observer-core

Observer posts Uniswap V3 oracle data on Starknet when price deviation or timed duration thresholds are met. Consumers of the oracle on StarkNet have access to the price feeds (e.g. ETH/USDC) from Uniswap with layer 1 liquidity. Bots on layer 1 are incentivized to push the oracle data up to StarkNet once price and duration thresholds are met through a >100% gas reimbursement.

Deployed Addresses

Ethereum (Goerli) L1 Observer Contract: 0x66e453faf0f7CE1a4Aa1e03328213BdCB793C24c
Starknet (hackathon-0) L2 Observer Contract: 0x046c3bac376724a5548735c42f97700456f257207a3e204b6a931069a9e0c29c

Active Oracles

Uniswap V3 WETH/USDC 0.05% (Goerli)

• oracle id: 0
• pool address: 0xfAe941346Ac34908b8D7d000f86056A18049146E
• base currency: WETH (0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6)
• quote currency: USDC (0x07865c6E87B9F70255377e024ace6630C1Eaa37F)
• TWAP period: 300 seconds = 5 minutes
• price deviation threshold: 0.5%
• duration threshold: 3600 seconds = 1 day
• caller incentive = +20% of base fee

StarkNet Oracle Consumers

To consume the price feed on StarkNet, simply use call function get_uni_v3_oracle_data on the L2 Observer Contract with the appropriate oracle_id.

The function returns a tuple of (twap, last_updated_at). The TWAP is the price scaled to 1e18, and last_updated_at is the L1 update at block.timestamp.

# Returns the oracle data of the given oracle_id.
@view
func get_uni_v3_oracle_data{
    syscall_ptr : felt*,
    pedersen_ptr : HashBuiltin*,
    range_check_ptr,
}(oracle_id : felt) -> (res : (felt, felt)):
    let (oracle_data) = uni_v3_oracles.read(oracle_id)
    return ((oracle_data[0], oracle_data[1])) 
end

Layer 1 Bots

The Observer.sol contract holds the data for each respective oracle. Oracles have the following configurations relevant to bots:

• price deviation threshold = the percentage amount (in 1e4) the TWAP must change before updating the TWAP is incentivized
• duration threshold = time in seconds that must pass before updating the TWAP is incentivized
• base fee incentive multiplier = base fee multiplier for incentivizing bots scaled by 1e4 i.e. 12000 = 1.2x base fee
• incentive available = ETH on the contract earmarked as incentive payment for that specific oracle caller

Bots should monitor the checkThresholds function off-chain to check whether the price deviation or duration threshold has hit. If checkThresholds returns true in either value, then calling updateUniV3Oracle will return an incentive. To collect the incentive, call updateUniV3Oracle with the appropriate oracle id.

function checkThresholds(uint oracleId) public view onlyInitializedUniV3Oracle(oracleId) returns (bool deviationThreshold, bool durationThreshold) 
function updateUniV3Oracle(uint oracleId) external onlyInitializedUniV3Oracle(oracleId)