Cost breakdown

Every simulated trade shows what it cost to execute: fees, book-walk slippage and funding. The breakdown is recomputed from the receipt inputs, never trusted from a stored result.

What is broken out

Component	How it is modelled
Fees	Versioned Hyperliquid perp schedule, split by taker and maker. Default `hl-perp-tier0-base-2026-10-16`: 4.5 bps taker, 1.5 bps maker.
Slippage	A taker walks the displayed book. Slippage is measured against mid. One-sided books leave mid unset.
Funding	Hourly, `size × oracle price × hourly rate`, split into paid and received.
Queue position	`NOT_MODELLED`
Liquidation	`NOT_MODELLED`

From code

import { costBreakdownFromReceipt } from "@perpbrain/sdk";

const costs = costBreakdownFromReceipt(receipt);

Agents can call the MCP tool get_cost_breakdown. See MCP usage.

Receipt version

Receipt version 2 stores the breakdown inside the hashed result, so result_sha256 covers it. Version 1 receipts still check.

Maker fills

A maker order that does not cross the touch fills only displayed size at the anchor price. No queue fill is invented. A maker request that crosses the touch is treated as a taker.

Read thisReal execution can cost more than the model shows, especially in thin books and fast markets. Each receipt lists what is not modelled.