IssuerBond

Inherits: AccessControl, ReentrancyGuard. Source: contracts/token/IssuerBond.sol.

IssuerBond is a skin-in-the-game gate for the bonded issuer path to CarbonCreditNFT's ISSUER_ROLE. It earns nothing: a bond is locked, can be slashed, and is returned only after a delay.

Mixed issuer model

bondRequired is the switch of this path only: true = the bond path is open (minimum enforced), false = no new bonding. Existing bonds can still unbond, withdraw and be slashed. It never affects trusted issuers.

Constructor

constructor(
    address carb_,
    address nft_,
    address admin,
    uint256 minBond_,
    uint256 unbondDelay,
    uint256 disputeWindow,
    bool bondRequired_,
    address slashTreasury_
)

ISSUER_ROLE is read from the NFT. admin receives DEFAULT_ADMIN_ROLE, PARAMETER_ROLE and SLASHER_ROLE. After deployment the NFT admin must call nft.grantRole(ISSUER_ADMIN_ROLE, bond); without it, granting and revoking the role fails.

Immutable and constant parameters

State

struct Bond {
    uint128 amount;     // CARB locked
    uint64  releaseAt;  // withdrawable at (only meaningful while unbonding)
    bool    unbonding;  // exit started; role already revoked
    bool    roleViaBond; // this contract granted ISSUER_ROLE
}

struct SlashProposal {
    address issuer;
    uint128 amount;
    uint64  executableAt; // proposal time + DISPUTE_WINDOW
    uint64  expiresAt;    // executableAt + EXECUTION_WINDOW
    bool    disputed;
    bool    resolved;     // executed or cancelled
}

Public state: bonds(address), slashProposals(id), activeSlashOf(issuer) (latest proposal id, 0 = none), blocked(address), nextSlashId (starts at 1), minBond, bondRequired, slashTreasury (address(0) = burn).

Lifecycle

1. bond(amount): locks CARB (prior approve needed). Once the bond is at least minBond, the role is granted if the issuer does not already hold it. May be called again to top up, for example after a slash.
2. startUnbond(): the bond-granted role is revoked immediately, and the bond becomes withdrawable after UNBOND_DELAY, so misbehaviour found after the last mint can still be slashed. Blocked while a slash proposal is active.
3. withdraw(): after the delay, and never while a slash proposal is active. Returns the whole remaining bond.

A role that the multisig revoked manually is not silently restored by a top-up; use setIssuerBlocked to bar the address from the bond path entirely.

Slashing

SLASHER_ROLE is intended for the governance timelock (and the multisig at bootstrap).

1. proposeSlash(issuer, amount, reason) opens a proposal. For DISPUTE_WINDOW seconds nothing executes, and the issuer cannot start unbonding or withdraw.
2. The issuer may disputeSlash(id, evidenceHash). This records an evidence hash onchain; a disputed proposal can then only be executed by a SLASHER_ROLE holder. It is not adjudication.
3. After the window, an undisputed proposal can be executed by anyone (liveness: a vanished slasher cannot hold a bond hostage). It stays executable for EXECUTION_WINDOW more seconds, then lapses and stops freezing the exit.
4. The slasher can cancelSlash at any time.
5. Slashed CARB is burned unless slashTreasury is set. At most amount is slashed, capped to the remaining bond. If the remaining bond falls below minBond, the bonded role is revoked until the issuer tops up. Slashing never reverts because the contract lost its NFT role (the revoke is skipped and the multisig revokes directly).

One active proposal per issuer, so an exit can be frozen for at most DISPUTE_WINDOW + EXECUTION_WINDOW per proposal.

Functions

Events

Errors (revert strings)

A disputed proposal executed by a non-slasher reverts with the OpenZeppelin AccessControl missing-role message.

Roles

Neither the admin nor governance can withdraw or redirect a bond except through the slash flow, and nobody can mint credits through this contract. On the NFT, IssuerBond holds ISSUER_ADMIN_ROLE (see CarbonCreditNFT).

Caveats

• Slashing is powerful. An issuer's loss of a bond is real money. Run it behind evidence and a documented appeals path, and at first through the multisig. The dispute flag only forces explicit slasher confirmation; it is not adjudication.
• A bond is not verification of credit quality.
• Bonded tokens carry no votes.
• Existing bonds are grandfathered when minBond is raised. The bond is compared with the current minBond again only when a slash executes: if the remaining bond is below it, the bond-granted role is revoked.
• Not upgradeable.