positive interest works

contracts/interfaces/IEverlong.sol

@@ -1,16 +1,16 @@
 // SPDX-License-Identifier: Apache-2.0
 pragma solidity ^0.8.20;
 
-import { IERC4626 } from "openzeppelin/interfaces/IERC4626.sol";
+import { ERC4626 } from "solady/tokens/ERC4626.sol";
 import { IEverlongAdmin } from "./IEverlongAdmin.sol";
 import { IEverlongEvents } from "./IEverlongEvents.sol";
-import { IEverlongPositions } from "./IEverlongPositions.sol";
+import { IEverlongPortfolio } from "./IEverlongPortfolio.sol";
 
-interface IEverlong is
+abstract contract IEverlong is
+    ERC4626,
     IEverlongAdmin,
-    IERC4626,
     IEverlongEvents,
-    IEverlongPositions
+    IEverlongPortfolio
 {
     // ╭─────────────────────────────────────────────────────────╮
     // │ Structs                                                 │
@@ -32,15 +32,15 @@ interface IEverlong is
     // ╰─────────────────────────────────────────────────────────╯
 
     /// @notice Gets the address of the underlying Hyperdrive Instance
-    function hyperdrive() external view returns (address);
+    function hyperdrive() external view virtual returns (address);
 
     /// @notice Gets the Everlong instance's kind.
     /// @return The Everlong instance's kind.
-    function kind() external pure returns (string memory);
+    function kind() external pure virtual returns (string memory);
 
     /// @notice Gets the Everlong instance's version.
     /// @return The Everlong instance's version.
-    function version() external pure returns (string memory);
+    function version() external pure virtual returns (string memory);
 
     // ╭─────────────────────────────────────────────────────────╮
     // │ Errors                                                  │

contracts/interfaces/IEverlongPositions.sol → contracts/interfaces/IEverlongPortfolio.sol

@@ -3,7 +3,7 @@ pragma solidity ^0.8.20;
 
 import { IEverlong } from "./IEverlong.sol";
 
-interface IEverlongPositions {
+interface IEverlongPortfolio {
     // ╭─────────────────────────────────────────────────────────╮
     // │ Stateful                                                │
     // ╰─────────────────────────────────────────────────────────╯
@@ -17,13 +17,13 @@ interface IEverlongPositions {
 
     /// @notice Gets the number of positions managed by the Everlong instance.
     /// @return The number of positions.
-    function getPositionCount() external view returns (uint256);
+    function positionCount() external view returns (uint256);
 
     /// @notice Gets the position at an index.
     ///         Position `maturityTime` increases with each index.
     /// @param _index The index of the position.
     /// @return The position.
-    function getPosition(
+    function positionAt(
         uint256 _index
     ) external view returns (IEverlong.Position memory);
 
@@ -34,7 +34,7 @@ interface IEverlongPositions {
     /// @notice Determines whether Everlong has sufficient excess liquidity
     ///         for opening a long.
     /// @return True if sufficient excess liquidity, false otherwise.
-    function hasSufficientExcessLiquidity() external view returns (bool);
+    // function hasSufficientExcessLiquidity() external view returns (bool);
 
     /// @notice Determines whether Everlong's portfolio can currently be rebalanced.
     /// @return True if the portfolio can be rebalanced, false otherwise.