WASM smart contracts

Deploy ink! smart contracts on subtensor via pallet-contracts and the custom chain extension.

Subtensor supports WebAssembly (WASM) smart contract functionality through the integration of pallet-contracts, enabling developers to deploy and execute WASM smart contracts on the network. Contracts are written in ink!, a Rust-based embedded domain-specific language (eDSL) for writing smart contracts on Substrate-based chains. For compatibility, WASM contracts can also be compiled from Solidity using Solang.

Getting Started

For general smart contract development on Subtensor, please refer to the official ink! documentation:

Subtensor-Specific Features

Chain Extension

Subtensor provides a custom chain extension that allows smart contracts to interact with Subtensor-specific functionality:

Available Functions

Function ID	Name	Description	Parameters	Returns
0	`get_stake_info_for_hotkey_coldkey_netuid`	Query stake information	`(AccountId, AccountId, NetUid)`	`Option<StakeInfo>`
1	`add_stake`	Delegate stake from coldkey to hotkey	`(AccountId, NetUid, TaoBalance)`	Error code
2	`remove_stake`	Withdraw stake from hotkey back to coldkey	`(AccountId, NetUid, AlphaBalance)`	Error code
3	`unstake_all`	Unstake all TAO from a hotkey	`(AccountId)`	Error code
4	`unstake_all_alpha`	Unstake all Alpha from a hotkey	`(AccountId)`	Error code
5	`move_stake`	Move stake between hotkeys	`(AccountId, AccountId, NetUid, NetUid, AlphaBalance)`	Error code
6	`transfer_stake`	Transfer stake between coldkeys	`(AccountId, AccountId, NetUid, NetUid, AlphaBalance)`	Error code
7	`swap_stake`	Swap stake allocations between subnets	`(AccountId, NetUid, NetUid, AlphaBalance)`	Error code
8	`add_stake_limit`	Delegate stake with a price limit	`(AccountId, NetUid, TaoBalance, TaoBalance, bool)`	Error code
9	`remove_stake_limit`	Withdraw stake with a price limit	`(AccountId, NetUid, AlphaBalance, TaoBalance, bool)`	Error code
10	`swap_stake_limit`	Swap stake between subnets with price limit	`(AccountId, NetUid, NetUid, AlphaBalance, TaoBalance, bool)`	Error code
11	`remove_stake_full_limit`	Fully withdraw stake with optional price limit	`(AccountId, NetUid, Option<TaoBalance>)`	Error code
12	`set_coldkey_auto_stake_hotkey`	Configure automatic stake destination	`(NetUid, AccountId)`	Error code
13	`add_proxy`	Add a staking proxy for the caller	`(AccountId)`	Error code
14	`remove_proxy`	Remove a staking proxy for the caller	`(AccountId)`	Error code
15	`get_alpha_price`	Query the current alpha price for a subnet	`(NetUid)`	`u64` (price × 10⁹)
16	`recycle_alpha`	Recycle alpha stake, reducing SubnetAlphaOut (supply reduction)	`(AccountId, NetUid, AlphaBalance)`	`u64` (actual amount recycled)
17	`burn_alpha`	Burn alpha stake without reducing SubnetAlphaOut (supply neutral)	`(AccountId, NetUid, AlphaBalance)`	`u64` (actual amount burned)
18	`add_stake_recycle`	Atomically add stake then recycle the resulting alpha	`(AccountId, NetUid, TaoBalance)`	`u64` (alpha amount recycled)
19	`add_stake_burn`	Atomically add stake then burn the resulting alpha	`(AccountId, NetUid, TaoBalance)`	`u64` (alpha amount burned)
20	`caller_add_stake`	Caller-origin variant of `add_stake` (ID 1)	`(AccountId, NetUid, TaoBalance)`	Error code
21	`caller_remove_stake`	Caller-origin variant of `remove_stake` (ID 2)	`(AccountId, NetUid, AlphaBalance)`	Error code
22	`caller_unstake_all`	Caller-origin variant of `unstake_all` (ID 3)	`(AccountId)`	Error code
23	`caller_unstake_all_alpha`	Caller-origin variant of `unstake_all_alpha` (ID 4)	`(AccountId)`	Error code
24	`caller_move_stake`	Caller-origin variant of `move_stake` (ID 5)	`(AccountId, AccountId, NetUid, NetUid, AlphaBalance)`	Error code
25	`caller_transfer_stake`	Caller-origin variant of `transfer_stake` (ID 6)	`(AccountId, AccountId, NetUid, NetUid, AlphaBalance)`	Error code
26	`caller_swap_stake`	Caller-origin variant of `swap_stake` (ID 7)	`(AccountId, NetUid, NetUid, AlphaBalance)`	Error code
27	`caller_add_stake_limit`	Caller-origin variant of `add_stake_limit` (ID 8)	`(AccountId, NetUid, TaoBalance, TaoBalance, bool)`	Error code
28	`caller_remove_stake_limit`	Caller-origin variant of `remove_stake_limit` (ID 9)	`(AccountId, NetUid, AlphaBalance, TaoBalance, bool)`	Error code
29	`caller_swap_stake_limit`	Caller-origin variant of `swap_stake_limit` (ID 10)	`(AccountId, NetUid, NetUid, AlphaBalance, TaoBalance, bool)`	Error code
30	`caller_remove_stake_full_limit`	Caller-origin variant of `remove_stake_full_limit` (ID 11)	`(AccountId, NetUid, Option<TaoBalance>)`	Error code
31	`caller_set_coldkey_auto_stake_hotkey`	Caller-origin variant of `set_coldkey_auto_stake_hotkey` (ID 12)	`(NetUid, AccountId)`	Error code
32	`caller_add_proxy`	Caller-origin variant of `add_proxy` (ID 13)	`(AccountId)`	Error code
33	`caller_remove_proxy`	Caller-origin variant of `remove_proxy` (ID 14)	`(AccountId)`	Error code
34	`get_subnet_registration_state`	Query whether a subnet exists and which registration generation currently owns the netuid	`(NetUid)`	`SubnetRegistrationState { netuid, exists, registered_subnet_counter }`
35	`get_coldkey_lock`	Query the current rolled-forward lock state for a coldkey on a subnet	`(AccountId, NetUid)`	`Option<ColdkeyLock { locked_mass: AlphaBalance, conviction_bits: u128, last_update: u64 }>`
36	`get_stake_availability`	Query total, locked, and currently available alpha for a coldkey on a subnet	`(AccountId, NetUid)`	`StakeAvailability { netuid: NetUid, total: AlphaBalance, locked: AlphaBalance, available: AlphaBalance }`

Example usage in your ink! contract:

#[ink::chain_extension(extension = 0)]
pub trait SubtensorExtension {
    type ErrorCode = SubtensorError;

    #[ink(function = 0)]
    fn get_stake_info(
        hotkey: AccountId,
        coldkey: AccountId,
        netuid: u16,
    ) -> Result<Option<StakeInfo>, SubtensorError>;
}

Error Codes

Chain extension functions that modify state return error codes as u32 values. The following codes are defined:

Code	Name	Description
0	`Success`	Operation completed successfully
1	`RuntimeError`	Unknown runtime error occurred
2	`NotEnoughBalanceToStake`	Insufficient balance to complete stake operation
3	`NonAssociatedColdKey`	Coldkey is not associated with the hotkey
4	`BalanceWithdrawalError`	Error occurred during balance withdrawal
5	`NotRegistered`	Hotkey is not registered in the subnet
6	`NotEnoughStakeToWithdraw`	Insufficient stake available for withdrawal
7	`TxRateLimitExceeded`	Transaction rate limit has been exceeded
8	`SlippageTooHigh`	Price slippage exceeds acceptable threshold
9	`SubnetNotExists`	Specified subnet does not exist
10	`HotKeyNotRegisteredInSubNet`	Hotkey is not registered in the specified subnet
11	`SameAutoStakeHotkeyAlreadySet`	Auto-stake hotkey is already configured
12	`InsufficientBalance`	Account has insufficient balance
13	`AmountTooLow`	Transaction amount is below minimum threshold
14	`InsufficientLiquidity`	Insufficient liquidity for swap operation
15	`SameNetuid`	Source and destination subnets are the same
16	`ProxyTooMany`	Too many proxies registered
17	`ProxyDuplicate`	Proxy already exists
18	`ProxyNoSelfProxy`	Cannot add self as proxy
19	`ProxyNotFound`	Proxy relationship not found
20	`CannotUseSystemAccount`	A system account cannot be used in this operation
21	`CannotBurnOrRecycleOnRootSubnet`	Cannot burn or recycle on the root subnet
22	`SubtokenDisabled`	Subtoken is not enabled for the specified subnet

Call Filter

For security, contracts can only directly dispatch a limited set of runtime calls:

Whitelisted Calls:

Proxy::proxy - Execute proxy calls

All other runtime calls are restricted and cannot be dispatched from contracts.

Configuration Parameters

Parameter	Value	Description
Maximum code size	128 KB	Maximum size of contract WASM code
Call stack depth	5 frames	Maximum nested contract call depth
Runtime memory	1 GB	Memory available during contract execution
Validator runtime memory	2 GB	Memory available for validators
Transient storage	1 MB	Maximum transient storage size