CoilFeeRouter¶

Coil DEX fee_recipient. Claims accrued protocol fees, routes USDC slices to Keep + gauge bribes, swaps remainder to TARE, donates to engine surplus.

Source: TARE-Stablecoin/src/CoilFeeRouter.vy (Vyper 0.4.3)

Concept guide: CoilFeeRouter protocol page

Wired by: Coil fee_recipient · TareEngine donate_to_surplus

Implementation overview¶

Permissionless harvest — harvest(token) pulls Coil fees + sweeps router balance.
TARE — donated as-is to engine surplus.
USDC — three-way split: keep_bps → CoilMakerStrategy, gauge_bps → USDC EmissionRouter, remainder swapped USDC→TARE via Curve NG EMA oracle.
Swap safety — min_dy from price_oracle(0) + slippage_bps; max_swap_in mandatory cap (0 = swap locked).
Core tokens non-recoverable — owner recover rejects TARE/USDC.

flowchart LR
    Coil[Coil DEX] -->|accrued fees| CFR[CoilFeeRouter]
    CFR -->|keep_bps USDC| Keep[CoilMakerStrategy]
    CFR -->|gauge_bps USDC| Gauge[EmissionRouter]
    CFR -->|swap remainder| TARE[TARE]
    TARE -->|donate_to_surplus| Engine[TareEngine]

Immutables¶

Name	Role
`TARE`	Engine-bound stablecoin (donated)
`USDC`	Paired stable (swapped → TARE)
`ENGINE`	TareEngine surplus receiver
`COIL`	Fee source DEX
`POOL`	TARE/USDC Curve StableSwap-NG (USDC idx 0, TARE idx 1)
`ORACLE_NUMER`	Decimal scaler for EMA price math

Constants¶

Name	Value	Role
`MAX_SLIPPAGE_BPS`	1_000	10% swap tolerance cap
`MAX_GAUGE_BPS`	5_000	50% gauge slice cap
`MAX_KEEP_BPS`	5_000	50% Keep slice cap

Events¶

Event	When
`FeesHarvested`	TARE donated to engine
`KeepFeesRouted` / `GaugeFeesRouted`	USDC slices routed
`SlippageUpdated` / `MaxSwapInUpdated` / `GaugeBpsUpdated` / `KeepBpsUpdated`	Admin param changes
`EmissionSinkUpdated` / `KeeperUpdated`	Sink addresses set
`Recovered`	Non-core token escape hatch

Admin¶

`set_slippage_bps`¶

CoilFeeRouter.set_slippage_bps(new_bps)

Set USDC→TARE swap slippage tolerance for harvest. Used with EMA price_oracle to compute min_dy.

Param	Type	Description
`new_bps`	`uint256`	Slippage below oracle quote (`0`–`MAX_SLIPPAGE_BPS`, max 1000 = 10%)

Returns / state: Updates slippage_bps. Default at deploy: 50 (0.5%).

Access: owner only. Reverts if new_bps > MAX_SLIPPAGE_BPS.

Events: SlippageUpdated(new_bps).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:235-245):

@external
def set_slippage_bps(new_bps: uint256):
    ownable._check_owner()
    assert new_bps <= MAX_SLIPPAGE_BPS, "router: slippage too high"
    self.slippage_bps = new_bps
    log SlippageUpdated(new_bps=new_bps)

Example:

router.set_slippage_bps(100)  # 1% below EMA oracle

Cross-links: set_max_swap_in · harvest

`set_max_swap_in`¶

CoilFeeRouter.set_max_swap_in(new_max)

Absolute USDC cap per harvest swap to TARE. Bounds multi-block EMA drift exposure (TARE-7).

Param	Type	Description
`new_max`	`uint256`	Max USDC notional per swap (`0` = swap path locked)

Returns / state: Updates max_swap_in. Must be set non-zero before USDC harvest can swap.

Access: owner only.

Events: MaxSwapInUpdated(new_max).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:248-261):

@external
def set_max_swap_in(new_max: uint256):
    ownable._check_owner()
    self.max_swap_in = new_max
    log MaxSwapInUpdated(new_max=new_max)

Example:

router.set_max_swap_in(500_000 * 10**6)  # 500k USDC per harvest swap

Cross-links: set_slippage_bps · harvest

`set_gauge_bps`¶

CoilFeeRouter.set_gauge_bps(new_bps)

Set USDC slice routed to emission_sink (veForge EmissionRouter) on each USDC harvest.

Param	Type	Description
`new_bps`	`uint256`	Gauge share of USDC harvest (`0`–`MAX_GAUGE_BPS`, max 5000 = 50%)

Returns / state: Updates gauge_bps. No effect until emission_sink set and harvest runs.

Access: owner only. Reverts if new_bps > MAX_GAUGE_BPS or new_bps + keep_bps > MAX_GAUGE_BPS (surplus always ≥50%).

Events: GaugeBpsUpdated(new_bps).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:264-277):

@external
def set_gauge_bps(new_bps: uint256):
    ownable._check_owner()
    assert new_bps <= MAX_GAUGE_BPS, "router: gauge bps too high"
    assert new_bps + self.keep_bps <= MAX_GAUGE_BPS, "router: keep+gauge starves surplus"
    self.gauge_bps = new_bps
    log GaugeBpsUpdated(new_bps=new_bps)

Example:

router.set_gauge_bps(2000)  # 20% of USDC fees to gauge bribes

Cross-links: set_emission_sink · set_keep_bps · harvest

`set_emission_sink`¶

CoilFeeRouter.set_emission_sink(sink)

Set USDC EmissionRouter receiving gauge_bps slice on USDC harvests. Pass empty to disable gauge routing.

Param	Type	Description
`sink`	`address`	veForge EmissionRouter (`reward_token = USDC`); `empty` = 100% to surplus path

Returns / state: Updates emission_sink storage.

Access: owner only.

Events: EmissionSinkUpdated(sink).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:280-288):

@external
def set_emission_sink(sink: address):
    ownable._check_owner()
    self.emission_sink = sink
    log EmissionSinkUpdated(sink=sink)

Example:

router.set_emission_sink(emission_router)

Cross-links: set_gauge_bps · harvest · set_keeper

`set_keep_bps`¶

CoilFeeRouter.set_keep_bps(new_bps)

Set USDC slice routed to keeper (CoilMakerStrategy) on each USDC harvest. FLYWHEEL 2.0 Keep path.

Param	Type	Description
`new_bps`	`uint256`	Keep share of USDC harvest (`0`–`MAX_KEEP_BPS`, max 5000 = 50%)

Returns / state: Updates keep_bps. No effect until keeper set and harvest runs.

Access: owner only. Reverts if new_bps > MAX_KEEP_BPS or new_bps + gauge_bps > MAX_GAUGE_BPS.

Events: KeepBpsUpdated(new_bps).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:295-306):

@external
def set_keep_bps(new_bps: uint256):
    ownable._check_owner()
    assert new_bps <= MAX_KEEP_BPS, "router: keep bps too high"
    assert new_bps + self.gauge_bps <= MAX_GAUGE_BPS, "router: keep+gauge starves surplus"
    self.keep_bps = new_bps
    log KeepBpsUpdated(new_bps=new_bps)

Example:

router.set_keep_bps(2500)  # 25% of USDC fees to CoilMakerStrategy

Cross-links: set_keeper · set_gauge_bps · harvest

`set_keeper`¶

CoilFeeRouter.set_keeper(new_keeper)

Set CoilMakerStrategy receiving keep_bps USDC slice on harvest. Must NOT be bare MultiStrategyVault.

Param	Type	Description
`new_keeper`	`address`	CoilMakerStrategy; `empty` = Keep slice disabled

Returns / state: Updates keeper storage.

Access: owner only.

Events: KeeperUpdated(keeper).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:309-319):

@external
def set_keeper(new_keeper: address):
    ownable._check_owner()
    self.keeper = new_keeper
    log KeeperUpdated(keeper=new_keeper)

Example:

router.set_keeper(coil_maker_strategy)

Cross-links: set_keep_bps · harvest · SurplusSplitter

Harvest¶

`harvest`¶

CoilFeeRouter.harvest(token) -> uint256

Permissionless. Claim Coil accrued fees for token, route USDC slices, convert to TARE, donate to engine surplus.

Param	Type	Description
`token`	`address`	Fee token to harvest (`TARE` or `USDC` only)

Returns: uint256 — TARE donated this call (0 if nothing to route).

Flow: - Pull from Coil if accrued_fees > 0, then sweep router's full token balance. - TARE — donate as-is via donate_to_surplus. - USDC — keep_bps → keeper, gauge_bps → emission_sink, remainder swapped USDC→TARE (EMA min_dy, max_swap_in cap).

Access: Any caller (@nonreentrant). Reverts on unsupported token.

Events: FeesHarvested, KeepFeesRouted, GaugeFeesRouted (USDC path).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:326-384):

@external
@nonreentrant
def harvest(token: address) -> uint256:
    if staticcall COIL.accrued_fees(token) > 0:
        extcall COIL.withdraw_accrued_fees(token)
    bal: uint256 = staticcall IERC20(token).balanceOf(self)
    if bal == 0:
        return 0
    # TARE: donate; USDC: keep/gauge slices then _swap_usdc_to_tare
    if tare_amount > 0:
        self._donate(tare_amount)
    return tare_amount

Example:

donated = router.harvest(usdc)
router.harvest(tare)

Cross-links: set_keep_bps · set_gauge_bps · set_max_swap_in · TareEngine donate_to_surplus · pending

Escape hatch¶

`recover`¶

CoilFeeRouter.recover(token, to)

Owner escape hatch for non-core tokens stranded in router (unsupported Coil fee tokens).

Param	Type	Description
`token`	`address`	Token to recover — not TARE or USDC
`to`	`address`	Recipient

Returns / state: Transfers full router balance of token to to.

Access: owner only. Reverts if token is TARE/USDC (core flywheel tokens cannot be redirected).

Events: Recovered(token, to, amount).

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:391-408):

@external
@nonreentrant
def recover(token: address, to: address):
    ownable._check_owner()
    assert token != TARE and token != USDC, "router: cannot recover core"
    assert to != empty(address), "router: zero recipient"
    bal: uint256 = staticcall IERC20(token).balanceOf(self)
    extcall IERC20(token).transfer(to, bal, default_return_value=True)
    log Recovered(token=token, to=to, amount=bal)

Example:

router.recover(stranded_token, treasury)

Cross-links: harvest

Views¶

`pending`¶

CoilFeeRouter.pending(token) -> uint256

Coil-accrued plus router-held balance available to harvest.

Param	Type	Description
`token`	`address`	Token to quote

Returns: uint256 — coil.accrued_fees(token) + balanceOf(router).

Access: view, any caller.

Source (TARE-Stablecoin/src/CoilFeeRouter.vy:415-419):

@external
@view
def pending(token: address) -> uint256:
    return staticcall COIL.accrued_fees(token) + staticcall IERC20(token).balanceOf(self)

Example:

claimable = router.pending(usdc)

Cross-links: harvest

CoilFeeRouter¶

Implementation overview¶

Immutables¶

Constants¶

Events¶

Admin¶

set_slippage_bps¶

set_max_swap_in¶

set_gauge_bps¶

set_emission_sink¶

set_keep_bps¶

set_keeper¶

Harvest¶

harvest¶

Escape hatch¶

recover¶

Views¶

pending¶

Cross-links¶

`set_slippage_bps`¶

`set_max_swap_in`¶

`set_gauge_bps`¶

`set_emission_sink`¶

`set_keep_bps`¶

`set_keeper`¶

`harvest`¶

`recover`¶

`pending`¶