Function: postFillCloseOrder(byte[32] asset, address account, PostFillOrderArgs args)

This function executes a market fill intended to close an existing position for a given account. It attempts to match an opposing order from the order book based on the provided parameters. If the fillOrderType is FILL_OR_KILL, the entire requested amount must be filled or the transaction reverts. If it is IMMEDIATE_OR_CANCEL, it fills as much as possible and cancels the rest.

Inputs

• asset

  • Control: Full control.

  • Constraints: Must be a valid, supported market.

  • Impact: Determines which asset the order is for.

• account

  • Control: Full control.

  • Constraints: Must own the subaccount and have an active position in the selected market. Must match msg.sender or be authorized to act on behalf of the user.

  • Impact: Specifies whose position is being closed. Position and collateral changes will apply to this address.

• args.amount

  • Control: Full control.

  • Constraints: Must be greater than zero — the amount of the order in base or quote units depending on amountIsBase.

  • Impact: The amount of the order to fill (in base or quote units depending on amountIsBase).

• args.price

  • Control: Full control.

  • Constraints: For BUY, the maximum price the user is willing to pay. For SELL, the minimum price the user is willing to accept.

  • Impact: Prevents the order from filling at worse prices than the user expects.

• args.side

  • Control: Full control.

  • Constraints: Must be opposite to the existing position side.

  • Impact: Determines the direction of the closing order.

• args.amountIsBase

  • Control: Full control.

  • Constraints: Boolean. If true, the amount is in base asset — if false, in quote asset. Only amountIsBase is allowed.

  • Impact: Affects how the order amount is interpreted and matched.

• args.fillOrderType

  • Control: Full control.

  • Constraints: Must be a valid enum value (FILL_OR_KILL, IMMEDIATE_OR_CANCEL). For FILL_OR_KILL, fills fully or reverts — or for IMMEDIATE_OR_CANCEL, partial fill is allowed.

  • Impact: Affects how the order is executed.

• args.subaccount

  • Control: Full control.

  • Constraints: Must be owned by the account. Must have an open position in this market.

  • Impact: Identifies which subaccount's position will be closed.

• args.leverage

  • Control: Full control.

  • Constraints: the margin per unit of quote amount should not less than the initMarginReq.

  • Impact: Leverage to apply if position is reopened.

• args.settlement

  • Control: Full control.

  • Constraints: Must be a valid settlement type (INSTANT, ACCOUNT). For settlement INSTANT, immediately returns, or for ACCOUNT, keeps funds inside the protocol.

  • Impact: Defines where the resulting funds go after the position is closed.

Branches and code coverage

Intended branches

• Closes entire position (full match).

  Test coverage

• Closes partial position (partially filled).

  Test coverage

• side to close is correct.

  Test coverage

• Filled price is only below or equal to the provided price for BUY.

  Test coverage

• Filled price fills only above or equal to the provided price for SELL.

  Test coverage

• Fill order type FILL_OR_KILL fully fills.

  Test coverage

• Fill order type IMMEDIATE_OR_CANCEL partially fills.

  Test coverage

• No matching liquidity and IMMEDIATE_OR_CANCEL.

  Test coverage

• amountIsBase == true.

  Test coverage

• Realized PNL is correctly computed on close.

  Test coverage

• Partially closed position updates parameters of the position.

  Test coverage

• Fully closed position fully resets.

  Test coverage

• Settlement type is INSTANT.

  Test coverage

• Settlement type is ACCOUNT.

  Test coverage

• Margin is reduced proportionally on partial close.

  Test coverage

• Margin is fully released if position is closed.

  Test coverage

• Closes across multiple prices.

  Test coverage

• Protocol reserves are updated.

  Test coverage

• Closes a position close to liquidation.

  Test coverage

Negative behavior

• Closes with an amount greater than the position amount.

  Negative test

• Closes a position that does not exist.

  Negative test

• Incorrect side.

  Negative test

• Fill order type FILL_OR_KILL partly fills.

  Negative test

• There is no matching liquidity in the book and FILL_OR_KILL.

  Negative test

• amount == 0.

  Negative test

• Invalid asset.

  Negative test

• price == 0.

  Negative test

• Subaccount does not belong to account.

  Negative test

• Position is already liquidated.

  Negative test

• Order book contains only the user’s own opposite order.

  Negative test

• Very large amount.

  Negative test

• amountIsBase == false.

  Negative test