Align board-specific stock order sizing

crates/fidc-core/tests/explicit_order_flow.rs

@@ -478,7 +478,7 @@ fn rebalance_optimizer_skips_unfunded_buy_when_existing_position_cannot_sell() {
 }
 
 #[test]
-fn broker_uses_instrument_round_lot_for_buy_sizing() {
+fn broker_uses_board_specific_min_quantity_and_step_size_for_buy_sizing() {
     let date = NaiveDate::from_ymd_opt(2024, 1, 10).unwrap();
     let data = DataSet::from_components(
         vec![Instrument {
@@ -563,7 +563,7 @@ fn broker_uses_instrument_round_lot_for_buy_sizing() {
                 order_intents: vec![OrderIntent::Value {
                     symbol: "688001.SH".to_string(),
                     value: 10_500.0,
-                    reason: "round_lot".to_string(),
+                    reason: "board_min_qty".to_string(),
                 }],
                 notes: Vec::new(),
                 diagnostics: Vec::new(),
@@ -572,7 +572,105 @@ fn broker_uses_instrument_round_lot_for_buy_sizing() {
         .expect("broker execution");
 
     assert_eq!(report.fill_events.len(), 1);
-    assert_eq!(report.fill_events[0].quantity, 1000);
+    assert_eq!(report.fill_events[0].quantity, 1049);
+}
+
+#[test]
+fn broker_allows_bjse_quantities_above_minimum_without_round_lot_step() {
+    let date = NaiveDate::from_ymd_opt(2024, 1, 10).unwrap();
+    let data = DataSet::from_components(
+        vec![Instrument {
+            symbol: "430001.BJ".to_string(),
+            name: "BJSE".to_string(),
+            board: "BJS".to_string(),
+            round_lot: 100,
+            listed_at: None,
+            delisted_at: None,
+            status: "active".to_string(),
+        }],
+        vec![DailyMarketSnapshot {
+            date,
+            symbol: "430001.BJ".to_string(),
+            timestamp: Some("2024-01-10 10:18:00".to_string()),
+            day_open: 10.0,
+            open: 10.0,
+            high: 10.1,
+            low: 9.9,
+            close: 10.0,
+            last_price: 10.0,
+            bid1: 9.99,
+            ask1: 10.01,
+            prev_close: 10.0,
+            volume: 100_000,
+            tick_volume: 100_000,
+            bid1_volume: 80_000,
+            ask1_volume: 80_000,
+            trading_phase: Some("continuous".to_string()),
+            paused: false,
+            upper_limit: 11.0,
+            lower_limit: 9.0,
+            price_tick: 0.01,
+        }],
+        vec![DailyFactorSnapshot {
+            date,
+            symbol: "430001.BJ".to_string(),
+            market_cap_bn: 50.0,
+            free_float_cap_bn: 45.0,
+            pe_ttm: 20.0,
+            turnover_ratio: Some(2.0),
+            effective_turnover_ratio: Some(1.8),
+            extra_factors: BTreeMap::new(),
+        }],
+        vec![CandidateEligibility {
+            date,
+            symbol: "430001.BJ".to_string(),
+            is_st: false,
+            is_new_listing: false,
+            is_paused: false,
+            allow_buy: true,
+            allow_sell: true,
+            is_kcb: false,
+            is_one_yuan: false,
+        }],
+        vec![BenchmarkSnapshot {
+            date,
+            benchmark: "000300.SH".to_string(),
+            open: 100.0,
+            close: 100.0,
+            prev_close: 99.0,
+            volume: 1_000_000,
+        }],
+    )
+    .expect("dataset");
+    let mut portfolio = PortfolioState::new(1_010.0);
+    let broker = BrokerSimulator::new_with_execution_price(
+        ChinaAShareCostModel::default(),
+        ChinaEquityRuleHooks::default(),
+        PriceField::Open,
+    );
+
+    let report = broker
+        .execute(
+            date,
+            &mut portfolio,
+            &data,
+            &StrategyDecision {
+                rebalance: false,
+                target_weights: BTreeMap::new(),
+                exit_symbols: BTreeSet::new(),
+                order_intents: vec![OrderIntent::Value {
+                    symbol: "430001.BJ".to_string(),
+                    value: 1_010.0,
+                    reason: "bj_min_qty".to_string(),
+                }],
+                notes: Vec::new(),
+                diagnostics: Vec::new(),
+            },
+        )
+        .expect("broker execution");
+
+    assert_eq!(report.fill_events.len(), 1);
+    assert_eq!(report.fill_events[0].quantity, 100);
 }
 
 #[test]