docs.md

Farcaster Contracts Documentation

Documentation that covers the high-level functionality of each contract in the system.

Table of Contents

1. ID Registry
2. Name Registry
3. Recovery System

1. ID Registry

The ID Registry contract issues Farcaster IDs (fids) for the Farcaster network.

An fid is a uint256 that represents a unique user of the network. Fids begin at 0 and increment by one for every new account. There is an infinite supply of fids since they can go as high as ~10^77. IDs begin in the invitable state, where they can only be registered by a pre-determined address. The owner can disable trusted registration which then allows anyone to register an fid.

Each address can only own a single fid at a time, but they can otherwise be freely transferred between addresses. The address that currently owns an fid is known as the custody address. The contract implements a recovery system that protects users if they lose access to this address.

State Machine

An fid can exist in these states:

• invitable - the fid has never been issued, and can be registered by the trusted caller
• registerable - the fid has never been issued, and can be registered by anyone
• registered - the fid has been issued to an address
• escrow - a recovery request has been submitted and is pending escrow
• recoverable - a recovery request has completed escrow and is pending completion.

    stateDiagram-v2
        direction LR
        invitable --> registerable: disable trusted register
        invitable --> registered: trusted register
        registerable --> registered: register
        registered --> registered: transfer
        registered --> escrow: request recovery
        escrow --> recoverable: end(escrow)
        recoverable --> registered: transfer, cancel <br>  or complete recovery
        escrow --> registered: transfer <br> cancel recovery

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The fid state transitions when users take specific actions:

• register - register a new fid from any address
• trusted register - register a new fid from the trusted caller
• disable trusted register - allow registration from any sender
• transfer - move an fid to a new custody address
• request recovery - request a recovery of the fid
• cancel recovery - cancel a recovery that is in progress
• complete recovery - complete a recovery that has passed the escrow period

The fid state can automatically transition when certain periods of time pass:

• end(escrow) - 3 days from the request recovery action

2. Name Registry

The Name Registry contract issues Farcaster names (fnames) for the Farcaster network.

An fname is an ERC-721 token that represents a unique name like @alice. An fname can have up to 16 characters that include lowercase letters, numbers or hyphens. It should that match the regular expression /^[a-z0-9][a-z0-9-]{0,15}$/. The address that owns an fname is known as the custody address. The contract implements a recovery system that protects users if they lose access to this address. Similar to IDs, Farcaster Names also begin in the invitable state, where they can only be registered by a pre-determined address. The owner can disable trusted registration which then allows anyone to register an fname.

Fnames can be registered for one year by paying the registration fee, similar to domain names. Unlike most ERC-721 tokens, minting the token does not imply permanent ownership. Registration uses a two-phase commit reveal system to prevent frontrunning.

1. When a new fname is registered, the user must pay the yearly fee, and the token enters the registered state. and remains for one year, or more specifically after .

2. After 365 days, the fname moves from registered to renewable. Owners have 30 days to renew the fname by paying a full year's fee to the contract.

3. If the fname is not renewed within this 30 day window, it becomes biddable and moves into a dutch auction. The initial bid is set to a premium of 1,000 ETH plus the fee for the remainder of the year. The premium is reduced by ~10% every hour until it reaches zero. An fname can remain indefinitely in this state until it is bid on and becomes registered.

4. If an fname is expired (renewable or biddable) the ownerOf function will return the zero address, while the balanceOf function will include expired names in its count.

State Machine

An fname can exist in these states:

• invitable - the name has never been minted, and can only be minted by the trusted caller
• registerable - the name has never been minted and can be minted by anyone
• registered - the name is registered to an address
• renewable - the name's registration has expired and it can only be renewed by the owner
• biddable - the name's registration has expired and it can be bid on by anyone
• escrow - a recovery request has been submitted and is pending escrow
• recoverable - a recovery request has completed escrow, but is pending completion.

    stateDiagram-v2
        direction LR
        invitable --> registerable: disable trusted register
        invitable --> registered: trusted register
        registerable --> registered: register
        registered --> renewable: end(registration)
        renewable --> biddable: end(renewal)
        biddable --> registered: bid
        registered --> registered: transfer
        registered --> escrow: request recovery
        escrow --> recoverable: end(escrow)
        escrow --> renewable: end(registration)
        recoverable --> registered: transfer, cancel <br>  or complete recovery
        recoverable --> renewable: end(registration)
        renewable --> registered: renew
        escrow --> registered: transfer <br> cancel recovery

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Only the registerable and biddable states are terminal, all other states have a time-based action that will eventually transition them to another state. The reclaim action is excluded from the diagram for brevity, but conceptually it can move a name from any state to the registered state.

The fname state transitions when users take certain actions:

• register - mint a new fname from any sender
• trusted register - mint a new fname from the trusted caller
• disable trusted register - allow registrations from any sender
• transfer - move a fname to a new custody address
• renew - pay the renewal fee on a renewable fname
• bid - place a bid on a biddable fname
• request recovery - request a recovery of the fname
• cancel recovery - cancel a recovery that is in progress
• complete recovery - complete a recovery that has passed the escrow period

The fname state can automatically transition when certain periods of time pass:

• end(registration) - 365 days after register is called
• end(renewal) - 30 days after end(registration)
• end(escrow) - 3 days after calling request recovery is called

Permissions

The Name Registry, unlike the ID Registry, implements an Access Control system that defines roles which can be granted to different addresses. The system has two high permissioned roles which must be kept secure to perform infrequent, sensitive operations:

• Default Admin - Can grant and revoke all other roles, including Admin.
• Admin - Used to upgrade the contract, change the vault, change the trusted caller and disable trusted sending.

The system also has three lower permissioned roles that can be granted to people performing more frequent operations:

• Operator - Used by on-call teams to pause and resume the contract.
• Moderator - Used by moderators to reclaim names from users and change the location to which they are reclaimed.
• Treasurer - Used to withdraw funds to the vault and set the fee rate.

3. Recovery System

Both contracts implement a recovery system that protects the owner against the loss of the custody address.

1. The custody address can nominate a recovery address that is authorized to move a fname/fid on its behalf. This can be changed or removed at any time.

2. The recovery address can send a recovery request which moves the fname/fid into the escrow state. After the escrow period, the fname/fid becomes recoverable, and the recovery address can complete the transfer.

3. During escrow, the custody address can cancel the recovery, which protects against malicious recovery addresses.

4. The recovery address is removed, and any active requests are cancelled if the custody address changes due to a transfer or other action.