remove same slot matching restriction

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Features
 
+- program: remove same slot matching restriction [#2104](https://github.com/drift-labs/protocol-v2/pull/2104)
+
 ### Fixes
 
 ### Breaking
@@ -47,6 +49,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixes
 
 ### Breaking
+
 - sdk: `channelOptions` in the GrpcConfigs type has been updated to work with new grpc lib
 
 ## [2.153.0] - 2025-12-30
@@ -104,11 +107,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixes
 
 ### Breaking
+
 - program: add DepositRecord::spot_balance_after [#2034](https://github.com/drift-labs/protocol-v2/pull/2034)
 
 ## [2.149.0] - 2025-11-19
 
 ### Features
+
 - sdk: allow deposit from external authority directly to drift account
 
 ### Fixes
@@ -171,7 +176,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Features
 
-- program: use-5min-for-target-expiry-price  ([#1967](https://github.com/drift-labs/protocol-v2/pull/1967))
+- program: use-5min-for-target-expiry-price ([#1967](https://github.com/drift-labs/protocol-v2/pull/1967))
 
 ### Fixes
 

programs/drift/src/math/matching.rs

@@ -17,10 +17,8 @@ pub fn is_maker_for_taker(
     taker_order: &Order,
     slot: u64,
 ) -> DriftResult<bool> {
-    // Maker and taker order not allowed to match if both were placed in the current slot
-    if slot == maker_order.slot && slot == taker_order.slot && !maker_order.is_jit_maker() {
-        return Ok(false);
-    };
+    // Self match protection handled upstream via maker_key != taker_key check.
+    // Removed slot equality restriction to enable same slot fills.
 
     // taker cant be post only and maker must be resting limit order
     if taker_order.post_only || !maker_order.is_resting_limit_order(slot)? {

programs/drift/src/math/matching/tests.rs

@@ -177,6 +177,55 @@ mod is_maker_for_taker {
 
         assert_eq!(is_maker_for_taker(&maker, &taker, slot).unwrap(), true);
     }
+
+    #[test]
+    fn same_slot_maker_taker_non_resting() {
+        let slot = 0;
+
+        // Taker market order
+        let taker = Order {
+            post_only: false,
+            order_type: OrderType::Market,
+            slot: 0,
+            ..Default::default()
+        };
+
+        // Maker resting with 0 auction
+        let maker = Order {
+            post_only: false,
+            order_type: OrderType::Limit,
+            slot: 0,
+            auction_duration: 0,
+            ..Default::default()
+        };
+
+        assert_eq!(is_maker_for_taker(&maker, &taker, slot).unwrap(), true);
+    }
+
+    #[test]
+    fn same_slot_maker_taker_both_resting() {
+        let slot = 20;
+
+        // Resting taker order
+        let taker = Order {
+            post_only: false,
+            order_type: OrderType::Limit,
+            slot: 10,
+            auction_duration: 5,
+            ..Default::default()
+        };
+
+        // Resting maker order (older)
+        let maker = Order {
+            post_only: false,
+            order_type: OrderType::Limit,
+            slot: 5,
+            auction_duration: 2,
+            ..Default::default()
+        };
+
+        assert_eq!(is_maker_for_taker(&maker, &taker, slot).unwrap(), true);
+    }
 }
 
 #[test]