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Runtime Upgrade Precompile

The contract-side of Fluent's runtime upgrade flow. The conceptual mechanism — governance owner, host enforcement, the privileged syscall — is documented in Runtime Upgrade. This page covers the precompile's address, calldata format, and authority.

Address​

ConstantAddress
PRECOMPILE_RUNTIME_UPGRADE0x0000000000000000000000000000000000520010

Authority​

ConstantDefault address
DEFAULT_UPDATE_GENESIS_AUTH0xa7bf6a9168fe8a111307b7c94b8883fe02b30934

The owner is initialized to the default at genesis. Live networks rotate it to a multisig immediately — treat the default as a starting point, not the current value. Ownership transfer goes through changeOwner(address) (zero-address rejected); renounceOwnership() sets the owner to the system address, freezing future upgrades through the owner-based path.

Interface​

Solidity-style 4-byte selector dispatch.

function upgradeTo(address target, uint256 genesisHash, string version, bytes wasmBytecode) external;
function changeOwner(address newOwner) external;
function owner() external view returns (address);
function renounceOwnership() external;

The function selector for upgradeTo is published as a constant:

UPDATE_GENESIS_PREFIX = 0x288fb3b8 = keccak256("upgradeTo(address,uint256,string,bytes)")[:4]

The full upgrade flow — what upgradeTo does internally, host-side enforcement, when each event fires — lives in Runtime Upgrade.

Events​

event RuntimeUpgraded(address indexed targetAddress, bytes32 indexed genesisHash, string genesisVersion, bytes32 codeHash);
event OwnerChanged(address newOwner);

RuntimeUpgraded is emitted on every successful upgradeTo after the host installs the new bytecode at targetAddress; codeHash is the hash of the installed bytecode. OwnerChanged is emitted by changeOwner and renounceOwnership.

Source​

fluentbase/contracts/runtime-upgrade/