mut weight = T::DbWeight::get().reads(1);
+
+    if HasMigrationRun::<T>::get(&migration_name) {
+        log::info!(
+            target: "runtime",
+            "Migration '{}' already run - skipping.",
+            String::from_utf8_lossy(&migration_name)
+        );
+        return weight;
+    }
+
+    log::info!(
+        target: "runtime",
+        "Running migration '{}'",
+        String::from_utf8_lossy(&migration_name),
+    );
+
+    // Collect identity netuids that no longer correspond to a registered subnet.
+    let orphan_netuids: Vec<NetUid> = SubnetIdentitiesV3::<T>::iter_keys()
+        .filter(|netuid| !NetworksAdded::<T>::get(netuid))
+        .collect();
+    let removed = orphan_netuids.len() as u64;
+    weight = weight.saturating_add(T::DbWeight::get().reads(removed));
+
+    for netuid in orphan_netuids {
+        SubnetIdentitiesV3::<T>::remove(netuid);
+        Pallet::<T>::deposit_event(Event::SubnetIdentityRemoved(netuid));
+    }
+    weight = weight.saturating_add(T::DbWeight::get().writes(removed));
+
+    HasMigrationRun::<T>::insert(&migration_name, true);
+    weight = weight.saturating_add(T::DbWeight::get().writes(1));
+
+    log::info!(
+        target: "runtime",
+        "Migration '{}' completed.",
+        String::from_utf8_lossy(&migration_name),
+    );
+
+    weight
+}

pallets/subtensor/src/migrations/mod.rs

@@ -8,6 +8,7 @@ pub mod migrate_associated_evm_address_index;
 pub mod migrate_auto_stake_destination;
 pub mod migrate_cleanup_swap_v3;
 pub mod migrate_clear_deprecated_registration_maps;
+pub mod migrate_clear_orphan_subnet_identities_v3;
 pub mod migrate_coldkey_swap_scheduled;
 pub mod migrate_coldkey_swap_scheduled_to_announcements;
 pub mod migrate_commit_reveal_settings;

pallets/subtensor/src/tests/migration.rs

@@ -78,6 +78,51 @@ fn test_migrate_associated_evm_address_index() {
     });
 }
 
+#[test]
+fn test_migrate_clear_orphan_subnet_identities_v3() {
+    new_test_ext(1).execute_with(|| {
+        let migration_name = b"migrate_clear_orphan_subnet_identities_v3".to_vec();
+        HasMigrationRun::<Test>::remove(&migration_name);
+
+        let orphan_netuid = NetUid::from(1);
+        let live_netuid = NetUid::from(2);
+
+        // live_netuid is a registered network; orphan_netuid is not.
+        NetworksAdded::<Test>::insert(live_netuid, true);
+
+        let orphan_identity = SubnetIdentityV3 {
+            subnet_name: b"orphan".to_vec(),
+            ..Default::default()
+        };
+        let live_identity = SubnetIdentityV3 {
+            subnet_name: b"live".to_vec(),
+            ..Default::default()
+        };
+
+        SubnetIdentitiesV3::<Test>::insert(orphan_netuid, orphan_identity);
+        SubnetIdentitiesV3::<Test>::insert(live_netuid, live_identity.clone());
+
+        crate::migrations::migrate_clear_orphan_subnet_identities_v3::migrate_clear_orphan_subnet_identities_v3::<Test>();
+
+        // The orphan identity is removed; the live subnet identity is preserved.
+        assert!(!SubnetIdentitiesV3::<Test>::contains_key(orphan_netuid));
+        assert_eq!(
+            SubnetIdentitiesV3::<Test>::get(live_netuid),
+            Some(live_identity.clone())
+        );
+
+        // Migration is marked as run.
+        assert!(HasMigrationRun::<Test>::get(&migration_name));
+
+        // Idempotent: re-running is a no-op (live identity still present).
+        crate::migrations::migrate_clear_orphan_subnet_identities_v3::migrate_clear_orphan_subnet_identities_v3::<Test>();
+        assert_eq!(
+            SubnetIdentitiesV3::<Test>::get(live_netuid),
+            Some(live_identity)
+        );
+    });
+}
+
 #[test]
 fn test_migrate_associated_evm_address_index_reconciles_over_cap_buckets() {
     new_test_ext(1).execute_with(|| {
@@ -1254,6 +1299,7 @@ fn test_per_u16_encodes_identically_to_u16() {
 }
 
 #[test]
+#[allow(deprecated)]
 fn test_migrate_last_tx_block_delegate_take() {
     new_test_ext(1).execute_with(|| {
         // ------------------------------

runtime/src/lib.rs

@@ -235,7 +235,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
     //   `spec_version`, and `authoring_version` are the same between Wasm and native.
     // This value is set to 100 to notify Polkadot-JS App (https://polkadot.js.org/apps) to use
     //   the compatible custom types.
-    spec_version: 429,
+    spec_version: 432,
     impl_version: 1,
     apis: RUNTIME_API_VERSIONS,
     transaction_version: 1,