Add suspended and ST data helpers

crates/fidc-core/src/data.rs

@@ -947,6 +947,18 @@ impl DataSet {
         self.calendar.next_trading_date(date, n)
     }
 
+    pub fn is_suspended_flags(&self, date: NaiveDate, symbol: &str, count: usize) -> Vec<bool> {
+        self.historical_daily_flags(date, symbol, count, |candidate, market| {
+            candidate.is_some_and(|row| row.is_paused) || market.is_some_and(|row| row.paused)
+        })
+    }
+
+    pub fn is_st_stock_flags(&self, date: NaiveDate, symbol: &str, count: usize) -> Vec<bool> {
+        self.historical_daily_flags(date, symbol, count, |candidate, _| {
+            candidate.is_some_and(|row| row.is_st)
+        })
+    }
+
     pub fn price(&self, date: NaiveDate, symbol: &str, field: PriceField) -> Option<f64> {
         let snapshot = self.market(date, symbol)?;
         Some(snapshot.price(field))
@@ -1047,6 +1059,36 @@ impl DataSet {
             .collect()
     }
 
+    fn historical_daily_flags<F>(
+        &self,
+        date: NaiveDate,
+        symbol: &str,
+        count: usize,
+        evaluator: F,
+    ) -> Vec<bool>
+    where
+        F: Fn(Option<&CandidateEligibility>, Option<&DailyMarketSnapshot>) -> bool,
+    {
+        if count == 0 {
+            return Vec::new();
+        }
+        let days = self
+            .calendar
+            .iter()
+            .filter(|day| *day <= date)
+            .collect::<Vec<_>>();
+        let start = days.len().saturating_sub(count);
+        days[start..]
+            .iter()
+            .map(|day| {
+                evaluator(
+                    self.candidate_index.get(&(*day, symbol.to_string())),
+                    self.market_index.get(&(*day, symbol.to_string())),
+                )
+            })
+            .collect()
+    }
+
     pub fn market_decision_close(&self, date: NaiveDate, symbol: &str) -> Option<f64> {
         self.market_series_by_symbol
             .get(symbol)