diff --git a/x10/perpetual/order_object.py b/x10/perpetual/order_object.py
index 653021c..e6f4100 100644
--- a/x10/perpetual/order_object.py
+++ b/x10/perpetual/order_object.py
@@ -13,6 +13,7 @@
 )
 from x10.perpetual.orders import (
     CreateOrderTpslTriggerModel,
+    CreateOrderConditionalTriggerModel,
     NewOrderModel,
     OrderPriceType,
     OrderSide,
@@ -21,12 +22,17 @@
     OrderType,
     SelfTradeProtectionLevel,
     TimeInForce,
+    OrderTriggerDirection,
 )
 from x10.utils.date import to_epoch_millis, utc_now
 from x10.utils.nonce import generate_nonce
 from x10.utils.tpsl import calc_entire_position_size
 
 
+# --------------------------------------------------
+# Trigger parameter models
+# --------------------------------------------------
+
 @dataclass(kw_only=True)
 class OrderTpslTriggerParam:
     trigger_price: Decimal
@@ -35,6 +41,18 @@ class OrderTpslTriggerParam:
     price_type: OrderPriceType
 
 
+@dataclass(kw_only=True)
+class OrderConditionalTriggerParam:
+    trigger_price: Decimal
+    trigger_price_type: OrderTriggerPriceType
+    direction: OrderTriggerDirection
+    execution_price_type: OrderPriceType
+
+
+# --------------------------------------------------
+# Public factory
+# --------------------------------------------------
+
 def create_order_object(
     *,
     account: StarkPerpetualAccount,
@@ -43,7 +61,6 @@ def create_order_object(
     price: Decimal,
     side: OrderSide,
     starknet_domain: StarknetDomain,
-    order_type: OrderType = OrderType.LIMIT,
     post_only: bool = False,
     previous_order_external_id: Optional[str] = None,
     expire_time: Optional[datetime] = None,
@@ -54,6 +71,12 @@ def create_order_object(
     builder_fee: Optional[Decimal] = None,
     builder_id: Optional[int] = None,
     reduce_only: bool = False,
+
+    # conditional-specific
+    order_type: OrderType = OrderType.LIMIT,
+    trigger: Optional[OrderConditionalTriggerParam] = None,
+
+    # TPSL-specific
     tp_sl_type: Optional[OrderTpslType] = None,
     take_profit: Optional[OrderTpslTriggerParam] = None,
     stop_loss: Optional[OrderTpslTriggerParam] = None,
@@ -89,12 +112,17 @@ def create_order_object(
         builder_fee=builder_fee,
         builder_id=builder_id,
         reduce_only=reduce_only,
+        trigger=trigger,
         tp_sl_type=tp_sl_type,
         take_profit=take_profit,
         stop_loss=stop_loss,
     )
 
 
+# --------------------------------------------------
+# Internal helpers
+# --------------------------------------------------
+
 def __create_order_tpsl_trigger_model(
     *,
     trigger_param: OrderTpslTriggerParam,
@@ -135,6 +163,10 @@ def __get_opposite_side(side: OrderSide) -> OrderSide:
     return OrderSide.BUY if side == OrderSide.SELL else OrderSide.SELL
 
 
+# --------------------------------------------------
+# Core builder
+# --------------------------------------------------
+
 def __create_order_object(
     *,
     market: MarketModel,
@@ -158,11 +190,16 @@ def __create_order_object(
     builder_fee: Optional[Decimal] = None,
     builder_id: Optional[int] = None,
     reduce_only: bool = False,
+    trigger: Optional[OrderConditionalTriggerParam] = None,
     tp_sl_type: Optional[OrderTpslType] = None,
     take_profit: Optional[OrderTpslTriggerParam] = None,
     stop_loss: Optional[OrderTpslTriggerParam] = None,
 ) -> NewOrderModel:
-    if order_type not in [OrderType.LIMIT, OrderType.TPSL]:
+
+    if side not in OrderSide:
+        raise ValueError(f"Unexpected order side value: {side}")
+              
+    if order_type not in [OrderType.LIMIT, OrderType.TPSL, OrderType.CONDITIONAL]:
         raise NotImplementedError(f"{order_type} order type is not supported yet")
 
     if exact_only:
@@ -178,14 +215,34 @@ def __create_order_object(
         if not reduce_only:
             raise ValueError("TPSL orders must be reduce-only")
 
+    # --------------------------------------------------
+    # Conditional order validation
+    # --------------------------------------------------
+    if order_type == OrderType.CONDITIONAL:
+        if trigger is None:
+            raise ValueError("Conditional order requires trigger")
+
+        if tp_sl_type or take_profit or stop_loss:
+            raise ValueError("Conditional orders cannot include TPSL fields")
+
+        if post_only:
+            raise ValueError("post_only is not supported for conditional orders")
+
+        if price <= 0:
+            raise ValueError("Conditional order requires valid execution price")
+            
+    # --------------------------------------------------
+    # TPSL validation
+    # --------------------------------------------------
+    if order_type == OrderType.TPSL:
         if post_only:
             raise ValueError("TPSL orders must not be post-only")
 
-        if tp_sl_type == OrderTpslType.POSITION and synthetic_amount != Decimal(0):
-            raise ValueError("`amount_of_synthetic` must be 0 for entire position TPSL orders")
+        if tp_sl_type == OrderTpslType.POSITION:
+            raise NotImplementedError("`POSITION` TPSL type is not supported yet")
 
         if price != Decimal(0):
-            raise ValueError("`price` must be 0 for TPSL orders")
+            raise ValueError("`price` must be 0 for TPSL orders")            
 
     if nonce is None:
         nonce = generate_nonce()
@@ -203,8 +260,12 @@ def __create_order_object(
         public_key=public_key,
         starknet_domain=starknet_domain,
     )
+
     settlement_data = create_order_settlement_data(
-        side=side, synthetic_amount=synthetic_amount, price=price, ctx=settlement_data_ctx
+        side=side,
+        synthetic_amount=synthetic_amount,
+        price=price,
+        ctx=settlement_data_ctx,
     )
 
     def create_tpsl_trigger_model(trigger_param: OrderTpslTriggerParam | None):
@@ -228,6 +289,7 @@ def create_tpsl_trigger_model(trigger_param: OrderTpslTriggerParam | None):
         )
 
     order_id = str(settlement_data.order_hash) if order_external_id is None else order_external_id
+
     order = NewOrderModel(
         id=order_id,
         market=market.name,
@@ -242,6 +304,16 @@ def create_tpsl_trigger_model(trigger_param: OrderTpslTriggerParam | None):
         self_trade_protection_level=self_trade_protection_level,
         nonce=Decimal(nonce),
         cancel_id=previous_order_external_id,
+        trigger=(
+            CreateOrderConditionalTriggerModel(
+                trigger_price=trigger.trigger_price,
+                trigger_price_type=trigger.trigger_price_type,
+                direction=trigger.direction,
+                execution_price_type=trigger.execution_price_type,
+            )
+            if order_type == OrderType.CONDITIONAL and trigger is not None
+            else None
+        ),
         settlement=settlement_data.settlement if order_type != OrderType.TPSL else None,
         tp_sl_type=tp_sl_type,
         take_profit=create_tpsl_trigger_model(take_profit),