Add pallet-contracts integration with Subtensor chain extension

Cargo.toml

@@ -142,6 +142,7 @@ pallet-transaction-payment = { git = "https://github.com/paritytech/polkadot-sdk
 pallet-transaction-payment-rpc = { git = "https://github.com/paritytech/polkadot-sdk.git", tag = "polkadot-stable2503-6", default-features = false }
 pallet-transaction-payment-rpc-runtime-api = { git = "https://github.com/paritytech/polkadot-sdk.git", tag = "polkadot-stable2503-6", default-features = false }
 pallet-root-testing = { git = "https://github.com/paritytech/polkadot-sdk.git", tag = "polkadot-stable2503-6", default-features = false }
+pallet-contracts = { git = "https://github.com/paritytech/polkadot-sdk.git", tag = "polkadot-stable2503-6", default-features = false }
 
 # NPoS
 frame-election-provider-support = { git = "https://github.com/paritytech/polkadot-sdk.git", tag = "polkadot-stable2503-6", default-features = false }

README.md

@@ -18,6 +18,7 @@ This repository contains Bittensor's substrate-chain. Subtensor contains the tru
 1. Runs Bittensor's [consensus mechanism](./docs/consensus.md);
 2. Advertises neuron information, IPs, etc., and
 3. Facilitates value transfer via TAO.
+4. Supports wasm smart contract functionality via `pallet-contracts` (see [contracts documentation](./docs/contracts.md)).
 
 ## System Requirements
 

docs/contracts.md

@@ -0,0 +1,66 @@
+# Smart Contracts on Subtensor
+
+## Overview
+
+Subtensor now supports smart contract functionality through the integration of `pallet-contracts`, enabling developers to deploy and execute WebAssembly (WASM) smart contracts on the network. Contracts are written in [ink!](https://use.ink/), a Rust-based embedded domain-specific language (eDSL) for writing smart contracts on Substrate-based chains.
+
+## Getting Started
+
+For general smart contract development on Subtensor, please refer to the official ink! documentation:
+- [ink! Documentation](https://use.ink/docs/v5/)
+- [ink! Getting Started Guide](https://use.ink/docs/v5/getting-started/setup)
+- [ink! Examples](https://github.com/use-ink/ink-examples/tree/v5.x.x)
+
+## 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 |
+|------------|------|-------------|------------|---------|
+| 1001 | `get_stake_info_for_hotkey_coldkey_netuid` | Query stake information | `(AccountId32, AccountId32, NetUid)` | Stake information |
+
+Example usage in your ink! contract:
+```rust
+#[ink::chain_extension(extension = 0)]
+pub trait SubtensorExtension {
+    type ErrorCode = SubtensorError;
+
+    #[ink(function = 1001)]
+    fn get_stake_info(
+        hotkey: AccountId,
+        coldkey: AccountId,
+        netuid: u16,
+    ) -> Result<Option<StakeInfo>, SubtensorError>;
+}
+```
+
+### Call Filter
+
+For security, contracts can only dispatch a limited set of runtime calls:
+
+**Whitelisted Calls:**
+- `SubtensorModule::move_stake` - Move stake between hotkeys
+- `SubtensorModule::transfer_stake` - Transfer stake between accounts
+- `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 |
+
+
+## Additional Resources
+
+- [cargo-contract CLI Tool](https://github.com/paritytech/cargo-contract)
+- [Contracts UI](https://contracts-ui.substrate.io/)

runtime/Cargo.toml

@@ -97,6 +97,10 @@ pallet-commitments.workspace = true
 
 # for prod_or_fast! macro
 runtime-common.workspace = true
+
+# Wasm smart contracts support
+pallet-contracts.workspace = true
+
 # NPoS
 frame-election-provider-support = { workspace = true }
 pallet-authority-discovery = { workspace = true }
@@ -267,6 +271,7 @@ std = [
 	"pallet-subtensor-swap/std",
 	"pallet-subtensor-swap-runtime-api/std",
 	"subtensor-swap-interface/std",
+	"pallet-contracts/std",
 ]
 runtime-benchmarks = [
 	"frame-benchmarking/runtime-benchmarks",
@@ -301,6 +306,7 @@ runtime-benchmarks = [
 	"pallet-nomination-pools/runtime-benchmarks",
 	"pallet-offences/runtime-benchmarks",
 	"sp-staking/runtime-benchmarks",
+	"pallet-contracts/runtime-benchmarks",
 
 	# EVM + Frontier
 	"pallet-ethereum/runtime-benchmarks",
@@ -342,6 +348,7 @@ try-runtime = [
 	"pallet-babe/try-runtime",
 	"pallet-session/try-runtime",
 	"pallet-staking/try-runtime",
+	"pallet-contracts/try-runtime",
 	"pallet-election-provider-multi-phase/try-runtime",
 	"frame-election-provider-support/try-runtime",
 	"pallet-authority-discovery/try-runtime",

runtime/src/chain_extension.rs

@@ -0,0 +1,52 @@
+use codec::Encode;
+use pallet_contracts::chain_extension::{
+    ChainExtension, Environment, Ext, InitState, RetVal, SysConfig,
+};
+use sp_runtime::{AccountId32, DispatchError};
+use subtensor_runtime_common::NetUid;
+
+use crate::{Runtime, SubtensorModule};
+
+#[derive(Default)]
+pub struct SubtensorChainExtension;
+
+impl ChainExtension<Runtime> for SubtensorChainExtension {
+    fn call<E: Ext>(&mut self, env: Environment<E, InitState>) -> Result<RetVal, DispatchError>
+    where
+        E::T: SysConfig,
+    {
+        let func_id = env.func_id();
+
+        match func_id {
+            // Function ID 1001: get_stake_info_for_hotkey_coldkey_netuid
+            1001 => {
+                let mut env = env.buf_in_buf_out();
+
+                let input: (AccountId32, AccountId32, NetUid) = env
+                    .read_as()
+                    .map_err(|_| DispatchError::Other("Failed to decode input parameters"))?;
+
+                let (hotkey, coldkey, netuid) = input;
+
+                let stake_info = SubtensorModule::get_stake_info_for_hotkey_coldkey_netuid(
+                    hotkey, coldkey, netuid,
+                );
+
+                let encoded_result = stake_info.encode();
+
+                env.write(&encoded_result, false, None)
+                    .map_err(|_| DispatchError::Other("Failed to write output"))?;
+
+                Ok(RetVal::Converging(0))
+            }
+            _ => {
+                log::error!("Called an unregistered chain extension function: {func_id}",);
+                Err(DispatchError::Other("Unimplemented function ID"))
+            }
+        }
+    }
+
+    fn enabled() -> bool {
+        true
+    }
+}