Owner Two Step Transfer Facet

Two-step ERC-173 ownership transfer for Compose diamonds

Key Features

• Two-step handoff: the owner calls transferOwnership; the nominated address calls acceptOwnership to become owner.
• Storage uses erc8042:erc173.owner and erc8042:erc173.owner.pending, shared with the two-step transfer module.

Storage

State Variables

Property	Type	Description
OWNER_STORAGE_POSITION	bytes32	Owner storage position within the diamond (Value: keccak256("erc173.owner"))
PENDING_OWNER_STORAGE_POSITION	bytes32	Pending owner storage position within the diamond (Value: keccak256("erc173.owner.pending"))

OwnerStorage

Definition

/** storage-location: erc8042:erc173.owner */
struct OwnerStorage {
  address owner;
}

PendingOwnerStorage

Definition

/** storage-location: erc8042:erc173.owner.pending */
struct PendingOwnerStorage {
  address pendingOwner;
}

Functions

transferOwnership

Callable only when msg.sender is the current owner; otherwise reverts OwnerUnauthorizedAccount. Sets pendingOwner to _newOwner and emits OwnershipTransferStarted(owner, _newOwner). The on-chain owner does not change until acceptOwnership.

function transferOwnership(address _newOwner) external;

Parameters:

Property	Type	Description
_newOwner	address	Address that will become owner after a successful acceptOwnership from that address.

---

acceptOwnership

Callable only when msg.sender is the pending owner; otherwise reverts OwnerUnauthorizedAccount. Assigns owner to the pending address, sets pendingOwner to address(0), and emits OwnershipTransferred(previousOwner, newOwner).

function acceptOwnership() external;

Events

Emitted when the current owner calls transferOwnership, before the pending address accepts.

Signature:

event OwnershipTransferStarted(address indexed _previousOwner, address indexed _newOwner);

Emitted when the pending owner calls acceptOwnership and ownership is updated.

Signature:

event OwnershipTransferred(address indexed _previousOwner, address indexed _newOwner);

Errors

Thrown when transferOwnership is called by anyone other than the current owner, or when acceptOwnership is called by anyone other than the pending owner.

Signature:

error OwnerUnauthorizedAccount();

Best Practices

• Initialize OwnerStorage.owner during deployment before relying on owner-only behavior elsewhere.
• After transferOwnership, ensure the nominated _newOwner can and will call acceptOwnership; until then, the previous owner remains owner.

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Last updated:March 24, 2026