chain-spec: getting ready for native-runtime-free world (#1256)

This PR prepares chains specs for _native-runtime-free_ world. This PR has following changes: - `substrate`: - adds support for: - JSON based `GenesisConfig` to `ChainSpec` allowing interaction with runtime `GenesisBuilder` API. - interacting with arbitrary runtime wasm blob to[ `chain-spec-builder`](https://github.com/paritytech/substrate/blob/3ef576eaeb3f42610e85daecc464961cf1295570/bin/utils/chain-spec-builder/src/lib.rs#L46) command line util, - removes [`code`](https://github.com/paritytech/substrate/blob/3ef576eaeb3f42610e85daecc464961cf1295570/frame/system/src/lib.rs#L660) from `system_pallet` - adds `code` to the `ChainSpec` - deprecates [`ChainSpec::from_genesis`](https://github.com/paritytech/substrate/blob/3ef576eaeb3f42610e85daecc464961cf1295570/client/chain-spec/src/chain_spec.rs#L263), but also changes the signature of this method extending it with `code` argument. [`ChainSpec::builder()`](https://github.com/paritytech/substrate/blob/20bee680ed098be7239cf7a6b804cd4de267983e/client/chain-spec/src/chain_spec.rs#L507) should be used instead. - `polkadot`: - all references to `RuntimeGenesisConfig` in `node/service` are removed, - all `(kusama|polkadot|versi|rococo|wococo)_(staging|dev)_genesis_config` functions now return the JSON patch for default runtime `GenesisConfig`, - `ChainSpecBuilder` is used, `ChainSpec::from_genesis` is removed, - `cumulus`: - `ChainSpecBuilder` is used, `ChainSpec::from_genesis` is removed, - _JSON_ patch configuration used instead of `RuntimeGenesisConfig struct` in all chain specs. --------- Co-authored-by: command-bot <> Co-authored-by: Javier Viola <javier@parity.io> Co-authored-by: Davide Galassi <davxy@datawok.net> Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com> Co-authored-by: Kevin Krone <kevin@parity.io> Co-authored-by: Bastian Köcher <git@kchr.de>
2026-06-12 20:31:13 +00:00 · 2023-11-05 15:19:23 +01:00
parent c46a7dbb61
commit 8ba7a6aba8
90 changed files with 4833 additions and 3059 deletions
@@ -17,6 +17,7 @@ subkey = { path = "bin/utils/subkey" }
 chain-spec-builder = { package = "staging-chain-spec-builder", path = "bin/utils/chain-spec-builder" }

 sc-service = { path = "client/service" }
+sc-chain-spec = { path = "client/chain-spec" }
 sc-cli = { path = "client/cli" }
 sc-consensus-aura = { path = "client/consensus/aura" }
 sc-consensus-babe = { path = "client/consensus/babe" }
@@ -21,6 +21,7 @@ clap = { version = "4.0.9", features = ["derive"] }
 futures = { version = "0.3.21", features = ["thread-pool"] }
 futures-timer = "3.0.1"
 jsonrpsee = { version = "0.16.2", features = ["server"] }
+serde_json = "1.0.107"

 sc-cli = { path = "../../../client/cli" }
 sc-executor = {  path = "../../../client/executor" }
@@ -15,12 +15,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.

-use runtime::{BalancesConfig, RuntimeGenesisConfig, SudoConfig, SystemConfig, WASM_BINARY};
+use runtime::{BalancesConfig, SudoConfig, WASM_BINARY};
 use sc_service::{ChainType, Properties};
+use serde_json::{json, Value};
 use sp_keyring::AccountKeyring;

 /// This is a specialization of the general Substrate ChainSpec type.
-pub type ChainSpec = sc_service::GenericChainSpec<RuntimeGenesisConfig>;
+pub type ChainSpec = sc_service::GenericChainSpec<()>;

 fn props() -> Properties {
 	let mut properties = Properties::new();
@@ -30,37 +31,25 @@ fn props() -> Properties {
 }

 pub fn development_config() -> Result<ChainSpec, String> {
-	let wasm_binary = WASM_BINARY.ok_or_else(|| "Development wasm not available".to_string())?;
-	Ok(ChainSpec::from_genesis(
-		"Development",
-		"dev",
-		ChainType::Development,
-		move || testnet_genesis(wasm_binary),
-		vec![],
-		None,
-		None,
-		None,
-		Some(props()),
-		None,
-	))
+	Ok(ChainSpec::builder(WASM_BINARY.expect("Development wasm not available"), Default::default())
+		.with_name("Development")
+		.with_id("dev")
+		.with_chain_type(ChainType::Development)
+		.with_genesis_config_patch(testnet_genesis())
+		.with_properties(props())
+		.build())
 }

 /// Configure initial storage state for FRAME pallets.
-fn testnet_genesis(wasm_binary: &[u8]) -> RuntimeGenesisConfig {
+fn testnet_genesis() -> Value {
 	use frame::traits::Get;
 	use runtime::interface::{Balance, MinimumBalance};
 	let endowment = <MinimumBalance as Get<Balance>>::get().max(1) * 1000;
 	let balances = AccountKeyring::iter()
 		.map(|a| (a.to_account_id(), endowment))
 		.collect::<Vec<_>>();
-	RuntimeGenesisConfig {
-		system: SystemConfig {
-			// Add Wasm runtime to storage.
-			code: wasm_binary.to_vec(),
-			_config: Default::default(),
-		},
-		balances: BalancesConfig { balances },
-		sudo: SudoConfig { key: Some(AccountKeyring::Alice.to_account_id()) },
-		..Default::default()
-	}
+	json!({
+		"balances": BalancesConfig { balances },
+		"sudo": SudoConfig { key: Some(AccountKeyring::Alice.to_account_id()) },
+	})
 }
@@ -9,6 +9,7 @@ scale-info = { version = "2.6.0", default-features = false }

 # this is a frame-based runtime, thus importing `frame` with runtime feature enabled.
 frame = { path = "../../../frame", default-features = false, features = ["runtime", "experimental"] }
+frame-support = { path = "../../../frame/support", default-features = false}

 # pallets that we want to use
 pallet-balances = { path = "../../../frame/balances", default-features = false }
@@ -17,6 +18,9 @@ pallet-timestamp = { path = "../../../frame/timestamp", default-features = false
 pallet-transaction-payment = { path = "../../../frame/transaction-payment", default-features = false }
 pallet-transaction-payment-rpc-runtime-api = { path = "../../../frame/transaction-payment/rpc/runtime-api", default-features = false }

+# genesis builder that allows us to interacto with runtime genesis config
+sp-genesis-builder = { path = "../../../primitives/genesis-builder", default-features = false}
+

 [build-dependencies]
 substrate-wasm-builder = { path = "../../../utils/wasm-builder", optional = true }
@@ -31,6 +31,7 @@ use frame::{
 		prelude::*,
 	},
 };
+use frame_support::genesis_builder_helper::{build_config, create_default_config};

 #[runtime_version]
 pub const VERSION: RuntimeVersion = RuntimeVersion {
@@ -210,6 +211,16 @@ impl_runtime_apis! {
 			TransactionPayment::length_to_fee(length)
 		}
 	}
+
+	impl sp_genesis_builder::GenesisBuilder<Block> for Runtime {
+		fn create_default_config() -> Vec<u8> {
+			create_default_config::<RuntimeGenesisConfig>()
+		}
+
+		fn build_config(config: Vec<u8>) -> sp_genesis_builder::Result {
+			build_config::<RuntimeGenesisConfig>(config)
+		}
+	}
 }

 /// Some re-exports that the node side code needs to know. Some are useful in this context as well.
@@ -19,6 +19,7 @@ name = "node-template"
 [dependencies]
 clap = { version = "4.4.6", features = ["derive"] }
 futures = { version = "0.3.21", features = ["thread-pool"]}
+serde_json = "1.0.85"

 sc-cli = { path = "../../../client/cli" }
 sp-core = { path = "../../../primitives/core" }
@@ -1,7 +1,4 @@
-use node_template_runtime::{
-	AccountId, AuraConfig, BalancesConfig, GrandpaConfig, RuntimeGenesisConfig, Signature,
-	SudoConfig, SystemConfig, WASM_BINARY,
-};
+use node_template_runtime::{AccountId, RuntimeGenesisConfig, Signature, WASM_BINARY};
 use sc_service::ChainType;
 use sp_consensus_aura::sr25519::AuthorityId as AuraId;
 use sp_consensus_grandpa::AuthorityId as GrandpaId;
@@ -37,122 +34,84 @@ pub fn authority_keys_from_seed(s: &str) -> (AuraId, GrandpaId) {
 }

 pub fn development_config() -> Result<ChainSpec, String> {
-	let wasm_binary = WASM_BINARY.ok_or_else(|| "Development wasm not available".to_string())?;
-
-	Ok(ChainSpec::from_genesis(
-		// Name
-		"Development",
-		// ID
-		"dev",
-		ChainType::Development,
-		move || {
-			testnet_genesis(
-				wasm_binary,
-				// Initial PoA authorities
-				vec![authority_keys_from_seed("Alice")],
-				// Sudo account
-				get_account_id_from_seed::<sr25519::Public>("Alice"),
-				// Pre-funded accounts
-				vec![
-					get_account_id_from_seed::<sr25519::Public>("Alice"),
-					get_account_id_from_seed::<sr25519::Public>("Bob"),
-					get_account_id_from_seed::<sr25519::Public>("Alice//stash"),
-					get_account_id_from_seed::<sr25519::Public>("Bob//stash"),
-				],
-				true,
-			)
-		},
-		// Bootnodes
-		vec![],
-		// Telemetry
-		None,
-		// Protocol ID
-		None,
-		None,
-		// Properties
-		None,
-		// Extensions
+	Ok(ChainSpec::builder(
+		WASM_BINARY.ok_or_else(|| "Development wasm not available".to_string())?,
 		None,
+	)
+	.with_name("Development")
+	.with_id("dev")
+	.with_chain_type(ChainType::Development)
+	.with_genesis_config_patch(testnet_genesis(
+		// Initial PoA authorities
+		vec![authority_keys_from_seed("Alice")],
+		// Sudo account
+		get_account_id_from_seed::<sr25519::Public>("Alice"),
+		// Pre-funded accounts
+		vec![
+			get_account_id_from_seed::<sr25519::Public>("Alice"),
+			get_account_id_from_seed::<sr25519::Public>("Bob"),
+			get_account_id_from_seed::<sr25519::Public>("Alice//stash"),
+			get_account_id_from_seed::<sr25519::Public>("Bob//stash"),
+		],
+		true,
 	))
+	.build())
 }

 pub fn local_testnet_config() -> Result<ChainSpec, String> {
-	let wasm_binary = WASM_BINARY.ok_or_else(|| "Development wasm not available".to_string())?;
-
-	Ok(ChainSpec::from_genesis(
-		// Name
-		"Local Testnet",
-		// ID
-		"local_testnet",
-		ChainType::Local,
-		move || {
-			testnet_genesis(
-				wasm_binary,
-				// Initial PoA authorities
-				vec![authority_keys_from_seed("Alice"), authority_keys_from_seed("Bob")],
-				// Sudo account
-				get_account_id_from_seed::<sr25519::Public>("Alice"),
-				// Pre-funded accounts
-				vec![
-					get_account_id_from_seed::<sr25519::Public>("Alice"),
-					get_account_id_from_seed::<sr25519::Public>("Bob"),
-					get_account_id_from_seed::<sr25519::Public>("Charlie"),
-					get_account_id_from_seed::<sr25519::Public>("Dave"),
-					get_account_id_from_seed::<sr25519::Public>("Eve"),
-					get_account_id_from_seed::<sr25519::Public>("Ferdie"),
-					get_account_id_from_seed::<sr25519::Public>("Alice//stash"),
-					get_account_id_from_seed::<sr25519::Public>("Bob//stash"),
-					get_account_id_from_seed::<sr25519::Public>("Charlie//stash"),
-					get_account_id_from_seed::<sr25519::Public>("Dave//stash"),
-					get_account_id_from_seed::<sr25519::Public>("Eve//stash"),
-					get_account_id_from_seed::<sr25519::Public>("Ferdie//stash"),
-				],
-				true,
-			)
-		},
-		// Bootnodes
-		vec![],
-		// Telemetry
-		None,
-		// Protocol ID
-		None,
-		// Properties
-		None,
-		None,
-		// Extensions
+	Ok(ChainSpec::builder(
+		WASM_BINARY.ok_or_else(|| "Development wasm not available".to_string())?,
 		None,
+	)
+	.with_name("Local Testnet")
+	.with_id("local_testnet")
+	.with_chain_type(ChainType::Local)
+	.with_genesis_config_patch(testnet_genesis(
+		// Initial PoA authorities
+		vec![authority_keys_from_seed("Alice"), authority_keys_from_seed("Bob")],
+		// Sudo account
+		get_account_id_from_seed::<sr25519::Public>("Alice"),
+		// Pre-funded accounts
+		vec![
+			get_account_id_from_seed::<sr25519::Public>("Alice"),
+			get_account_id_from_seed::<sr25519::Public>("Bob"),
+			get_account_id_from_seed::<sr25519::Public>("Charlie"),
+			get_account_id_from_seed::<sr25519::Public>("Dave"),
+			get_account_id_from_seed::<sr25519::Public>("Eve"),
+			get_account_id_from_seed::<sr25519::Public>("Ferdie"),
+			get_account_id_from_seed::<sr25519::Public>("Alice//stash"),
+			get_account_id_from_seed::<sr25519::Public>("Bob//stash"),
+			get_account_id_from_seed::<sr25519::Public>("Charlie//stash"),
+			get_account_id_from_seed::<sr25519::Public>("Dave//stash"),
+			get_account_id_from_seed::<sr25519::Public>("Eve//stash"),
+			get_account_id_from_seed::<sr25519::Public>("Ferdie//stash"),
+		],
+		true,
 	))
+	.build())
 }

 /// Configure initial storage state for FRAME modules.
 fn testnet_genesis(
-	wasm_binary: &[u8],
 	initial_authorities: Vec<(AuraId, GrandpaId)>,
 	root_key: AccountId,
 	endowed_accounts: Vec<AccountId>,
 	_enable_println: bool,
-) -> RuntimeGenesisConfig {
-	RuntimeGenesisConfig {
-		system: SystemConfig {
-			// Add Wasm runtime to storage.
-			code: wasm_binary.to_vec(),
-			..Default::default()
-		},
-		balances: BalancesConfig {
+) -> serde_json::Value {
+	serde_json::json!({
+		"balances": {
 			// Configure endowed accounts with initial balance of 1 << 60.
-			balances: endowed_accounts.iter().cloned().map(|k| (k, 1 << 60)).collect(),
+			"balances": endowed_accounts.iter().cloned().map(|k| (k, 1u64 << 60)).collect::<Vec<_>>(),
 		},
-		aura: AuraConfig {
-			authorities: initial_authorities.iter().map(|x| (x.0.clone())).collect(),
+		"aura": {
+			"authorities": initial_authorities.iter().map(|x| (x.0.clone())).collect::<Vec<_>>(),
 		},
-		grandpa: GrandpaConfig {
-			authorities: initial_authorities.iter().map(|x| (x.1.clone(), 1)).collect(),
-			..Default::default()
+		"grandpa": {
+			"authorities": initial_authorities.iter().map(|x| (x.1.clone(), 1)).collect::<Vec<_>>(),
 		},
-		sudo: SudoConfig {
+		"sudo": {
 			// Assign network admin rights.
-			key: Some(root_key),
+			"key": Some(root_key),
 		},
-		transaction_payment: Default::default(),
-	}
+	})
 }
@@ -14,7 +14,7 @@ targets = ["x86_64-unknown-linux-gnu"]

 [dependencies]
 codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false, features = ["derive"] }
-scale-info = { version = "2.10.0", default-features = false, features = ["derive"] }
+scale-info = { version = "2.10.0", default-features = false, features = ["derive", "serde"] }

 pallet-aura = { path = "../../../frame/aura", default-features = false}
 pallet-balances = { path = "../../../frame/balances", default-features = false}
@@ -28,17 +28,18 @@ pallet-transaction-payment = { path = "../../../frame/transaction-payment", defa
 frame-executive = { path = "../../../frame/executive", default-features = false}
 sp-api = { path = "../../../primitives/api", default-features = false}
 sp-block-builder = { path = "../../../primitives/block-builder", default-features = false}
-sp-consensus-aura = { path = "../../../primitives/consensus/aura", default-features = false}
-sp-consensus-grandpa = { path = "../../../primitives/consensus/grandpa", default-features = false}
-sp-core = { path = "../../../primitives/core", default-features = false}
+sp-consensus-aura = { path = "../../../primitives/consensus/aura", default-features = false, features = ["serde"] }
+sp-consensus-grandpa = { path = "../../../primitives/consensus/grandpa", default-features = false, features = ["serde"] }
+sp-core = { path = "../../../primitives/core", default-features = false, features = ["serde"]}
 sp-inherents = { path = "../../../primitives/inherents", default-features = false}
 sp-offchain = { path = "../../../primitives/offchain", default-features = false}
-sp-runtime = { path = "../../../primitives/runtime", default-features = false}
+sp-runtime = { path = "../../../primitives/runtime", default-features = false, features = ["serde"] }
 sp-session = { path = "../../../primitives/session", default-features = false}
 sp-std = { path = "../../../primitives/std", default-features = false}
 sp-storage = { path = "../../../primitives/storage", default-features = false}
 sp-transaction-pool = { path = "../../../primitives/transaction-pool", default-features = false}
-sp-version = { path = "../../../primitives/version", default-features = false}
+sp-version = { path = "../../../primitives/version", default-features = false, features = ["serde"] }
+serde_json = { version = "1.0.85", default-features = false, features = ["alloc"] }
 sp-genesis-builder = { default-features = false, path = "../../../primitives/genesis-builder" }

 # Used for the node template's RPCs
@@ -75,6 +76,7 @@ std = [
 	"pallet-transaction-payment-rpc-runtime-api/std",
 	"pallet-transaction-payment/std",
 	"scale-info/std",
+	"serde_json/std",
 	"sp-api/std",
 	"sp-block-builder/std",
 	"sp-consensus-aura/std",
@@ -124,7 +124,6 @@ futures = "0.3.21"
 tempfile = "3.1.0"
 assert_cmd = "2.0.2"
 nix = { version = "0.26.1", features = ["signal"] }
-serde_json = "1.0"
 regex = "1.6.0"
 platforms = "3.0"
 soketto = "0.7.1"
@@ -20,10 +20,7 @@

 use grandpa_primitives::AuthorityId as GrandpaId;
 use kitchensink_runtime::{
-	constants::currency::*, wasm_binary_unwrap, BabeConfig, BalancesConfig, Block, CouncilConfig,
-	DemocracyConfig, ElectionsConfig, ImOnlineConfig, IndicesConfig, MaxNominations,
-	NominationPoolsConfig, SessionConfig, SessionKeys, SocietyConfig, StakerStatus, StakingConfig,
-	SudoConfig, SystemConfig, TechnicalCommitteeConfig,
+	constants::currency::*, wasm_binary_unwrap, Block, MaxNominations, SessionKeys, StakerStatus,
 };
 use pallet_im_online::sr25519::AuthorityId as ImOnlineId;
 use sc_chain_spec::ChainSpecExtension;
@@ -45,6 +42,8 @@ pub use node_primitives::{AccountId, Balance, Signature};
 type AccountPublic = <Signature as Verify>::Signer;

 const STAGING_TELEMETRY_URL: &str = "wss://telemetry.polkadot.io/submit/";
+const ENDOWMENT: Balance = 10_000_000 * DOLLARS;
+const STASH: Balance = ENDOWMENT / 1000;

 /// Node `ChainSpec` extensions.
 ///
@@ -78,7 +77,11 @@ fn session_keys(
 	SessionKeys { grandpa, babe, im_online, authority_discovery, mixnet }
 }

-fn staging_testnet_config_genesis() -> RuntimeGenesisConfig {
+fn configure_accounts_for_staging_testnet() -> (
+	Vec<(AccountId, AccountId, GrandpaId, BabeId, ImOnlineId, AuthorityDiscoveryId, MixnetId)>,
+	AccountId,
+	Vec<AccountId>,
+) {
 	#[rustfmt::skip]
 	// stash, controller, session-key
 	// generated with secret:
@@ -190,28 +193,27 @@ fn staging_testnet_config_genesis() -> RuntimeGenesisConfig {
 	);

 	let endowed_accounts: Vec<AccountId> = vec![root_key.clone()];
+	(initial_authorities, root_key, endowed_accounts)
+}

+fn staging_testnet_config_genesis() -> serde_json::Value {
+	let (initial_authorities, root_key, endowed_accounts) =
+		configure_accounts_for_staging_testnet();
 	testnet_genesis(initial_authorities, vec![], root_key, Some(endowed_accounts))
 }

 /// Staging testnet config.
 pub fn staging_testnet_config() -> ChainSpec {
-	let boot_nodes = vec![];
-	ChainSpec::from_genesis(
-		"Staging Testnet",
-		"staging_testnet",
-		ChainType::Live,
-		staging_testnet_config_genesis,
-		boot_nodes,
-		Some(
+	ChainSpec::builder(wasm_binary_unwrap(), Default::default())
+		.with_name("Staging Testnet")
+		.with_id("staging_testnet")
+		.with_chain_type(ChainType::Live)
+		.with_genesis_config_patch(staging_testnet_config_genesis())
+		.with_telemetry_endpoints(
 			TelemetryEndpoints::new(vec![(STAGING_TELEMETRY_URL.to_string(), 0)])
 				.expect("Staging telemetry url is valid; qed"),
-		),
-		None,
-		None,
-		None,
-		Default::default(),
-	)
+		)
+		.build()
 }

 /// Helper function to generate a crypto pair from seed.
@@ -244,8 +246,7 @@ pub fn authority_keys_from_seed(
 	)
 }

-/// Helper function to create RuntimeGenesisConfig for testing.
-pub fn testnet_genesis(
+fn configure_accounts(
 	initial_authorities: Vec<(
 		AccountId,
 		AccountId,
@@ -256,9 +257,14 @@ pub fn testnet_genesis(
 		MixnetId,
 	)>,
 	initial_nominators: Vec<AccountId>,
-	root_key: AccountId,
 	endowed_accounts: Option<Vec<AccountId>>,
-) -> RuntimeGenesisConfig {
+	stash: Balance,
+) -> (
+	Vec<(AccountId, AccountId, GrandpaId, BabeId, ImOnlineId, AuthorityDiscoveryId, MixnetId)>,
+	Vec<AccountId>,
+	usize,
+	Vec<(AccountId, AccountId, Balance, StakerStatus<AccountId>)>,
+) {
 	let mut endowed_accounts: Vec<AccountId> = endowed_accounts.unwrap_or_else(|| {
 		vec![
 			get_account_id_from_seed::<sr25519::Public>("Alice"),
@@ -290,7 +296,7 @@ pub fn testnet_genesis(
 	let mut rng = rand::thread_rng();
 	let stakers = initial_authorities
 		.iter()
-		.map(|x| (x.0.clone(), x.0.clone(), STASH, StakerStatus::Validator))
+		.map(|x| (x.0.clone(), x.0.clone(), stash, StakerStatus::Validator))
 		.chain(initial_nominators.iter().map(|x| {
 			use rand::{seq::SliceRandom, Rng};
 			let limit = (MaxNominations::get() as usize).min(initial_authorities.len());
@@ -301,23 +307,39 @@ pub fn testnet_genesis(
 				.into_iter()
 				.map(|choice| choice.0.clone())
 				.collect::<Vec<_>>();
-			(x.clone(), x.clone(), STASH, StakerStatus::Nominator(nominations))
+			(x.clone(), x.clone(), stash, StakerStatus::Nominator(nominations))
 		}))
 		.collect::<Vec<_>>();

 	let num_endowed_accounts = endowed_accounts.len();

-	const ENDOWMENT: Balance = 10_000_000 * DOLLARS;
-	const STASH: Balance = ENDOWMENT / 1000;
+	(initial_authorities, endowed_accounts, num_endowed_accounts, stakers)
+}

-	RuntimeGenesisConfig {
-		system: SystemConfig { code: wasm_binary_unwrap().to_vec(), ..Default::default() },
-		balances: BalancesConfig {
-			balances: endowed_accounts.iter().cloned().map(|x| (x, ENDOWMENT)).collect(),
+/// Helper function to create RuntimeGenesisConfig json patch for testing.
+pub fn testnet_genesis(
+	initial_authorities: Vec<(
+		AccountId,
+		AccountId,
+		GrandpaId,
+		BabeId,
+		ImOnlineId,
+		AuthorityDiscoveryId,
+		MixnetId,
+	)>,
+	initial_nominators: Vec<AccountId>,
+	root_key: AccountId,
+	endowed_accounts: Option<Vec<AccountId>>,
+) -> serde_json::Value {
+	let (initial_authorities, endowed_accounts, num_endowed_accounts, stakers) =
+		configure_accounts(initial_authorities, initial_nominators, endowed_accounts, STASH);
+
+	serde_json::json!({
+		"balances": {
+			"balances": endowed_accounts.iter().cloned().map(|x| (x, ENDOWMENT)).collect::<Vec<_>>(),
 		},
-		indices: IndicesConfig { indices: vec![] },
-		session: SessionConfig {
-			keys: initial_authorities
+		"session": {
+			"keys": initial_authorities
 				.iter()
 				.map(|x| {
 					(
@@ -334,67 +356,45 @@ pub fn testnet_genesis(
 				})
 				.collect::<Vec<_>>(),
 		},
-		staking: StakingConfig {
-			validator_count: initial_authorities.len() as u32,
-			minimum_validator_count: initial_authorities.len() as u32,
-			invulnerables: initial_authorities.iter().map(|x| x.0.clone()).collect(),
-			slash_reward_fraction: Perbill::from_percent(10),
-			stakers,
-			..Default::default()
+		"staking": {
+			"validatorCount": initial_authorities.len() as u32,
+			"minimumValidatorCount": initial_authorities.len() as u32,
+			"invulnerables": initial_authorities.iter().map(|x| x.0.clone()).collect::<Vec<_>>(),
+			"slashRewardFraction": Perbill::from_percent(10),
+			"stakers": stakers.clone(),
 		},
-		democracy: DemocracyConfig::default(),
-		elections: ElectionsConfig {
-			members: endowed_accounts
+		"elections": {
+			"members": endowed_accounts
 				.iter()
 				.take((num_endowed_accounts + 1) / 2)
 				.cloned()
 				.map(|member| (member, STASH))
-				.collect(),
+				.collect::<Vec<_>>(),
 		},
-		council: CouncilConfig::default(),
-		technical_committee: TechnicalCommitteeConfig {
-			members: endowed_accounts
+		"technicalCommittee": {
+			"members": endowed_accounts
 				.iter()
 				.take((num_endowed_accounts + 1) / 2)
 				.cloned()
-				.collect(),
-			phantom: Default::default(),
+				.collect::<Vec<_>>(),
 		},
-		sudo: SudoConfig { key: Some(root_key) },
-		babe: BabeConfig {
-			epoch_config: Some(kitchensink_runtime::BABE_GENESIS_EPOCH_CONFIG),
-			..Default::default()
+		"sudo": { "key": Some(root_key.clone()) },
+		"babe": {
+			"epochConfig": Some(kitchensink_runtime::BABE_GENESIS_EPOCH_CONFIG),
 		},
-		im_online: ImOnlineConfig { keys: vec![] },
-		authority_discovery: Default::default(),
-		grandpa: Default::default(),
-		technical_membership: Default::default(),
-		treasury: Default::default(),
-		society: SocietyConfig { pot: 0 },
-		vesting: Default::default(),
-		assets: pallet_assets::GenesisConfig {
+		"society": { "pot": 0 },
+		"assets": {
 			// This asset is used by the NIS pallet as counterpart currency.
-			assets: vec![(9, get_account_id_from_seed::<sr25519::Public>("Alice"), true, 1)],
-			..Default::default()
+			"assets": vec![(9, get_account_id_from_seed::<sr25519::Public>("Alice"), true, 1)],
 		},
-		pool_assets: Default::default(),
-		transaction_storage: Default::default(),
-		transaction_payment: Default::default(),
-		alliance: Default::default(),
-		safe_mode: Default::default(),
-		tx_pause: Default::default(),
-		alliance_motion: Default::default(),
-		nomination_pools: NominationPoolsConfig {
-			min_create_bond: 10 * DOLLARS,
-			min_join_bond: 1 * DOLLARS,
-			..Default::default()
+		"nominationPools": {
+			"minCreateBond": 10 * DOLLARS,
+			"minJoinBond": 1 * DOLLARS,
 		},
-		glutton: Default::default(),
-		mixnet: Default::default(),
-	}
+	})
 }

-fn development_config_genesis() -> RuntimeGenesisConfig {
+fn development_config_genesis_json() -> serde_json::Value {
 	testnet_genesis(
 		vec![authority_keys_from_seed("Alice")],
 		vec![],
@@ -405,21 +405,15 @@ fn development_config_genesis() -> RuntimeGenesisConfig {

 /// Development config (single validator Alice).
 pub fn development_config() -> ChainSpec {
-	ChainSpec::from_genesis(
-		"Development",
-		"dev",
-		ChainType::Development,
-		development_config_genesis,
-		vec![],
-		None,
-		None,
-		None,
-		None,
-		Default::default(),
-	)
+	ChainSpec::builder(wasm_binary_unwrap(), Default::default())
+		.with_name("Development")
+		.with_id("dev")
+		.with_chain_type(ChainType::Development)
+		.with_genesis_config_patch(development_config_genesis_json())
+		.build()
 }

-fn local_testnet_genesis() -> RuntimeGenesisConfig {
+fn local_testnet_genesis() -> serde_json::Value {
 	testnet_genesis(
 		vec![authority_keys_from_seed("Alice"), authority_keys_from_seed("Bob")],
 		vec![],
@@ -430,18 +424,12 @@ fn local_testnet_genesis() -> RuntimeGenesisConfig {

 /// Local testnet config (multivalidator Alice + Bob).
 pub fn local_testnet_config() -> ChainSpec {
-	ChainSpec::from_genesis(
-		"Local Testnet",
-		"local_testnet",
-		ChainType::Local,
-		local_testnet_genesis,
-		vec![],
-		None,
-		None,
-		None,
-		None,
-		Default::default(),
-	)
+	ChainSpec::builder(wasm_binary_unwrap(), Default::default())
+		.with_name("Local Testnet")
+		.with_id("local_testnet")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config_patch(local_testnet_genesis())
+		.build()
 }

 #[cfg(test)]
@@ -451,45 +439,29 @@ pub(crate) mod tests {
 	use sc_service_test;
 	use sp_runtime::BuildStorage;

-	fn local_testnet_genesis_instant_single() -> RuntimeGenesisConfig {
-		testnet_genesis(
-			vec![authority_keys_from_seed("Alice")],
-			vec![],
-			get_account_id_from_seed::<sr25519::Public>("Alice"),
-			None,
-		)
-	}
-
 	/// Local testnet config (single validator - Alice).
 	pub fn integration_test_config_with_single_authority() -> ChainSpec {
-		ChainSpec::from_genesis(
-			"Integration Test",
-			"test",
-			ChainType::Development,
-			local_testnet_genesis_instant_single,
-			vec![],
-			None,
-			None,
-			None,
-			None,
-			Default::default(),
-		)
+		ChainSpec::builder(wasm_binary_unwrap(), Default::default())
+			.with_name("Integration Test")
+			.with_id("test")
+			.with_chain_type(ChainType::Development)
+			.with_genesis_config_patch(testnet_genesis(
+				vec![authority_keys_from_seed("Alice")],
+				vec![],
+				get_account_id_from_seed::<sr25519::Public>("Alice"),
+				None,
+			))
+			.build()
 	}

 	/// Local testnet config (multivalidator Alice + Bob).
 	pub fn integration_test_config_with_two_authorities() -> ChainSpec {
-		ChainSpec::from_genesis(
-			"Integration Test",
-			"test",
-			ChainType::Development,
-			local_testnet_genesis,
-			vec![],
-			None,
-			None,
-			None,
-			None,
-			Default::default(),
-		)
+		ChainSpec::builder(wasm_binary_unwrap(), Default::default())
+			.with_name("Integration Test")
+			.with_id("test")
+			.with_chain_type(ChainType::Development)
+			.with_genesis_config_patch(local_testnet_genesis())
+			.build()
 	}

 	#[test]
@@ -14,17 +14,17 @@ targets = ["x86_64-unknown-linux-gnu"]

 [dependencies]
 codec = { package = "parity-scale-codec", version = "3.6.1" }
-scale-info = { version = "2.10.0", features = ["derive"] }
+scale-info = { version = "2.10.0", features = ["derive", "serde"] }
 frame-benchmarking = { path = "../../../frame/benchmarking" }
 node-primitives = { path = "../primitives" }
 kitchensink-runtime = { path = "../runtime" }
 sc-executor = { path = "../../../client/executor" }
-sp-core = { path = "../../../primitives/core" }
+sp-core = { path = "../../../primitives/core", features=["serde"] }
 sp-keystore = { path = "../../../primitives/keystore" }
 sp-state-machine = { path = "../../../primitives/state-machine" }
 sp-tracing = { path = "../../../primitives/tracing" }
 sp-trie = { path = "../../../primitives/trie" }
-sp-statement-store = { path = "../../../primitives/statement-store" }
+sp-statement-store = { path = "../../../primitives/statement-store", features=["serde"] }

 [dev-dependencies]
 criterion = "0.4.0"
@@ -47,6 +47,7 @@ sp-consensus-babe = { path = "../../../primitives/consensus/babe" }
 sp-externalities = { path = "../../../primitives/externalities" }
 sp-keyring = { path = "../../../primitives/keyring" }
 sp-runtime = { path = "../../../primitives/runtime" }
+serde_json = "1.0.85"

 [features]
 stress-test = []
@@ -190,7 +190,7 @@ fn bench_execute_block(c: &mut Criterion) {

 	for strategy in execution_methods {
 		group.bench_function(format!("{:?}", strategy), |b| {
-			let genesis_config = node_testing::genesis::config(Some(compact_code_unwrap()));
+			let genesis_config = node_testing::genesis::config();
 			let use_native = match strategy {
 				ExecutionMethod::Native => true,
 				ExecutionMethod::Wasm(..) => false,
@@ -857,3 +857,19 @@ fn should_import_block_with_test_client() {

 	futures::executor::block_on(client.import(BlockOrigin::Own, block)).unwrap();
 }
+
+#[test]
+fn default_config_as_json_works() {
+	let mut t = new_test_ext(compact_code_unwrap());
+	let r = executor_call(&mut t, "GenesisBuilder_create_default_config", &vec![], false)
+		.0
+		.unwrap();
+	let r = Vec::<u8>::decode(&mut &r[..]).unwrap();
+	let json = String::from_utf8(r.into()).expect("returned value is json. qed.");
+	let expected = include_str!("res/default_genesis_config.json").to_string();
+
+	assert_eq!(
+		serde_json::from_str::<serde_json::Value>(&expected).unwrap(),
+		serde_json::from_str::<serde_json::Value>(&json).unwrap()
+	);
+}
@@ -124,7 +124,7 @@ pub fn executor_call(
 pub fn new_test_ext(code: &[u8]) -> TestExternalities<BlakeTwo256> {
 	let ext = TestExternalities::new_with_code(
 		code,
-		node_testing::genesis::config(Some(code)).build_storage().unwrap(),
+		node_testing::genesis::config().build_storage().unwrap(),
 	);
 	ext
 }
@@ -0,0 +1,108 @@
+{
+  "system": {},
+  "babe": {
+    "authorities": [],
+    "epochConfig": null
+  },
+  "indices": {
+    "indices": []
+  },
+  "balances": {
+    "balances": []
+  },
+  "transactionPayment": {
+    "multiplier": "1000000000000000000"
+  },
+  "staking": {
+    "validatorCount": 0,
+    "minimumValidatorCount": 0,
+    "invulnerables": [],
+    "forceEra": "NotForcing",
+    "slashRewardFraction": 0,
+    "canceledPayout": 0,
+    "stakers": [],
+    "minNominatorBond": 0,
+    "minValidatorBond": 0,
+    "maxValidatorCount": null,
+    "maxNominatorCount": null
+  },
+  "session": {
+    "keys": []
+  },
+  "democracy": {},
+  "council": {
+    "members": []
+  },
+  "technicalCommittee": {
+    "members": []
+  },
+  "elections": {
+    "members": []
+  },
+  "technicalMembership": {
+    "members": []
+  },
+  "grandpa": {
+    "authorities": []
+  },
+  "treasury": {},
+  "sudo": {
+    "key": null
+  },
+  "imOnline": {
+    "keys": []
+  },
+  "authorityDiscovery": {
+    "keys": []
+  },
+  "society": {
+    "pot": 0
+  },
+  "vesting": {
+    "vesting": []
+  },
+  "glutton": {
+    "compute": "0",
+    "storage": "0",
+    "trashDataCount": 0
+  },
+  "assets": {
+    "assets": [],
+    "metadata": [],
+    "accounts": []
+  },
+  "poolAssets": {
+    "assets": [],
+    "metadata": [],
+    "accounts": []
+  },
+  "transactionStorage": {
+    "byteFee": 10,
+    "entryFee": 1000,
+    "storagePeriod": 100800
+  },
+  "allianceMotion": {
+    "members": []
+  },
+  "alliance": {
+    "fellows": [],
+    "allies": []
+  },
+  "mixnet": {
+    "mixnodes": []
+  },
+  "nominationPools": {
+    "minJoinBond": 0,
+    "minCreateBond": 0,
+    "maxPools": 16,
+    "maxMembersPerPool": 32,
+    "maxMembers": 512,
+    "globalMaxCommission": null
+  },
+  "txPause": {
+    "paused": []
+  },
+  "safeMode": {
+    "enteredUntil": null
+  }
+}
@@ -20,33 +20,34 @@ codec = { package = "parity-scale-codec", version = "3.6.1", default-features =
 	"derive",
 	"max-encoded-len",
 ] }
-scale-info = { version = "2.10.0", default-features = false, features = ["derive"] }
+scale-info = { version = "2.10.0", default-features = false, features = ["derive", "serde"] }
 static_assertions = "1.1.0"
 log = { version = "0.4.17", default-features = false }
+serde_json = { version = "1.0.85", default-features = false, features = ["alloc", "arbitrary_precision"] }

 # pallet-asset-conversion: turn on "num-traits" feature
 primitive-types = { version = "0.12.0", default-features = false, features = ["codec", "scale-info", "num-traits"] }

 # primitives
-sp-authority-discovery = { path = "../../../primitives/authority-discovery", default-features = false}
-sp-consensus-babe = { path = "../../../primitives/consensus/babe", default-features = false}
-sp-consensus-grandpa = { path = "../../../primitives/consensus/grandpa", default-features = false}
+sp-authority-discovery = { path = "../../../primitives/authority-discovery", default-features = false, features=["serde"] }
+sp-consensus-babe = { path = "../../../primitives/consensus/babe", default-features = false, features=["serde"] }
+sp-consensus-grandpa = { path = "../../../primitives/consensus/grandpa", default-features = false, features=["serde"] }
 sp-block-builder = { path = "../../../primitives/block-builder", default-features = false}
 sp-genesis-builder = { default-features = false, path = "../../../primitives/genesis-builder" }
 sp-inherents = { path = "../../../primitives/inherents", default-features = false}
 node-primitives = { path = "../primitives", default-features = false}
 sp-mixnet = { path = "../../../primitives/mixnet", default-features = false }
 sp-offchain = { path = "../../../primitives/offchain", default-features = false}
-sp-core = { path = "../../../primitives/core", default-features = false}
+sp-core = { path = "../../../primitives/core", default-features = false, features=["serde"] }
 sp-std = { path = "../../../primitives/std", default-features = false}
 sp-api = { path = "../../../primitives/api", default-features = false}
-sp-runtime = { path = "../../../primitives/runtime", default-features = false}
-sp-staking = { path = "../../../primitives/staking", default-features = false}
+sp-runtime = { path = "../../../primitives/runtime", default-features = false, features=["serde"] }
+sp-staking = { path = "../../../primitives/staking", default-features = false, features=["serde"] }
 sp-storage = { path = "../../../primitives/storage", default-features = false}
 sp-session = { path = "../../../primitives/session", default-features = false}
 sp-transaction-pool = { path = "../../../primitives/transaction-pool", default-features = false}
-sp-statement-store = { path = "../../../primitives/statement-store", default-features = false}
-sp-version = { path = "../../../primitives/version", default-features = false}
+sp-statement-store = { path = "../../../primitives/statement-store", default-features = false, features=["serde"] }
+sp-version = { path = "../../../primitives/version", default-features = false, features=["serde"] }
 sp-io = { path = "../../../primitives/io", default-features = false}

 # frame dependencies
@@ -230,6 +231,7 @@ std = [
 	"pallet-whitelist/std",
 	"primitive-types/std",
 	"scale-info/std",
+	"serde_json/std",
 	"sp-api/std",
 	"sp-authority-discovery/std",
 	"sp-block-builder/std",
@@ -398,7 +398,7 @@ impl BenchDb {

 		let client_config = sc_service::ClientConfig::default();
 		let genesis_block_builder = sc_service::GenesisBlockBuilder::new(
-			&keyring.generate_genesis(),
+			keyring.as_storage_builder(),
 			!client_config.no_genesis,
 			backend.clone(),
 			executor.clone(),
@@ -590,12 +590,20 @@ impl BenchKeyring {
 		}
 	}

-	/// Generate genesis with accounts from this keyring endowed with some balance.
-	pub fn generate_genesis(&self) -> kitchensink_runtime::RuntimeGenesisConfig {
-		crate::genesis::config_endowed(
-			Some(kitchensink_runtime::wasm_binary_unwrap()),
-			self.collect_account_ids(),
-		)
+	/// Generate genesis with accounts from this keyring endowed with some balance and
+	/// kitchensink_runtime code blob.
+	pub fn as_storage_builder(&self) -> &dyn sp_runtime::BuildStorage {
+		self
+	}
+}
+
+impl sp_runtime::BuildStorage for BenchKeyring {
+	fn assimilate_storage(&self, storage: &mut sp_core::storage::Storage) -> Result<(), String> {
+		storage.top.insert(
+			sp_core::storage::well_known_keys::CODE.to_vec(),
+			kitchensink_runtime::wasm_binary_unwrap().into(),
+		);
+		crate::genesis::config_endowed(self.collect_account_ids()).assimilate_storage(storage)
 	}
 }

@@ -42,7 +42,12 @@ pub struct GenesisParameters;

 impl substrate_test_client::GenesisInit for GenesisParameters {
 	fn genesis_storage(&self) -> Storage {
-		crate::genesis::config(None).build_storage().unwrap()
+		let mut storage = crate::genesis::config().build_storage().unwrap();
+		storage.top.insert(
+			sp_core::storage::well_known_keys::CODE.to_vec(),
+			kitchensink_runtime::wasm_binary_unwrap().into(),
+		);
+		storage
 	}
 }

@@ -20,22 +20,21 @@

 use crate::keyring::*;
 use kitchensink_runtime::{
-	constants::currency::*, wasm_binary_unwrap, AccountId, AssetsConfig, BabeConfig,
-	BalancesConfig, GluttonConfig, GrandpaConfig, IndicesConfig, RuntimeGenesisConfig,
-	SessionConfig, SocietyConfig, StakerStatus, StakingConfig, SystemConfig,
-	BABE_GENESIS_EPOCH_CONFIG,
+	constants::currency::*, AccountId, AssetsConfig, BabeConfig, BalancesConfig, GluttonConfig,
+	GrandpaConfig, IndicesConfig, RuntimeGenesisConfig, SessionConfig, SocietyConfig, StakerStatus,
+	StakingConfig, BABE_GENESIS_EPOCH_CONFIG,
 };
 use sp_keyring::{Ed25519Keyring, Sr25519Keyring};
 use sp_runtime::Perbill;

 /// Create genesis runtime configuration for tests.
-pub fn config(code: Option<&[u8]>) -> RuntimeGenesisConfig {
-	config_endowed(code, Default::default())
+pub fn config() -> RuntimeGenesisConfig {
+	config_endowed(Default::default())
 }

 /// Create genesis runtime configuration for tests with some extra
 /// endowed accounts.
-pub fn config_endowed(code: Option<&[u8]>, extra_endowed: Vec<AccountId>) -> RuntimeGenesisConfig {
+pub fn config_endowed(extra_endowed: Vec<AccountId>) -> RuntimeGenesisConfig {
 	let mut endowed = vec![
 		(alice(), 111 * DOLLARS),
 		(bob(), 100 * DOLLARS),
@@ -48,10 +47,7 @@ pub fn config_endowed(code: Option<&[u8]>, extra_endowed: Vec<AccountId>) -> Run
 	endowed.extend(extra_endowed.into_iter().map(|endowed| (endowed, 100 * DOLLARS)));

 	RuntimeGenesisConfig {
-		system: SystemConfig {
-			code: code.map(|x| x.to_vec()).unwrap_or_else(|| wasm_binary_unwrap().to_vec()),
-			..Default::default()
-		},
+		system: Default::default(),
 		indices: IndicesConfig { indices: vec![] },
 		balances: BalancesConfig { balances: endowed },
 		session: SessionConfig {
@@ -23,8 +23,12 @@ crate-type = ["rlib"]
 ansi_term = "0.12.1"
 clap = { version = "4.4.6", features = ["derive"] }
 rand = "0.8"
+kitchensink-runtime = { version = "3.0.0-dev", path = "../../node/runtime" }
+log = "0.4.17"
 node-cli = { package = "staging-node-cli", path = "../../node/cli" }
 sc-chain-spec = { path = "../../../client/chain-spec" }
 sc-keystore = { path = "../../../client/keystore" }
+serde_json = "1.0.100"
 sp-core = { path = "../../../primitives/core" }
 sp-keystore = { path = "../../../primitives/keystore" }
+sp-tracing = { version = "10.0.0", path = "../../../primitives/tracing" }
@@ -17,28 +17,40 @@
 // along with this program. If not, see <https://www.gnu.org/licenses/>.

 use chain_spec_builder::{
-	generate_authority_keys_and_store, generate_chain_spec, print_seeds, ChainSpecBuilder,
+	generate_authority_keys_and_store, generate_chain_spec, generate_chain_spec_for_runtime,
+	print_seeds, ChainSpecBuilder, ChainSpecBuilderCmd, EditCmd, GenerateCmd, NewCmd, VerifyCmd,
 };
 use clap::Parser;
 use node_cli::chain_spec;
 use rand::{distributions::Alphanumeric, rngs::OsRng, Rng};
+use sc_chain_spec::{update_code_in_json_chain_spec, GenericChainSpec};
 use sp_core::{crypto::Ss58Codec, sr25519};
 use staging_chain_spec_builder as chain_spec_builder;
 use std::fs;

 fn main() -> Result<(), String> {
-	#[cfg(build_type = "debug")]
-	println!(
-		"The chain spec builder builds a chain specification that includes a Substrate runtime \
-		 compiled as WASM. To ensure proper functioning of the included runtime compile (or run) \
-		 the chain spec builder binary in `--release` mode.\n",
-	);
+	sp_tracing::try_init_simple();

 	let builder = ChainSpecBuilder::parse();
-	let chain_spec_path = builder.chain_spec_path().to_path_buf();
+	#[cfg(build_type = "debug")]
+	if matches!(builder.command, ChainSpecBuilderCmd::Generate(_) | ChainSpecBuilderCmd::New(_)) {
+		println!(
+			"The chain spec builder builds a chain specification that includes a Substrate runtime \
+		 compiled as WASM. To ensure proper functioning of the included runtime compile (or run) \
+		 the chain spec builder binary in `--release` mode.\n",
+		 );
+	}

-	let (authority_seeds, nominator_accounts, endowed_accounts, sudo_account) = match builder {
-		ChainSpecBuilder::Generate { authorities, nominators, endowed, keystore_path, .. } => {
+	let chain_spec_path = builder.chain_spec_path.to_path_buf();
+	let mut write_chain_spec = true;
+
+	let chain_spec_json = match builder.command {
+		ChainSpecBuilderCmd::Generate(GenerateCmd {
+			authorities,
+			nominators,
+			endowed,
+			keystore_path,
+		}) => {
 			let authorities = authorities.max(1);
 			let rand_str = || -> String {
 				OsRng.sample_iter(&Alphanumeric).take(32).map(char::from).collect()
@@ -72,19 +84,58 @@ fn main() -> Result<(), String> {
 			let sudo_account =
 				chain_spec::get_account_id_from_seed::<sr25519::Public>(&sudo_seed).to_ss58check();

-			(authority_seeds, nominator_accounts, endowed_accounts, sudo_account)
+			generate_chain_spec(authority_seeds, nominator_accounts, endowed_accounts, sudo_account)
 		},
-		ChainSpecBuilder::New {
+		ChainSpecBuilderCmd::New(NewCmd {
 			authority_seeds,
 			nominator_accounts,
 			endowed_accounts,
 			sudo_account,
-			..
-		} => (authority_seeds, nominator_accounts, endowed_accounts, sudo_account),
-	};
+		}) =>
+			generate_chain_spec(authority_seeds, nominator_accounts, endowed_accounts, sudo_account),
+		ChainSpecBuilderCmd::Runtime(cmd) => generate_chain_spec_for_runtime(&cmd),
+		ChainSpecBuilderCmd::Edit(EditCmd {
+			ref input_chain_spec,
+			ref runtime_wasm_path,
+			convert_to_raw,
+		}) => {
+			let chain_spec = GenericChainSpec::<()>::from_json_file(input_chain_spec.clone())?;

-	let json =
-		generate_chain_spec(authority_seeds, nominator_accounts, endowed_accounts, sudo_account)?;
+			let mut chain_spec_json =
+				serde_json::from_str::<serde_json::Value>(&chain_spec.as_json(convert_to_raw)?)
+					.map_err(|e| format!("Conversion to json failed: {e}"))?;
+			if let Some(path) = runtime_wasm_path {
+				update_code_in_json_chain_spec(
+					&mut chain_spec_json,
+					&fs::read(path.as_path())
+						.map_err(|e| format!("Wasm blob file could not be read: {e}"))?[..],
+				);
+			}

-	fs::write(chain_spec_path, json).map_err(|err| err.to_string())
+			serde_json::to_string_pretty(&chain_spec_json)
+				.map_err(|e| format!("to pretty failed: {e}"))
+		},
+		ChainSpecBuilderCmd::Verify(VerifyCmd { ref input_chain_spec, ref runtime_wasm_path }) => {
+			write_chain_spec = false;
+			let chain_spec = GenericChainSpec::<()>::from_json_file(input_chain_spec.clone())?;
+			let mut chain_spec_json =
+				serde_json::from_str::<serde_json::Value>(&chain_spec.as_json(true)?)
+					.map_err(|e| format!("Conversion to json failed: {e}"))?;
+			if let Some(path) = runtime_wasm_path {
+				update_code_in_json_chain_spec(
+					&mut chain_spec_json,
+					&fs::read(path.as_path())
+						.map_err(|e| format!("Wasm blob file could not be read: {e}"))?[..],
+				);
+			};
+			serde_json::to_string_pretty(&chain_spec_json)
+				.map_err(|e| format!("to pretty failed: {e}"))
+		},
+	}?;
+
+	if write_chain_spec {
+		fs::write(chain_spec_path, chain_spec_json).map_err(|err| err.to_string())
+	} else {
+		Ok(())
+	}
 }
@@ -29,96 +29,169 @@
 //! [`sc-chain-spec`]: ../sc_chain_spec/index.html
 //! [`node-cli`]: ../node_cli/index.html

-use std::path::{Path, PathBuf};
+use std::{
+	fs,
+	path::{Path, PathBuf},
+};

 use ansi_term::Style;
-use clap::Parser;
+use clap::{Parser, Subcommand};
+use sc_chain_spec::GenesisConfigBuilderRuntimeCaller;

 use node_cli::chain_spec::{self, AccountId};
 use sc_keystore::LocalKeystore;
+use serde_json::Value;
 use sp_core::crypto::{ByteArray, Ss58Codec};
 use sp_keystore::KeystorePtr;

 /// A utility to easily create a testnet chain spec definition with a given set
 /// of authorities and endowed accounts and/or generate random accounts.
-#[derive(Parser)]
+#[derive(Debug, Parser)]
 #[command(rename_all = "kebab-case")]
-pub enum ChainSpecBuilder {
-	/// Create a new chain spec with the given authorities, endowed and sudo
-	/// accounts.
-	New {
-		/// Authority key seed.
-		#[arg(long, short, required = true)]
-		authority_seeds: Vec<String>,
-		/// Active nominators (SS58 format), each backing a random subset of the aforementioned
-		/// authorities.
-		#[arg(long, short, default_value = "0")]
-		nominator_accounts: Vec<String>,
-		/// Endowed account address (SS58 format).
-		#[arg(long, short)]
-		endowed_accounts: Vec<String>,
-		/// Sudo account address (SS58 format).
-		#[arg(long, short)]
-		sudo_account: String,
-		/// The path where the chain spec should be saved.
-		#[arg(long, short, default_value = "./chain_spec.json")]
-		chain_spec_path: PathBuf,
-	},
-	/// Create a new chain spec with the given number of authorities and endowed
-	/// accounts. Random keys will be generated as required.
-	Generate {
-		/// The number of authorities.
-		#[arg(long, short)]
-		authorities: usize,
-		/// The number of nominators backing the aforementioned authorities.
-		///
-		/// Will nominate a random subset of `authorities`.
-		#[arg(long, short, default_value_t = 0)]
-		nominators: usize,
-		/// The number of endowed accounts.
-		#[arg(long, short, default_value_t = 0)]
-		endowed: usize,
-		/// The path where the chain spec should be saved.
-		#[arg(long, short, default_value = "./chain_spec.json")]
-		chain_spec_path: PathBuf,
-		/// Path to use when saving generated keystores for each authority.
-		///
-		/// At this path, a new folder will be created for each authority's
-		/// keystore named `auth-$i` where `i` is the authority index, i.e.
-		/// `auth-0`, `auth-1`, etc.
-		#[arg(long, short)]
-		keystore_path: Option<PathBuf>,
-	},
+pub struct ChainSpecBuilder {
+	#[command(subcommand)]
+	pub command: ChainSpecBuilderCmd,
+	/// The path where the chain spec should be saved.
+	#[arg(long, short, default_value = "./chain_spec.json")]
+	pub chain_spec_path: PathBuf,
 }

-impl ChainSpecBuilder {
-	/// Returns the path where the chain spec should be saved.
-	pub fn chain_spec_path(&self) -> &Path {
-		match self {
-			ChainSpecBuilder::New { chain_spec_path, .. } => chain_spec_path.as_path(),
-			ChainSpecBuilder::Generate { chain_spec_path, .. } => chain_spec_path.as_path(),
-		}
-	}
+#[derive(Debug, Subcommand)]
+#[command(rename_all = "kebab-case")]
+pub enum ChainSpecBuilderCmd {
+	New(NewCmd),
+	Generate(GenerateCmd),
+	Runtime(RuntimeCmd),
+	Edit(EditCmd),
+	Verify(VerifyCmd),
 }

-fn genesis_constructor(
-	authority_seeds: &[String],
-	nominator_accounts: &[AccountId],
-	endowed_accounts: &[AccountId],
-	sudo_account: &AccountId,
-) -> chain_spec::RuntimeGenesisConfig {
-	let authorities = authority_seeds
-		.iter()
-		.map(AsRef::as_ref)
-		.map(chain_spec::authority_keys_from_seed)
-		.collect::<Vec<_>>();
+/// Create a new chain spec with the given authorities, endowed and sudo
+/// accounts. Only works for kitchen-sink runtime
+#[derive(Parser, Debug)]
+#[command(rename_all = "kebab-case")]
+pub struct NewCmd {
+	/// Authority key seed.
+	#[arg(long, short, required = true)]
+	pub authority_seeds: Vec<String>,
+	/// Active nominators (SS58 format), each backing a random subset of the aforementioned
+	/// authorities.
+	#[arg(long, short, default_value = "0")]
+	pub nominator_accounts: Vec<String>,
+	/// Endowed account address (SS58 format).
+	#[arg(long, short)]
+	pub endowed_accounts: Vec<String>,
+	/// Sudo account address (SS58 format).
+	#[arg(long, short)]
+	pub sudo_account: String,
+}

-	chain_spec::testnet_genesis(
-		authorities,
-		nominator_accounts.to_vec(),
-		sudo_account.clone(),
-		Some(endowed_accounts.to_vec()),
-	)
+/// Create a new chain spec with the given number of authorities and endowed
+/// accounts. Random keys will be generated as required.
+#[derive(Parser, Debug)]
+pub struct GenerateCmd {
+	/// The number of authorities.
+	#[arg(long, short)]
+	pub authorities: usize,
+	/// The number of nominators backing the aforementioned authorities.
+	///
+	/// Will nominate a random subset of `authorities`.
+	#[arg(long, short, default_value_t = 0)]
+	pub nominators: usize,
+	/// The number of endowed accounts.
+	#[arg(long, short, default_value_t = 0)]
+	pub endowed: usize,
+	/// Path to use when saving generated keystores for each authority.
+	///
+	/// At this path, a new folder will be created for each authority's
+	/// keystore named `auth-$i` where `i` is the authority index, i.e.
+	/// `auth-0`, `auth-1`, etc.
+	#[arg(long, short)]
+	pub keystore_path: Option<PathBuf>,
+}
+
+/// Create a new chain spec by interacting with the provided runtime wasm blob.
+#[derive(Parser, Debug)]
+pub struct RuntimeCmd {
+	/// The name of chain
+	#[arg(long, short = 'n', default_value = "Custom")]
+	chain_name: String,
+	/// The chain id
+	#[arg(long, short = 'i', default_value = "custom")]
+	chain_id: String,
+	/// The path to runtime wasm blob
+	#[arg(long, short)]
+	runtime_wasm_path: PathBuf,
+	/// Export chainspec as raw storage
+	#[arg(long, short = 's')]
+	raw_storage: bool,
+	/// Verify the genesis config. This silently generates the raw storage from genesis config. Any
+	/// errors will be reported.
+	#[arg(long, short = 'v')]
+	verify: bool,
+	#[command(subcommand)]
+	action: GenesisBuildAction,
+}
+
+#[derive(Subcommand, Debug, Clone)]
+enum GenesisBuildAction {
+	Patch(PatchCmd),
+	Full(FullCmd),
+	Default(DefaultCmd),
+}
+
+/// Patches the runtime's default genesis config with provided patch.
+#[derive(Parser, Debug, Clone)]
+struct PatchCmd {
+	/// The path to the runtime genesis config patch.
+	#[arg(long, short)]
+	patch_path: PathBuf,
+}
+
+/// Build the genesis config for runtime using provided json file. No defaults will be used.
+#[derive(Parser, Debug, Clone)]
+struct FullCmd {
+	/// The path to the full runtime genesis config json file.
+	#[arg(long, short)]
+	config_path: PathBuf,
+}
+
+/// Gets the default genesis config for the runtime and uses it in ChainSpec. Please note that
+/// default genesis config may not be valid. For some runtimes initial values should be added there
+/// (e.g. session keys, babe epoch).
+#[derive(Parser, Debug, Clone)]
+struct DefaultCmd {
+	/// If provided stores the default genesis config json file at given path (in addition to
+	/// chain-spec).
+	#[arg(long, short)]
+	default_config_path: Option<PathBuf>,
+}
+
+/// Edits provided input chain spec. Input can be converted into raw storage chain-spec. The code
+/// can be updated with the runtime provided in the command line.
+#[derive(Parser, Debug, Clone)]
+pub struct EditCmd {
+	/// Chain spec to be edited
+	#[arg(long, short)]
+	pub input_chain_spec: PathBuf,
+	/// The path to new runtime wasm blob to be stored into chain-spec
+	#[arg(long, short = 'r')]
+	pub runtime_wasm_path: Option<PathBuf>,
+	/// Convert genesis spec to raw format
+	#[arg(long, short = 's')]
+	pub convert_to_raw: bool,
+}
+
+/// Verifies provided input chain spec. If the runtime is provided verification is performed against
+/// new runtime.
+#[derive(Parser, Debug, Clone)]
+pub struct VerifyCmd {
+	/// Chain spec to be edited
+	#[arg(long, short)]
+	pub input_chain_spec: PathBuf,
+	/// The path to new runtime wasm blob to be stored into chain-spec
+	#[arg(long, short = 'r')]
+	pub runtime_wasm_path: Option<PathBuf>,
 }

 /// Generate the chain spec using the given seeds and accounts.
@@ -145,27 +218,24 @@ pub fn generate_chain_spec(

 	let sudo_account = parse_account(sudo_account)?;

-	let chain_spec = chain_spec::ChainSpec::from_genesis(
-		"Custom",
-		"custom",
-		sc_chain_spec::ChainType::Live,
-		move || {
-			genesis_constructor(
-				&authority_seeds,
-				&nominator_accounts,
-				&endowed_accounts,
-				&sudo_account,
-			)
-		},
-		vec![],
-		None,
-		None,
-		None,
-		None,
-		Default::default(),
-	);
+	let authorities = authority_seeds
+		.iter()
+		.map(AsRef::as_ref)
+		.map(chain_spec::authority_keys_from_seed)
+		.collect::<Vec<_>>();

-	chain_spec.as_json(false)
+	chain_spec::ChainSpec::builder(kitchensink_runtime::wasm_binary_unwrap(), Default::default())
+		.with_name("Custom")
+		.with_id("custom")
+		.with_chain_type(sc_chain_spec::ChainType::Live)
+		.with_genesis_config_patch(chain_spec::testnet_genesis(
+			authorities,
+			nominator_accounts,
+			sudo_account,
+			Some(endowed_accounts),
+		))
+		.build()
+		.as_json(false)
 }

 /// Generate the authority keys and store them in the given `keystore_path`.
@@ -241,3 +311,54 @@ pub fn print_seeds(
 	println!("{}", header.paint("Sudo seed"));
 	println!("//{}", sudo_seed);
 }
+
+/// Processes `RuntimeCmd` and returns JSON version of `ChainSpec`
+pub fn generate_chain_spec_for_runtime(cmd: &RuntimeCmd) -> Result<String, String> {
+	let code = fs::read(cmd.runtime_wasm_path.as_path())
+		.map_err(|e| format!("wasm blob shall be readable {e}"))?;
+
+	let builder = chain_spec::ChainSpec::builder(&code[..], Default::default())
+		.with_name(&cmd.chain_name[..])
+		.with_id(&cmd.chain_id[..])
+		.with_chain_type(sc_chain_spec::ChainType::Live);
+
+	let builder = match cmd.action {
+		GenesisBuildAction::Patch(PatchCmd { ref patch_path }) => {
+			let patch = fs::read(patch_path.as_path())
+				.map_err(|e| format!("patch file {patch_path:?} shall be readable: {e}"))?;
+			builder.with_genesis_config_patch(serde_json::from_slice::<Value>(&patch[..]).map_err(
+				|e| format!("patch file {patch_path:?} shall contain a valid json: {e}"),
+			)?)
+		},
+		GenesisBuildAction::Full(FullCmd { ref config_path }) => {
+			let config = fs::read(config_path.as_path())
+				.map_err(|e| format!("config file {config_path:?} shall be readable: {e}"))?;
+			builder.with_genesis_config(serde_json::from_slice::<Value>(&config[..]).map_err(
+				|e| format!("config file {config_path:?} shall contain a valid json: {e}"),
+			)?)
+		},
+		GenesisBuildAction::Default(DefaultCmd { ref default_config_path }) => {
+			let caller = GenesisConfigBuilderRuntimeCaller::new(&code[..]);
+			let default_config = caller
+				.get_default_config()
+				.map_err(|e| format!("getting default config from runtime should work: {e}"))?;
+			default_config_path.clone().map(|path| {
+				fs::write(path.as_path(), serde_json::to_string_pretty(&default_config).unwrap())
+					.map_err(|err| err.to_string())
+			});
+			builder.with_genesis_config(default_config)
+		},
+	};
+
+	let chain_spec = builder.build();
+
+	match (cmd.verify, cmd.raw_storage) {
+		(_, true) => chain_spec.as_json(true),
+		(true, false) => {
+			chain_spec.as_json(true)?;
+			println!("Genesis config verification: OK");
+			chain_spec.as_json(false)
+		},
+		(false, false) => chain_spec.as_json(false),
+	}
+}
@@ -13,15 +13,27 @@ readme = "README.md"
 targets = ["x86_64-unknown-linux-gnu"]

 [dependencies]
+codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false, features = ["derive"] }
 memmap2 = "0.5.0"
 serde = { version = "1.0.188", features = ["derive"] }
 serde_json = "1.0.107"
 sc-client-api = { path = "../api" }
 sc-chain-spec-derive = { path = "derive" }
 sc-executor = { path = "../executor" }
+sp-io = { default-features = false, path = "../../primitives/io" }
 sc-network = { path = "../network" }
 sc-telemetry = { path = "../telemetry" }
 sp-blockchain = { path = "../../primitives/blockchain" }
 sp-core = { path = "../../primitives/core" }
+sp-genesis-builder = { path = "../../primitives/genesis-builder" }
 sp-runtime = { path = "../../primitives/runtime" }
 sp-state-machine = { path = "../../primitives/state-machine" }
+log = { version = "0.4.17", default-features = false }
+array-bytes = { version = "6.1" }
+docify = "0.2.0"
+
+[dev-dependencies]
+substrate-test-runtime = { path = "../../test-utils/runtime" }
+sp-keyring = { path = "../../primitives/keyring" }
+sp-application-crypto = { default-features = false, path = "../../primitives/application-crypto", features = ["serde"]  }
+sp-consensus-babe = { default-features = false, path = "../../primitives/consensus/babe", features = ["serde"] }
@@ -1,92 +1,6 @@
 Substrate chain configurations.

-This crate contains structs and utilities to declare
-a runtime-specific configuration file (a.k.a chain spec).
-
-Basic chain spec type containing all required parameters is
-[`ChainSpec`](https://docs.rs/sc-chain-spec/latest/sc_chain_spec/struct.GenericChainSpec.html). It can be extended with
-additional options that contain configuration specific to your chain.
-Usually the extension is going to be an amalgamate of types exposed
-by Substrate core modules. To allow the core modules to retrieve
-their configuration from your extension you should use `ChainSpecExtension`
-macro exposed by this crate.
-
-```rust
-use std::collections::HashMap;
-use sc_chain_spec::{GenericChainSpec, ChainSpecExtension};
-
-#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecExtension)]
-pub struct MyExtension {
-		pub known_blocks: HashMap<u64, String>,
-}
-
-pub type MyChainSpec<G> = GenericChainSpec<G, MyExtension>;
-```
-
-Some parameters may require different values depending on the
-current blockchain height (a.k.a. forks). You can use `ChainSpecGroup`
-macro and provided [`Forks`](https://docs.rs/sc-chain-spec/latest/sc_chain_spec/struct.Forks.html) structure to put
-such parameters to your chain spec.
-This will allow to override a single parameter starting at specific
-block number.
-
-```rust
-use sc_chain_spec::{Forks, ChainSpecGroup, ChainSpecExtension, GenericChainSpec};
-
-#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecGroup)]
-pub struct ClientParams {
-		max_block_size: usize,
-		max_extrinsic_size: usize,
-}
-
-#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecGroup)]
-pub struct PoolParams {
-		max_transaction_size: usize,
-}
-
-#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecGroup, ChainSpecExtension)]
-pub struct Extension {
-		pub client: ClientParams,
-		pub pool: PoolParams,
-}
-
-pub type BlockNumber = u64;
-
-/// A chain spec supporting forkable `ClientParams`.
-pub type MyChainSpec1<G> = GenericChainSpec<G, Forks<BlockNumber, ClientParams>>;
-
-/// A chain spec supporting forkable `Extension`.
-pub type MyChainSpec2<G> = GenericChainSpec<G, Forks<BlockNumber, Extension>>;
-```
-
-It's also possible to have a set of parameters that is allowed to change
-with block numbers (i.e. is forkable), and another set that is not subject to changes.
-This is also possible by declaring an extension that contains `Forks` within it.
-
-
-```rust
-use serde::{Serialize, Deserialize};
-use sc_chain_spec::{Forks, GenericChainSpec, ChainSpecGroup, ChainSpecExtension};
-
-#[derive(Clone, Debug, Serialize, Deserialize, ChainSpecGroup)]
-pub struct ClientParams {
-		max_block_size: usize,
-		max_extrinsic_size: usize,
-}
-
-#[derive(Clone, Debug, Serialize, Deserialize, ChainSpecGroup)]
-pub struct PoolParams {
-		max_transaction_size: usize,
-}
-
-#[derive(Clone, Debug, Serialize, Deserialize, ChainSpecExtension)]
-pub struct Extension {
-		pub client: ClientParams,
-		#[forks]
-		pub pool: Forks<u64, PoolParams>,
-}
-
-pub type MyChainSpec<G> = GenericChainSpec<G, Extension>;
-```
+This crate contains structs and utilities to declare a runtime-specific configuration file (a.k.a chain spec).
+Refer to crate documentation for details.

 License: GPL-3.0-or-later WITH Classpath-exception-2.0
@@ -0,0 +1,18 @@
+{
+  "name": "TestName",
+  "id": "test_id",
+  "chainType": "Local",
+  "bootNodes": [],
+  "telemetryEndpoints": null,
+  "protocolId": null,
+  "properties": null,
+  "codeSubstitutes": {},
+  "genesis": {
+    "raw": {
+      "top": {
+        "0x3a636f6465": "0x010101"
+      },
+      "childrenDefault": {}
+    }
+  }
+}
@@ -0,0 +1,19 @@
+{
+  "name": "TestName",
+  "id": "test_id",
+  "chainType": "Local",
+  "bootNodes": [],
+  "telemetryEndpoints": null,
+  "protocolId": null,
+  "properties": null,
+  "codeSubstitutes": {},
+  "genesis": {
+    "raw": {
+      "top": {
+        "0x3a636f6465": "0x010101"
+      },
+      "childrenDefault": {}
+    }
+  },
+  "code": "0x060708"
+}
@@ -0,0 +1,128 @@
+{
+  "name": "TestName",
+  "id": "test_id",
+  "chainType": "Local",
+  "bootNodes": [],
+  "telemetryEndpoints": null,
+  "protocolId": null,
+  "properties": null,
+  "codeSubstitutes": {},
+  "genesis": {
+    "runtimeGenesis": {
+      "config": {
+        "babe": {
+          "authorities": [
+            [
+              "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
+              1
+            ],
+            [
+              "5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty",
+              1
+            ],
+            [
+              "5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y",
+              1
+            ]
+          ],
+          "epochConfig": {
+            "allowed_slots": "PrimaryAndSecondaryPlainSlots",
+            "c": [
+              3,
+              10
+            ]
+          }
+        },
+        "balances": {
+          "balances": [
+            [
+              "5D34dL5prEUaGNQtPPZ3yN5Y6BnkfXunKXXz6fo7ZJbLwRRH",
+              100000000000000000
+            ],
+            [
+              "5GBNeWRhZc2jXu7D55rBimKYDk8PGk8itRYFTPfC8RJLKG5o",
+              100000000000000000
+            ],
+            [
+              "5Dfis6XL8J2P6JHUnUtArnFWndn62SydeP8ee8sG2ky9nfm9",
+              100000000000000000
+            ],
+            [
+              "5F4H97f7nQovyrbiq4ZetaaviNwThSVcFobcA5aGab6167dK",
+              100000000000000000
+            ],
+            [
+              "5DiDShBWa1fQx6gLzpf3SFBhMinCoyvHM1BWjPNsmXS8hkrW",
+              100000000000000000
+            ],
+            [
+              "5EFb84yH9tpcFuiKUcsmdoF7xeeY3ajG1ZLQimxQoFt9HMKR",
+              100000000000000000
+            ],
+            [
+              "5DZLHESsfGrJ5YzT3HuRPXsSNb589xQ4Unubh1mYLodzKdVY",
+              100000000000000000
+            ],
+            [
+              "5GHJzqvG6tXnngCpG7B12qjUvbo5e4e9z8Xjidk3CQZHxTPZ",
+              100000000000000000
+            ],
+            [
+              "5CUnSsgAyLND3bxxnfNhgWXSe9Wn676JzLpGLgyJv858qhoX",
+              100000000000000000
+            ],
+            [
+              "5CVKn7HAZW1Ky4r7Vkgsr7VEW88C2sHgUNDiwHY9Ct2hjU8q",
+              100000000000000000
+            ],
+            [
+              "5H673aukQ4PeDe1U2nuv1bi32xDEziimh3PZz7hDdYUB7TNz",
+              100000000000000000
+            ],
+            [
+              "5HTe9L15LJryjUAt1jZXZCBPnzbbGnpvFwbjE3NwCWaAqovf",
+              100000000000000000
+            ],
+            [
+              "5D7LFzGpMwHPyDBavkRbWSKWTtJhCaPPZ379wWLT23bJwXJz",
+              100000000000000000
+            ],
+            [
+              "5CLepMARnEgtVR1EkUuJVUvKh97gzergpSxUU3yKGx1v6EwC",
+              100000000000000000
+            ],
+            [
+              "5Chb2UhfvZpmjjEziHbFbotM4quX32ZscRV6QJBt1rUKzz51",
+              100000000000000000
+            ],
+            [
+              "5HmRp3i3ZZk7xsAvbi8hyXVP6whSMnBJGebVC4FsiZVhx52e",
+              100000000000000000
+            ],
+            [
+              "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
+              100000000000000000
+            ],
+            [
+              "5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty",
+              100000000000000000
+            ],
+            [
+              "5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y",
+              100000000000000000
+            ]
+          ]
+        },
+        "substrateTest": {
+          "authorities": [
+            "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
+            "5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty",
+            "5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y"
+          ]
+        },
+        "system": {}
+      },
+      "code": "0x0"
+    }
+  }
+}
@@ -0,0 +1,53 @@
+{
+  "name": "TestName",
+  "id": "test_id",
+  "chainType": "Local",
+  "bootNodes": [],
+  "telemetryEndpoints": null,
+  "protocolId": null,
+  "properties": null,
+  "codeSubstitutes": {},
+  "genesis": {
+    "raw": {
+      "top": {
+        "0x00771836bebdd29870ff246d305c578c4e7b9012096b41c4eb3aaf947f6ea429": "0x0000",
+        "0x00771836bebdd29870ff246d305c578c5e0621c4869aa60c02be9adcc98a0d1d": "0x0cd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d8eaf04151687736326c9fea17e25fc5287613693c912909cb226aa4794f26a4890b5ab205c6974c9ea841be688864633dc9ca8a357843eeacf2314649965fe22",
+        "0x1cb6f36e027abb2091cfb5110ab5087f4e7b9012096b41c4eb3aaf947f6ea429": "0x0000",
+        "0x1cb6f36e027abb2091cfb5110ab5087f5e0621c4869aa60c02be9adcc98a0d1d": "0x0cd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d01000000000000008eaf04151687736326c9fea17e25fc5287613693c912909cb226aa4794f26a48010000000000000090b5ab205c6974c9ea841be688864633dc9ca8a357843eeacf2314649965fe220100000000000000",
+        "0x1cb6f36e027abb2091cfb5110ab5087f66e8f035c8adbe7f1547b43c51e6f8a4": "0x00000000",
+        "0x1cb6f36e027abb2091cfb5110ab5087faacf00b9b41fda7a9268821c2a2b3e4c": "0x0cd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d01000000000000008eaf04151687736326c9fea17e25fc5287613693c912909cb226aa4794f26a48010000000000000090b5ab205c6974c9ea841be688864633dc9ca8a357843eeacf2314649965fe220100000000000000",
+        "0x1cb6f36e027abb2091cfb5110ab5087fdc6b171b77304263c292cc3ea5ed31ef": "0x03000000000000000a0000000000000001",
+        "0x26aa394eea5630e07c48ae0c9558cef74e7b9012096b41c4eb3aaf947f6ea429": "0x0000",
+        "0x26aa394eea5630e07c48ae0c9558cef75684a022a34dd8bfa2baaf44f172b710": "0x01",
+        "0x26aa394eea5630e07c48ae0c9558cef78a42f33323cb5ced3b44dd825fda9fcc": "0x4545454545454545454545454545454545454545454545454545454545454545",
+        "0x26aa394eea5630e07c48ae0c9558cef7a44704b568d21667356a5a050c118746bb1bdbcacd6ac9340000000000000000": "0x4545454545454545454545454545454545454545454545454545454545454545",
+        "0x26aa394eea5630e07c48ae0c9558cef7a7fd6c28836b9a28522dc924110cf439": "0x01",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da901cae4e3edfbb32c91ed3f01ab964f4eeeab50338d8e5176d3141802d7b010a55dadcd5f23cf8aaafa724627e967e90e": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da91b614bd4a126f2d5d294e9a8af9da25248d7e931307afb4b68d8d565d4c66e00d856c6d65f5fed6bb82dcfb60e936c67": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da94b21aff9fe1e8b2fc4b0775b8cbeff28ba8e2c7594dd74730f3ca835e95455d199261897edc9735d602ea29615e2b10b": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da94f9aea1afa791265fae359272badc1cf8eaf04151687736326c9fea17e25fc5287613693c912909cb226aa4794f26a48": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da95786a2916fcb81e1bd5dcd81e0d2452884617f575372edb5a36d85c04cdf2e4699f96fe33eb5f94a28c041b88e398d0c": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da95b8542d9672c7b7e779cc7c1e6b605691c2115d06120ea2bee32dd601d02f36367564e7ddf84ae2717ca3f097459652e": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da996c30bdbfab640838e6b6d3c33ab4adb4211b79e34ee8072eab506edd4b93a7b85a14c9a05e5cdd056d98e7dbca87730": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da99dc65b1339ec388fbf2ca0cdef51253512c6cfd663203ea16968594f24690338befd906856c4d2f4ef32dad578dba20c": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da99e6eb5abd62f5fd54793da91a47e6af6125d57171ff9241f07acaa1bb6a6103517965cf2cd00e643b27e7599ebccba70": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9b0edae20838083f2cde1c4080db8cf8090b5ab205c6974c9ea841be688864633dc9ca8a357843eeacf2314649965fe22": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9d0052993b6f3bd0544fd1f5e4125b9fbde3e789ecd53431fe5c06c12b72137153496dace35c695b5f4d7b41f7ed5763b": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9d6b7e9a5f12bc571053265dade10d3b4b606fc73f57f03cdb4c932d475ab426043e429cecc2ffff0d2672b0df8398c48": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9de1e86a9a8c739864cf3cc5ec2bea59fd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9e1a35f56ee295d39287cbffcfc60c4b346f136b564e1fad55031404dd84e5cd3fa76bfe7cc7599b39d38fd06663bbc0a": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9e2c1dc507e2035edbbd8776c440d870460c57f0008067cc01c5ff9eb2e2f9b3a94299a915a91198bd1021a6c55596f57": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9eca0e653a94f4080f6311b4e7b6934eb2afba9278e30ccf6a6ceb3a8b6e336b70068f045c666f2e7f4f9cc5f47db8972": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9ee8bf7ef90fc56a8aa3b90b344c599550c29b161e27ff8ba45bf6bad4711f326fc506a8803453a4d7e3158e993495f10": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9f5d6f1c082fe63eec7a71fcad00f4a892e3d43b7b0d04e776e69e7be35247cecdac65504c579195731eaf64b7940966e": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da9fbf0818841edf110e05228a6379763c4fc3c37459d9bdc61f58a5ebc01e9e2305a19d390c0543dc733861ec3cf1de01f": "0x000000000000000000000000010000000000000000008a5d784563010000000000000000000000000000000000000000000000000000000000000080",
+        "0x26aa394eea5630e07c48ae0c9558cef7f9cce9c888469bb1a0dceaa129672ef8": "0x0000",
+        "0x3a636f6465": "0x0",
+        "0x3a65787472696e7369635f696e646578": "0x00000000",
+        "0xc2261276cc9d1f8598ea4b6a74b15c2f4e7b9012096b41c4eb3aaf947f6ea429": "0x0100",
+        "0xc2261276cc9d1f8598ea4b6a74b15c2f57c875e4cff74148e4628f264b974c80": "0x00003ef1ee275e1a"
+      },
+      "childrenDefault": {}
+    }
+  }
+}
@@ -0,0 +1,32 @@
+{
+  "name": "TestName",
+  "id": "test_id",
+  "chainType": "Local",
+  "bootNodes": [],
+  "telemetryEndpoints": null,
+  "protocolId": null,
+  "properties": null,
+  "codeSubstitutes": {},
+  "genesis": {
+    "runtimeGenesis": {
+      "patch": {
+        "babe": {
+          "epochConfig": {
+            "allowed_slots": "PrimaryAndSecondaryPlainSlots",
+            "c": [
+              7,
+              10
+            ]
+          }
+        },
+        "substrateTest": {
+          "authorities": [
+            "5CiPPseXPECbkjWCa6MnjNokrgYjMqmKndv2rSnekmSK2DjL",
+            "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY"
+          ]
+        }
+      },
+      "code": "0x0"
+    }
+  }
+}
@@ -0,0 +1,32 @@
+{
+  "name": "TestName",
+  "id": "test_id",
+  "chainType": "Local",
+  "bootNodes": [],
+  "telemetryEndpoints": null,
+  "protocolId": null,
+  "properties": null,
+  "codeSubstitutes": {},
+  "genesis": {
+    "raw": {
+      "top": {
+        "0x00771836bebdd29870ff246d305c578c4e7b9012096b41c4eb3aaf947f6ea429": "0x0000",
+        "0x00771836bebdd29870ff246d305c578c5e0621c4869aa60c02be9adcc98a0d1d": "0x081cbd2d43530a44705ad088af313e18f80b53ef16b36177cd4b77b846f2a5f07cd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d",
+        "0x1cb6f36e027abb2091cfb5110ab5087f4e7b9012096b41c4eb3aaf947f6ea429": "0x0000",
+        "0x1cb6f36e027abb2091cfb5110ab5087f66e8f035c8adbe7f1547b43c51e6f8a4": "0x00000000",
+        "0x1cb6f36e027abb2091cfb5110ab5087fdc6b171b77304263c292cc3ea5ed31ef": "0x07000000000000000a0000000000000001",
+        "0x26aa394eea5630e07c48ae0c9558cef74e7b9012096b41c4eb3aaf947f6ea429": "0x0000",
+        "0x26aa394eea5630e07c48ae0c9558cef75684a022a34dd8bfa2baaf44f172b710": "0x01",
+        "0x26aa394eea5630e07c48ae0c9558cef78a42f33323cb5ced3b44dd825fda9fcc": "0x4545454545454545454545454545454545454545454545454545454545454545",
+        "0x26aa394eea5630e07c48ae0c9558cef7a44704b568d21667356a5a050c118746bb1bdbcacd6ac9340000000000000000": "0x4545454545454545454545454545454545454545454545454545454545454545",
+        "0x26aa394eea5630e07c48ae0c9558cef7a7fd6c28836b9a28522dc924110cf439": "0x01",
+        "0x26aa394eea5630e07c48ae0c9558cef7f9cce9c888469bb1a0dceaa129672ef8": "0x0000",
+        "0x3a636f6465": "0x0",
+        "0x3a65787472696e7369635f696e646578": "0x00000000",
+        "0xc2261276cc9d1f8598ea4b6a74b15c2f4e7b9012096b41c4eb3aaf947f6ea429": "0x0100",
+        "0xc2261276cc9d1f8598ea4b6a74b15c2f57c875e4cff74148e4628f264b974c80": "0x0000000000000000"
+      },
+      "childrenDefault": {}
+    }
+  }
+}
@@ -18,8 +18,10 @@

 //! Substrate chain configurations.
 #![warn(missing_docs)]
-
-use crate::{extension::GetExtension, ChainType, Properties, RuntimeGenesis};
+use crate::{
+	extension::GetExtension, ChainType, GenesisConfigBuilderRuntimeCaller as RuntimeCaller,
+	Properties, RuntimeGenesis,
+};
 use sc_network::config::MultiaddrWithPeerId;
 use sc_telemetry::TelemetryEndpoints;
 use serde::{Deserialize, Serialize};
@@ -29,13 +31,32 @@ use sp_core::{
 	Bytes,
 };
 use sp_runtime::BuildStorage;
-use std::{borrow::Cow, collections::BTreeMap, fs::File, path::PathBuf, sync::Arc};
+use std::{
+	borrow::Cow,
+	collections::{BTreeMap, VecDeque},
+	fs::File,
+	marker::PhantomData,
+	path::PathBuf,
+	sync::Arc,
+};

+#[derive(Serialize, Deserialize, Clone)]
+#[serde(rename_all = "camelCase")]
+enum GenesisBuildAction {
+	Patch(json::Value),
+	Full(json::Value),
+}
+
+#[allow(deprecated)]
 enum GenesisSource<G> {
 	File(PathBuf),
 	Binary(Cow<'static, [u8]>),
-	Factory(Arc<dyn Fn() -> G + Send + Sync>),
+	/// factory function + code
+	//Factory and G type parameter shall be removed togheter with `ChainSpec::from_genesis`
+	Factory(Arc<dyn Fn() -> G + Send + Sync>, Vec<u8>),
 	Storage(Storage),
+	/// build action + code
+	GenesisBuilderApi(GenesisBuildAction, Vec<u8>),
 }

 impl<G> Clone for GenesisSource<G> {
@@ -43,14 +64,17 @@ impl<G> Clone for GenesisSource<G> {
 		match *self {
 			Self::File(ref path) => Self::File(path.clone()),
 			Self::Binary(ref d) => Self::Binary(d.clone()),
-			Self::Factory(ref f) => Self::Factory(f.clone()),
+			Self::Factory(ref f, ref c) => Self::Factory(f.clone(), c.clone()),
 			Self::Storage(ref s) => Self::Storage(s.clone()),
+			Self::GenesisBuilderApi(ref s, ref c) => Self::GenesisBuilderApi(s.clone(), c.clone()),
 		}
 	}
 }

 impl<G: RuntimeGenesis> GenesisSource<G> {
 	fn resolve(&self) -> Result<Genesis<G>, String> {
+		/// helper container for deserializing genesis from the JSON file (ChainSpec JSON file is
+		/// also supported here)
 		#[derive(Serialize, Deserialize)]
 		struct GenesisContainer<G> {
 			genesis: Genesis<G>,
@@ -79,31 +103,21 @@ impl<G: RuntimeGenesis> GenesisSource<G> {
 					.map_err(|e| format!("Error parsing embedded file: {}", e))?;
 				Ok(genesis.genesis)
 			},
-			Self::Factory(f) => Ok(Genesis::Runtime(f())),
-			Self::Storage(storage) => {
-				let top = storage
-					.top
-					.iter()
-					.map(|(k, v)| (StorageKey(k.clone()), StorageData(v.clone())))
-					.collect();
-
-				let children_default = storage
-					.children_default
-					.iter()
-					.map(|(k, child)| {
-						(
-							StorageKey(k.clone()),
-							child
-								.data
-								.iter()
-								.map(|(k, v)| (StorageKey(k.clone()), StorageData(v.clone())))
-								.collect(),
-						)
-					})
-					.collect();
-
-				Ok(Genesis::Raw(RawGenesis { top, children_default }))
-			},
+			Self::Factory(f, code) => Ok(Genesis::RuntimeAndCode(RuntimeInnerWrapper {
+				runtime: f(),
+				code: code.clone(),
+			})),
+			Self::Storage(storage) => Ok(Genesis::Raw(RawGenesis::from(storage.clone()))),
+			Self::GenesisBuilderApi(GenesisBuildAction::Full(config), code) =>
+				Ok(Genesis::RuntimeGenesis(RuntimeGenesisInner {
+					json_blob: RuntimeGenesisConfigJson::Config(config.clone()),
+					code: code.clone(),
+				})),
+			Self::GenesisBuilderApi(GenesisBuildAction::Patch(patch), code) =>
+				Ok(Genesis::RuntimeGenesis(RuntimeGenesisInner {
+					json_blob: RuntimeGenesisConfigJson::Patch(patch.clone()),
+					code: code.clone(),
+				})),
 		}
 	}
 }
@@ -111,7 +125,18 @@ impl<G: RuntimeGenesis> GenesisSource<G> {
 impl<G: RuntimeGenesis, E> BuildStorage for ChainSpec<G, E> {
 	fn assimilate_storage(&self, storage: &mut Storage) -> Result<(), String> {
 		match self.genesis.resolve()? {
-			Genesis::Runtime(gc) => gc.assimilate_storage(storage),
+			#[allow(deprecated)]
+			Genesis::Runtime(runtime_genesis_config) => {
+				runtime_genesis_config.assimilate_storage(storage)?;
+			},
+			#[allow(deprecated)]
+			Genesis::RuntimeAndCode(RuntimeInnerWrapper {
+				runtime: runtime_genesis_config,
+				code,
+			}) => {
+				runtime_genesis_config.assimilate_storage(storage)?;
+				storage.top.insert(sp_core::storage::well_known_keys::CODE.to_vec(), code);
+			},
 			Genesis::Raw(RawGenesis { top: map, children_default: children_map }) => {
 				storage.top.extend(map.into_iter().map(|(k, v)| (k.0, v.0)));
 				children_map.into_iter().for_each(|(k, v)| {
@@ -123,13 +148,37 @@ impl<G: RuntimeGenesis, E> BuildStorage for ChainSpec<G, E> {
 						.data
 						.extend(v.into_iter().map(|(k, v)| (k.0, v.0)));
 				});
-				Ok(())
 			},
 			// The `StateRootHash` variant exists as a way to keep note that other clients support
 			// it, but Substrate itself isn't capable of loading chain specs with just a hash at the
 			// moment.
-			Genesis::StateRootHash(_) => Err("Genesis storage in hash format not supported".into()),
-		}
+			Genesis::StateRootHash(_) =>
+				return Err("Genesis storage in hash format not supported".into()),
+			Genesis::RuntimeGenesis(RuntimeGenesisInner {
+				json_blob: RuntimeGenesisConfigJson::Config(config),
+				code,
+			}) => {
+				RuntimeCaller::new(&code[..])
+					.get_storage_for_config(config)?
+					.assimilate_storage(storage)?;
+				storage
+					.top
+					.insert(sp_core::storage::well_known_keys::CODE.to_vec(), code.clone());
+			},
+			Genesis::RuntimeGenesis(RuntimeGenesisInner {
+				json_blob: RuntimeGenesisConfigJson::Patch(patch),
+				code,
+			}) => {
+				RuntimeCaller::new(&code[..])
+					.get_storage_for_patch(patch)?
+					.assimilate_storage(storage)?;
+				storage
+					.top
+					.insert(sp_core::storage::well_known_keys::CODE.to_vec(), code.clone());
+			},
+		};
+
+		Ok(())
 	}
 }

@@ -144,20 +193,98 @@ pub struct RawGenesis {
 	pub children_default: BTreeMap<StorageKey, GenesisStorage>,
 }

+impl From<sp_core::storage::Storage> for RawGenesis {
+	fn from(value: sp_core::storage::Storage) -> Self {
+		Self {
+			top: value.top.into_iter().map(|(k, v)| (StorageKey(k), StorageData(v))).collect(),
+			children_default: value
+				.children_default
+				.into_iter()
+				.map(|(sk, child)| {
+					(
+						StorageKey(sk),
+						child
+							.data
+							.into_iter()
+							.map(|(k, v)| (StorageKey(k), StorageData(v)))
+							.collect(),
+					)
+				})
+				.collect(),
+		}
+	}
+}
+
+/// Inner representation of [`Genesis<G>::RuntimeGenesis`] format
+#[derive(Serialize, Deserialize, Debug)]
+struct RuntimeGenesisInner {
+	/// Runtime wasm code, expected to be hex-encoded in JSON.
+	/// The code shall be capable of parsing `json_blob`.
+	#[serde(default, with = "sp_core::bytes")]
+	code: Vec<u8>,
+	/// The patch or full representation of runtime's `RuntimeGenesisConfig` struct.
+	#[serde(flatten)]
+	json_blob: RuntimeGenesisConfigJson,
+}
+
+/// Represents two possible variants of the contained JSON blob for the
+/// [`Genesis<G>::RuntimeGenesis`] format.
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+enum RuntimeGenesisConfigJson {
+	/// Represents the explicit and comprehensive runtime genesis config in JSON format.
+	/// The contained object is a JSON blob that can be parsed by a compatible runtime.
+	///
+	/// Using a full config is useful for when someone wants to ensure that a change in the runtime
+	/// makes the deserialization fail and not silently add some default values.
+	Config(json::Value),
+	/// Represents a patch for the default runtime genesis config in JSON format which is
+	/// essentially a list of keys that are to be customized in runtime genesis config.
+	/// The contained value is a JSON blob that can be parsed by a compatible runtime.
+	Patch(json::Value),
+}
+
+/// Inner variant wrapper for deprecated runtime.
+#[derive(Serialize, Deserialize, Debug)]
+struct RuntimeInnerWrapper<G> {
+	/// The native `RuntimeGenesisConfig` struct.
+	runtime: G,
+	/// Runtime code.
+	#[serde(with = "sp_core::bytes")]
+	code: Vec<u8>,
+}
+
+/// Represents the different formats of the genesis state within chain spec JSON blob.
 #[derive(Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
 enum Genesis<G> {
+	/// (Deprecated) Contains the JSON representation of G (the native type representing the
+	/// runtime's  `RuntimeGenesisConfig` struct) (will be removed with `ChainSpec::from_genesis`)
+	/// without the runtime code. It is required to deserialize the legacy chainspecs genereted
+	/// with `ChainsSpec::from_genesis` method.
 	Runtime(G),
+	/// (Deprecated) Contains the JSON representation of G (the native type representing the
+	/// runtime's  `RuntimeGenesisConfig` struct) (will be removed with `ChainSpec::from_genesis`)
+	/// and the runtime code. It is required to create and deserialize JSON chainspecs created with
+	/// deprecated `ChainSpec::from_genesis` method.
+	RuntimeAndCode(RuntimeInnerWrapper<G>),
+	/// The genesis storage as raw data. Typically raw key-value entries in state.
 	Raw(RawGenesis),
 	/// State root hash of the genesis storage.
 	StateRootHash(StorageData),
+	/// Represents the runtime genesis config in JSON format toghether with runtime code.
+	RuntimeGenesis(RuntimeGenesisInner),
 }

 /// A configuration of a client. Does not include runtime storage initialization.
+/// Note: `genesis` field is ignored due to way how the chain specification is serialized into
+/// JSON file. Refer to [`ChainSpecJsonContainer`], which flattens [`ClientSpec`] and denies uknown
+/// fields.
 #[derive(Serialize, Deserialize, Clone, Debug)]
 #[serde(rename_all = "camelCase")]
-#[serde(deny_unknown_fields)]
+// we cannot #[serde(deny_unknown_fields)]. Otherwise chain-spec-builder will fail on any
+// non-standard spec
 struct ClientSpec<E> {
 	name: String,
 	id: String,
@@ -194,6 +321,137 @@ struct ClientSpec<E> {
 /// We use `Option` here since `()` is not flattenable by serde.
 pub type NoExtension = Option<()>;

+/// Builder for creating [`ChainSpec`] instances.
+pub struct ChainSpecBuilder<G, E = NoExtension> {
+	code: Vec<u8>,
+	extensions: E,
+	name: String,
+	id: String,
+	chain_type: ChainType,
+	genesis_build_action: GenesisBuildAction,
+	boot_nodes: Option<Vec<MultiaddrWithPeerId>>,
+	telemetry_endpoints: Option<TelemetryEndpoints>,
+	protocol_id: Option<String>,
+	fork_id: Option<String>,
+	properties: Option<Properties>,
+	_genesis: PhantomData<G>,
+}
+
+impl<G, E> ChainSpecBuilder<G, E> {
+	/// Creates a new builder instance with no defaults.
+	pub fn new(code: &[u8], extensions: E) -> Self {
+		Self {
+			code: code.into(),
+			extensions,
+			name: "Development".to_string(),
+			id: "dev".to_string(),
+			chain_type: ChainType::Local,
+			genesis_build_action: GenesisBuildAction::Patch(Default::default()),
+			boot_nodes: None,
+			telemetry_endpoints: None,
+			protocol_id: None,
+			fork_id: None,
+			properties: None,
+			_genesis: Default::default(),
+		}
+	}
+
+	/// Sets the spec name.
+	pub fn with_name(mut self, name: &str) -> Self {
+		self.name = name.into();
+		self
+	}
+
+	/// Sets the spec ID.
+	pub fn with_id(mut self, id: &str) -> Self {
+		self.id = id.into();
+		self
+	}
+
+	/// Sets the type of the chain.
+	pub fn with_chain_type(mut self, chain_type: ChainType) -> Self {
+		self.chain_type = chain_type;
+		self
+	}
+
+	/// Sets a list of bootnode addresses.
+	pub fn with_boot_nodes(mut self, boot_nodes: Vec<MultiaddrWithPeerId>) -> Self {
+		self.boot_nodes = Some(boot_nodes);
+		self
+	}
+
+	/// Sets telemetry endpoints.
+	pub fn with_telemetry_endpoints(mut self, telemetry_endpoints: TelemetryEndpoints) -> Self {
+		self.telemetry_endpoints = Some(telemetry_endpoints);
+		self
+	}
+
+	/// Sets the network protocol ID.
+	pub fn with_protocol_id(mut self, protocol_id: &str) -> Self {
+		self.protocol_id = Some(protocol_id.into());
+		self
+	}
+
+	/// Sets an optional network fork identifier.
+	pub fn with_fork_id(mut self, fork_id: &str) -> Self {
+		self.fork_id = Some(fork_id.into());
+		self
+	}
+
+	/// Sets additional loosely-typed properties of the chain.
+	pub fn with_properties(mut self, properties: Properties) -> Self {
+		self.properties = Some(properties);
+		self
+	}
+
+	/// Sets chain spec extensions.
+	pub fn with_extensions(mut self, extensions: E) -> Self {
+		self.extensions = extensions;
+		self
+	}
+
+	/// Sets the code.
+	pub fn with_code(mut self, code: &[u8]) -> Self {
+		self.code = code.into();
+		self
+	}
+
+	/// Sets the JSON patch for runtime's GenesisConfig.
+	pub fn with_genesis_config_patch(mut self, patch: json::Value) -> Self {
+		self.genesis_build_action = GenesisBuildAction::Patch(patch);
+		self
+	}
+
+	/// Sets the full runtime's GenesisConfig JSON.
+	pub fn with_genesis_config(mut self, config: json::Value) -> Self {
+		self.genesis_build_action = GenesisBuildAction::Full(config);
+		self
+	}
+
+	/// Builds a [`ChainSpec`] instance using the provided settings.
+	pub fn build(self) -> ChainSpec<G, E> {
+		let client_spec = ClientSpec {
+			name: self.name,
+			id: self.id,
+			chain_type: self.chain_type,
+			boot_nodes: self.boot_nodes.unwrap_or_default(),
+			telemetry_endpoints: self.telemetry_endpoints,
+			protocol_id: self.protocol_id,
+			fork_id: self.fork_id,
+			properties: self.properties,
+			extensions: self.extensions,
+			consensus_engine: (),
+			genesis: Default::default(),
+			code_substitutes: BTreeMap::new(),
+		};
+
+		ChainSpec {
+			client_spec,
+			genesis: GenesisSource::GenesisBuilderApi(self.genesis_build_action, self.code.into()),
+		}
+	}
+}
+
 /// A configuration of a chain. Can be used to build a genesis block.
 pub struct ChainSpec<G, E = NoExtension> {
 	client_spec: ClientSpec<E>,
@@ -260,6 +518,10 @@ impl<G, E> ChainSpec<G, E> {
 	}

 	/// Create hardcoded spec.
+	#[deprecated(
+		note = "`from_genesis` is planned to be removed in May 2024. Use `builder()` instead."
+	)]
+	// deprecated note: Genesis<G>::Runtime + GenesisSource::Factory shall also be removed
 	pub fn from_genesis<F: Fn() -> G + 'static + Send + Sync>(
 		name: &str,
 		id: &str,
@@ -271,6 +533,7 @@ impl<G, E> ChainSpec<G, E> {
 		fork_id: Option<&str>,
 		properties: Option<Properties>,
 		extensions: E,
+		code: &[u8],
 	) -> Self {
 		let client_spec = ClientSpec {
 			name: name.to_owned(),
@@ -287,21 +550,30 @@ impl<G, E> ChainSpec<G, E> {
 			code_substitutes: BTreeMap::new(),
 		};

-		ChainSpec { client_spec, genesis: GenesisSource::Factory(Arc::new(constructor)) }
+		ChainSpec {
+			client_spec,
+			genesis: GenesisSource::Factory(Arc::new(constructor), code.into()),
+		}
 	}

 	/// Type of the chain.
 	fn chain_type(&self) -> ChainType {
 		self.client_spec.chain_type.clone()
 	}
+
+	/// Provides a `ChainSpec` builder.
+	pub fn builder(code: &[u8], extensions: E) -> ChainSpecBuilder<G, E> {
+		ChainSpecBuilder::new(code, extensions)
+	}
 }

-impl<G, E: serde::de::DeserializeOwned> ChainSpec<G, E> {
+impl<G: serde::de::DeserializeOwned, E: serde::de::DeserializeOwned> ChainSpec<G, E> {
 	/// Parse json content into a `ChainSpec`
 	pub fn from_json_bytes(json: impl Into<Cow<'static, [u8]>>) -> Result<Self, String> {
 		let json = json.into();
 		let client_spec = json::from_slice(json.as_ref())
 			.map_err(|e| format!("Error parsing spec file: {}", e))?;
+
 		Ok(ChainSpec { client_spec, genesis: GenesisSource::Binary(json) })
 	}

@@ -318,50 +590,74 @@ impl<G, E: serde::de::DeserializeOwned> ChainSpec<G, E> {
 			memmap2::Mmap::map(&file)
 				.map_err(|e| format!("Error mmaping spec file `{}`: {}", path.display(), e))?
 		};
-
 		let client_spec =
 			json::from_slice(&bytes).map_err(|e| format!("Error parsing spec file: {}", e))?;
+
 		Ok(ChainSpec { client_spec, genesis: GenesisSource::File(path) })
 	}
 }

+/// Helper structure for serializing (and only serializing) the ChainSpec into JSON file. It
+/// represents the layout of `ChainSpec` JSON file.
 #[derive(Serialize, Deserialize)]
-struct JsonContainer<G, E> {
+// we cannot #[serde(deny_unknown_fields)]. Otherwise chain-spec-builder will fail on any
+// non-standard spec.
+struct ChainSpecJsonContainer<G, E> {
 	#[serde(flatten)]
 	client_spec: ClientSpec<E>,
 	genesis: Genesis<G>,
 }

 impl<G: RuntimeGenesis, E: serde::Serialize + Clone + 'static> ChainSpec<G, E> {
-	fn json_container(&self, raw: bool) -> Result<JsonContainer<G, E>, String> {
-		let genesis = match (raw, self.genesis.resolve()?) {
+	fn json_container(&self, raw: bool) -> Result<ChainSpecJsonContainer<G, E>, String> {
+		let raw_genesis = match (raw, self.genesis.resolve()?) {
+			(
+				true,
+				Genesis::RuntimeGenesis(RuntimeGenesisInner {
+					json_blob: RuntimeGenesisConfigJson::Config(config),
+					code,
+				}),
+			) => {
+				let mut storage = RuntimeCaller::new(&code[..]).get_storage_for_config(config)?;
+				storage.top.insert(sp_core::storage::well_known_keys::CODE.to_vec(), code);
+				RawGenesis::from(storage)
+			},
+			(
+				true,
+				Genesis::RuntimeGenesis(RuntimeGenesisInner {
+					json_blob: RuntimeGenesisConfigJson::Patch(patch),
+					code,
+				}),
+			) => {
+				let mut storage = RuntimeCaller::new(&code[..]).get_storage_for_patch(patch)?;
+				storage.top.insert(sp_core::storage::well_known_keys::CODE.to_vec(), code);
+				RawGenesis::from(storage)
+			},
+
+			#[allow(deprecated)]
+			(true, Genesis::RuntimeAndCode(RuntimeInnerWrapper { runtime: g, code })) => {
+				let mut storage = g.build_storage()?;
+				storage.top.insert(sp_core::storage::well_known_keys::CODE.to_vec(), code);
+				RawGenesis::from(storage)
+			},
+			#[allow(deprecated)]
 			(true, Genesis::Runtime(g)) => {
 				let storage = g.build_storage()?;
-				let top =
-					storage.top.into_iter().map(|(k, v)| (StorageKey(k), StorageData(v))).collect();
-				let children_default = storage
-					.children_default
-					.into_iter()
-					.map(|(sk, child)| {
-						(
-							StorageKey(sk),
-							child
-								.data
-								.into_iter()
-								.map(|(k, v)| (StorageKey(k), StorageData(v)))
-								.collect(),
-						)
-					})
-					.collect();
-
-				Genesis::Raw(RawGenesis { top, children_default })
+				RawGenesis::from(storage)
 			},
-			(_, genesis) => genesis,
+			(true, Genesis::Raw(raw)) => raw,
+
+			(_, genesis) =>
+				return Ok(ChainSpecJsonContainer { client_spec: self.client_spec.clone(), genesis }),
 		};
-		Ok(JsonContainer { client_spec: self.client_spec.clone(), genesis })
+
+		Ok(ChainSpecJsonContainer {
+			client_spec: self.client_spec.clone(),
+			genesis: Genesis::Raw(raw_genesis),
+		})
 	}

-	/// Dump to json string.
+	/// Dump the chain specification to JSON string.
 	pub fn as_json(&self, raw: bool) -> Result<String, String> {
 		let container = self.json_container(raw)?;
 		json::to_string_pretty(&container).map_err(|e| format!("Error generating spec json: {}", e))
@@ -442,9 +738,87 @@ where
 	}
 }

+/// The `fun` will be called with the value at `path`.
+///
+/// If exists, the value at given `path` will be passed to the `fun` and the result of `fun`
+/// call will be returned. Otherwise false is returned.
+/// `path` will be modified.
+///
+/// # Examples
+/// ```ignore
+/// use serde_json::{from_str, json, Value};
+/// let doc = json!({"a":{"b":{"c":"5"}}});
+/// let mut path = ["a", "b", "c"].into();
+/// assert!(json_eval_value_at_key(&doc, &mut path, &|v| { assert_eq!(v,"5"); true }));
+/// ```
+fn json_eval_value_at_key(
+	doc: &json::Value,
+	path: &mut VecDeque<&str>,
+	fun: &dyn Fn(&json::Value) -> bool,
+) -> bool {
+	let Some(key) = path.pop_front() else {
+		return false;
+	};
+
+	if path.is_empty() {
+		doc.as_object().map_or(false, |o| o.get(key).map_or(false, |v| fun(v)))
+	} else {
+		doc.as_object()
+			.map_or(false, |o| o.get(key).map_or(false, |v| json_eval_value_at_key(v, path, fun)))
+	}
+}
+
+macro_rules! json_path {
+	[ $($x:expr),+ ] => {
+		VecDeque::<&str>::from([$($x),+])
+	};
+}
+
+fn json_contains_path(doc: &json::Value, path: &mut VecDeque<&str>) -> bool {
+	json_eval_value_at_key(doc, path, &|_| true)
+}
+
+/// This function updates the code in given chain spec.
+///
+/// Function support updating the runtime code in provided JSON chain spec blob. `Genesis<G>::Raw`
+/// and `Genesis<G>::RuntimeGenesis` formats are supported.
+///
+/// If update was successful `true` is returned, otherwise `false`. Chain spec JSON is modified in
+/// place.
+pub fn update_code_in_json_chain_spec(chain_spec: &mut json::Value, code: &[u8]) -> bool {
+	let mut path = json_path!["genesis", "runtimeGenesis", "code"];
+	let mut raw_path = json_path!["genesis", "raw", "top"];
+
+	if json_contains_path(&chain_spec, &mut path) {
+		#[derive(Serialize)]
+		struct Container<'a> {
+			#[serde(with = "sp_core::bytes")]
+			code: &'a [u8],
+		}
+		let code_patch = json::json!({"genesis":{"runtimeGenesis": Container { code }}});
+		crate::json_patch::merge(chain_spec, code_patch);
+		true
+	} else if json_contains_path(&chain_spec, &mut raw_path) {
+		#[derive(Serialize)]
+		struct Container<'a> {
+			#[serde(with = "sp_core::bytes", rename = "0x3a636f6465")]
+			code: &'a [u8],
+		}
+		let code_patch = json::json!({"genesis":{"raw":{"top": Container { code }}}});
+		crate::json_patch::merge(chain_spec, code_patch);
+		true
+	} else {
+		false
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;
+	use serde_json::{from_str, json, Value};
+	use sp_application_crypto::Ss58Codec;
+	use sp_core::storage::well_known_keys;
+	use sp_keyring::AccountKeyring;

 	#[derive(Debug, Serialize, Deserialize)]
 	struct Genesis(BTreeMap<String, String>);
@@ -536,4 +910,336 @@ mod tests {
 			);
 		}
 	}
+
+	#[test]
+	// some tests for json path utils
+	fn test_json_eval_value_at_key() {
+		let doc = json!({"a":{"b1":"20","b":{"c":{"d":"10"}}}});
+
+		assert!(json_eval_value_at_key(&doc, &mut json_path!["a", "b1"], &|v| { *v == "20" }));
+		assert!(json_eval_value_at_key(&doc, &mut json_path!["a", "b", "c", "d"], &|v| {
+			*v == "10"
+		}));
+		assert!(!json_eval_value_at_key(&doc, &mut json_path!["a", "c", "d"], &|_| { true }));
+		assert!(!json_eval_value_at_key(&doc, &mut json_path!["d"], &|_| { true }));
+
+		assert!(json_contains_path(&doc, &mut json_path!["a", "b1"]));
+		assert!(json_contains_path(&doc, &mut json_path!["a", "b"]));
+		assert!(json_contains_path(&doc, &mut json_path!["a", "b", "c"]));
+		assert!(json_contains_path(&doc, &mut json_path!["a", "b", "c", "d"]));
+		assert!(!json_contains_path(&doc, &mut json_path!["a", "b", "c", "d", "e"]));
+		assert!(!json_contains_path(&doc, &mut json_path!["a", "b", "b1"]));
+		assert!(!json_contains_path(&doc, &mut json_path!["d"]));
+	}
+
+	fn zeroize_code_key_in_json(encoded: bool, json: &str) -> Value {
+		let mut json = from_str::<Value>(json).unwrap();
+		let (zeroing_patch, mut path) = if encoded {
+			(
+				json!({"genesis":{"raw":{"top":{"0x3a636f6465":"0x0"}}}}),
+				json_path!["genesis", "raw", "top", "0x3a636f6465"],
+			)
+		} else {
+			(
+				json!({"genesis":{"runtimeGenesis":{"code":"0x0"}}}),
+				json_path!["genesis", "runtimeGenesis", "code"],
+			)
+		};
+		assert!(json_contains_path(&json, &mut path));
+		crate::json_patch::merge(&mut json, zeroing_patch);
+		json
+	}
+
+	#[docify::export]
+	#[test]
+	fn build_chain_spec_with_patch_works() {
+		let output: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config_patch(json!({
+			"babe": {
+				"epochConfig": {
+					"c": [
+						7,
+						10
+					],
+					"allowed_slots": "PrimaryAndSecondaryPlainSlots"
+				}
+			},
+			"substrateTest": {
+				"authorities": [
+					AccountKeyring::Ferdie.public().to_ss58check(),
+					AccountKeyring::Alice.public().to_ss58check()
+				],
+			}
+		}))
+		.build();
+
+		let raw_chain_spec = output.as_json(true);
+		assert!(raw_chain_spec.is_ok());
+	}
+
+	#[docify::export]
+	#[test]
+	fn generate_chain_spec_with_patch_works() {
+		let output: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config_patch(json!({
+			"babe": {
+				"epochConfig": {
+					"c": [
+						7,
+						10
+					],
+					"allowed_slots": "PrimaryAndSecondaryPlainSlots"
+				}
+			},
+			"substrateTest": {
+				"authorities": [
+					AccountKeyring::Ferdie.public().to_ss58check(),
+					AccountKeyring::Alice.public().to_ss58check()
+				],
+			}
+		}))
+		.build();
+
+		let actual = output.as_json(false).unwrap();
+		let actual_raw = output.as_json(true).unwrap();
+
+		let expected =
+			from_str::<Value>(include_str!("../res/substrate_test_runtime_from_patch.json"))
+				.unwrap();
+		let expected_raw =
+			from_str::<Value>(include_str!("../res/substrate_test_runtime_from_patch_raw.json"))
+				.unwrap();
+
+		//wasm blob may change overtime so let's zero it. Also ensure it is there:
+		let actual = zeroize_code_key_in_json(false, actual.as_str());
+		let actual_raw = zeroize_code_key_in_json(true, actual_raw.as_str());
+
+		assert_eq!(actual, expected);
+		assert_eq!(actual_raw, expected_raw);
+	}
+
+	#[test]
+	fn generate_chain_spec_with_full_config_works() {
+		let j = include_str!("../../../test-utils/runtime/res/default_genesis_config.json");
+		let output: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config(from_str(j).unwrap())
+		.build();
+
+		let actual = output.as_json(false).unwrap();
+		let actual_raw = output.as_json(true).unwrap();
+
+		let expected =
+			from_str::<Value>(include_str!("../res/substrate_test_runtime_from_config.json"))
+				.unwrap();
+		let expected_raw =
+			from_str::<Value>(include_str!("../res/substrate_test_runtime_from_config_raw.json"))
+				.unwrap();
+
+		//wasm blob may change overtime so let's zero it. Also ensure it is there:
+		let actual = zeroize_code_key_in_json(false, actual.as_str());
+		let actual_raw = zeroize_code_key_in_json(true, actual_raw.as_str());
+
+		assert_eq!(actual, expected);
+		assert_eq!(actual_raw, expected_raw);
+	}
+
+	#[test]
+	fn chain_spec_as_json_fails_with_invalid_config() {
+		let j =
+			include_str!("../../../test-utils/runtime/res/default_genesis_config_invalid_2.json");
+		let output: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config(from_str(j).unwrap())
+		.build();
+
+		assert_eq!(
+			output.as_json(true),
+			Err("Invalid JSON blob: unknown field `babex`, expected one of `system`, `babe`, `substrateTest`, `balances` at line 1 column 8".to_string())
+		);
+	}
+
+	#[test]
+	fn chain_spec_as_json_fails_with_invalid_patch() {
+		let output: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config_patch(json!({
+			"invalid_pallet": {},
+			"substrateTest": {
+				"authorities": [
+					AccountKeyring::Ferdie.public().to_ss58check(),
+					AccountKeyring::Alice.public().to_ss58check()
+				],
+			}
+		}))
+		.build();
+
+		assert!(output.as_json(true).unwrap_err().contains("Invalid JSON blob: unknown field `invalid_pallet`, expected one of `system`, `babe`, `substrateTest`, `balances`"));
+	}
+
+	#[test]
+	fn check_if_code_is_valid_for_raw_without_code() {
+		let spec = ChainSpec::<()>::from_json_bytes(Cow::Owned(
+			include_bytes!("../res/raw_no_code.json").to_vec(),
+		))
+		.unwrap();
+
+		let j = from_str::<Value>(&spec.as_json(true).unwrap()).unwrap();
+
+		assert!(json_eval_value_at_key(
+			&j,
+			&mut json_path!["genesis", "raw", "top", "0x3a636f6465"],
+			&|v| { *v == "0x010101" }
+		));
+		assert!(!json_contains_path(&j, &mut json_path!["code"]));
+	}
+
+	#[test]
+	fn check_code_in_assimilated_storage_for_raw_without_code() {
+		let spec = ChainSpec::<()>::from_json_bytes(Cow::Owned(
+			include_bytes!("../res/raw_no_code.json").to_vec(),
+		))
+		.unwrap();
+
+		let storage = spec.build_storage().unwrap();
+		assert!(storage
+			.top
+			.get(&well_known_keys::CODE.to_vec())
+			.map(|v| *v == vec![1, 1, 1])
+			.unwrap())
+	}
+
+	#[test]
+	fn update_code_works_with_runtime_genesis_config() {
+		let j = include_str!("../../../test-utils/runtime/res/default_genesis_config.json");
+		let chain_spec: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config(from_str(j).unwrap())
+		.build();
+
+		let mut chain_spec_json = from_str::<Value>(&chain_spec.as_json(false).unwrap()).unwrap();
+		assert!(update_code_in_json_chain_spec(&mut chain_spec_json, &[0, 1, 2, 4, 5, 6]));
+
+		assert!(json_eval_value_at_key(
+			&chain_spec_json,
+			&mut json_path!["genesis", "runtimeGenesis", "code"],
+			&|v| { *v == "0x000102040506" }
+		));
+	}
+
+	#[test]
+	fn update_code_works_for_raw() {
+		let j = include_str!("../../../test-utils/runtime/res/default_genesis_config.json");
+		let chain_spec: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config(from_str(j).unwrap())
+		.build();
+
+		let mut chain_spec_json = from_str::<Value>(&chain_spec.as_json(true).unwrap()).unwrap();
+		assert!(update_code_in_json_chain_spec(&mut chain_spec_json, &[0, 1, 2, 4, 5, 6]));
+
+		assert!(json_eval_value_at_key(
+			&chain_spec_json,
+			&mut json_path!["genesis", "raw", "top", "0x3a636f6465"],
+			&|v| { *v == "0x000102040506" }
+		));
+	}
+
+	#[test]
+	fn update_code_works_with_runtime_genesis_patch() {
+		let chain_spec: ChainSpec<()> = ChainSpec::builder(
+			substrate_test_runtime::wasm_binary_unwrap().into(),
+			Default::default(),
+		)
+		.with_name("TestName")
+		.with_id("test_id")
+		.with_chain_type(ChainType::Local)
+		.with_genesis_config_patch(json!({}))
+		.build();
+
+		let mut chain_spec_json = from_str::<Value>(&chain_spec.as_json(false).unwrap()).unwrap();
+		assert!(update_code_in_json_chain_spec(&mut chain_spec_json, &[0, 1, 2, 4, 5, 6]));
+
+		assert!(json_eval_value_at_key(
+			&chain_spec_json,
+			&mut json_path!["genesis", "runtimeGenesis", "code"],
+			&|v| { *v == "0x000102040506" }
+		));
+	}
+
+	#[test]
+	fn generate_from_genesis_is_still_supported() {
+		#[allow(deprecated)]
+		let chain_spec: ChainSpec<substrate_test_runtime::RuntimeGenesisConfig> = ChainSpec::from_genesis(
+			"TestName",
+			"test",
+			ChainType::Local,
+			move || substrate_test_runtime::RuntimeGenesisConfig {
+				babe: substrate_test_runtime::BabeConfig {
+					epoch_config: Some(
+						substrate_test_runtime::TEST_RUNTIME_BABE_EPOCH_CONFIGURATION,
+					),
+					..Default::default()
+				},
+				..Default::default()
+			},
+			Vec::new(),
+			None,
+			None,
+			None,
+			None,
+			Default::default(),
+			&vec![0, 1, 2, 4, 5, 6],
+		);
+
+		let chain_spec_json = from_str::<Value>(&chain_spec.as_json(false).unwrap()).unwrap();
+		assert!(json_eval_value_at_key(
+			&chain_spec_json,
+			&mut json_path!["genesis", "runtimeAndCode", "code"],
+			&|v| { *v == "0x000102040506" }
+		));
+		let chain_spec_json = from_str::<Value>(&chain_spec.as_json(true).unwrap()).unwrap();
+		assert!(json_eval_value_at_key(
+			&chain_spec_json,
+			&mut json_path!["genesis", "raw", "top", "0x3a636f6465"],
+			&|v| { *v == "0x000102040506" }
+		));
+	}
 }
@@ -0,0 +1,183 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! A helper module for calling the GenesisBuilder API from arbitrary runtime wasm blobs.
+
+use codec::{Decode, Encode};
+use sc_executor::{error::Result, WasmExecutor};
+use serde_json::{from_slice, Value};
+use sp_core::{
+	storage::Storage,
+	traits::{CallContext, CodeExecutor, Externalities, FetchRuntimeCode, RuntimeCode},
+};
+use sp_genesis_builder::Result as BuildResult;
+use sp_state_machine::BasicExternalities;
+use std::borrow::Cow;
+
+/// A utility that facilitates calling the GenesisBuilder API from the runtime wasm code blob.
+pub struct GenesisConfigBuilderRuntimeCaller<'a> {
+	code: Cow<'a, [u8]>,
+	code_hash: Vec<u8>,
+	executor: WasmExecutor<sp_io::SubstrateHostFunctions>,
+}
+
+impl<'a> FetchRuntimeCode for GenesisConfigBuilderRuntimeCaller<'a> {
+	fn fetch_runtime_code(&self) -> Option<Cow<[u8]>> {
+		Some(self.code.as_ref().into())
+	}
+}
+
+impl<'a> GenesisConfigBuilderRuntimeCaller<'a> {
+	/// Creates new instance using the provided code blob.
+	///
+	/// This code is later referred to as `runtime`.
+	pub fn new(code: &'a [u8]) -> Self {
+		GenesisConfigBuilderRuntimeCaller {
+			code: code.into(),
+			code_hash: sp_core::blake2_256(code).to_vec(),
+			executor: WasmExecutor::<sp_io::SubstrateHostFunctions>::builder()
+				.with_allow_missing_host_functions(true)
+				.build(),
+		}
+	}
+
+	fn call(&self, ext: &mut dyn Externalities, method: &str, data: &[u8]) -> Result<Vec<u8>> {
+		self.executor
+			.call(
+				ext,
+				&RuntimeCode { heap_pages: None, code_fetcher: self, hash: self.code_hash.clone() },
+				method,
+				data,
+				false,
+				CallContext::Offchain,
+			)
+			.0
+	}
+
+	/// Returns the default `GenesisConfig` provided by the `runtime`.
+	///
+	/// Calls [`GenesisBuilder::create_default_config`](sp_genesis_builder::GenesisBuilder::create_default_config) in the `runtime`.
+	pub fn get_default_config(&self) -> core::result::Result<Value, String> {
+		let mut t = BasicExternalities::new_empty();
+		let call_result = self
+			.call(&mut t, "GenesisBuilder_create_default_config", &[])
+			.map_err(|e| format!("wasm call error {e}"))?;
+		let default_config = Vec::<u8>::decode(&mut &call_result[..])
+			.map_err(|e| format!("scale codec error: {e}"))?;
+		Ok(from_slice(&default_config[..]).expect("returned value is json. qed."))
+	}
+
+	/// Build the given `GenesisConfig` and returns the genesis state.
+	///
+	/// Calls [`GenesisBuilder::build_config`](sp_genesis_builder::GenesisBuilder::build_config)
+	/// provided by the `runtime`.
+	pub fn get_storage_for_config(&self, config: Value) -> core::result::Result<Storage, String> {
+		let mut ext = BasicExternalities::new_empty();
+
+		let call_result = self
+			.call(&mut ext, "GenesisBuilder_build_config", &config.to_string().encode())
+			.map_err(|e| format!("wasm call error {e}"))?;
+
+		BuildResult::decode(&mut &call_result[..])
+			.map_err(|e| format!("scale codec error: {e}"))??;
+
+		Ok(ext.into_storages())
+	}
+
+	/// Creates the genesis state by patching the default `GenesisConfig` and applying it.
+	///
+	/// This function generates the `GenesisConfig` for the runtime by applying a provided JSON
+	/// patch. The patch modifies the default `GenesisConfig` allowing customization of the specific
+	/// keys. The resulting `GenesisConfig` is then deserialized from the patched JSON
+	/// representation and stored in the storage.
+	///
+	/// If the provided JSON patch is incorrect or the deserialization fails the error will be
+	/// returned.
+	///
+	/// The patching process modifies the default `GenesisConfig` according to the following rules:
+	/// 1. Existing keys in the default configuration will be overridden by the corresponding values
+	///    in the patch.
+	/// 2. If a key exists in the patch but not in the default configuration, it will be added to
+	///    the resulting `GenesisConfig`.
+	/// 3. Keys in the default configuration that have null values in the patch will be removed from
+	///    the resulting  `GenesisConfig`. This is helpful for changing enum variant value.
+	///
+	/// Please note that the patch may contain full `GenesisConfig`.
+	pub fn get_storage_for_patch(&self, patch: Value) -> core::result::Result<Storage, String> {
+		let mut config = self.get_default_config()?;
+		crate::json_patch::merge(&mut config, patch);
+		self.get_storage_for_config(config)
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use serde_json::{from_str, json};
+	pub use sp_consensus_babe::{AllowedSlots, BabeEpochConfiguration, Slot};
+
+	#[test]
+	fn get_default_config_works() {
+		let config =
+			GenesisConfigBuilderRuntimeCaller::new(substrate_test_runtime::wasm_binary_unwrap())
+				.get_default_config()
+				.unwrap();
+		let expected = r#"{"system":{},"babe":{"authorities":[],"epochConfig":null},"substrateTest":{"authorities":[]},"balances":{"balances":[]}}"#;
+		assert_eq!(from_str::<Value>(expected).unwrap(), config);
+	}
+
+	#[test]
+	fn get_storage_for_patch_works() {
+		let patch = json!({
+			"babe": {
+				"epochConfig": {
+					"c": [
+						69,
+						696
+					],
+					"allowed_slots": "PrimaryAndSecondaryPlainSlots"
+				}
+			},
+		});
+
+		let storage =
+			GenesisConfigBuilderRuntimeCaller::new(substrate_test_runtime::wasm_binary_unwrap())
+				.get_storage_for_patch(patch)
+				.unwrap();
+
+		//Babe|Authorities
+		let value: Vec<u8> = storage
+			.top
+			.get(
+				&array_bytes::hex2bytes(
+					"1cb6f36e027abb2091cfb5110ab5087fdc6b171b77304263c292cc3ea5ed31ef",
+				)
+				.unwrap(),
+			)
+			.unwrap()
+			.clone();
+
+		assert_eq!(
+			BabeEpochConfiguration::decode(&mut &value[..]).unwrap(),
+			BabeEpochConfiguration {
+				c: (69, 696),
+				allowed_slots: AllowedSlots::PrimaryAndSecondaryPlainSlots
+			}
+		);
+	}
+}
@@ -0,0 +1,191 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! A helper module providing json patching functions.
+
+use serde_json::Value;
+
+/// Recursively merges two JSON objects, `a` and `b`, into a single object.
+///
+/// If a key exists in both objects, the value from `b` will override the value from `a`.
+/// If a key exists in `b` with a `null` value, it will be removed from `a`.
+/// If a key exists only in `b` and not in `a`, it will be added to `a`.
+///
+/// # Arguments
+///
+/// * `a` - A mutable reference to the target JSON object to merge into.
+/// * `b` - The JSON object to merge with `a`.
+pub fn merge(a: &mut Value, b: Value) {
+	match (a, b) {
+		(Value::Object(a), Value::Object(b)) =>
+			for (k, v) in b {
+				if v.is_null() {
+					a.remove(&k);
+				} else {
+					merge(a.entry(k).or_insert(Value::Null), v);
+				}
+			},
+		(a, b) => *a = b,
+	};
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use serde_json::json;
+
+	#[test]
+	fn test1_simple_merge() {
+		let mut j1 = json!({ "a":123 });
+		merge(&mut j1, json!({ "b":256 }));
+		assert_eq!(j1, json!({ "a":123, "b":256 }));
+	}
+
+	#[test]
+	fn test2_patch_simple_merge_nested() {
+		let mut j1 = json!({
+			"a": {
+				"name": "xxx",
+				"value": 123
+			},
+			"b": { "c" : { "inner_name": "yyy" } }
+		});
+
+		let j2 = json!({
+			"a": {
+				"keys": ["a", "b", "c" ]
+			}
+		});
+
+		merge(&mut j1, j2);
+		assert_eq!(
+			j1,
+			json!({"a":{"keys":["a","b","c"],"name":"xxx","value":123}, "b": { "c" : { "inner_name": "yyy" } }})
+		);
+	}
+
+	#[test]
+	fn test3_patch_overrides_existing_keys() {
+		let mut j1 = json!({
+			"a": {
+				"name": "xxx",
+				"value": 123,
+				"keys": ["d"]
+
+			}
+		});
+
+		let j2 = json!({
+			"a": {
+				"keys": ["a", "b", "c" ]
+			}
+		});
+
+		merge(&mut j1, j2);
+		assert_eq!(j1, json!({"a":{"keys":["a","b","c"],"name":"xxx","value":123}}));
+	}
+
+	#[test]
+	fn test4_patch_overrides_existing_keys() {
+		let mut j1 = json!({
+			"a": {
+				"name": "xxx",
+				"value": 123,
+				"b" : {
+					"inner_name": "yyy"
+				}
+			}
+		});
+
+		let j2 = json!({
+			"a": {
+				"name": "new_name",
+				"b" : {
+					"inner_name": "inner_new_name"
+				}
+			}
+		});
+
+		merge(&mut j1, j2);
+		assert_eq!(
+			j1,
+			json!({ "a": {"name":"new_name", "value":123, "b" : { "inner_name": "inner_new_name" }} })
+		);
+	}
+
+	#[test]
+	fn test5_patch_overrides_existing_nested_keys() {
+		let mut j1 = json!({
+			"a": {
+				"name": "xxx",
+				"value": 123,
+				"b": {
+					"c": {
+						"d": {
+							"name": "yyy",
+							"value": 256
+						}
+					}
+				}
+			},
+		});
+
+		let j2 = json!({
+			"a": {
+				"value": 456,
+				"b": {
+					"c": {
+						"d": {
+							"name": "new_name"
+						}
+					}
+				}
+			}
+		});
+
+		merge(&mut j1, j2);
+		assert_eq!(
+			j1,
+			json!({ "a": {"name":"xxx", "value":456, "b": { "c": { "d": { "name": "new_name", "value": 256 }}}}})
+		);
+	}
+
+	#[test]
+	fn test6_patch_removes_keys_if_null() {
+		let mut j1 = json!({
+			"a": {
+				"name": "xxx",
+				"value": 123,
+				"enum_variant_1": {
+					"name": "yyy",
+				}
+			},
+		});
+
+		let j2 = json!({
+			"a": {
+				"value": 456,
+				"enum_variant_1": null,
+				"enum_variant_2": 32,
+			}
+		});
+
+		merge(&mut j1, j2);
+		assert_eq!(j1, json!({ "a": {"name":"xxx", "value":456, "enum_variant_2": 32 }}));
+	}
+}
@@ -16,38 +16,253 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.

-//! Substrate chain configurations.
+//! This crate includes structs and utilities for defining configuration files (known as chain
+//! specification) for both runtime and node.
 //!
-//! This crate contains structs and utilities to declare
-//! a runtime-specific configuration file (a.k.a chain spec).
+//! # Intro: Chain Specification
 //!
-//! Basic chain spec type containing all required parameters is
-//! [`GenericChainSpec`]. It can be extended with
-//! additional options that contain configuration specific to your chain.
-//! Usually the extension is going to be an amalgamate of types exposed
-//! by Substrate core modules. To allow the core modules to retrieve
-//! their configuration from your extension you should use `ChainSpecExtension`
-//! macro exposed by this crate.
+//! The chain specification comprises parameters and settings that define the properties and an
+//! initial state of a chain. Users typically interact with the JSON representation of the chain
+//! spec. Internally, the chain spec is embodied by the [`GenericChainSpec`] struct, and specific
+//! properties can be accessed using the [`ChainSpec`] trait.
 //!
+//! In summary, although not restricted to, the primary role of the chain spec is to provide a list
+//! of well-known boot nodes for the blockchain network and the means for initializing the genesis
+//! storage. This initialization is necessary for creating a genesis block upon which subsequent
+//! blocks are built. When the node is launched for the first time, it reads the chain spec,
+//! initializes the genesis block, and establishes connections with the boot nodes.
+//!
+//! The JSON chain spec is divided into two main logical sections:
+//! - one section details general chain properties,
+//! - second explicitly or indirectly defines the genesis storage, which, in turn, determines the
+//!   genesis hash of the chain,
+//!
+//! The chain specification consists of the following fields:
+//!
+//! <table>
+//!   <thead>
+//!     <tr>
+//!       <th>Chain spec key</th>
+//!       <th>Description</th>
+//!     </tr>
+//!   </thead>
+//!   <tbody>
+//!     <tr>
+//!       <td>name</td>
+//!       <td>The human readable name of the chain.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>id</td>
+//!       <td>The id of the chain.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>chainType</td>
+//!       <td>The chain type of this chain
+//!           (refer to
+//!            <a href="enum.ChainType.html" title="enum sc_chain_spec::ChainType">
+//!              <code>ChainType</code>
+//!            </a>).
+//!       </td>
+//!     </tr>
+//!     <tr>
+//!       <td>bootNodes</td>
+//!       <td>A list of
+//!       <a href="https://github.com/multiformats/multiaddr">multi addresses</a>
+//!       that belong to boot nodes of the chain.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>telemetryEndpoints</td>
+//!       <td>Optional list of <code>multi address, verbosity</code> of telemetry endpoints. The
+//! verbosity goes from 0 to 9. With 0 being the mode with the lowest verbosity.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>protocolId</td>
+//!       <td>Optional networking protocol id that identifies the chain.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>forkId</td>
+//!       <td>Optional fork id. Should most likely be left empty. Can be used to signal a fork on
+//! the network level when two chains have the same genesis hash.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>properties</td>
+//!       <td>Custom properties. Shall be provided in the form of
+//! <code>key</code>-<code>value</code> json object.
+//!     </td>
+//!     </tr>
+//!     <tr>
+//!       <td>consensusEngine</td>
+//!       <td>Deprecated field. Should be ignored.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>codeSubstitutes</td>
+//!       <td>Optional map of <code>block_number</code> to <code>wasm_code</code>. More details in
+//! material to follow.</td>
+//!     </tr>
+//!     <tr>
+//!       <td>genesis</td>
+//!       <td>Defines the initial state of the runtime. More details in material to follow.</td>
+//!     </tr>
+//!   </tbody>
+//! </table>
+//!
+//! # `genesis`: Initial Runtime State
+//!
+//! All nodes in the network must build subsequent blocks upon exactly the same genesis block.
+//!
+//! The information configured in the `genesis` section of a chain specification is used to build
+//! the genesis storage, which is essential for creating the genesis block, since the block header
+//! includes the storage root hash.
+//!
+//! The `genesis` key of the chain specification definition describes the
+//! initial state of the runtime. For example, it may contain:
+//! - an initial list of funded accounts,
+//! - the administrative account that controls the sudo key,
+//! - an initial authorities set for consensus, etc.
+//!
+//! As the compiled WASM blob of the runtime code is stored in the chain's state, the initial
+//! runtime must also be provided within the chain specification.
+//!
+//! In essence, the most important formats of genesis initial state are:
+//!
+//! <table>
+//!   <thead>
+//!     <tr>
+//!       <th>Format</th>
+//!       <th>Description</th>
+//!     </tr>
+//!   </thead>
+//!   <tbody>
+//!     <tr>
+//!       <td>
+//! 		<code>runtime / full config</code>
+//!       </td>
+//!       <td>A JSON object that provides an explicit and comprehensive representation of the
+//! <code>RuntimeGenesisConfig</code> struct, which is generated by <a
+//! href="../frame_support_procedural/macro.construct_runtime.html"
+//! ><code>frame::runtime::prelude::construct_runtime</code></a> macro (<a
+//! href="../substrate_test_runtime/struct.RuntimeGenesisConfig.html#"
+//! >example of generated struct</a>). Must contain all the keys of
+//! the genesis config, no defaults will be used.
+//!
+//! This format explicitly provides the code of the runtime.
+//! </td></tr>
+//!     <tr>
+//!       <td>
+//! 		<code>patch</code>
+//!       </td>
+//!       <td>A JSON object that offers a partial representation of the
+//!       <code>RuntimeGenesisConfig</code> provided by the runtime. It contains a patch, which is
+//! essentially a list of key-value pairs to customize in the default runtime's
+//! <code>RuntimeGenesisConfig</code>.
+//! This format explicitly provides the code of the runtime.
+//! </td></tr>
+//!     <tr>
+//!       <td>
+//! 		<code>raw</code>
+//!       </td>
+//!       <td>A JSON object with two fields: <code>top</code> and <code>children_default</code>.
+//! Each field is a map of <code>key => value</code> pairs representing entries in a genesis storage
+//! trie. The runtime code is one of such entries.</td>
+//!     </tr>
+//!   </tbody>
+//! </table>
+//!
+//! For production or long-lasting blockchains, using the `raw` format in the chain specification is
+//! recommended. Only the `raw` format guarantees that storage root hash will remain unchanged when
+//! the `RuntimeGenesisConfig` format changes due to software upgrade.
+//!
+//! JSON examples in the [following section](#json-chain-specification-example) illustrate the `raw`
+//! `patch` and full genesis fields.
+//!
+//! # From Initial State to Raw Genesis.
+//!
+//! To generate a raw genesis storage from the JSON representation of the runtime genesis config,
+//! the node needs to interact with the runtime.
+//!
+//! This interaction involves passing the runtime genesis config JSON blob to the runtime using the
+//! [`sp_genesis_builder::GenesisBuilder::build_config`] function. During this operation, the
+//! runtime converts the JSON representation of the genesis config into [`sp_io::storage`] items. It
+//! is a crucial step for computing the storage root hash, which is a key component in determining
+//! the genesis hash.
+//!
+//! Consequently, the runtime must support the [`sp_genesis_builder::GenesisBuilder`] API to
+//! utilize either `patch` or `full` formats.
+//!
+//! This entire process is encapsulated within the implementation of the [`BuildStorage`] trait,
+//! which can be accessed through the [`ChainSpec::as_storage_builder`] method. There is an
+//! intermediate internal helper that facilitates this interaction,
+//! [`GenesisConfigBuilderRuntimeCaller`], which serves as a straightforward wrapper for
+//! [`sc_executor::WasmExecutor`].
+//!
+//! In case of `raw` genesis state the node does not interact with the runtime regarding the
+//! computation of initial state.
+//!
+//! The plain and `raw` chain specification JSON blobs can be found in
+//! [JSON examples](#json-chain-specification-example) section.
+//!
+//! # Optional Code Mapping
+//!
+//! Optional map of `block_number` to `wasm_code`.
+//!
+//! The given `wasm_code` will be used to substitute the on-chain wasm code starting with the
+//! given block number until the `spec_version` on-chain changes. The given `wasm_code` should
+//! be as close as possible to the on-chain wasm code. A substitute should be used to fix a bug
+//! that cannot be fixed with a runtime upgrade, if for example the runtime is constantly
+//! panicking. Introducing new runtime APIs isn't supported, because the node
+//! will read the runtime version from the on-chain wasm code.
+//!
+//! Use this functionality only when there is no other way around it, and only patch the problematic
+//! bug; the rest should be done with an on-chain runtime upgrade.
+//!
+//! # Building a Chain Specification
+//!
+//! The [`ChainSpecBuilder`] should be used to create an instance of a chain specification. Its API
+//! allows configuration of all fields of the chain spec. To generate a JSON representation of the
+//! specification, use [`ChainSpec::as_json`].
+//!
+//! The sample code to generate a chain spec is as follows:
+#![doc = docify::embed!("src/chain_spec.rs", build_chain_spec_with_patch_works)]
+//! # JSON chain specification example
+//!
+//! The following are the plain and `raw` versions of the chain specification JSON files, resulting
+//! from executing of the above [example](#building-a-chain-specification):
+//! ```ignore
+#![doc = include_str!("../res/substrate_test_runtime_from_patch.json")]
+//! ```
+//! ```ignore
+#![doc = include_str!("../res/substrate_test_runtime_from_patch_raw.json")]
+//! ```
+//! The following example shows the plain full config version of chain spec:
+//! ```ignore
+#![doc = include_str!("../res/substrate_test_runtime_from_config.json")]
+//! ```
+//! The [`ChainSpec`] trait represents the API to access values defined in the JSON chain specification.
+//!
+//!
+//! # Custom Chain Spec Extensions
+//!
+//! The basic chain spec type containing all required parameters is [`GenericChainSpec`]. It can be
+//! extended with additional options containing configuration specific to your chain. Usually, the
+//! extension will be a combination of types exposed by Substrate core modules.
+//!
+//! To allow the core modules to retrieve their configuration from your extension, you should use
+//! `ChainSpecExtension` macro exposed by this crate.
 //! ```rust
 //! use std::collections::HashMap;
 //! use sc_chain_spec::{GenericChainSpec, ChainSpecExtension};
 //!
 //! #[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecExtension)]
 //! pub struct MyExtension {
-//! 		pub known_blocks: HashMap<u64, String>,
+//! 	pub known_blocks: HashMap<u64, String>,
 //! }
 //!
 //! pub type MyChainSpec<G> = GenericChainSpec<G, MyExtension>;
 //! ```
-//!
-//! Some parameters may require different values depending on the
-//! current blockchain height (a.k.a. forks). You can use `ChainSpecGroup`
-//! macro and provided [`Forks`](./struct.Forks.html) structure to put
-//! such parameters to your chain spec.
-//! This will allow to override a single parameter starting at specific
-//! block number.
-//!
+//! Some parameters may require different values depending on the current blockchain height (a.k.a.
+//! forks). You can use the [`ChainSpecGroup`](macro@ChainSpecGroup) macro and the provided [`Forks`]
+//! structure to add such parameters to your chain spec. This will allow overriding a single
+//! parameter starting at a specific block number.
 //! ```rust
 //! use sc_chain_spec::{Forks, ChainSpecGroup, ChainSpecExtension, GenericChainSpec};
 //!
@@ -76,12 +291,9 @@
 //! /// A chain spec supporting forkable `Extension`.
 //! pub type MyChainSpec2<G> = GenericChainSpec<G, Forks<BlockNumber, Extension>>;
 //! ```
-//!
-//! It's also possible to have a set of parameters that is allowed to change
-//! with block numbers (i.e. is forkable), and another set that is not subject to changes.
-//! This is also possible by declaring an extension that contains `Forks` within it.
-//!
-//!
+//! It's also possible to have a set of parameters that are allowed to change with block numbers
+//! (i.e., they are forkable), and another set that is not subject to changes. This can also be
+//! achieved by declaring an extension that contains [`Forks`] within it.
 //! ```rust
 //! use serde::{Serialize, Deserialize};
 //! use sc_chain_spec::{Forks, GenericChainSpec, ChainSpecGroup, ChainSpecExtension};
@@ -106,98 +318,26 @@
 //!
 //! pub type MyChainSpec<G> = GenericChainSpec<G, Extension>;
 //! ```
-//!
-//! # Substrate chain specification format
-//!
-//! The Substrate chain specification is a `json` file that describes the basics of a chain. Most
-//! importantly it lays out the genesis storage which leads to the genesis hash. The default
-//! Substrate chain specification format is the following:
-//!
-//! ```json
-//! // The human readable name of the chain.
-//! "name": "Flaming Fir",
-//!
-//! // The id of the chain.
-//! "id": "flamingfir9",
-//!
-//! // The chain type of this chain.
-//! // Possible values are `Live`, `Development`, `Local`.
-//! "chainType": "Live",
-//!
-//! // A list of multi addresses that belong to boot nodes of the chain.
-//! "bootNodes": [
-//!   "/dns/0.flamingfir.paritytech.net/tcp/30333/p2p/12D3KooWLK2gMLhWsYJzjW3q35zAs9FDDVqfqVfVuskiGZGRSMvR",
-//! ],
-//!
-//! // Optional list of "multi address, verbosity" of telemetry endpoints.
-//! // The verbosity goes from `0` to `9`. With `0` being the mode with the lowest verbosity.
-//! "telemetryEndpoints": [
-//!   [
-//!     "/dns/telemetry.polkadot.io/tcp/443/x-parity-wss/%2Fsubmit%2F",
-//!     0
-//!   ]
-//! ],
-//!
-//! // Optional networking protocol id that identifies the chain.
-//! "protocolId": "fir9",
-//!
-//! // Optional fork id. Should most likely be left empty.
-//! // Can be used to signal a fork on the network level when two chains have the
-//! // same genesis hash.
-//! "forkId": "random_fork",
-//!
-//! // Custom properties.
-//! "properties": {
-//!   "tokenDecimals": 15,
-//!   "tokenSymbol": "FIR"
-//! },
-//!
-//! // Deprecated field. Should be ignored.
-//! "consensusEngine": null,
-//!
-//! // The genesis declaration of the chain.
-//! //
-//! // `runtime`, `raw`, `stateRootHash` denote the type of the genesis declaration.
-//! //
-//! // These declarations are in the following formats:
-//! // - `runtime` is a `json` object that can be parsed by a compatible `GenesisConfig`. This
-//! //  `GenesisConfig` is declared by a runtime and opaque to the node.
-//! // - `raw` is a `json` object with two fields `top` and `children_default`. Each of these
-//! //   fields is a map of `key => value`. These key/value pairs represent the genesis storage.
-//! // - `stateRootHash` is a single hex encoded hash that represents the genesis hash. The hash
-//! //   type depends on the hash used by the chain.
-//! //
-//! "genesis": { "runtime": {} },
-//!
-//! /// Optional map of `block_number` to `wasm_code`.
-//! ///
-//! /// The given `wasm_code` will be used to substitute the on-chain wasm code starting with the
-//! /// given block number until the `spec_version` on-chain changes. The given `wasm_code` should
-//! /// be as close as possible to the on-chain wasm code. A substitute should be used to fix a bug
-//! /// that can not be fixed with a runtime upgrade, if for example the runtime is constantly
-//! /// panicking. Introducing new runtime apis isn't supported, because the node
-//! /// will read the runtime version from the on-chain wasm code. Use this functionality only when
-//! /// there is no other way around it and only patch the problematic bug, the rest should be done
-//! /// with a on-chain runtime upgrade.
-//! "codeSubstitutes": [],
-//! ```
-//!
-//! See [`ChainSpec`] for a trait representation of the above.
-//!
 //! The chain spec can be extended with other fields that are opaque to the default chain spec.
 //! Specific node implementations will need to be able to deserialize these extensions.

 mod chain_spec;
 mod extension;
-mod genesis;
+mod genesis_block;
+mod genesis_config_builder;
+mod json_patch;

 pub use self::{
-	chain_spec::{ChainSpec as GenericChainSpec, NoExtension},
+	chain_spec::{
+		update_code_in_json_chain_spec, ChainSpec as GenericChainSpec, ChainSpecBuilder,
+		NoExtension,
+	},
 	extension::{get_extension, get_extension_mut, Extension, Fork, Forks, GetExtension, Group},
-	genesis::{
+	genesis_block::{
 		construct_genesis_block, resolve_state_version_from_wasm, BuildGenesisBlock,
 		GenesisBlockBuilder,
 	},
+	genesis_config_builder::GenesisConfigBuilderRuntimeCaller,
 };
 pub use sc_chain_spec_derive::{ChainSpecExtension, ChainSpecGroup};

@@ -126,18 +126,14 @@ mod tests {
 		}

 		fn load_spec(&self, _: &str) -> std::result::Result<Box<dyn ChainSpec>, String> {
-			Ok(Box::new(GenericChainSpec::from_genesis(
-				"test",
-				"test_id",
-				ChainType::Development,
-				|| unimplemented!("Not required in tests"),
-				Vec::new(),
-				None,
-				None,
-				None,
-				None,
-				NoExtension::None,
-			)))
+			Ok(Box::new(
+				GenericChainSpec::<()>::builder(Default::default(), NoExtension::None)
+					.with_name("test")
+					.with_id("test_id")
+					.with_chain_type(ChainType::Development)
+					.with_genesis_config_patch(Default::default())
+					.build(),
+			))
 		}
 	}

@@ -251,18 +251,14 @@ mod tests {
 				trie_cache_maximum_size: None,
 				state_pruning: None,
 				blocks_pruning: sc_client_db::BlocksPruning::KeepAll,
-				chain_spec: Box::new(GenericChainSpec::from_genesis(
-					"test",
-					"test_id",
-					ChainType::Development,
-					|| unimplemented!("Not required in tests"),
-					Vec::new(),
-					None,
-					None,
-					None,
-					None,
-					NoExtension::None,
-				)),
+				chain_spec: Box::new(
+					GenericChainSpec::<()>::builder(Default::default(), NoExtension::None)
+						.with_name("test")
+						.with_id("test_id")
+						.with_chain_type(ChainType::Development)
+						.with_genesis_config_patch(Default::default())
+						.build(),
+				),
 				wasm_method: Default::default(),
 				wasm_runtime_overrides: None,
 				rpc_addr: None,
@@ -724,8 +724,6 @@ pub mod pallet {
 	#[derive(frame_support::DefaultNoBound)]
 	#[pallet::genesis_config]
 	pub struct GenesisConfig<T: Config> {
-		#[serde(with = "sp_core::bytes")]
-		pub code: Vec<u8>,
 		#[serde(skip)]
 		pub _config: sp_std::marker::PhantomData<T>,
 	}
@@ -739,7 +737,6 @@ pub mod pallet {
 			<UpgradedToU32RefCount<T>>::put(true);
 			<UpgradedToTripleRefCount<T>>::put(true);

-			sp_io::storage::set(well_known_keys::CODE, &self.code);
 			sp_io::storage::set(well_known_keys::EXTRINSIC_INDEX, &0u32.encode());
 		}
 	}
@@ -141,8 +141,9 @@
 //!   side features. The corresponding runtime, called [`kitchensink_runtime`] contains all of the
 //!   modules that are provided with `FRAME`. This node and runtime is only used for testing and
 //!   demonstration.
-//!     * [`chain-spec-builder`]: Utility to build more detailed chain-specs for the aforementioned
-//!       node. Other projects typically contain a `build-spec` subcommand that does the same.
+//! * [`chain-spec-builder`]: Utility to build more detailed [chain-spec][`sc-chain-spec`] for the
+//!   aforementioned node. Other projects typically contain a `build-spec` subcommand that does the
+//!   same.
 //! * [`node-template`]: a template node that contains a minimal set of features and can act as a
 //!   starting point of a project.
 //! * [`subkey`]: Substrate's key management utility.
@@ -177,6 +178,8 @@
 //!
 //! Additional noteworthy crates within substrate:
 //!
+//! - Chain specification of a Substrate node:
+//!     - [`sc-chain-spec`]
 //! - RPC APIs of a Substrate node: [`sc-rpc-api`]/[`sc-rpc`]
 //! - CLI Options of a Substrate node: [`sc-cli`]
 //! - All of the consensus related crates provided by Substrate:
@@ -217,6 +220,7 @@
 //! [`sp-api`]: ../sp_api/index.html
 //! [`sp-api`]: ../sp_api/index.html
 //! [`sc-client-db`]: ../sc_client_db/index.html
+//! [`sc-chain-spec`]: ../sc_chain_spec/index.html
 //! [`sc-network`]: ../sc_network/index.html
 //! [`sc-rpc-api`]: ../sc_rpc_api/index.html
 //! [`sc-rpc`]: ../sc_rpc/index.html
@@ -48,8 +48,6 @@ sp-externalities = { path = "../../primitives/externalities", default-features =
 # 3rd party
 array-bytes = { version = "6.1", optional = true }
 log = { version = "0.4.17", default-features = false }
-serde = { version = "1.0.188", features = ["alloc", "derive"], default-features = false }
-serde_json = { version = "1.0.107", default-features = false, features = ["alloc"] }

 [dev-dependencies]
 futures = "0.3.21"
@@ -60,6 +58,8 @@ sp-consensus = { path = "../../primitives/consensus/common" }
 substrate-test-runtime-client = { path = "client" }
 sp-tracing = { path = "../../primitives/tracing" }
 json-patch = { version = "1.0.0", default-features = false }
+serde = { version = "1.0.188", features = ["alloc", "derive"], default-features = false }
+serde_json = { version = "1.0.107", default-features = false, features = ["alloc"] }

 [build-dependencies]
 substrate-wasm-builder = { path = "../../utils/wasm-builder", optional = true }
@@ -1,7 +1,5 @@
 {
-  "system": {
-    "code": "0x52"
-  },
+  "system": {},
  "babe": {
    "authorities": [
      [
@@ -1,7 +1,5 @@
 {
-  "system": {
-    "code": "0x52"
-  },
+  "system": {},
  "babe": {
    "epochConfig": {
      "c": [
@@ -1,7 +1,5 @@
 {
-  "system": {
-    "code": "0x52"
-  },
+  "system": {},
  "babe": {
    "renamed_authorities": [
      [
@@ -0,0 +1,113 @@
+{
+  "system": {},
+  "babex": {
+    "authorities": [
+      [
+        "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
+        1
+      ],
+      [
+        "5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty",
+        1
+      ],
+      [
+        "5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y",
+        1
+      ]
+    ],
+    "epochConfig": {
+      "c": [
+        3,
+        10
+      ],
+      "allowed_slots": "PrimaryAndSecondaryPlainSlots"
+    }
+  },
+  "substrateTest": {
+    "authorities": [
+      "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
+      "5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty",
+      "5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y"
+    ]
+  },
+  "balances": {
+    "balances": [
+      [
+        "5D34dL5prEUaGNQtPPZ3yN5Y6BnkfXunKXXz6fo7ZJbLwRRH",
+        100000000000000000
+      ],
+      [
+        "5GBNeWRhZc2jXu7D55rBimKYDk8PGk8itRYFTPfC8RJLKG5o",
+        100000000000000000
+      ],
+      [
+        "5Dfis6XL8J2P6JHUnUtArnFWndn62SydeP8ee8sG2ky9nfm9",
+        100000000000000000
+      ],
+      [
+        "5F4H97f7nQovyrbiq4ZetaaviNwThSVcFobcA5aGab6167dK",
+        100000000000000000
+      ],
+      [
+        "5DiDShBWa1fQx6gLzpf3SFBhMinCoyvHM1BWjPNsmXS8hkrW",
+        100000000000000000
+      ],
+      [
+        "5EFb84yH9tpcFuiKUcsmdoF7xeeY3ajG1ZLQimxQoFt9HMKR",
+        100000000000000000
+      ],
+      [
+        "5DZLHESsfGrJ5YzT3HuRPXsSNb589xQ4Unubh1mYLodzKdVY",
+        100000000000000000
+      ],
+      [
+        "5GHJzqvG6tXnngCpG7B12qjUvbo5e4e9z8Xjidk3CQZHxTPZ",
+        100000000000000000
+      ],
+      [
+        "5CUnSsgAyLND3bxxnfNhgWXSe9Wn676JzLpGLgyJv858qhoX",
+        100000000000000000
+      ],
+      [
+        "5CVKn7HAZW1Ky4r7Vkgsr7VEW88C2sHgUNDiwHY9Ct2hjU8q",
+        100000000000000000
+      ],
+      [
+        "5H673aukQ4PeDe1U2nuv1bi32xDEziimh3PZz7hDdYUB7TNz",
+        100000000000000000
+      ],
+      [
+        "5HTe9L15LJryjUAt1jZXZCBPnzbbGnpvFwbjE3NwCWaAqovf",
+        100000000000000000
+      ],
+      [
+        "5D7LFzGpMwHPyDBavkRbWSKWTtJhCaPPZ379wWLT23bJwXJz",
+        100000000000000000
+      ],
+      [
+        "5CLepMARnEgtVR1EkUuJVUvKh97gzergpSxUU3yKGx1v6EwC",
+        100000000000000000
+      ],
+      [
+        "5Chb2UhfvZpmjjEziHbFbotM4quX32ZscRV6QJBt1rUKzz51",
+        100000000000000000
+      ],
+      [
+        "5HmRp3i3ZZk7xsAvbi8hyXVP6whSMnBJGebVC4FsiZVhx52e",
+        100000000000000000
+      ],
+      [
+        "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
+        100000000000000000
+      ],
+      [
+        "5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty",
+        100000000000000000
+      ],
+      [
+        "5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y",
+        100000000000000000
+      ]
+    ]
+  }
+}
@@ -117,10 +117,7 @@ impl GenesisStorageBuilder {
 			.collect();

 		RuntimeGenesisConfig {
-			system: frame_system::GenesisConfig {
-				code: self.wasm_code.clone().unwrap_or(wasm_binary_unwrap().to_vec()),
-				..Default::default()
-			},
+			system: Default::default(),
 			babe: pallet_babe::GenesisConfig {
 				authorities: authorities_sr25519
 					.clone()
@@ -149,6 +146,11 @@ impl GenesisStorageBuilder {
 			storage.top.insert(well_known_keys::HEAP_PAGES.into(), heap_pages.encode());
 		}

+		storage.top.insert(
+			well_known_keys::CODE.into(),
+			self.wasm_code.clone().unwrap_or(wasm_binary_unwrap().to_vec()),
+		);
+
 		storage.top.extend(self.extra_storage.top.clone());
 		storage.children_default.extend(self.extra_storage.children_default.clone());

@@ -464,11 +464,10 @@ impl_opaque_keys! {
 	}
 }

-pub(crate) const TEST_RUNTIME_BABE_EPOCH_CONFIGURATION: BabeEpochConfiguration =
-	BabeEpochConfiguration {
-		c: (3, 10),
-		allowed_slots: AllowedSlots::PrimaryAndSecondaryPlainSlots,
-	};
+pub const TEST_RUNTIME_BABE_EPOCH_CONFIGURATION: BabeEpochConfiguration = BabeEpochConfiguration {
+	c: (3, 10),
+	allowed_slots: AllowedSlots::PrimaryAndSecondaryPlainSlots,
+};

 impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {
@@ -1237,7 +1236,7 @@ mod tests {
 		#[test]
 		fn build_minimal_genesis_config_works() {
 			sp_tracing::try_init_simple();
-			let default_minimal_json = r#"{"system":{"code":"0x"},"babe":{"authorities":[],"epochConfig":{"c": [ 3, 10 ],"allowed_slots":"PrimaryAndSecondaryPlainSlots"}},"substrateTest":{"authorities":[]},"balances":{"balances":[]}}"#;
+			let default_minimal_json = r#"{"system":{},"babe":{"authorities":[],"epochConfig":{"c": [ 3, 10 ],"allowed_slots":"PrimaryAndSecondaryPlainSlots"}},"substrateTest":{"authorities":[]},"balances":{"balances":[]}}"#;
 			let mut t = BasicExternalities::new_empty();

 			executor_call(&mut t, "GenesisBuilder_build_config", &default_minimal_json.encode())
@@ -1264,8 +1263,6 @@ mod tests {

 				// System|LastRuntimeUpgrade
 				"26aa394eea5630e07c48ae0c9558cef7f9cce9c888469bb1a0dceaa129672ef8",
-				// :code
-				"3a636f6465",
 				// :extrinsic_index
 				"3a65787472696e7369635f696e646578",
 				// Balances|TotalIssuance
@@ -1294,35 +1291,55 @@ mod tests {
 			let r = Vec::<u8>::decode(&mut &r[..]).unwrap();
 			let json = String::from_utf8(r.into()).expect("returned value is json. qed.");

-			let expected = r#"{"system":{"code":"0x"},"babe":{"authorities":[],"epochConfig":null},"substrateTest":{"authorities":[]},"balances":{"balances":[]}}"#;
+			let expected = r#"{"system":{},"babe":{"authorities":[],"epochConfig":null},"substrateTest":{"authorities":[]},"balances":{"balances":[]}}"#;
 			assert_eq!(expected.to_string(), json);
 		}

 		#[test]
 		fn build_config_from_json_works() {
 			sp_tracing::try_init_simple();
-			let j = include_str!("test_json/default_genesis_config.json");
+			let j = include_str!("../res/default_genesis_config.json");

 			let mut t = BasicExternalities::new_empty();
 			let r = executor_call(&mut t, "GenesisBuilder_build_config", &j.encode()).unwrap();
 			let r = BuildResult::decode(&mut &r[..]);
 			assert!(r.is_ok());

-			let keys = t.into_storages().top.keys().cloned().map(hex).collect::<Vec<String>>();
+			let mut keys = t.into_storages().top.keys().cloned().map(hex).collect::<Vec<String>>();
+
+			// following keys are not placed during `<RuntimeGenesisConfig as GenesisBuild>::build`
+			// process, add them `keys` to assert against known keys.
+			keys.push(hex(b":code"));
+			keys.sort();
+
 			assert_eq!(keys, storage_key_generator::get_expected_storage_hashed_keys(false));
 		}

 		#[test]
 		fn build_config_from_invalid_json_fails() {
 			sp_tracing::try_init_simple();
-			let j = include_str!("test_json/default_genesis_config_invalid.json");
+			let j = include_str!("../res/default_genesis_config_invalid.json");
 			let mut t = BasicExternalities::new_empty();
 			let r = executor_call(&mut t, "GenesisBuilder_build_config", &j.encode()).unwrap();
 			let r = BuildResult::decode(&mut &r[..]).unwrap();
 			log::info!("result: {:#?}", r);
 			assert_eq!(r, Err(
 				sp_runtime::RuntimeString::Owned(
-					"Invalid JSON blob: unknown field `renamed_authorities`, expected `authorities` or `epochConfig` at line 6 column 25".to_string(),
+					"Invalid JSON blob: unknown field `renamed_authorities`, expected `authorities` or `epochConfig` at line 4 column 25".to_string(),
+				))
+			);
+		}
+
+		#[test]
+		fn build_config_from_invalid_json_fails_2() {
+			sp_tracing::try_init_simple();
+			let j = include_str!("../res/default_genesis_config_invalid_2.json");
+			let mut t = BasicExternalities::new_empty();
+			let r = executor_call(&mut t, "GenesisBuilder_build_config", &j.encode()).unwrap();
+			let r = BuildResult::decode(&mut &r[..]).unwrap();
+			assert_eq!(r, Err(
+				sp_runtime::RuntimeString::Owned(
+					"Invalid JSON blob: unknown field `babex`, expected one of `system`, `babe`, `substrateTest`, `balances` at line 3 column 9".to_string(),
 				))
 			);
 		}
@@ -1330,7 +1347,7 @@ mod tests {
 		#[test]
 		fn build_config_from_incomplete_json_fails() {
 			sp_tracing::try_init_simple();
-			let j = include_str!("test_json/default_genesis_config_incomplete.json");
+			let j = include_str!("../res/default_genesis_config_incomplete.json");

 			let mut t = BasicExternalities::new_empty();
 			let r = executor_call(&mut t, "GenesisBuilder_build_config", &j.encode()).unwrap();
@@ -1339,7 +1356,7 @@ mod tests {
 			assert_eq!(
 				r,
 				Err(sp_runtime::RuntimeString::Owned(
-					"Invalid JSON blob: missing field `authorities` at line 13 column 3"
+					"Invalid JSON blob: missing field `authorities` at line 11 column 3"
 						.to_string()
 				))
 			);
@@ -1438,10 +1455,6 @@ mod tests {
 			);
 			assert_eq!(u64::decode(&mut &value[..]).unwrap(), 0);

-			// :code
-			let value: Vec<u8> = get_from_storage("3a636f6465");
-			assert!(Vec::<u8>::decode(&mut &value[..]).is_err());
-
 			//System|ParentHash
 			let value: Vec<u8> = get_from_storage(
 				"26aa394eea5630e07c48ae0c9558cef78a42f33323cb5ced3b44dd825fda9fcc",