From 46522b3f9ebc817c50a8b96aad9ef55cbb3750bd Mon Sep 17 00:00:00 2001
From: paplo75 <monberras@gmail.com>
Date: Fri, 14 Aug 2026 15:33:41 +0200
Subject: [PATCH] Fix market order price rounding for builder-deployed perp
 dexs

_slippage_price classifies an asset as spot with `asset >= 10_000`, but
builder-deployed (HIP-3) perp dex assets start at 110000, so they are
also caught by that check. Those perps are then rounded to 8 - szDecimals
decimals instead of 6 - szDecimals, and market_open/market_close can
produce a price with too many decimal places, which the exchange rejects.

Spot asset ids live in [10000, 110000), so bound the check on both sides.
---
 hyperliquid/exchange.py |  4 +--
 tests/exchange_test.py  | 57 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100644 tests/exchange_test.py

diff --git a/hyperliquid/exchange.py b/hyperliquid/exchange.py
index 41a2f66b..ad6c0737 100644
--- a/hyperliquid/exchange.py
+++ b/hyperliquid/exchange.py
@@ -123,8 +123,8 @@ def _slippage_price(
             px = float(self.info.all_mids(dex)[coin])
 
         asset = self.info.coin_to_asset[coin]
-        # spot assets start at 10000
-        is_spot = asset >= 10_000
+        # spot assets start at 10000 and builder-deployed perp dex assets start at 110000
+        is_spot = 10_000 <= asset < 110_000
 
         # Calculate Slippage
         px *= (1 + slippage) if is_buy else (1 - slippage)
diff --git a/tests/exchange_test.py b/tests/exchange_test.py
new file mode 100644
index 00000000..4f85bcd2
--- /dev/null
+++ b/tests/exchange_test.py
@@ -0,0 +1,57 @@
+import eth_account
+
+from hyperliquid.exchange import Exchange
+from hyperliquid.utils.types import Meta, SpotMeta
+
+TEST_META: Meta = {"universe": [{"name": "ABC", "szDecimals": 0}]}
+TEST_SPOT_META: SpotMeta = {
+    "universe": [{"name": "@1", "tokens": [1, 0], "index": 1, "isCanonical": False}],
+    "tokens": [
+        {
+            "name": "USDC",
+            "szDecimals": 8,
+            "weiDecimals": 8,
+            "index": 0,
+            "tokenId": "0x6d1e7cde53ba9467b783cb7c530ce054",
+            "isCanonical": True,
+            "evmContract": None,
+            "fullName": None,
+        },
+        {
+            "name": "PURR",
+            "szDecimals": 0,
+            "weiDecimals": 5,
+            "index": 1,
+            "tokenId": "0xc1fb593aeffbeb02f85e0308e9956a90",
+            "isCanonical": True,
+            "evmContract": None,
+            "fullName": None,
+        },
+    ],
+}
+
+
+def make_exchange() -> Exchange:
+    wallet = eth_account.Account.from_key("0x0123456789012345678901234567890123456789012345678901234567890123")
+    return Exchange(wallet, meta=TEST_META, spot_meta=TEST_SPOT_META)
+
+
+def test_slippage_price_perp():
+    exchange = make_exchange()
+    # 5 significant figures, then at most 6 - szDecimals decimals
+    assert exchange._slippage_price("ABC", True, 0.05, 0.0012345678) == 0.001296
+
+
+def test_slippage_price_spot():
+    exchange = make_exchange()
+    # spot allows 8 - szDecimals decimals
+    assert exchange._slippage_price("@1", True, 0.05, 0.0012345678) == 0.0012963
+
+
+def test_slippage_price_builder_deployed_perp():
+    exchange = make_exchange()
+    # builder-deployed perp dex assets start at 110000, above the spot range, but are still perps
+    exchange.info.name_to_coin["test:ABC"] = "test:ABC"
+    exchange.info.coin_to_asset["test:ABC"] = 110000
+    exchange.info.asset_to_sz_decimals[110000] = 0
+    assert exchange._slippage_price("test:ABC", True, 0.05, 0.0012345678) == 0.001296