commit 334864cbc56601e0976553798a29b932352c1803
Author: zsb <zsb@example.com>
Date:   Mon Apr 6 23:56:37 2026 -0700

    初始化回测核心引擎骨架

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+
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+edition = "2024"
+license = "MIT"
+version = "0.1.0"
+authors = ["OpenAI Codex"]
+
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+thiserror = "=2.0.18"
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..679cd85
--- /dev/null
+++ b/README.md
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+# fidc-backtest-engine
+
+一个面向中国 A 股长周期选股策略的 Rust 回测核心骨架。这个仓库的第一版目标不是“玩具回测器”，而是提供一个可以继续演化为平台化引擎的最小可用核心，方向参考 `nautilus_trader` 的分层架构和 `rqalpha` 的中国股票规则约束。
+
+## 当前能力
+
+- 日频交易日历与确定性逐日回放
+- A 股日频市场快照、估值/因子快照、基准快照、候选资格标记
+- 策略接口与引擎驱动，不直接模拟 `jqdata` API
+- Universe 选择器：按指数位置动态切换市值带，再取最小市值 Top-N
+- 风险节流：基于指数均线状态切换 100% / 50% / 0% 仓位
+- Broker Simulator：按次日开盘价撮合，支持手续费、印花税、最小佣金
+- 中国 A 股规则钩子：T+1、停牌、涨停不可买、跌停不可卖
+- 回测输出：权益曲线、成交记录、期末持仓摘要
+- `cargo run --bin bt-demo` 可直接运行仓库内置 demo 数据
+
+## Workspace 布局
+
+```text
+.
+├── Cargo.toml
+├── crates
+│   ├── bt-demo
+│   │   └── src/main.rs
+│   └── fidc-core
+│       └── src
+│           ├── broker.rs
+│           ├── calendar.rs
+│           ├── cost.rs
+│           ├── data.rs
+│           ├── engine.rs
+│           ├── events.rs
+│           ├── instrument.rs
+│           ├── portfolio.rs
+│           ├── rules.rs
+│           ├── strategy.rs
+│           └── universe.rs
+└── data/demo
+```
+
+## 核心模块概览
+
+- `calendar`: 交易日历和滚动窗口工具，负责日频迭代和均线 lookback。
+- `instrument`: 证券静态定义。
+- `data`: 日频市场、因子、基准、候选资格数据模型与 CSV loader。
+- `universe`: 动态市值带 Universe Selector。
+- `portfolio`: 现金、持仓、FIFO lots、T+1 可卖数量、盈亏汇总。
+- `rules`: 中国股票规则钩子，隔离停牌、涨跌停、T+1 检查。
+- `cost`: 佣金、印花税、最低佣金模型。
+- `broker`: 目标权重到订单执行的模拟器，先卖后买，买单按 100 股向下取整。
+- `strategy`: 引擎驱动的策略 trait 与具体策略实现。
+- `engine`: 确定性的逐日回测循环和结果收集。
+
+## 策略实现
+
+示例策略 `CnSmallCapRotationStrategy` 对应一类典型的 A 股小市值轮动逻辑：
+
+1. 用指数点位相对基准水平切换市值带：
+   - 强势区间：更偏小市值
+   - 中性区间：中小市值
+   - 弱势区间：偏大一些的防御市值带
+2. 在当前市值带内，按总市值升序取 Top-N。
+3. 用指数短均线/长均线关系控制总仓位：
+   - `1.0`: 风险偏好正常
+   - `0.5`: 降半仓
+   - `0.0`: 全部转现金
+4. 固定交易日频率再平衡。
+5. 非再平衡日也会检查止损/止盈钩子并触发退出。
+
+这个接口不是 `jqdata` 风格的 `before_trading_start` / `handle_data` 直接脚本 API，而是：
+
+- 策略收到 `StrategyContext`
+- 返回 `StrategyDecision`
+- 引擎和 broker 负责把目标权重和退出指令变成实际成交
+
+这更接近平台化引擎需要的“策略意图”和“执行语义”分离。
+
+## 与原始 jqdata 策略族的映射
+
+如果原始逻辑大致是：
+
+- 依据指数强弱切换可接受市值带
+- 从候选股票里选最小市值若干只
+- 按均线决定是否降仓
+- 周期性调仓
+- 带止损/止盈
+
+那么本仓库中的映射关系是：
+
+- `get_fundamentals` / `valuation.market_cap` -> `DailyFactorSnapshot.market_cap_bn`
+- `get_price` / `history` -> `DailyMarketSnapshot` + `BenchmarkSnapshot`
+- `set_benchmark` -> `BacktestConfig.benchmark_code`
+- `filter_paused` / `filter_st` / 新股过滤 -> `CandidateEligibility`
+- `order_target_value` -> `StrategyDecision.target_weights` 由 `BrokerSimulator` 解释执行
+- 风险控制逻辑 -> `CnSmallCapRotationStrategy::gross_exposure`
+
+## V1 明确简化点
+
+下面这些是刻意保留为 v1 简化，而不是遗漏：
+
+- 只支持日频，不做分钟级、集合竞价、盘中撮合。
+- 决策基于 `T-1` 收盘后可见数据，在 `T` 开盘价执行。
+- 不模拟盘口排队、成交量约束和滑点模型，成交默认按开盘价完成。
+- 买单按 100 股整手向下取整，卖单允许按实际持仓数量退出。
+- 未处理复权、分红送转、融资融券、可转债、科创板/北交所差异规则。
+- 止损止盈基于上一交易日收盘价相对持仓成本触发，下一交易日开盘执行。
+
+这些简化都在代码结构上留了扩展位，不会阻断后续升级到更完整的执行层。
+
+## 运行方式
+
+```bash
+cargo run --bin bt-demo
+```
+
+运行后会生成：
+
+- `output/demo/equity_curve.csv`
+- `output/demo/trades.csv`
+- `output/demo/holdings_summary.csv`
+
+## 测试与构建
+
+```bash
+cargo fmt
+cargo test
+cargo build
+```
+
+## 为什么这个设计适合后续做快
+
+这个版本已经按“预计算后高速回放”的思路组织：
+
+- 因子与资格数据和市场行情解耦，适合把 `T x N` 的选股输入预先展开。
+- 快照结构是列式数据库友好的固定字段模型，后续可以自然对接 ClickHouse/Parquet。
+- Engine 逐日回放时只做：
+  - 取当天切片
+  - 策略计算 target weights
+  - broker 做持仓差量执行
+- 不把查询逻辑塞进策略内部，避免回测时频繁回源数据层。
+
+如果未来把日频因子、资格标记、可交易标记和开/收盘价全部预计算到列式存储，再按日期分块读入内存，6 年全市场回测在 5 分钟内是合理目标，原因是：
+
+- 回测时不再做昂贵的 SQL join
+- 因子筛选可直接消费预先物化的 snapshot
+- 组合调仓只关心“目标持仓”和“当前持仓”的差量
+- 事件流是 append-only，适合批量写出和后处理分析
+
+## Roadmap
+
+- 引入更明确的事件总线和 portfolio/account ledger 分层
+- 增加多 benchmark、多 universe、多个 broker model
+- 支持企业行为、前后复权与现金分红
+- 增加滑点、量比约束、成交量参与率
+- 增加 parquet / ClickHouse 数据源与预计算管线
+- 增加指标分析、分组收益、归因和 walk-forward 框架
diff --git a/crates/bt-demo/Cargo.toml b/crates/bt-demo/Cargo.toml
new file mode 100644
index 0000000..c384fa3
--- /dev/null
+++ b/crates/bt-demo/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "bt-demo"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+authors.workspace = true
+
+[dependencies]
+fidc-core = { path = "../fidc-core" }
diff --git a/crates/bt-demo/src/main.rs b/crates/bt-demo/src/main.rs
new file mode 100644
index 0000000..c865042
--- /dev/null
+++ b/crates/bt-demo/src/main.rs
@@ -0,0 +1,180 @@
+use std::error::Error;
+use std::fs;
+use std::io::Write;
+use std::path::{Path, PathBuf};
+
+use fidc_core::{
+    BacktestConfig,
+    BacktestEngine,
+    BenchmarkSnapshot,
+    BrokerSimulator,
+    ChinaAShareCostModel,
+    ChinaEquityRuleHooks,
+    CnSmallCapRotationConfig,
+    CnSmallCapRotationStrategy,
+    DataSet,
+    DailyEquityPoint,
+    FillEvent,
+    HoldingSummary,
+};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let root = workspace_root();
+    let data_dir = root.join("data/demo");
+    let output_dir = root.join("output/demo");
+
+    fs::create_dir_all(&output_dir)?;
+
+    let data = DataSet::from_csv_dir(&data_dir)?;
+    let strategy = CnSmallCapRotationStrategy::new(CnSmallCapRotationConfig::demo());
+    let broker = BrokerSimulator::new(ChinaAShareCostModel::default(), ChinaEquityRuleHooks::default());
+    let config = BacktestConfig {
+        initial_cash: 1_000_000.0,
+        benchmark_code: data.benchmark_code().to_string(),
+    };
+
+    let mut engine = BacktestEngine::new(data, strategy, broker, config);
+    let result = engine.run()?;
+
+    write_equity_curve_csv(&output_dir.join("equity_curve.csv"), &result.equity_curve)?;
+    write_trades_csv(&output_dir.join("trades.csv"), &result.fills)?;
+    write_holdings_csv(&output_dir.join("holdings_summary.csv"), &result.holdings_summary)?;
+
+    print_summary(
+        &result.equity_curve,
+        &result.fills,
+        &result.holdings_summary,
+        result.benchmark_series.last(),
+    );
+
+    println!("Artifacts written under {}", output_dir.display());
+    Ok(())
+}
+
+fn workspace_root() -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR"))
+        .join("../..")
+        .canonicalize()
+        .expect("workspace root")
+}
+
+fn write_equity_curve_csv(path: &Path, rows: &[DailyEquityPoint]) -> Result<(), Box<dyn Error>> {
+    let mut file = fs::File::create(path)?;
+    writeln!(file, "date,cash,market_value,total_equity,benchmark_close,notes")?;
+    for row in rows {
+        writeln!(
+            file,
+            "{},{:.2},{:.2},{:.2},{:.2},{}",
+            row.date,
+            row.cash,
+            row.market_value,
+            row.total_equity,
+            row.benchmark_close,
+            sanitize_csv_field(&row.notes),
+        )?;
+    }
+    Ok(())
+}
+
+fn write_trades_csv(path: &Path, rows: &[FillEvent]) -> Result<(), Box<dyn Error>> {
+    let mut file = fs::File::create(path)?;
+    writeln!(
+        file,
+        "date,symbol,side,quantity,price,gross_amount,commission,stamp_tax,net_cash_flow,reason"
+    )?;
+    for row in rows {
+        writeln!(
+            file,
+            "{},{},{:?},{},{:.2},{:.2},{:.2},{:.2},{:.2},{}",
+            row.date,
+            row.symbol,
+            row.side,
+            row.quantity,
+            row.price,
+            row.gross_amount,
+            row.commission,
+            row.stamp_tax,
+            row.net_cash_flow,
+            sanitize_csv_field(&row.reason),
+        )?;
+    }
+    Ok(())
+}
+
+fn write_holdings_csv(path: &Path, rows: &[HoldingSummary]) -> Result<(), Box<dyn Error>> {
+    let mut file = fs::File::create(path)?;
+    writeln!(
+        file,
+        "date,symbol,quantity,average_cost,last_price,market_value,unrealized_pnl,realized_pnl"
+    )?;
+    for row in rows {
+        writeln!(
+            file,
+            "{},{},{},{:.2},{:.2},{:.2},{:.2},{:.2}",
+            row.date,
+            row.symbol,
+            row.quantity,
+            row.average_cost,
+            row.last_price,
+            row.market_value,
+            row.unrealized_pnl,
+            row.realized_pnl,
+        )?;
+    }
+    Ok(())
+}
+
+fn sanitize_csv_field(text: &str) -> String {
+    text.replace(',', ";")
+}
+
+fn print_summary(
+    equity_curve: &[DailyEquityPoint],
+    fills: &[FillEvent],
+    holdings: &[HoldingSummary],
+    benchmark_last: Option<&BenchmarkSnapshot>,
+) {
+    let Some(first) = equity_curve.first() else {
+        println!("No equity curve points generated.");
+        return;
+    };
+    let Some(last) = equity_curve.last() else {
+        println!("No equity curve points generated.");
+        return;
+    };
+
+    let total_return = (last.total_equity / first.total_equity) - 1.0;
+    println!("Strategy: cn-smallcap-rotation");
+    println!("Start equity: {:.2}", first.total_equity);
+    println!("Final equity: {:.2}", last.total_equity);
+    println!("Total return: {:.2}%", total_return * 100.0);
+    println!("Trades: {}", fills.len());
+    println!("Final holdings: {}", holdings.len());
+
+    if let Some(benchmark) = benchmark_last {
+        println!(
+            "Benchmark last close: {} {:.2}",
+            benchmark.benchmark, benchmark.close
+        );
+    }
+
+    println!("Recent equity points:");
+    for point in equity_curve.iter().rev().take(3).collect::<Vec<_>>().into_iter().rev() {
+        println!(
+            "  {} equity {:.2} cash {:.2} mv {:.2}",
+            point.date, point.total_equity, point.cash, point.market_value
+        );
+    }
+
+    if holdings.is_empty() {
+        println!("No holdings at the end of the demo run.");
+    } else {
+        println!("Ending holdings:");
+        for holding in holdings {
+            println!(
+                "  {} qty {} mv {:.2} pnl {:.2}",
+                holding.symbol, holding.quantity, holding.market_value, holding.unrealized_pnl
+            );
+        }
+    }
+}
diff --git a/crates/fidc-core/Cargo.toml b/crates/fidc-core/Cargo.toml
new file mode 100644
index 0000000..ffc7848
--- /dev/null
+++ b/crates/fidc-core/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "fidc-core"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+authors.workspace = true
+
+[dependencies]
+chrono.workspace = true
+serde.workspace = true
+thiserror.workspace = true
diff --git a/crates/fidc-core/src/broker.rs b/crates/fidc-core/src/broker.rs
new file mode 100644
index 0000000..08d3812
--- /dev/null
+++ b/crates/fidc-core/src/broker.rs
@@ -0,0 +1,390 @@
+use std::collections::{BTreeMap, BTreeSet};
+
+use chrono::NaiveDate;
+
+use crate::cost::CostModel;
+use crate::data::{DataSet, PriceField};
+use crate::engine::BacktestError;
+use crate::events::{AccountEvent, FillEvent, OrderEvent, OrderSide, OrderStatus, PositionEvent};
+use crate::portfolio::PortfolioState;
+use crate::rules::EquityRuleHooks;
+use crate::strategy::StrategyDecision;
+
+#[derive(Debug, Default)]
+pub struct BrokerExecutionReport {
+    pub order_events: Vec<OrderEvent>,
+    pub fill_events: Vec<FillEvent>,
+    pub position_events: Vec<PositionEvent>,
+    pub account_events: Vec<AccountEvent>,
+}
+
+pub struct BrokerSimulator<C, R> {
+    cost_model: C,
+    rules: R,
+    board_lot_size: u32,
+}
+
+impl<C, R> BrokerSimulator<C, R> {
+    pub fn new(cost_model: C, rules: R) -> Self {
+        Self {
+            cost_model,
+            rules,
+            board_lot_size: 100,
+        }
+    }
+}
+
+impl<C, R> BrokerSimulator<C, R>
+where
+    C: CostModel,
+    R: EquityRuleHooks,
+{
+    pub fn execute(
+        &self,
+        date: NaiveDate,
+        portfolio: &mut PortfolioState,
+        data: &DataSet,
+        decision: &StrategyDecision,
+    ) -> Result<BrokerExecutionReport, BacktestError> {
+        let mut report = BrokerExecutionReport::default();
+        let target_quantities = if decision.rebalance {
+            self.target_quantities(date, portfolio, data, &decision.target_weights)?
+        } else {
+            BTreeMap::new()
+        };
+
+        let mut sell_symbols = BTreeSet::new();
+        sell_symbols.extend(portfolio.positions().keys().cloned());
+        sell_symbols.extend(decision.exit_symbols.iter().cloned());
+        sell_symbols.extend(target_quantities.keys().cloned());
+
+        for symbol in sell_symbols {
+            let current_qty = portfolio.position(&symbol).map(|pos| pos.quantity).unwrap_or(0);
+            if current_qty == 0 {
+                continue;
+            }
+
+            let target_qty = if decision.exit_symbols.contains(&symbol) {
+                0
+            } else if decision.rebalance {
+                *target_quantities.get(&symbol).unwrap_or(&0)
+            } else {
+                current_qty
+            };
+
+            if current_qty > target_qty {
+                let requested_qty = current_qty - target_qty;
+                self.process_sell(
+                    date,
+                    portfolio,
+                    data,
+                    &symbol,
+                    requested_qty,
+                    sell_reason(decision, &symbol),
+                    &mut report,
+                )?;
+            }
+        }
+
+        if decision.rebalance {
+            for (symbol, target_qty) in target_quantities {
+                let current_qty = portfolio.position(&symbol).map(|pos| pos.quantity).unwrap_or(0);
+                if target_qty > current_qty {
+                    let requested_qty = target_qty - current_qty;
+                    self.process_buy(
+                        date,
+                        portfolio,
+                        data,
+                        &symbol,
+                        requested_qty,
+                        "rebalance_buy",
+                        &mut report,
+                    )?;
+                }
+            }
+        }
+
+        portfolio.prune_flat_positions();
+        Ok(report)
+    }
+
+    fn target_quantities(
+        &self,
+        date: NaiveDate,
+        portfolio: &PortfolioState,
+        data: &DataSet,
+        target_weights: &BTreeMap<String, f64>,
+    ) -> Result<BTreeMap<String, u32>, BacktestError> {
+        let equity = self.total_equity_at(date, portfolio, data, PriceField::Open)?;
+        let mut targets = BTreeMap::new();
+
+        for (symbol, weight) in target_weights {
+            let price = data
+                .price(date, symbol, PriceField::Open)
+                .ok_or_else(|| BacktestError::MissingPrice {
+                    date,
+                    symbol: symbol.clone(),
+                    field: "open",
+                })?;
+            let raw_qty = ((equity * weight) / price).floor() as u32;
+            let rounded_qty = self.round_buy_quantity(raw_qty);
+            targets.insert(symbol.clone(), rounded_qty);
+        }
+
+        Ok(targets)
+    }
+
+    fn process_sell(
+        &self,
+        date: NaiveDate,
+        portfolio: &mut PortfolioState,
+        data: &DataSet,
+        symbol: &str,
+        requested_qty: u32,
+        reason: &str,
+        report: &mut BrokerExecutionReport,
+    ) -> Result<(), BacktestError> {
+        let snapshot = data.require_market(date, symbol)?;
+        let candidate = data.require_candidate(date, symbol)?;
+        let Some(position) = portfolio.position(symbol) else {
+            return Ok(());
+        };
+
+        let rule = self.rules.can_sell(date, snapshot, candidate, position);
+        if !rule.allowed {
+            report.order_events.push(OrderEvent {
+                date,
+                symbol: symbol.to_string(),
+                side: OrderSide::Sell,
+                requested_quantity: requested_qty,
+                filled_quantity: 0,
+                status: OrderStatus::Rejected,
+                reason: format!("{reason}: {}", rule.reason.unwrap_or_default()),
+            });
+            return Ok(());
+        }
+
+        let sellable = position.sellable_qty(date);
+        let filled_qty = requested_qty.min(sellable);
+        if filled_qty == 0 {
+            report.order_events.push(OrderEvent {
+                date,
+                symbol: symbol.to_string(),
+                side: OrderSide::Sell,
+                requested_quantity: requested_qty,
+                filled_quantity: 0,
+                status: OrderStatus::Rejected,
+                reason: format!("{reason}: no sellable quantity"),
+            });
+            return Ok(());
+        }
+
+        let cash_before = portfolio.cash();
+        let gross_amount = snapshot.open * filled_qty as f64;
+        let cost = self.cost_model.calculate(OrderSide::Sell, gross_amount);
+        let net_cash = gross_amount - cost.total();
+
+        let realized_pnl = portfolio
+            .position_mut(symbol)
+            .sell(filled_qty, snapshot.open)
+            .map_err(BacktestError::Execution)?;
+        portfolio.apply_cash_delta(net_cash);
+
+        let status = if filled_qty < requested_qty {
+            OrderStatus::PartiallyFilled
+        } else {
+            OrderStatus::Filled
+        };
+
+        report.order_events.push(OrderEvent {
+            date,
+            symbol: symbol.to_string(),
+            side: OrderSide::Sell,
+            requested_quantity: requested_qty,
+            filled_quantity: filled_qty,
+            status,
+            reason: reason.to_string(),
+        });
+        report.fill_events.push(FillEvent {
+            date,
+            symbol: symbol.to_string(),
+            side: OrderSide::Sell,
+            quantity: filled_qty,
+            price: snapshot.open,
+            gross_amount,
+            commission: cost.commission,
+            stamp_tax: cost.stamp_tax,
+            net_cash_flow: net_cash,
+            reason: reason.to_string(),
+        });
+        report.position_events.push(PositionEvent {
+            date,
+            symbol: symbol.to_string(),
+            delta_quantity: -(filled_qty as i32),
+            quantity_after: portfolio.position(symbol).map(|pos| pos.quantity).unwrap_or(0),
+            average_cost: portfolio
+                .position(symbol)
+                .map(|pos| pos.average_cost)
+                .unwrap_or(0.0),
+            realized_pnl_delta: realized_pnl,
+            reason: reason.to_string(),
+        });
+        report.account_events.push(AccountEvent {
+            date,
+            cash_before,
+            cash_after: portfolio.cash(),
+            total_equity: self.total_equity_at(date, portfolio, data, PriceField::Open)?,
+            note: format!("sell {symbol} {reason}"),
+        });
+        Ok(())
+    }
+
+    fn process_buy(
+        &self,
+        date: NaiveDate,
+        portfolio: &mut PortfolioState,
+        data: &DataSet,
+        symbol: &str,
+        requested_qty: u32,
+        reason: &str,
+        report: &mut BrokerExecutionReport,
+    ) -> Result<(), BacktestError> {
+        let snapshot = data.require_market(date, symbol)?;
+        let candidate = data.require_candidate(date, symbol)?;
+
+        let rule = self.rules.can_buy(date, snapshot, candidate);
+        if !rule.allowed {
+            report.order_events.push(OrderEvent {
+                date,
+                symbol: symbol.to_string(),
+                side: OrderSide::Buy,
+                requested_quantity: requested_qty,
+                filled_quantity: 0,
+                status: OrderStatus::Rejected,
+                reason: format!("{reason}: {}", rule.reason.unwrap_or_default()),
+            });
+            return Ok(());
+        }
+
+        let filled_qty =
+            self.affordable_buy_quantity(portfolio.cash(), snapshot.open, requested_qty);
+        if filled_qty == 0 {
+            report.order_events.push(OrderEvent {
+                date,
+                symbol: symbol.to_string(),
+                side: OrderSide::Buy,
+                requested_quantity: requested_qty,
+                filled_quantity: 0,
+                status: OrderStatus::Rejected,
+                reason: format!("{reason}: insufficient cash after fees"),
+            });
+            return Ok(());
+        }
+
+        let cash_before = portfolio.cash();
+        let gross_amount = snapshot.open * filled_qty as f64;
+        let cost = self.cost_model.calculate(OrderSide::Buy, gross_amount);
+        let cash_out = gross_amount + cost.total();
+
+        portfolio.apply_cash_delta(-cash_out);
+        portfolio.position_mut(symbol).buy(date, filled_qty, snapshot.open);
+
+        let status = if filled_qty < requested_qty {
+            OrderStatus::PartiallyFilled
+        } else {
+            OrderStatus::Filled
+        };
+
+        report.order_events.push(OrderEvent {
+            date,
+            symbol: symbol.to_string(),
+            side: OrderSide::Buy,
+            requested_quantity: requested_qty,
+            filled_quantity: filled_qty,
+            status,
+            reason: reason.to_string(),
+        });
+        report.fill_events.push(FillEvent {
+            date,
+            symbol: symbol.to_string(),
+            side: OrderSide::Buy,
+            quantity: filled_qty,
+            price: snapshot.open,
+            gross_amount,
+            commission: cost.commission,
+            stamp_tax: cost.stamp_tax,
+            net_cash_flow: -cash_out,
+            reason: reason.to_string(),
+        });
+        report.position_events.push(PositionEvent {
+            date,
+            symbol: symbol.to_string(),
+            delta_quantity: filled_qty as i32,
+            quantity_after: portfolio.position(symbol).map(|pos| pos.quantity).unwrap_or(0),
+            average_cost: portfolio
+                .position(symbol)
+                .map(|pos| pos.average_cost)
+                .unwrap_or(0.0),
+            realized_pnl_delta: 0.0,
+            reason: reason.to_string(),
+        });
+        report.account_events.push(AccountEvent {
+            date,
+            cash_before,
+            cash_after: portfolio.cash(),
+            total_equity: self.total_equity_at(date, portfolio, data, PriceField::Open)?,
+            note: format!("buy {symbol} {reason}"),
+        });
+        Ok(())
+    }
+
+    fn total_equity_at(
+        &self,
+        date: NaiveDate,
+        portfolio: &PortfolioState,
+        data: &DataSet,
+        field: PriceField,
+    ) -> Result<f64, BacktestError> {
+        let mut market_value = 0.0;
+        for position in portfolio.positions().values() {
+            let price = data
+                .price(date, &position.symbol, field)
+                .ok_or_else(|| BacktestError::MissingPrice {
+                    date,
+                    symbol: position.symbol.clone(),
+                    field: match field {
+                        PriceField::Open => "open",
+                        PriceField::Close => "close",
+                    },
+                })?;
+            market_value += price * position.quantity as f64;
+        }
+
+        Ok(portfolio.cash() + market_value)
+    }
+
+    fn round_buy_quantity(&self, quantity: u32) -> u32 {
+        (quantity / self.board_lot_size) * self.board_lot_size
+    }
+
+    fn affordable_buy_quantity(&self, cash: f64, price: f64, requested_qty: u32) -> u32 {
+        let mut quantity = self.round_buy_quantity(requested_qty);
+        while quantity > 0 {
+            let gross = price * quantity as f64;
+            let cost = self.cost_model.calculate(OrderSide::Buy, gross);
+            if gross + cost.total() <= cash + 1e-6 {
+                return quantity;
+            }
+            quantity = quantity.saturating_sub(self.board_lot_size);
+        }
+        0
+    }
+}
+
+fn sell_reason(decision: &StrategyDecision, symbol: &str) -> &'static str {
+    if decision.exit_symbols.contains(symbol) {
+        "exit_hook_sell"
+    } else {
+        "rebalance_sell"
+    }
+}
diff --git a/crates/fidc-core/src/calendar.rs b/crates/fidc-core/src/calendar.rs
new file mode 100644
index 0000000..9dc3adc
--- /dev/null
+++ b/crates/fidc-core/src/calendar.rs
@@ -0,0 +1,58 @@
+use std::collections::HashMap;
+
+use chrono::NaiveDate;
+
+#[derive(Debug, Clone)]
+pub struct TradingCalendar {
+    days: Vec<NaiveDate>,
+    index: HashMap<NaiveDate, usize>,
+}
+
+impl TradingCalendar {
+    pub fn new(mut days: Vec<NaiveDate>) -> Self {
+        days.sort_unstable();
+        days.dedup();
+
+        let index = days
+            .iter()
+            .copied()
+            .enumerate()
+            .map(|(idx, day)| (day, idx))
+            .collect();
+
+        Self { days, index }
+    }
+
+    pub fn days(&self) -> &[NaiveDate] {
+        &self.days
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = NaiveDate> + '_ {
+        self.days.iter().copied()
+    }
+
+    pub fn len(&self) -> usize {
+        self.days.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.days.is_empty()
+    }
+
+    pub fn index_of(&self, date: NaiveDate) -> Option<usize> {
+        self.index.get(&date).copied()
+    }
+
+    pub fn previous_day(&self, date: NaiveDate) -> Option<NaiveDate> {
+        let idx = self.index_of(date)?;
+        idx.checked_sub(1).and_then(|prev| self.days.get(prev).copied())
+    }
+
+    pub fn trailing_days(&self, end: NaiveDate, lookback: usize) -> Vec<NaiveDate> {
+        let Some(end_idx) = self.index_of(end) else {
+            return Vec::new();
+        };
+        let start = end_idx.saturating_add(1).saturating_sub(lookback);
+        self.days[start..=end_idx].to_vec()
+    }
+}
diff --git a/crates/fidc-core/src/cost.rs b/crates/fidc-core/src/cost.rs
new file mode 100644
index 0000000..f814191
--- /dev/null
+++ b/crates/fidc-core/src/cost.rs
@@ -0,0 +1,56 @@
+use crate::events::OrderSide;
+
+#[derive(Debug, Clone, Copy)]
+pub struct TradingCost {
+    pub commission: f64,
+    pub stamp_tax: f64,
+}
+
+impl TradingCost {
+    pub fn total(self) -> f64 {
+        self.commission + self.stamp_tax
+    }
+}
+
+pub trait CostModel {
+    fn calculate(&self, side: OrderSide, gross_amount: f64) -> TradingCost;
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct ChinaAShareCostModel {
+    pub commission_rate: f64,
+    pub stamp_tax_rate: f64,
+    pub minimum_commission: f64,
+}
+
+impl Default for ChinaAShareCostModel {
+    fn default() -> Self {
+        Self {
+            commission_rate: 0.0003,
+            stamp_tax_rate: 0.001,
+            minimum_commission: 5.0,
+        }
+    }
+}
+
+impl CostModel for ChinaAShareCostModel {
+    fn calculate(&self, side: OrderSide, gross_amount: f64) -> TradingCost {
+        if gross_amount <= 0.0 {
+            return TradingCost {
+                commission: 0.0,
+                stamp_tax: 0.0,
+            };
+        }
+
+        let commission = (gross_amount * self.commission_rate).max(self.minimum_commission);
+        let stamp_tax = match side {
+            OrderSide::Buy => 0.0,
+            OrderSide::Sell => gross_amount * self.stamp_tax_rate,
+        };
+
+        TradingCost {
+            commission,
+            stamp_tax,
+        }
+    }
+}
diff --git a/crates/fidc-core/src/data.rs b/crates/fidc-core/src/data.rs
new file mode 100644
index 0000000..9799bb9
--- /dev/null
+++ b/crates/fidc-core/src/data.rs
@@ -0,0 +1,471 @@
+use std::collections::{BTreeMap, HashMap};
+use std::fs;
+use std::path::Path;
+
+use chrono::NaiveDate;
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+
+use crate::calendar::TradingCalendar;
+use crate::instrument::Instrument;
+
+mod date_format {
+    use chrono::NaiveDate;
+    use serde::{self, Deserialize, Deserializer, Serializer};
+
+    const FORMAT: &str = "%Y-%m-%d";
+
+    pub fn serialize<S>(date: &NaiveDate, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&date.format(FORMAT).to_string())
+    }
+
+    pub fn deserialize<'de, D>(deserializer: D) -> Result<NaiveDate, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let text = String::deserialize(deserializer)?;
+        NaiveDate::parse_from_str(&text, FORMAT).map_err(serde::de::Error::custom)
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum DataSetError {
+    #[error("failed to read file {path}: {source}")]
+    Io {
+        path: String,
+        #[source]
+        source: std::io::Error,
+    },
+    #[error("invalid csv row in {path} at line {line}: {message}")]
+    InvalidRow {
+        path: String,
+        line: usize,
+        message: String,
+    },
+    #[error("benchmark file contains multiple benchmark codes")]
+    MultipleBenchmarks,
+    #[error("missing data for {kind} on {date} / {symbol}")]
+    MissingSnapshot {
+        kind: &'static str,
+        date: NaiveDate,
+        symbol: String,
+    },
+    #[error("benchmark snapshot missing for {date}")]
+    MissingBenchmark { date: NaiveDate },
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum PriceField {
+    Open,
+    Close,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DailyMarketSnapshot {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub symbol: String,
+    pub open: f64,
+    pub high: f64,
+    pub low: f64,
+    pub close: f64,
+    pub prev_close: f64,
+    pub volume: u64,
+    pub paused: bool,
+    pub upper_limit: f64,
+    pub lower_limit: f64,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DailyFactorSnapshot {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub symbol: String,
+    pub market_cap_bn: f64,
+    pub free_float_cap_bn: f64,
+    pub pe_ttm: f64,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct BenchmarkSnapshot {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub benchmark: String,
+    pub open: f64,
+    pub close: f64,
+    pub prev_close: f64,
+    pub volume: u64,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CandidateEligibility {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub symbol: String,
+    pub is_st: bool,
+    pub is_new_listing: bool,
+    pub is_paused: bool,
+    pub allow_buy: bool,
+    pub allow_sell: bool,
+}
+
+impl CandidateEligibility {
+    pub fn eligible_for_selection(&self) -> bool {
+        !self.is_st && !self.is_new_listing && !self.is_paused && self.allow_buy && self.allow_sell
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct DataSet {
+    instruments: HashMap<String, Instrument>,
+    calendar: TradingCalendar,
+    market_by_date: BTreeMap<NaiveDate, Vec<DailyMarketSnapshot>>,
+    market_index: HashMap<(NaiveDate, String), DailyMarketSnapshot>,
+    factor_by_date: BTreeMap<NaiveDate, Vec<DailyFactorSnapshot>>,
+    factor_index: HashMap<(NaiveDate, String), DailyFactorSnapshot>,
+    candidate_by_date: BTreeMap<NaiveDate, Vec<CandidateEligibility>>,
+    candidate_index: HashMap<(NaiveDate, String), CandidateEligibility>,
+    benchmark_by_date: BTreeMap<NaiveDate, BenchmarkSnapshot>,
+    benchmark_code: String,
+}
+
+impl DataSet {
+    pub fn from_csv_dir(path: &Path) -> Result<Self, DataSetError> {
+        let instruments = read_instruments(&path.join("instruments.csv"))?;
+        let market = read_market(&path.join("market.csv"))?;
+        let factors = read_factors(&path.join("factors.csv"))?;
+        let candidates = read_candidates(&path.join("candidate_flags.csv"))?;
+        let benchmarks = read_benchmarks(&path.join("benchmark.csv"))?;
+
+        let benchmark_code = collect_benchmark_code(&benchmarks)?;
+        let calendar = TradingCalendar::new(benchmarks.iter().map(|item| item.date).collect());
+
+        let instruments = instruments
+            .into_iter()
+            .map(|instrument| (instrument.symbol.clone(), instrument))
+            .collect::<HashMap<_, _>>();
+
+        let market_by_date = group_by_date(market.clone(), |item| item.date);
+        let market_index = market
+            .into_iter()
+            .map(|item| ((item.date, item.symbol.clone()), item))
+            .collect::<HashMap<_, _>>();
+
+        let factor_by_date = group_by_date(factors.clone(), |item| item.date);
+        let factor_index = factors
+            .into_iter()
+            .map(|item| ((item.date, item.symbol.clone()), item))
+            .collect::<HashMap<_, _>>();
+
+        let candidate_by_date = group_by_date(candidates.clone(), |item| item.date);
+        let candidate_index = candidates
+            .into_iter()
+            .map(|item| ((item.date, item.symbol.clone()), item))
+            .collect::<HashMap<_, _>>();
+
+        let benchmark_by_date = benchmarks
+            .into_iter()
+            .map(|item| (item.date, item))
+            .collect::<BTreeMap<_, _>>();
+
+        Ok(Self {
+            instruments,
+            calendar,
+            market_by_date,
+            market_index,
+            factor_by_date,
+            factor_index,
+            candidate_by_date,
+            candidate_index,
+            benchmark_by_date,
+            benchmark_code,
+        })
+    }
+
+    pub fn calendar(&self) -> &TradingCalendar {
+        &self.calendar
+    }
+
+    pub fn benchmark_code(&self) -> &str {
+        &self.benchmark_code
+    }
+
+    pub fn instruments(&self) -> &HashMap<String, Instrument> {
+        &self.instruments
+    }
+
+    pub fn market(&self, date: NaiveDate, symbol: &str) -> Option<&DailyMarketSnapshot> {
+        self.market_index.get(&(date, symbol.to_string()))
+    }
+
+    pub fn factor(&self, date: NaiveDate, symbol: &str) -> Option<&DailyFactorSnapshot> {
+        self.factor_index.get(&(date, symbol.to_string()))
+    }
+
+    pub fn candidate(&self, date: NaiveDate, symbol: &str) -> Option<&CandidateEligibility> {
+        self.candidate_index.get(&(date, symbol.to_string()))
+    }
+
+    pub fn benchmark(&self, date: NaiveDate) -> Option<&BenchmarkSnapshot> {
+        self.benchmark_by_date.get(&date)
+    }
+
+    pub fn benchmark_series(&self) -> Vec<BenchmarkSnapshot> {
+        self.benchmark_by_date.values().cloned().collect()
+    }
+
+    pub fn price(&self, date: NaiveDate, symbol: &str, field: PriceField) -> Option<f64> {
+        let snapshot = self.market(date, symbol)?;
+        Some(match field {
+            PriceField::Open => snapshot.open,
+            PriceField::Close => snapshot.close,
+        })
+    }
+
+    pub fn factor_snapshots_on(&self, date: NaiveDate) -> Vec<&DailyFactorSnapshot> {
+        self.factor_by_date
+            .get(&date)
+            .map(|rows| rows.iter().collect())
+            .unwrap_or_default()
+    }
+
+    pub fn market_snapshots_on(&self, date: NaiveDate) -> Vec<&DailyMarketSnapshot> {
+        self.market_by_date
+            .get(&date)
+            .map(|rows| rows.iter().collect())
+            .unwrap_or_default()
+    }
+
+    pub fn candidate_snapshots_on(&self, date: NaiveDate) -> Vec<&CandidateEligibility> {
+        self.candidate_by_date
+            .get(&date)
+            .map(|rows| rows.iter().collect())
+            .unwrap_or_default()
+    }
+
+    pub fn benchmark_closes_up_to(&self, date: NaiveDate, lookback: usize) -> Vec<f64> {
+        self.calendar
+            .trailing_days(date, lookback)
+            .into_iter()
+            .filter_map(|day| self.benchmark(day).map(|row| row.close))
+            .collect()
+    }
+
+    pub fn require_market(
+        &self,
+        date: NaiveDate,
+        symbol: &str,
+    ) -> Result<&DailyMarketSnapshot, DataSetError> {
+        self.market(date, symbol).ok_or_else(|| DataSetError::MissingSnapshot {
+            kind: "market",
+            date,
+            symbol: symbol.to_string(),
+        })
+    }
+
+    pub fn require_candidate(
+        &self,
+        date: NaiveDate,
+        symbol: &str,
+    ) -> Result<&CandidateEligibility, DataSetError> {
+        self.candidate(date, symbol)
+            .ok_or_else(|| DataSetError::MissingSnapshot {
+                kind: "candidate",
+                date,
+                symbol: symbol.to_string(),
+            })
+    }
+}
+
+fn read_instruments(path: &Path) -> Result<Vec<Instrument>, DataSetError> {
+    let rows = read_rows(path)?;
+    let mut instruments = Vec::new();
+    for row in rows {
+        instruments.push(Instrument {
+            symbol: row.get(0)?.to_string(),
+            name: row.get(1)?.to_string(),
+            board: row.get(2)?.to_string(),
+        });
+    }
+    Ok(instruments)
+}
+
+fn read_market(path: &Path) -> Result<Vec<DailyMarketSnapshot>, DataSetError> {
+    let rows = read_rows(path)?;
+    let mut snapshots = Vec::new();
+    for row in rows {
+        let prev_close = row.parse_f64(6)?;
+        snapshots.push(DailyMarketSnapshot {
+            date: row.parse_date(0)?,
+            symbol: row.get(1)?.to_string(),
+            open: row.parse_f64(2)?,
+            high: row.parse_f64(3)?,
+            low: row.parse_f64(4)?,
+            close: row.parse_f64(5)?,
+            prev_close,
+            volume: row.parse_u64(7)?,
+            paused: row.parse_bool(8)?,
+            upper_limit: round2(prev_close * 1.10),
+            lower_limit: round2(prev_close * 0.90),
+        });
+    }
+    Ok(snapshots)
+}
+
+fn read_factors(path: &Path) -> Result<Vec<DailyFactorSnapshot>, DataSetError> {
+    let rows = read_rows(path)?;
+    let mut snapshots = Vec::new();
+    for row in rows {
+        snapshots.push(DailyFactorSnapshot {
+            date: row.parse_date(0)?,
+            symbol: row.get(1)?.to_string(),
+            market_cap_bn: row.parse_f64(2)?,
+            free_float_cap_bn: row.parse_f64(3)?,
+            pe_ttm: row.parse_f64(4)?,
+        });
+    }
+    Ok(snapshots)
+}
+
+fn read_candidates(path: &Path) -> Result<Vec<CandidateEligibility>, DataSetError> {
+    let rows = read_rows(path)?;
+    let mut snapshots = Vec::new();
+    for row in rows {
+        snapshots.push(CandidateEligibility {
+            date: row.parse_date(0)?,
+            symbol: row.get(1)?.to_string(),
+            is_st: row.parse_bool(2)?,
+            is_new_listing: row.parse_bool(3)?,
+            is_paused: row.parse_bool(4)?,
+            allow_buy: row.parse_bool(5)?,
+            allow_sell: row.parse_bool(6)?,
+        });
+    }
+    Ok(snapshots)
+}
+
+fn read_benchmarks(path: &Path) -> Result<Vec<BenchmarkSnapshot>, DataSetError> {
+    let rows = read_rows(path)?;
+    let mut snapshots = Vec::new();
+    for row in rows {
+        snapshots.push(BenchmarkSnapshot {
+            date: row.parse_date(0)?,
+            benchmark: row.get(1)?.to_string(),
+            open: row.parse_f64(2)?,
+            close: row.parse_f64(3)?,
+            prev_close: row.parse_f64(4)?,
+            volume: row.parse_u64(5)?,
+        });
+    }
+    Ok(snapshots)
+}
+
+struct CsvRow {
+    path: String,
+    line: usize,
+    fields: Vec<String>,
+}
+
+impl CsvRow {
+    fn get(&self, index: usize) -> Result<&str, DataSetError> {
+        self.fields.get(index).map(String::as_str).ok_or_else(|| DataSetError::InvalidRow {
+            path: self.path.clone(),
+            line: self.line,
+            message: format!("missing column {index}"),
+        })
+    }
+
+    fn parse_date(&self, index: usize) -> Result<NaiveDate, DataSetError> {
+        NaiveDate::parse_from_str(self.get(index)?, "%Y-%m-%d").map_err(|err| DataSetError::InvalidRow {
+            path: self.path.clone(),
+            line: self.line,
+            message: format!("invalid date: {err}"),
+        })
+    }
+
+    fn parse_f64(&self, index: usize) -> Result<f64, DataSetError> {
+        self.get(index)?
+            .parse::<f64>()
+            .map_err(|err| DataSetError::InvalidRow {
+                path: self.path.clone(),
+                line: self.line,
+                message: format!("invalid f64: {err}"),
+            })
+    }
+
+    fn parse_u64(&self, index: usize) -> Result<u64, DataSetError> {
+        self.get(index)?
+            .parse::<u64>()
+            .map_err(|err| DataSetError::InvalidRow {
+                path: self.path.clone(),
+                line: self.line,
+                message: format!("invalid u64: {err}"),
+            })
+    }
+
+    fn parse_bool(&self, index: usize) -> Result<bool, DataSetError> {
+        self.get(index)?
+            .parse::<bool>()
+            .map_err(|err| DataSetError::InvalidRow {
+                path: self.path.clone(),
+                line: self.line,
+                message: format!("invalid bool: {err}"),
+            })
+    }
+}
+
+fn read_rows(path: &Path) -> Result<Vec<CsvRow>, DataSetError> {
+    let content = fs::read_to_string(path).map_err(|source| DataSetError::Io {
+        path: path.display().to_string(),
+        source,
+    })?;
+
+    let mut rows = Vec::new();
+    for (line_idx, line) in content.lines().enumerate() {
+        let line_no = line_idx + 1;
+        if line_no == 1 || line.trim().is_empty() {
+            continue;
+        }
+
+        rows.push(CsvRow {
+            path: path.display().to_string(),
+            line: line_no,
+            fields: line.split(',').map(|field| field.trim().to_string()).collect(),
+        });
+    }
+
+    Ok(rows)
+}
+
+fn group_by_date<T, F>(rows: Vec<T>, mut date_of: F) -> BTreeMap<NaiveDate, Vec<T>>
+where
+    F: FnMut(&T) -> NaiveDate,
+{
+    let mut grouped = BTreeMap::<NaiveDate, Vec<T>>::new();
+    for row in rows {
+        grouped.entry(date_of(&row)).or_default().push(row);
+    }
+    grouped
+}
+
+fn collect_benchmark_code(benchmarks: &[BenchmarkSnapshot]) -> Result<String, DataSetError> {
+    let mut codes = benchmarks
+        .iter()
+        .map(|row| row.benchmark.clone())
+        .collect::<Vec<_>>();
+    codes.sort_unstable();
+    codes.dedup();
+
+    if codes.len() == 1 {
+        Ok(codes.remove(0))
+    } else {
+        Err(DataSetError::MultipleBenchmarks)
+    }
+}
+
+fn round2(value: f64) -> f64 {
+    (value * 100.0).round() / 100.0
+}
diff --git a/crates/fidc-core/src/engine.rs b/crates/fidc-core/src/engine.rs
new file mode 100644
index 0000000..164a19d
--- /dev/null
+++ b/crates/fidc-core/src/engine.rs
@@ -0,0 +1,167 @@
+use chrono::NaiveDate;
+use serde::Serialize;
+use thiserror::Error;
+
+use crate::broker::{BrokerExecutionReport, BrokerSimulator};
+use crate::cost::CostModel;
+use crate::data::{BenchmarkSnapshot, DataSet, DataSetError, PriceField};
+use crate::events::{AccountEvent, FillEvent, OrderEvent, PositionEvent};
+use crate::portfolio::{HoldingSummary, PortfolioState};
+use crate::rules::EquityRuleHooks;
+use crate::strategy::{Strategy, StrategyContext, StrategyDecision};
+
+#[derive(Debug, Error)]
+pub enum BacktestError {
+    #[error(transparent)]
+    Data(#[from] DataSetError),
+    #[error("missing {field} price for {symbol} on {date}")]
+    MissingPrice {
+        date: NaiveDate,
+        symbol: String,
+        field: &'static str,
+    },
+    #[error("benchmark snapshot missing for {date}")]
+    MissingBenchmark { date: NaiveDate },
+    #[error("{0}")]
+    Execution(String),
+}
+
+#[derive(Debug, Clone)]
+pub struct BacktestConfig {
+    pub initial_cash: f64,
+    pub benchmark_code: String,
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct DailyEquityPoint {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub cash: f64,
+    pub market_value: f64,
+    pub total_equity: f64,
+    pub benchmark_close: f64,
+    pub notes: String,
+}
+
+#[derive(Debug, Clone)]
+pub struct BacktestResult {
+    pub strategy_name: String,
+    pub equity_curve: Vec<DailyEquityPoint>,
+    pub benchmark_series: Vec<BenchmarkSnapshot>,
+    pub order_events: Vec<OrderEvent>,
+    pub fills: Vec<FillEvent>,
+    pub position_events: Vec<PositionEvent>,
+    pub account_events: Vec<AccountEvent>,
+    pub holdings_summary: Vec<HoldingSummary>,
+}
+
+pub struct BacktestEngine<S, C, R> {
+    data: DataSet,
+    strategy: S,
+    broker: BrokerSimulator<C, R>,
+    config: BacktestConfig,
+}
+
+impl<S, C, R> BacktestEngine<S, C, R> {
+    pub fn new(
+        data: DataSet,
+        strategy: S,
+        broker: BrokerSimulator<C, R>,
+        config: BacktestConfig,
+    ) -> Self {
+        Self {
+            data,
+            strategy,
+            broker,
+            config,
+        }
+    }
+}
+
+impl<S, C, R> BacktestEngine<S, C, R>
+where
+    S: Strategy,
+    C: CostModel,
+    R: EquityRuleHooks,
+{
+    pub fn run(&mut self) -> Result<BacktestResult, BacktestError> {
+        let mut portfolio = PortfolioState::new(self.config.initial_cash);
+        let mut result = BacktestResult {
+            strategy_name: self.strategy.name().to_string(),
+            benchmark_series: self.data.benchmark_series(),
+            order_events: Vec::new(),
+            fills: Vec::new(),
+            position_events: Vec::new(),
+            account_events: Vec::new(),
+            equity_curve: Vec::new(),
+            holdings_summary: Vec::new(),
+        };
+
+        for execution_date in self.data.calendar().iter() {
+            let decision = match self.data.calendar().previous_day(execution_date) {
+                Some(decision_date) => {
+                    let decision_index = self.data.calendar().index_of(decision_date).unwrap_or(0);
+                    self.strategy.on_day(&StrategyContext {
+                        execution_date,
+                        decision_date,
+                        decision_index,
+                        data: &self.data,
+                        portfolio: &portfolio,
+                    })?
+                }
+                None => StrategyDecision::default(),
+            };
+
+            let report = self
+                .broker
+                .execute(execution_date, &mut portfolio, &self.data, &decision)?;
+            self.extend_result(&mut result, report);
+
+            portfolio.update_prices(execution_date, &self.data, PriceField::Close)?;
+
+            let benchmark = self
+                .data
+                .benchmark(execution_date)
+                .ok_or(BacktestError::MissingBenchmark {
+                    date: execution_date,
+                })?;
+            let notes = decision.notes.join(" | ");
+
+            result.equity_curve.push(DailyEquityPoint {
+                date: execution_date,
+                cash: portfolio.cash(),
+                market_value: portfolio.market_value(),
+                total_equity: portfolio.total_equity(),
+                benchmark_close: benchmark.close,
+                notes,
+            });
+        }
+
+        if let Some(last_date) = self.data.calendar().days().last().copied() {
+            result.holdings_summary = portfolio.holdings_summary(last_date);
+        }
+
+        Ok(result)
+    }
+
+    fn extend_result(&self, result: &mut BacktestResult, report: BrokerExecutionReport) {
+        result.order_events.extend(report.order_events);
+        result.fills.extend(report.fill_events);
+        result.position_events.extend(report.position_events);
+        result.account_events.extend(report.account_events);
+    }
+}
+
+mod date_format {
+    use chrono::NaiveDate;
+    use serde::Serializer;
+
+    const FORMAT: &str = "%Y-%m-%d";
+
+    pub fn serialize<S>(date: &NaiveDate, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&date.format(FORMAT).to_string())
+    }
+}
diff --git a/crates/fidc-core/src/events.rs b/crates/fidc-core/src/events.rs
new file mode 100644
index 0000000..9bd284f
--- /dev/null
+++ b/crates/fidc-core/src/events.rs
@@ -0,0 +1,86 @@
+use chrono::NaiveDate;
+use serde::{Deserialize, Serialize};
+
+mod date_format {
+    use chrono::NaiveDate;
+    use serde::{self, Deserialize, Deserializer, Serializer};
+
+    const FORMAT: &str = "%Y-%m-%d";
+
+    pub fn serialize<S>(date: &NaiveDate, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&date.format(FORMAT).to_string())
+    }
+
+    pub fn deserialize<'de, D>(deserializer: D) -> Result<NaiveDate, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let text = String::deserialize(deserializer)?;
+        NaiveDate::parse_from_str(&text, FORMAT).map_err(serde::de::Error::custom)
+    }
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+pub enum OrderSide {
+    Buy,
+    Sell,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+pub enum OrderStatus {
+    Filled,
+    PartiallyFilled,
+    Rejected,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct OrderEvent {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub symbol: String,
+    pub side: OrderSide,
+    pub requested_quantity: u32,
+    pub filled_quantity: u32,
+    pub status: OrderStatus,
+    pub reason: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct FillEvent {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub symbol: String,
+    pub side: OrderSide,
+    pub quantity: u32,
+    pub price: f64,
+    pub gross_amount: f64,
+    pub commission: f64,
+    pub stamp_tax: f64,
+    pub net_cash_flow: f64,
+    pub reason: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PositionEvent {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub symbol: String,
+    pub delta_quantity: i32,
+    pub quantity_after: u32,
+    pub average_cost: f64,
+    pub realized_pnl_delta: f64,
+    pub reason: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AccountEvent {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub cash_before: f64,
+    pub cash_after: f64,
+    pub total_equity: f64,
+    pub note: String,
+}
diff --git a/crates/fidc-core/src/instrument.rs b/crates/fidc-core/src/instrument.rs
new file mode 100644
index 0000000..d921ccc
--- /dev/null
+++ b/crates/fidc-core/src/instrument.rs
@@ -0,0 +1,8 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Instrument {
+    pub symbol: String,
+    pub name: String,
+    pub board: String,
+}
diff --git a/crates/fidc-core/src/lib.rs b/crates/fidc-core/src/lib.rs
new file mode 100644
index 0000000..558ba78
--- /dev/null
+++ b/crates/fidc-core/src/lib.rs
@@ -0,0 +1,50 @@
+pub mod broker;
+pub mod calendar;
+pub mod cost;
+pub mod data;
+pub mod engine;
+pub mod events;
+pub mod instrument;
+pub mod portfolio;
+pub mod rules;
+pub mod strategy;
+pub mod universe;
+
+pub use broker::{BrokerExecutionReport, BrokerSimulator};
+pub use calendar::TradingCalendar;
+pub use cost::{ChinaAShareCostModel, CostModel, TradingCost};
+pub use data::{
+    BenchmarkSnapshot,
+    CandidateEligibility,
+    DailyFactorSnapshot,
+    DailyMarketSnapshot,
+    DataSet,
+    DataSetError,
+    PriceField,
+};
+pub use engine::{BacktestConfig, BacktestEngine, BacktestError, BacktestResult, DailyEquityPoint};
+pub use events::{
+    AccountEvent,
+    FillEvent,
+    OrderEvent,
+    OrderSide,
+    OrderStatus,
+    PositionEvent,
+};
+pub use instrument::Instrument;
+pub use portfolio::{HoldingSummary, PortfolioState, Position};
+pub use rules::{ChinaEquityRuleHooks, EquityRuleHooks, RuleCheck};
+pub use strategy::{
+    CnSmallCapRotationConfig,
+    CnSmallCapRotationStrategy,
+    Strategy,
+    StrategyContext,
+    StrategyDecision,
+};
+pub use universe::{
+    BandRegime,
+    DynamicMarketCapBandSelector,
+    SelectionContext,
+    UniverseCandidate,
+    UniverseSelector,
+};
diff --git a/crates/fidc-core/src/portfolio.rs b/crates/fidc-core/src/portfolio.rs
new file mode 100644
index 0000000..89d5b76
--- /dev/null
+++ b/crates/fidc-core/src/portfolio.rs
@@ -0,0 +1,242 @@
+use std::collections::BTreeMap;
+
+use chrono::NaiveDate;
+use serde::Serialize;
+
+use crate::data::{DataSet, DataSetError, PriceField};
+
+#[derive(Debug, Clone)]
+pub struct PositionLot {
+    pub acquired_date: NaiveDate,
+    pub quantity: u32,
+    pub price: f64,
+}
+
+#[derive(Debug, Clone)]
+pub struct Position {
+    pub symbol: String,
+    pub quantity: u32,
+    pub average_cost: f64,
+    pub last_price: f64,
+    pub realized_pnl: f64,
+    lots: Vec<PositionLot>,
+}
+
+impl Position {
+    pub fn new(symbol: impl Into<String>) -> Self {
+        Self {
+            symbol: symbol.into(),
+            quantity: 0,
+            average_cost: 0.0,
+            last_price: 0.0,
+            realized_pnl: 0.0,
+            lots: Vec::new(),
+        }
+    }
+
+    pub fn is_flat(&self) -> bool {
+        self.quantity == 0
+    }
+
+    pub fn buy(&mut self, date: NaiveDate, quantity: u32, price: f64) {
+        if quantity == 0 {
+            return;
+        }
+
+        self.lots.push(PositionLot {
+            acquired_date: date,
+            quantity,
+            price,
+        });
+        self.quantity += quantity;
+        self.last_price = price;
+        self.recalculate_average_cost();
+    }
+
+    pub fn sell(&mut self, quantity: u32, price: f64) -> Result<f64, String> {
+        if quantity > self.quantity {
+            return Err(format!(
+                "sell quantity {} exceeds current quantity {} for {}",
+                quantity, self.quantity, self.symbol
+            ));
+        }
+
+        let mut remaining = quantity;
+        let mut realized = 0.0;
+
+        while remaining > 0 {
+            let Some(first_lot) = self.lots.first_mut() else {
+                return Err(format!("position {} has no lots to sell", self.symbol));
+            };
+
+            let lot_sell = remaining.min(first_lot.quantity);
+            realized += (price - first_lot.price) * lot_sell as f64;
+            first_lot.quantity -= lot_sell;
+            remaining -= lot_sell;
+
+            if first_lot.quantity == 0 {
+                self.lots.remove(0);
+            }
+        }
+
+        self.quantity -= quantity;
+        self.last_price = price;
+        self.realized_pnl += realized;
+        self.recalculate_average_cost();
+        Ok(realized)
+    }
+
+    pub fn sellable_qty(&self, date: NaiveDate) -> u32 {
+        self.lots
+            .iter()
+            .filter(|lot| lot.acquired_date < date)
+            .map(|lot| lot.quantity)
+            .sum()
+    }
+
+    pub fn market_value(&self) -> f64 {
+        self.quantity as f64 * self.last_price
+    }
+
+    pub fn unrealized_pnl(&self) -> f64 {
+        (self.last_price - self.average_cost) * self.quantity as f64
+    }
+
+    pub fn holding_return(&self, price: f64) -> Option<f64> {
+        if self.quantity == 0 || self.average_cost <= 0.0 {
+            None
+        } else {
+            Some((price / self.average_cost) - 1.0)
+        }
+    }
+
+    fn recalculate_average_cost(&mut self) {
+        if self.quantity == 0 {
+            self.average_cost = 0.0;
+            return;
+        }
+
+        let total_cost = self
+            .lots
+            .iter()
+            .map(|lot| lot.price * lot.quantity as f64)
+            .sum::<f64>();
+
+        self.average_cost = total_cost / self.quantity as f64;
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct PortfolioState {
+    cash: f64,
+    positions: BTreeMap<String, Position>,
+}
+
+impl PortfolioState {
+    pub fn new(initial_cash: f64) -> Self {
+        Self {
+            cash: initial_cash,
+            positions: BTreeMap::new(),
+        }
+    }
+
+    pub fn cash(&self) -> f64 {
+        self.cash
+    }
+
+    pub fn positions(&self) -> &BTreeMap<String, Position> {
+        &self.positions
+    }
+
+    pub fn position(&self, symbol: &str) -> Option<&Position> {
+        self.positions.get(symbol)
+    }
+
+    pub fn position_mut(&mut self, symbol: &str) -> &mut Position {
+        self.positions
+            .entry(symbol.to_string())
+            .or_insert_with(|| Position::new(symbol))
+    }
+
+    pub fn apply_cash_delta(&mut self, delta: f64) {
+        self.cash += delta;
+    }
+
+    pub fn prune_flat_positions(&mut self) {
+        self.positions.retain(|_, position| !position.is_flat());
+    }
+
+    pub fn update_prices(
+        &mut self,
+        date: NaiveDate,
+        data: &DataSet,
+        field: PriceField,
+    ) -> Result<(), DataSetError> {
+        for position in self.positions.values_mut() {
+            let price = data
+                .price(date, &position.symbol, field)
+                .ok_or_else(|| DataSetError::MissingSnapshot {
+                    kind: match field {
+                        PriceField::Open => "open price",
+                        PriceField::Close => "close price",
+                    },
+                    date,
+                    symbol: position.symbol.clone(),
+                })?;
+            position.last_price = price;
+        }
+        Ok(())
+    }
+
+    pub fn market_value(&self) -> f64 {
+        self.positions.values().map(Position::market_value).sum()
+    }
+
+    pub fn total_equity(&self) -> f64 {
+        self.cash + self.market_value()
+    }
+
+    pub fn holdings_summary(&self, date: NaiveDate) -> Vec<HoldingSummary> {
+        self.positions
+            .values()
+            .filter(|position| position.quantity > 0)
+            .map(|position| HoldingSummary {
+                date,
+                symbol: position.symbol.clone(),
+                quantity: position.quantity,
+                average_cost: position.average_cost,
+                last_price: position.last_price,
+                market_value: position.market_value(),
+                unrealized_pnl: position.unrealized_pnl(),
+                realized_pnl: position.realized_pnl,
+            })
+            .collect()
+    }
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct HoldingSummary {
+    #[serde(with = "date_format")]
+    pub date: NaiveDate,
+    pub symbol: String,
+    pub quantity: u32,
+    pub average_cost: f64,
+    pub last_price: f64,
+    pub market_value: f64,
+    pub unrealized_pnl: f64,
+    pub realized_pnl: f64,
+}
+
+mod date_format {
+    use chrono::NaiveDate;
+    use serde::Serializer;
+
+    const FORMAT: &str = "%Y-%m-%d";
+
+    pub fn serialize<S>(date: &NaiveDate, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&date.format(FORMAT).to_string())
+    }
+}
diff --git a/crates/fidc-core/src/rules.rs b/crates/fidc-core/src/rules.rs
new file mode 100644
index 0000000..a9a45c2
--- /dev/null
+++ b/crates/fidc-core/src/rules.rs
@@ -0,0 +1,100 @@
+use chrono::NaiveDate;
+
+use crate::data::{CandidateEligibility, DailyMarketSnapshot};
+use crate::portfolio::Position;
+
+#[derive(Debug, Clone)]
+pub struct RuleCheck {
+    pub allowed: bool,
+    pub reason: Option<String>,
+}
+
+impl RuleCheck {
+    pub fn allow() -> Self {
+        Self {
+            allowed: true,
+            reason: None,
+        }
+    }
+
+    pub fn reject(reason: impl Into<String>) -> Self {
+        Self {
+            allowed: false,
+            reason: Some(reason.into()),
+        }
+    }
+}
+
+pub trait EquityRuleHooks {
+    fn can_buy(
+        &self,
+        execution_date: NaiveDate,
+        snapshot: &DailyMarketSnapshot,
+        candidate: &CandidateEligibility,
+    ) -> RuleCheck;
+
+    fn can_sell(
+        &self,
+        execution_date: NaiveDate,
+        snapshot: &DailyMarketSnapshot,
+        candidate: &CandidateEligibility,
+        position: &Position,
+    ) -> RuleCheck;
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct ChinaEquityRuleHooks;
+
+impl ChinaEquityRuleHooks {
+    fn at_upper_limit(snapshot: &DailyMarketSnapshot) -> bool {
+        snapshot.open >= snapshot.upper_limit - 1e-6
+    }
+
+    fn at_lower_limit(snapshot: &DailyMarketSnapshot) -> bool {
+        snapshot.open <= snapshot.lower_limit + 1e-6
+    }
+}
+
+impl EquityRuleHooks for ChinaEquityRuleHooks {
+    fn can_buy(
+        &self,
+        _execution_date: NaiveDate,
+        snapshot: &DailyMarketSnapshot,
+        candidate: &CandidateEligibility,
+    ) -> RuleCheck {
+        if snapshot.paused || candidate.is_paused {
+            return RuleCheck::reject("paused");
+        }
+        if !candidate.allow_buy {
+            return RuleCheck::reject("buy disabled by eligibility flags");
+        }
+        if Self::at_upper_limit(snapshot) {
+            return RuleCheck::reject("open at or above upper limit");
+        }
+
+        RuleCheck::allow()
+    }
+
+    fn can_sell(
+        &self,
+        execution_date: NaiveDate,
+        snapshot: &DailyMarketSnapshot,
+        candidate: &CandidateEligibility,
+        position: &Position,
+    ) -> RuleCheck {
+        if snapshot.paused || candidate.is_paused {
+            return RuleCheck::reject("paused");
+        }
+        if !candidate.allow_sell {
+            return RuleCheck::reject("sell disabled by eligibility flags");
+        }
+        if Self::at_lower_limit(snapshot) {
+            return RuleCheck::reject("open at or below lower limit");
+        }
+        if position.sellable_qty(execution_date) == 0 {
+            return RuleCheck::reject("t+1 sellable quantity is zero");
+        }
+
+        RuleCheck::allow()
+    }
+}
diff --git a/crates/fidc-core/src/strategy.rs b/crates/fidc-core/src/strategy.rs
new file mode 100644
index 0000000..4479e0e
--- /dev/null
+++ b/crates/fidc-core/src/strategy.rs
@@ -0,0 +1,192 @@
+use std::collections::{BTreeMap, BTreeSet};
+
+use chrono::NaiveDate;
+
+use crate::data::{DataSet, PriceField};
+use crate::engine::BacktestError;
+use crate::portfolio::PortfolioState;
+use crate::universe::{DynamicMarketCapBandSelector, SelectionContext, UniverseSelector};
+
+pub trait Strategy {
+    fn name(&self) -> &'static str;
+    fn on_day(&mut self, ctx: &StrategyContext<'_>) -> Result<StrategyDecision, BacktestError>;
+}
+
+pub struct StrategyContext<'a> {
+    pub execution_date: NaiveDate,
+    pub decision_date: NaiveDate,
+    pub decision_index: usize,
+    pub data: &'a DataSet,
+    pub portfolio: &'a PortfolioState,
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct StrategyDecision {
+    pub rebalance: bool,
+    pub target_weights: BTreeMap<String, f64>,
+    pub exit_symbols: BTreeSet<String>,
+    pub notes: Vec<String>,
+}
+
+#[derive(Debug, Clone)]
+pub struct CnSmallCapRotationConfig {
+    pub rebalance_every_n_days: usize,
+    pub max_positions: usize,
+    pub short_ma_days: usize,
+    pub long_ma_days: usize,
+    pub stop_loss_pct: f64,
+    pub take_profit_pct: f64,
+}
+
+impl CnSmallCapRotationConfig {
+    pub fn demo() -> Self {
+        Self {
+            rebalance_every_n_days: 3,
+            max_positions: 2,
+            short_ma_days: 3,
+            long_ma_days: 5,
+            stop_loss_pct: 0.08,
+            take_profit_pct: 0.10,
+        }
+    }
+}
+
+pub struct CnSmallCapRotationStrategy {
+    config: CnSmallCapRotationConfig,
+    selector: DynamicMarketCapBandSelector,
+    last_gross_exposure: Option<f64>,
+}
+
+impl CnSmallCapRotationStrategy {
+    pub fn new(config: CnSmallCapRotationConfig) -> Self {
+        Self {
+            selector: DynamicMarketCapBandSelector::demo(config.max_positions),
+            config,
+            last_gross_exposure: None,
+        }
+    }
+
+    fn moving_average(values: &[f64], lookback: usize) -> f64 {
+        let len = values.len();
+        let window = values.iter().skip(len.saturating_sub(lookback));
+        let (sum, count) = window.fold((0.0, 0usize), |(sum, count), value| (sum + value, count + 1));
+        if count == 0 {
+            0.0
+        } else {
+            sum / count as f64
+        }
+    }
+
+    fn gross_exposure(&self, closes: &[f64]) -> f64 {
+        if closes.is_empty() {
+            return 0.0;
+        }
+
+        let current = *closes.last().unwrap_or(&0.0);
+        let short_ma = Self::moving_average(closes, self.config.short_ma_days);
+        let long_ma = Self::moving_average(closes, self.config.long_ma_days);
+
+        if current >= long_ma && short_ma >= long_ma {
+            1.0
+        } else if current >= long_ma || short_ma >= long_ma {
+            0.5
+        } else {
+            0.0
+        }
+    }
+
+    fn stop_exit_symbols(&self, ctx: &StrategyContext<'_>) -> Result<BTreeSet<String>, BacktestError> {
+        let mut exits = BTreeSet::new();
+        for position in ctx.portfolio.positions().values() {
+            if position.quantity == 0 {
+                continue;
+            }
+
+            let close_price = ctx
+                .data
+                .price(ctx.decision_date, &position.symbol, PriceField::Close)
+                .ok_or_else(|| BacktestError::MissingPrice {
+                    date: ctx.decision_date,
+                    symbol: position.symbol.clone(),
+                    field: "close",
+                })?;
+
+            let Some(holding_return) = position.holding_return(close_price) else {
+                continue;
+            };
+
+            if holding_return <= -self.config.stop_loss_pct
+                || holding_return >= self.config.take_profit_pct
+            {
+                exits.insert(position.symbol.clone());
+            }
+        }
+
+        Ok(exits)
+    }
+}
+
+impl Strategy for CnSmallCapRotationStrategy {
+    fn name(&self) -> &'static str {
+        "cn-smallcap-rotation"
+    }
+
+    fn on_day(&mut self, ctx: &StrategyContext<'_>) -> Result<StrategyDecision, BacktestError> {
+        let benchmark = ctx
+            .data
+            .benchmark(ctx.decision_date)
+            .ok_or(BacktestError::MissingBenchmark {
+                date: ctx.decision_date,
+            })?;
+        let benchmark_closes = ctx
+            .data
+            .benchmark_closes_up_to(ctx.decision_date, self.config.long_ma_days);
+        let gross_exposure = self.gross_exposure(&benchmark_closes);
+        let periodic_rebalance = ctx.decision_index % self.config.rebalance_every_n_days == 0;
+        let exposure_changed = self
+            .last_gross_exposure
+            .map(|previous| (previous - gross_exposure).abs() > f64::EPSILON)
+            .unwrap_or(true);
+        let exit_symbols = self.stop_exit_symbols(ctx)?;
+
+        let rebalance = periodic_rebalance || exposure_changed;
+        let mut target_weights = BTreeMap::new();
+        let mut notes = vec![format!(
+            "decision={} exec={} exposure={:.2}",
+            ctx.decision_date, ctx.execution_date, gross_exposure
+        )];
+
+        if rebalance && gross_exposure > 0.0 {
+            let selected = self.selector.select(&SelectionContext {
+                decision_date: ctx.decision_date,
+                benchmark,
+                data: ctx.data,
+            });
+
+            if !selected.is_empty() {
+                let per_name_weight = gross_exposure / selected.len() as f64;
+                for candidate in selected {
+                    target_weights.insert(candidate.symbol.clone(), per_name_weight);
+                }
+            }
+
+            notes.push(format!("rebalance names={}", target_weights.len()));
+        }
+
+        if !exit_symbols.is_empty() {
+            notes.push(format!("exit hooks={}", exit_symbols.len()));
+        }
+        if rebalance && gross_exposure == 0.0 {
+            notes.push("risk throttle forced all-cash".to_string());
+        }
+
+        self.last_gross_exposure = Some(gross_exposure);
+
+        Ok(StrategyDecision {
+            rebalance,
+            target_weights,
+            exit_symbols,
+            notes,
+        })
+    }
+}
diff --git a/crates/fidc-core/src/universe.rs b/crates/fidc-core/src/universe.rs
new file mode 100644
index 0000000..ccac5e6
--- /dev/null
+++ b/crates/fidc-core/src/universe.rs
@@ -0,0 +1,110 @@
+use chrono::NaiveDate;
+
+use crate::data::{BenchmarkSnapshot, DataSet};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BandRegime {
+    Bullish,
+    Neutral,
+    Defensive,
+}
+
+#[derive(Debug, Clone)]
+pub struct UniverseCandidate {
+    pub symbol: String,
+    pub market_cap_bn: f64,
+    pub free_float_cap_bn: f64,
+}
+
+pub struct SelectionContext<'a> {
+    pub decision_date: NaiveDate,
+    pub benchmark: &'a BenchmarkSnapshot,
+    pub data: &'a DataSet,
+}
+
+pub trait UniverseSelector {
+    fn select(&self, ctx: &SelectionContext<'_>) -> Vec<UniverseCandidate>;
+}
+
+#[derive(Debug, Clone)]
+pub struct DynamicMarketCapBandSelector {
+    pub base_index_level: f64,
+    pub bullish_threshold: f64,
+    pub neutral_threshold: f64,
+    pub bullish_band: (f64, f64),
+    pub neutral_band: (f64, f64),
+    pub defensive_band: (f64, f64),
+    pub top_n: usize,
+}
+
+impl DynamicMarketCapBandSelector {
+    pub fn demo(top_n: usize) -> Self {
+        Self {
+            base_index_level: 3000.0,
+            bullish_threshold: 1.02,
+            neutral_threshold: 1.0,
+            bullish_band: (30.0, 60.0),
+            neutral_band: (40.0, 90.0),
+            defensive_band: (60.0, 120.0),
+            top_n,
+        }
+    }
+
+    pub fn regime(&self, benchmark_level: f64) -> BandRegime {
+        let ratio = benchmark_level / self.base_index_level;
+        if ratio >= self.bullish_threshold {
+            BandRegime::Bullish
+        } else if ratio >= self.neutral_threshold {
+            BandRegime::Neutral
+        } else {
+            BandRegime::Defensive
+        }
+    }
+
+    fn band(&self, regime: BandRegime) -> (f64, f64) {
+        match regime {
+            BandRegime::Bullish => self.bullish_band,
+            BandRegime::Neutral => self.neutral_band,
+            BandRegime::Defensive => self.defensive_band,
+        }
+    }
+}
+
+impl UniverseSelector for DynamicMarketCapBandSelector {
+    fn select(&self, ctx: &SelectionContext<'_>) -> Vec<UniverseCandidate> {
+        let regime = self.regime(ctx.benchmark.close);
+        let (min_cap, max_cap) = self.band(regime);
+
+        let mut selected = ctx
+            .data
+            .factor_snapshots_on(ctx.decision_date)
+            .into_iter()
+            .filter_map(|factor| {
+                let candidate = ctx.data.candidate(ctx.decision_date, &factor.symbol)?;
+                let market = ctx.data.market(ctx.decision_date, &factor.symbol)?;
+
+                if !candidate.eligible_for_selection() || market.paused {
+                    return None;
+                }
+                if factor.market_cap_bn < min_cap || factor.market_cap_bn > max_cap {
+                    return None;
+                }
+
+                Some(UniverseCandidate {
+                    symbol: factor.symbol.clone(),
+                    market_cap_bn: factor.market_cap_bn,
+                    free_float_cap_bn: factor.free_float_cap_bn,
+                })
+            })
+            .collect::<Vec<_>>();
+
+        selected.sort_by(|left, right| {
+            left.market_cap_bn
+                .partial_cmp(&right.market_cap_bn)
+                .unwrap_or(std::cmp::Ordering::Equal)
+                .then_with(|| left.symbol.cmp(&right.symbol))
+        });
+        selected.truncate(self.top_n);
+        selected
+    }
+}
diff --git a/crates/fidc-core/tests/core_rules.rs b/crates/fidc-core/tests/core_rules.rs
new file mode 100644
index 0000000..a5d9b16
--- /dev/null
+++ b/crates/fidc-core/tests/core_rules.rs
@@ -0,0 +1,103 @@
+use chrono::NaiveDate;
+use fidc_core::cost::CostModel;
+use fidc_core::rules::EquityRuleHooks;
+use fidc_core::{
+    CandidateEligibility,
+    ChinaAShareCostModel,
+    ChinaEquityRuleHooks,
+    DailyMarketSnapshot,
+    OrderSide,
+    Position,
+};
+
+fn d(year: i32, month: u32, day: u32) -> NaiveDate {
+    NaiveDate::from_ymd_opt(year, month, day).expect("valid date")
+}
+
+fn candidate() -> CandidateEligibility {
+    CandidateEligibility {
+        date: d(2024, 1, 3),
+        symbol: "000001.SZ".to_string(),
+        is_st: false,
+        is_new_listing: false,
+        is_paused: false,
+        allow_buy: true,
+        allow_sell: true,
+    }
+}
+
+fn snapshot(open: f64, upper_limit: f64, lower_limit: f64) -> DailyMarketSnapshot {
+    DailyMarketSnapshot {
+        date: d(2024, 1, 3),
+        symbol: "000001.SZ".to_string(),
+        open,
+        high: open,
+        low: open,
+        close: open,
+        prev_close: 10.0,
+        volume: 1_000_000,
+        paused: false,
+        upper_limit,
+        lower_limit,
+    }
+}
+
+#[test]
+fn china_cost_model_applies_minimum_commission_and_stamp_tax() {
+    let model = ChinaAShareCostModel::default();
+
+    let buy = model.calculate(OrderSide::Buy, 1_000.0);
+    assert!((buy.commission - 5.0).abs() < 1e-9);
+    assert_eq!(buy.stamp_tax, 0.0);
+
+    let sell = model.calculate(OrderSide::Sell, 100_000.0);
+    assert!((sell.commission - 30.0).abs() < 1e-9);
+    assert!((sell.stamp_tax - 100.0).abs() < 1e-9);
+}
+
+#[test]
+fn china_rule_hooks_block_same_day_sell_under_t_plus_one() {
+    let hooks = ChinaEquityRuleHooks;
+    let mut position = Position::new("000001.SZ");
+    let trade_date = d(2024, 1, 3);
+    position.buy(trade_date, 1_000, 10.0);
+
+    let check = hooks.can_sell(
+        trade_date,
+        &snapshot(10.1, 11.0, 9.0),
+        &candidate(),
+        &position,
+    );
+
+    assert!(!check.allowed);
+    assert!(check
+        .reason
+        .as_deref()
+        .unwrap_or_default()
+        .contains("t+1"));
+}
+
+#[test]
+fn china_rule_hooks_block_buy_at_limit_up_and_sell_at_limit_down() {
+    let hooks = ChinaEquityRuleHooks;
+    let candidate = candidate();
+    let mut position = Position::new("000001.SZ");
+    position.buy(d(2024, 1, 2), 1_000, 10.0);
+
+    let buy_check = hooks.can_buy(d(2024, 1, 3), &snapshot(11.0, 11.0, 9.0), &candidate);
+    assert!(!buy_check.allowed);
+    assert!(buy_check
+        .reason
+        .as_deref()
+        .unwrap_or_default()
+        .contains("upper limit"));
+
+    let sell_check =
+        hooks.can_sell(d(2024, 1, 3), &snapshot(9.0, 11.0, 9.0), &candidate, &position);
+    assert!(!sell_check.allowed);
+    assert!(sell_check
+        .reason
+        .as_deref()
+        .unwrap_or_default()
+        .contains("lower limit"));
+}
diff --git a/data/demo/benchmark.csv b/data/demo/benchmark.csv
new file mode 100644
index 0000000..df11a3c
--- /dev/null
+++ b/data/demo/benchmark.csv
@@ -0,0 +1,10 @@
+date,benchmark,open,close,prev_close,volume
+2024-01-02,CSI300.DEMO,2990,3000,2980,100000000
+2024-01-03,CSI300.DEMO,3005,3020,3000,102000000
+2024-01-04,CSI300.DEMO,3025,3050,3020,105000000
+2024-01-05,CSI300.DEMO,3055,3080,3050,108000000
+2024-01-08,CSI300.DEMO,3085,3110,3080,109000000
+2024-01-09,CSI300.DEMO,3100,3090,3110,107000000
+2024-01-10,CSI300.DEMO,3080,3040,3090,111000000
+2024-01-11,CSI300.DEMO,3030,2990,3040,115000000
+2024-01-12,CSI300.DEMO,2980,2950,2990,118000000
diff --git a/data/demo/candidate_flags.csv b/data/demo/candidate_flags.csv
new file mode 100644
index 0000000..96e6098
--- /dev/null
+++ b/data/demo/candidate_flags.csv
@@ -0,0 +1,37 @@
+date,symbol,is_st,is_new_listing,is_paused,allow_buy,allow_sell
+2024-01-02,000001.SZ,false,true,false,false,true
+2024-01-02,000002.SZ,false,false,false,true,true
+2024-01-02,000003.SZ,false,false,false,true,true
+2024-01-02,600001.SH,false,false,false,true,true
+2024-01-03,000001.SZ,false,true,false,false,true
+2024-01-03,000002.SZ,false,false,false,true,true
+2024-01-03,000003.SZ,false,false,false,true,true
+2024-01-03,600001.SH,false,false,false,true,true
+2024-01-04,000001.SZ,false,false,false,true,true
+2024-01-04,000002.SZ,false,false,false,true,true
+2024-01-04,000003.SZ,false,false,false,true,true
+2024-01-04,600001.SH,false,false,false,true,true
+2024-01-05,000001.SZ,false,false,false,true,true
+2024-01-05,000002.SZ,false,false,false,true,true
+2024-01-05,000003.SZ,false,false,false,true,true
+2024-01-05,600001.SH,false,false,false,true,true
+2024-01-08,000001.SZ,false,false,false,true,true
+2024-01-08,000002.SZ,false,false,false,true,true
+2024-01-08,000003.SZ,false,false,false,true,true
+2024-01-08,600001.SH,false,false,false,true,true
+2024-01-09,000001.SZ,false,false,false,true,true
+2024-01-09,000002.SZ,false,false,false,true,true
+2024-01-09,000003.SZ,false,false,false,true,true
+2024-01-09,600001.SH,false,false,false,true,true
+2024-01-10,000001.SZ,false,false,false,true,true
+2024-01-10,000002.SZ,false,false,false,true,true
+2024-01-10,000003.SZ,false,false,false,true,true
+2024-01-10,600001.SH,false,false,false,true,true
+2024-01-11,000001.SZ,false,false,false,true,true
+2024-01-11,000002.SZ,false,false,false,true,true
+2024-01-11,000003.SZ,false,false,false,true,true
+2024-01-11,600001.SH,false,false,true,false,false
+2024-01-12,000001.SZ,false,false,false,true,true
+2024-01-12,000002.SZ,false,false,false,true,true
+2024-01-12,000003.SZ,false,false,false,true,true
+2024-01-12,600001.SH,false,false,false,true,true
diff --git a/data/demo/factors.csv b/data/demo/factors.csv
new file mode 100644
index 0000000..537868d
--- /dev/null
+++ b/data/demo/factors.csv
@@ -0,0 +1,37 @@
+date,symbol,market_cap_bn,free_float_cap_bn,pe_ttm
+2024-01-02,000001.SZ,38,24,18
+2024-01-02,000002.SZ,45,30,20
+2024-01-02,000003.SZ,65,40,15
+2024-01-02,600001.SH,85,55,13
+2024-01-03,000001.SZ,39,24.5,18
+2024-01-03,000002.SZ,46,30.5,20
+2024-01-03,000003.SZ,64,39.5,15
+2024-01-03,600001.SH,85,55,13
+2024-01-04,000001.SZ,40,25,18
+2024-01-04,000002.SZ,47,31,20
+2024-01-04,000003.SZ,63,39,15
+2024-01-04,600001.SH,86,55.5,13
+2024-01-05,000001.SZ,41,25.5,18
+2024-01-05,000002.SZ,48,32,20
+2024-01-05,000003.SZ,62,38.5,15
+2024-01-05,600001.SH,86,56,13
+2024-01-08,000001.SZ,42,26,18
+2024-01-08,000002.SZ,50,33,21
+2024-01-08,000003.SZ,61,38,15
+2024-01-08,600001.SH,87,56.5,13
+2024-01-09,000001.SZ,44,27,19
+2024-01-09,000002.SZ,52,34,21
+2024-01-09,000003.SZ,60,37.5,15
+2024-01-09,600001.SH,88,57,13
+2024-01-10,000001.SZ,43,26.5,19
+2024-01-10,000002.SZ,53,34.5,21
+2024-01-10,000003.SZ,59,37,15
+2024-01-10,600001.SH,89,57.5,13
+2024-01-11,000001.SZ,42,26,18
+2024-01-11,000002.SZ,52,34,21
+2024-01-11,000003.SZ,58,36.5,15
+2024-01-11,600001.SH,90,58,13
+2024-01-12,000001.SZ,40,25,18
+2024-01-12,000002.SZ,50,33,20
+2024-01-12,000003.SZ,57,36,15
+2024-01-12,600001.SH,92,59,13
diff --git a/data/demo/instruments.csv b/data/demo/instruments.csv
new file mode 100644
index 0000000..f73bb3b
--- /dev/null
+++ b/data/demo/instruments.csv
@@ -0,0 +1,5 @@
+symbol,name,board
+000001.SZ,Alpha Components,Main
+000002.SZ,Beta Precision,Main
+000003.SZ,Charlie Materials,Main
+600001.SH,Delta Industrials,Main
diff --git a/data/demo/market.csv b/data/demo/market.csv
new file mode 100644
index 0000000..f10bfd5
--- /dev/null
+++ b/data/demo/market.csv
@@ -0,0 +1,37 @@
+date,symbol,open,high,low,close,prev_close,volume,paused
+2024-01-02,000001.SZ,10.0,10.2,9.9,10.1,9.8,1200000,false
+2024-01-02,000002.SZ,11.0,11.3,10.9,11.2,10.8,1100000,false
+2024-01-02,000003.SZ,8.0,8.1,7.8,7.9,8.0,900000,false
+2024-01-02,600001.SH,15.0,15.2,14.9,15.1,15.0,800000,false
+2024-01-03,000001.SZ,10.2,10.5,10.1,10.4,10.1,1250000,false
+2024-01-03,000002.SZ,11.2,11.6,11.1,11.5,11.2,1120000,false
+2024-01-03,000003.SZ,7.8,7.9,7.3,7.4,7.9,930000,false
+2024-01-03,600001.SH,15.1,15.3,15.0,15.2,15.1,820000,false
+2024-01-04,000001.SZ,10.5,10.8,10.4,10.7,10.4,1280000,false
+2024-01-04,000002.SZ,11.4,11.9,11.3,11.8,11.5,1150000,false
+2024-01-04,000003.SZ,7.3,7.4,7.0,7.1,7.4,940000,false
+2024-01-04,600001.SH,15.2,15.5,15.1,15.4,15.2,830000,false
+2024-01-05,000001.SZ,10.8,11.1,10.7,11.0,10.7,1300000,false
+2024-01-05,000002.SZ,11.9,12.1,11.8,12.0,11.8,1180000,false
+2024-01-05,000003.SZ,7.0,7.1,6.8,6.9,7.1,950000,false
+2024-01-05,600001.SH,15.4,15.6,15.3,15.5,15.4,840000,false
+2024-01-08,000001.SZ,11.1,11.6,11.0,11.5,11.0,1400000,false
+2024-01-08,000002.SZ,12.1,12.5,12.0,12.4,12.0,1200000,false
+2024-01-08,000003.SZ,7.0,7.3,6.9,7.2,6.9,980000,false
+2024-01-08,600001.SH,15.5,15.7,15.4,15.6,15.5,850000,false
+2024-01-09,000001.SZ,11.6,12.4,11.5,12.3,11.5,1500000,false
+2024-01-09,000002.SZ,12.5,12.9,12.4,12.8,12.4,1250000,false
+2024-01-09,000003.SZ,7.2,7.5,7.1,7.4,7.2,990000,false
+2024-01-09,600001.SH,15.6,15.7,15.4,15.5,15.6,860000,false
+2024-01-10,000001.SZ,12.2,12.3,11.9,12.0,12.3,1450000,false
+2024-01-10,000002.SZ,12.7,12.8,12.5,12.6,12.8,1220000,false
+2024-01-10,000003.SZ,7.5,7.6,7.4,7.5,7.4,1000000,false
+2024-01-10,600001.SH,15.4,15.5,15.1,15.2,15.5,870000,false
+2024-01-11,000001.SZ,12.0,12.1,11.5,11.6,12.0,1420000,false
+2024-01-11,000002.SZ,12.5,12.6,12.1,12.2,12.6,1210000,false
+2024-01-11,000003.SZ,7.4,7.5,7.2,7.3,7.5,980000,false
+2024-01-11,600001.SH,15.2,15.2,15.2,15.2,15.2,0,true
+2024-01-12,000001.SZ,11.5,11.6,11.1,11.2,11.6,1380000,false
+2024-01-12,000002.SZ,12.1,12.2,11.8,11.9,12.2,1190000,false
+2024-01-12,000003.SZ,7.2,7.2,6.9,7.0,7.3,960000,false
+2024-01-12,600001.SH,14.8,15.0,14.7,14.9,15.2,850000,false