asset-hub-kusama: Prepare ElasticScaling with 3 cores on asset hub kusama and enable buffered election

CHANGELOG.md

@@ -4,8 +4,7 @@ Changelog for the runtimes governed by the Polkadot Fellowship.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
-## [Unreleased]
-
+## [2.0.4] 18.12.2025
 
 ### Changed
 
@@ -14,6 +13,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - asset-hub-polkadot: increase the base deposit for a signed NPoS solution from 4 to 100 DOT, significantly mitigating the risk of transaction spamming ([#1022](https://github.com/polkadot-fellows/runtimes/pull/1022))
 - Adjust OpenGov parameters based on WFC 1701 ([polkadot-fellows/runtimes/pull/873](https://github.com/polkadot-fellows/runtimes/pull/873))
 - asset-hub-kusama: update to latest version of pallet-revive with EVM backend ([polkadot-fellows/runtimes/pull/1029](https://github.com/polkadot-fellows/runtimes/pull/1029))
+- Enable Elastic Scaling on Assethub Kusama ([polkadot-fellows/runtimes/pull/1037](https://github.com/polkadot-fellows/runtimes/pull/1037))
+- Enable buffered validator selection on Assethub Kusama ([polkadot-fellows/runtimes/pull/1037](https://github.com/polkadot-fellows/runtimes/pull/1037))
 
 ### Added
 

Cargo.toml

@@ -10,7 +10,7 @@ pallet-ah-migrator = { path = "pallets/ah-migrator", default-features = false }
 pallet-rc-migrator = { path = "pallets/rc-migrator", default-features = false }
 pallet-ah-ops = { path = "pallets/ah-ops", default-features = false }
 pallet-election-provider-multi-block = { version = "0.5.0", default-features = false }
-pallet-staking-async = { version = "0.7.0", default-features = false }
+pallet-staking-async = { version = "0.7.1", default-features = false }
 hex = { version = "0.4.3", default-features = false }
 rand = { version = "0.9.2" }
 impl-trait-for-tuples = { version = "0.2.3", default-features = false }
@@ -188,7 +188,7 @@ pallet-xcm-bridge-hub = { version = "0.20.0", default-features = false }
 pallet-xcm-bridge-hub-router = { version = "0.22.0", default-features = false }
 parachain-info = { version = "0.24.0", default-features = false, package = "staging-parachain-info" }
 parachains-common = { version = "26.0.0", default-features = false }
-parachains-runtimes-test-utils = { version = "27.0.0" }
+parachains-runtimes-test-utils = { version = "27.0.1" }
 paste = { version = "1.0.14" }
 penpal-emulated-chain = { path = "integration-tests/emulated/chains/parachains/testing/penpal" }
 penpal-runtime = { version = "0.34.0" }
@@ -266,7 +266,7 @@ system-parachains-common = { path = "system-parachains/common", default-features
 tokio = { version = "1.45.0" }
 xcm = { version = "20.0.0", default-features = false, package = "staging-xcm" }
 xcm-builder = { version = "24.0.0", default-features = false, package = "staging-xcm-builder" }
-xcm-emulator = { version = "0.24.0" }
+xcm-emulator = { version = "0.24.1" }
 xcm-executor = { version = "23.0.0", default-features = false, package = "staging-xcm-executor" }
 xcm-runtime-apis = { version = "0.11.0", default-features = false }
 anyhow = { version = "1.0.82" }

relay/kusama/src/lib.rs

@@ -188,7 +188,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: alloc::borrow::Cow::Borrowed("kusama"),
 	impl_name: alloc::borrow::Cow::Borrowed("parity-kusama"),
 	authoring_version: 2,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 26,

relay/polkadot/src/lib.rs

@@ -177,7 +177,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: alloc::borrow::Cow::Borrowed("polkadot"),
 	impl_name: alloc::borrow::Cow::Borrowed("parity-polkadot"),
 	authoring_version: 0,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 26,

system-parachains/asset-hubs/asset-hub-kusama/src/lib.rs

@@ -109,7 +109,9 @@ use system_parachains_constants::{
 	},
 	kusama::{
 		consensus::{
-			async_backing::UNINCLUDED_SEGMENT_CAPACITY, BLOCK_PROCESSING_VELOCITY,
+			elastic_scaling::{
+				BLOCK_PROCESSING_VELOCITY, RELAY_PARENT_OFFSET, UNINCLUDED_SEGMENT_CAPACITY,
+			},
 			RELAY_CHAIN_SLOT_DURATION_MILLIS,
 		},
 		currency::*,
@@ -145,7 +147,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("statemine"),
 	impl_name: Cow::Borrowed("statemine"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 15,
@@ -850,7 +852,7 @@ impl cumulus_pallet_parachain_system::Config for Runtime {
 	type ConsensusHook = ConsensusHook;
 	type WeightInfo = weights::cumulus_pallet_parachain_system::WeightInfo<Runtime>;
 	type SelectCore = cumulus_pallet_parachain_system::DefaultCoreSelector<Runtime>;
-	type RelayParentOffset = ConstU32<0>;
+	type RelayParentOffset = ConstU32<RELAY_PARENT_OFFSET>;
 }
 
 type ConsensusHook = cumulus_pallet_aura_ext::FixedVelocityConsensusHook<
@@ -2313,7 +2315,7 @@ pallet_revive::impl_runtime_apis_plus_revive_traits!(
 
 	impl cumulus_primitives_core::RelayParentOffsetApi<Block> for Runtime {
 		fn relay_parent_offset() -> u32 {
-			0
+			RELAY_PARENT_OFFSET
 		}
 	}
 

system-parachains/asset-hubs/asset-hub-kusama/src/staking/mod.rs

@@ -412,8 +412,8 @@ impl pallet_staking_async::Config for Runtime {
 	type EventListeners = (NominationPools, DelegatedStaking);
 	// Note used; don't care.
 	type MaxInvulnerables = frame_support::traits::ConstU32<20>;
-	type PlanningEraOffset =
-		pallet_staking_async::PlanningEraOffsetOf<Self, RelaySessionDuration, ConstU32<10>>;
+	// This will start election for the next era as soon as an era starts.
+	type PlanningEraOffset = ConstU32<6>;
 	type RcClientInterface = StakingRcClient;
 	type MaxEraDuration = MaxEraDuration;
 	type WeightInfo = weights::pallet_staking_async::WeightInfo<Runtime>;
@@ -425,6 +425,8 @@ impl pallet_staking_async_rc_client::Config for Runtime {
 	type AHStakingInterface = Staking;
 	type SendToRelayChain = StakingXcmToRelayChain;
 	type MaxValidatorSetRetries = ConstU32<64>;
+	// Export elected validator set at end of session 4.
+	type ValidatorSetExportSession = ConstU32<4>;
 }
 
 #[derive(Encode, Decode)]

system-parachains/asset-hubs/asset-hub-polkadot/src/lib.rs

@@ -191,7 +191,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	impl_name: Cow::Borrowed("statemint"),
 	spec_name: Cow::Borrowed("statemint"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 15,

system-parachains/asset-hubs/asset-hub-polkadot/src/staking/mod.rs

@@ -389,6 +389,8 @@ impl pallet_staking_async_rc_client::Config for Runtime {
 	type AHStakingInterface = Staking;
 	type SendToRelayChain = StakingXcmToRelayChain;
 	type MaxValidatorSetRetries = ConstU32<64>;
+	// export validators as soon as election results are ready.
+	type ValidatorSetExportSession = ConstU32<0>;
 }
 
 #[derive(Encode, Decode)]

system-parachains/bridge-hubs/bridge-hub-kusama/src/lib.rs

@@ -179,7 +179,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("bridge-hub-kusama"),
 	impl_name: Cow::Borrowed("bridge-hub-kusama"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 5,

system-parachains/bridge-hubs/bridge-hub-polkadot/src/lib.rs

@@ -186,7 +186,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("bridge-hub-polkadot"),
 	impl_name: Cow::Borrowed("bridge-hub-polkadot"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 4,

system-parachains/collectives/collectives-polkadot/src/lib.rs

@@ -130,7 +130,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("collectives"),
 	impl_name: Cow::Borrowed("collectives"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 7,

system-parachains/constants/src/kusama.rs

@@ -33,6 +33,23 @@ pub mod consensus {
 		/// the relay chain.
 		pub const UNINCLUDED_SEGMENT_CAPACITY: u32 = 3;
 	}
+
+	/// Parameters enabling elastic scaling functionality.
+	pub mod elastic_scaling {
+		/// Build with an offset of 1 behind the relay chain.
+		pub const RELAY_PARENT_OFFSET: u32 = 1;
+
+		/// The upper limit of how many parachain blocks are processed by the relay chain per
+		/// parent. Limits the number of blocks authored per slot. This determines the minimum
+		/// block time of the parachain:
+		/// `RELAY_CHAIN_SLOT_DURATION_MILLIS/BLOCK_PROCESSING_VELOCITY`
+		pub const BLOCK_PROCESSING_VELOCITY: u32 = 3;
+
+		/// Maximum number of blocks simultaneously accepted by the Runtime, not yet included
+		/// into the relay chain.
+		pub const UNINCLUDED_SEGMENT_CAPACITY: u32 =
+			(3 + RELAY_PARENT_OFFSET) * BLOCK_PROCESSING_VELOCITY;
+	}
 }
 
 /// Constants relating to KSM.

system-parachains/coretime/coretime-kusama/src/lib.rs

@@ -153,7 +153,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("coretime-kusama"),
 	impl_name: Cow::Borrowed("coretime-kusama"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 1,

system-parachains/coretime/coretime-polkadot/src/lib.rs

@@ -150,7 +150,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("coretime-polkadot"),
 	impl_name: Cow::Borrowed("coretime-polkadot"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 0,

system-parachains/encointer/src/lib.rs

@@ -146,7 +146,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("encointer-parachain"),
 	impl_name: Cow::Borrowed("encointer-parachain"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 1,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 4,

system-parachains/gluttons/glutton-kusama/src/lib.rs

@@ -94,7 +94,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("glutton"),
 	impl_name: Cow::Borrowed("glutton"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 1,

system-parachains/people/people-kusama/src/lib.rs

@@ -174,7 +174,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("people-kusama"),
 	impl_name: Cow::Borrowed("people-kusama"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 1,

system-parachains/people/people-polkadot/src/lib.rs

@@ -152,7 +152,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("people-polkadot"),
 	impl_name: Cow::Borrowed("people-polkadot"),
 	authoring_version: 1,
-	spec_version: 2_000_003,
+	spec_version: 2_000_004,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 0,