Fee Collector

AgamaFeeCollector is a push-based fee router. Protocol contracts call collectFee(token, from, amount, feeType) and the collector forwards the funds to the Treasury in the same transaction. There is no per-fee-type accumulator and no two-step distribute call — the design is intentionally minimal in V1.

The earlier doc described an Aave-style pull-based design with accumulated[feeType][token] and a separate distributeFees call. The shipped contract dropped that in favour of an immediate forward, which keeps the audit surface minimal and means fees never sit in the collector. Off-chain dashboards still get per-feeType events, so accounting parity is preserved.

Supported fee types

Constant	Triggered by
`FEE_ORIGINATION`	`LendingPool.borrow` (`originationFeeBps`, default 0) — pulled into the FeeCollector via `collectFee` and forwarded to Treasury under this tag.
`FEE_PROTOCOL_REVENUE`	Interest reserve accrual driven by `reserveFactorBps` (default 10%). Swept via `settle(USDr, FEE_PROTOCOL_REVENUE)`.
`FEE_VAULT_OPENING`	Constant declared on the FeeCollector for off-chain consistency, but not currently routed through `collectFee` in V1 — vault-opening fees use a direct `safeTransferFrom(user, feeRecipient, fee)` from the LendingPool, bypassing the FeeCollector tagging path. The constant is reserved for V2 if vault-opening fees are unified through the collector. The default is `vaultOpeningFee = 0` so this is moot in practice today.

Distribution

100% of every collected fee is forwarded to the Treasury in the same transaction the fee is collected. There is no on-contract split between Treasury and Reserve Fund — the Reserve Fund participates in protocol revenue as a Stability Pool staker, earning its pro-rata share through sagYLD appreciation rather than through a hard-coded fee channel. If Treasury wants to top up the Reserve Fund, that's a governance action, not a parameter on this contract.

Access control

Role	Capability
`DEFAULT_ADMIN_ROLE`	Full admin: set Treasury address, grant `POOL_ROLE`.
`POOL_ROLE`	Call `collectFee` and `settle`. Held by the LendingPool.

There is no FEE_MANAGER_ROLE, DISTRIBUTOR_ROLE, or EMERGENCY_ROLE in V1.

Functions

/// Pull `amount` of `token` from `from` (which must have approved the
/// collector) and forward to Treasury in the same call.
function collectFee(
    address token,
    address from,
    uint256 amount,
    bytes32 feeType
) external onlyRole(POOL_ROLE);
 
/// Sweep any idle balance the LendingPool already pushed in via
/// safeTransfer (instead of approve + transferFrom). Tags the swept
/// amount under `feeType` for the dashboard.
function settle(address token, bytes32 feeType) external onlyRole(POOL_ROLE);
 
/// Update the Treasury recipient (governance-timelocked).
function setTreasury(ITreasuryDeposit _treasury)
    external onlyRole(DEFAULT_ADMIN_ROLE);
 
/// Whitelist a contract (typically the LendingPool) to call collectFee/settle.
function grantPool(address pool) external onlyRole(DEFAULT_ADMIN_ROLE);

State

ITreasuryDeposit public treasury;
 
/// Lifetime cumulative fees per (feeType, token) — drives the off-chain
/// dashboard. The collector never holds a non-zero balance after a call
/// because every collection forwards immediately.
mapping(bytes32 feeType => mapping(address token => uint256)) public lifetimeFees;

Events

event FeeCollected(address indexed token, address indexed from, uint256 amount, bytes32 indexed feeType);
event FeeForwarded(address indexed token, uint256 amount, bytes32 indexed feeType);
event TreasuryUpdated(address indexed treasury);

FeeCollected fires on every collectFee and on every settle sweep. FeeForwarded fires whenever the collector pushes funds to Treasury — paired 1:1 with FeeCollected because the forward is atomic with the collection. The off-chain dashboard subscribes to both and reconciles per feeType.