Internals
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 contract's account | (AccountId) | Error code |
| 14 | remove_proxy | Remove a staking proxy for the contract's account | (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) |
| 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 } |
| 37 | move_stake_limit | Move stake between hotkeys and subnets with a relative price limit | (AccountId, AccountId, NetUid, NetUid, AlphaBalance, TaoBalance, bool) | Error code |
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 |