Idea: min subordination manager

src/managers/MinSubordinationRatio.sol

@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: BUSL-1.1
+pragma solidity 0.8.28;
+
+import {Auth} from "src/misc/Auth.sol";
+import {D18, d18} from "src/misc/types/D18.sol";
+
+import {PoolId} from "src/common/types/PoolId.sol";
+import {AssetId} from "src/common/types/AssetId.sol";
+import {ShareClassId} from "src/common/types/ShareClassId.sol";
+
+import {IHub} from "src/hub/interfaces/IHub.sol";
+import {IHoldings} from "src/hub/interfaces/IHoldings.sol";
+import {IShareClassManager} from "src/hub/interfaces/IShareClassManager.sol";
+
+contract MinSubordination is Auth {
+    error InvalidJuniorRatio(D18 newRatio, D18 minRatio);
+
+    IHub public immutable hub;
+    IHoldings public immutable holdings;
+    IShareClassManager public immutable scm;
+
+    PoolId public immutable poolId;
+    ShareClassId public immutable seniorScId;
+    ShareClassId public immutable juniorScId;
+
+    D18 public minJuniorRatio;
+
+    constructor(
+        IHub hub_,
+        IHoldings holdings_,
+        IShareClassManager scm_,
+        PoolId poolId_,
+        ShareClassId seniorScId_,
+        ShareClassId juniorScId_
+    ) Auth(msg.sender) {
+        hub = hub_;
+        holdings = holdings_;
+        scm = scm_;
+
+        poolId = poolId_;
+        seniorScId = seniorScId_;
+        juniorScId = juniorScId_;
+    }
+
+    // --- Administration ---
+    function setMinJuniorRatio(D18 newRatio) external auth {
+        minJuniorRatio = newRatio;
+        _checkRatio();
+    }
+
+    // --- Pool management ---
+    function fulfill(
+        AssetId assetId,
+        uint128 seniorDeposit,
+        uint128 seniorRedeem,
+        D18 seniorNavPerShare,
+        uint128 juniorDeposit,
+        uint128 juniorRedeem,
+        D18 juniorNavPerShare
+    ) external auth {
+        hub.updateSharePrice(poolId, seniorScId, seniorNavPerShare);
+        hub.updateSharePrice(poolId, juniorScId, juniorNavPerShare);
+
+        hub.approveDeposits(poolId, seniorScId, assetId, scm.nowDepositEpoch(seniorScId, assetId), seniorDeposit);
+        hub.issueShares(poolId, seniorScId, assetId, scm.nowIssueEpoch(seniorScId, assetId), seniorNavPerShare, 0);
+
+        hub.approveRedeems(poolId, seniorScId, assetId, scm.nowRedeemEpoch(seniorScId, assetId), seniorRedeem);
+        hub.revokeShares(poolId, seniorScId, assetId, scm.nowRevokeEpoch(seniorScId, assetId), seniorNavPerShare, 0);
+
+        hub.approveDeposits(poolId, juniorScId, assetId, scm.nowDepositEpoch(juniorScId, assetId), juniorDeposit);
+        hub.issueShares(poolId, juniorScId, assetId, scm.nowIssueEpoch(juniorScId, assetId), juniorNavPerShare, 0);
+
+        hub.approveRedeems(poolId, juniorScId, assetId, scm.nowRedeemEpoch(juniorScId, assetId), juniorRedeem);
+        hub.revokeShares(poolId, juniorScId, assetId, scm.nowRevokeEpoch(juniorScId, assetId), juniorNavPerShare, 0);
+
+        _checkRatio();
+    }
+
+    // --- Validation ---
+    function _checkRatio() internal view {
+        (uint128 seniorIssuance, D18 seniorPrice) = scm.metrics(seniorScId);
+        (uint128 juniorIssuance, D18 juniorPrice) = scm.metrics(juniorScId);
+
+        D18 seniorValue = d18(seniorIssuance) * seniorPrice;
+        D18 juniorValue = d18(juniorIssuance) * juniorPrice;
+
+        D18 juniorRatio = juniorValue / (seniorValue + juniorValue);
+        require(juniorRatio >= minJuniorRatio, InvalidJuniorRatio(juniorRatio, minJuniorRatio));
+    }
+}

src/misc/types/D18.sol

@@ -91,6 +91,10 @@ function eq(D18 a, D18 b) pure returns (bool) {
     return D18.unwrap(a) == D18.unwrap(b);
 }
 
+function geq(D18 a, D18 b) pure returns (bool) {
+    return D18.unwrap(a) >= D18.unwrap(b);
+}
+
 function isZero(D18 a) pure returns (bool) {
     return D18.unwrap(a) == 0;
 }
@@ -108,6 +112,7 @@ using {
     sub as -,
     divD18 as /,
     eq,
+    geq as >=,
     mulD18 as *,
     mulUint128,
     mulUint256,