diff --git a/crates/fidc-core/src/broker.rs b/crates/fidc-core/src/broker.rs
index 72b4fc2..4beaa87 100644
--- a/crates/fidc-core/src/broker.rs
+++ b/crates/fidc-core/src/broker.rs
@@ -7,7 +7,7 @@ use chrono::{Duration, NaiveDate, NaiveDateTime, NaiveTime};
 use crate::cost::CostModel;
 use crate::data::{DataSet, IntradayExecutionQuote, PriceField};
 use crate::engine::BacktestError;
-use crate::execution_capacity::{CapacityError, ParticipationRate};
+use crate::execution_capacity::{CapacityError, ParticipationRate, VolumeObservation, VolumeObservationKind};
 use crate::events::{
     AccountEvent, FillEvent, OrderEvent, OrderSide, OrderStatus, PositionEvent, ProcessEvent,
     ProcessEventKind,
@@ -7696,9 +7696,11 @@ where
         let mut liquidity_consumption = Vec::new();
 
         for (quote_index, quote) in eligible_quotes.iter().enumerate() {
-            // Approximate platform-native market-order fills with the evolving L1 book after
-            // the decision time instead of trade VWAP. This keeps quantities/prices
-            // closer to the observed 10:18 execution logs.
+            let execution_at = if use_decision_time_quote {
+                start_cursor.expect("as-of orders have an execution clock").max(quote.timestamp)
+            } else {
+                quote.timestamp
+            };
             let Some(raw_quote_price) =
                 self.select_quote_reference_price(snapshot, quote, side, matching_type)
             else {
@@ -7706,7 +7708,7 @@ where
             };
             if let Some(reason) = self.execution_limit_rejection_reason(snapshot, side, raw_quote_price) {
                 execution_block_reason.get_or_insert(reason);
-                execution_block_timestamp = Some(quote.timestamp);
+                execution_block_timestamp = Some(execution_at);
                 continue;
             }
             let mark_price = self.quote_mark_price(quote, raw_quote_price);
@@ -7760,8 +7762,18 @@ where
                             .copied()
                             .unwrap_or(0),
                     );
-                let raw_limit = self.volume_rate.map_err(|error| BacktestError::Execution(error.to_string()))?
-                    .remaining(quote.volume_delta, u64::from(consumed), remaining_qty);
+                let observation = VolumeObservation {
+                    kind: VolumeObservationKind::TradeIncrement,
+                    start: quote.timestamp,
+                    end: quote.timestamp,
+                    available_at: quote.timestamp,
+                    shares: quote.volume_delta,
+                };
+                let raw_limit = observation.remaining(
+                    execution_at,
+                    self.volume_rate.map_err(|error| BacktestError::Execution(error.to_string()))?,
+                    u64::from(consumed), remaining_qty,
+                ).map_err(|error| BacktestError::Execution(error.to_string()))?;
                 let volume_limited = if side == OrderSide::Sell && allow_odd_lot_sell {
                     raw_limit
                 } else {
@@ -7794,7 +7806,7 @@ where
             if let Some(reason) = self.execution_limit_rejection_reason(snapshot, side, quote_price)
             {
                 execution_block_reason.get_or_insert(reason);
-                execution_block_timestamp = Some(quote.timestamp);
+                execution_block_timestamp = Some(execution_at);
                 continue;
             }
             saw_non_blocked_execution_price = true;
@@ -7822,7 +7834,7 @@ where
                         self.execution_limit_rejection_reason(snapshot, side, quote_price)
                     {
                         execution_block_reason.get_or_insert(reason);
-                        execution_block_timestamp = Some(quote.timestamp);
+                        execution_block_timestamp = Some(execution_at);
                         take_qty = 0;
                         break;
                     }
@@ -7867,21 +7879,21 @@ where
             if let Some(reason) = self.execution_limit_rejection_reason(snapshot, side, quote_price)
             {
                 execution_block_reason.get_or_insert(reason);
-                execution_block_timestamp = Some(quote.timestamp);
+                execution_block_timestamp = Some(execution_at);
                 continue;
             }
 
             gross_amount += quote_price * take_qty as f64;
             mark_amount += mark_price * take_qty as f64;
             filled_qty += take_qty;
-            first_timestamp.get_or_insert(quote.timestamp);
-            last_timestamp = Some(quote.timestamp);
+            first_timestamp.get_or_insert(execution_at);
+            last_timestamp = Some(execution_at);
             legs.push(ExecutionLeg {
                 price: quote_price,
                 mark_price,
                 quantity: take_qty,
-                execution_start_timestamp: Some(quote.timestamp),
-                execution_timestamp: Some(quote.timestamp),
+                execution_start_timestamp: Some(execution_at),
+                execution_timestamp: Some(execution_at),
             });
             if consume_depth {
                 let state = depth_state
@@ -11592,14 +11604,51 @@ mod tests {
         assert_eq!(fill.quantity, 200);
         assert_eq!(fill.legs.len(), 1);
         assert_eq!(fill.legs[0].price, 10.8);
-        assert_eq!(fill.legs[0].execution_timestamp, Some(quote_timestamp));
-        assert!(fill.legs[0].execution_timestamp.unwrap() <= decision_time);
+        assert!(quote_timestamp < decision_time);
+        assert_eq!(fill.legs[0].execution_timestamp, Some(decision_time));
         assert_eq!(
             fill.next_cursor,
-            quote_timestamp + chrono::Duration::seconds(1)
+            decision_time + chrono::Duration::seconds(1)
         );
     }
 
+    #[test]
+    fn later_execution_clocks_do_not_replenish_the_same_observed_volume() {
+        let date = NaiveDate::from_ymd_opt(2025,1,2).unwrap();
+        let broker = BrokerSimulator::new_with_execution_price(
+            ChinaAShareCostModel::default(), ChinaEquityRuleHooks, PriceField::Last,
+        ).with_volume_limit(true).with_volume_percent(0.25).with_liquidity_limit(false);
+        let snapshot = limit_test_snapshot();
+        let mut quote = limit_test_quote(10.8,10.79,10.81);
+        quote.timestamp = date.and_hms_opt(9,32,58).unwrap();
+        quote.volume_delta = 1000;
+        let quotes = [quote];
+        let mut ledger = super::IntradayExecutionLedger::default();
+        let clock = date.and_hms_opt(9,33,0).unwrap();
+        let first = broker.select_execution_fill_with_ledger(
+            &snapshot.symbol,&snapshot,&quotes,OrderSide::Buy,MatchingType::MinuteLast,
+            Some(clock),Some(clock),200,100,100,100,false,None,None,None,&ledger,None,
+        ).unwrap().unwrap();
+        assert_eq!(first.quantity,200);
+        assert_eq!(first.legs[0].execution_timestamp,Some(clock));
+        assert_eq!(first.liquidity_consumption[0].timestamp,quotes[0].timestamp);
+        ledger.apply_liquidity_consumption(&first.liquidity_consumption);
+        let later = clock + Duration::seconds(1);
+        let second = broker.select_execution_fill_with_ledger(
+            &snapshot.symbol,&snapshot,&quotes,OrderSide::Sell,MatchingType::MinuteLast,
+            Some(later),Some(later),100,100,100,100,true,None,None,None,&ledger,None,
+        ).unwrap().unwrap();
+        assert_eq!(second.quantity,50);
+        assert_eq!(second.legs[0].execution_timestamp,Some(later));
+        ledger.apply_liquidity_consumption(&second.liquidity_consumption);
+        assert_eq!(ledger.volume_consumed(&snapshot.symbol,quotes[0].timestamp),250);
+        let third = broker.select_execution_fill_with_ledger(
+            &snapshot.symbol,&snapshot,&quotes,OrderSide::Buy,MatchingType::MinuteLast,
+            Some(later),Some(later),100,100,100,100,false,None,None,None,&ledger,None,
+        ).unwrap();
+        assert!(third.is_none());
+    }
+
     #[test]
     fn value_buy_process_uses_latest_quote_before_decision_time() {
         let date = chrono::NaiveDate::from_ymd_opt(2025, 1, 2).expect("valid date");
diff --git a/crates/fidc-core/src/platform_expr_strategy.rs b/crates/fidc-core/src/platform_expr_strategy.rs
index ba11257..ae748b1 100644
--- a/crates/fidc-core/src/platform_expr_strategy.rs
+++ b/crates/fidc-core/src/platform_expr_strategy.rs
@@ -3410,7 +3410,7 @@ impl PlatformExprStrategy {
             }
             gross_amount += quote_price * take_qty as f64;
             filled_qty += take_qty;
-            last_timestamp = Some(quote.timestamp);
+            last_timestamp = Some(start_cursor.max(quote.timestamp));
             if filled_qty >= requested_qty {
                 break;
             }