分离股票池精确预算比例与展示基点并持久化状态

crates/fidc-core/src/stock_pool_frozen.rs

@@ -26,9 +26,58 @@ pub(super) fn validate(
     {
         return Err("stock_pool_prior_target_weights_invalid".into());
     }
+    if constraints.prior_target_weight_ratios.iter().any(|(symbol, ratio)| {
+        normalize_stock_symbol(symbol).as_ref() != Some(symbol) || *ratio < Decimal::ZERO || *ratio > Decimal::ONE
+    }) { return Err("stock_pool_prior_target_weight_ratios_invalid".into()); }
     Ok(())
 }
 
+/// Never size cash with the rounded display bps. Paused holdings keep the
+/// actually recorded prior ratio. Legacy bps are preserved, not guessed as 1/N.
+pub(super) fn sizing_ratios(
+    original: &[String], active: &[String], explicit: &BTreeMap<String, i32>,
+    constraints: &StockPoolDecisionConstraints, reserved_slots: usize,
+    display: &BTreeMap<String, i32>,
+) -> Result<BTreeMap<String, Decimal>, String> {
+    if !explicit.is_empty() {
+        return Ok(display.iter().map(|(symbol, weight)| (symbol.clone(), Decimal::from(*weight) / Decimal::from(10_000))).collect());
+    }
+    if constraints.frozen_positions.is_empty() {
+        let count = active.len() + reserved_slots;
+        let share = if count == 0 { Decimal::ZERO } else { Decimal::ONE / Decimal::from(count as u64) };
+        return Ok(active.iter().map(|symbol| (symbol.clone(), share)).collect());
+    }
+    let count = original.len() + reserved_slots;
+    let base = if count == 0 { Decimal::ZERO } else { Decimal::ONE / Decimal::from(count as u64) };
+    let mut result = BTreeMap::new();
+    for symbol in constraints.frozen_positions.keys() {
+        let ratio = constraints.prior_target_weight_ratios.get(symbol).copied()
+            .or_else(|| constraints.prior_target_weights.get(symbol).map(|bps| Decimal::from(*bps) / Decimal::from(10_000)))
+            .unwrap_or(base);
+        result.insert(symbol.clone(), ratio);
+    }
+    let frozen_total = result.values().copied().sum::<Decimal>();
+    // Only allow last-digit residue from Decimal division, never a meaningful
+    // over-allocation. All actual cash/fee checks remain downstream.
+    if frozen_total > Decimal::ONE + Decimal::new(1, 24) {
+        return Err("stock_pool_frozen_position_ratios_exceed_budget".into());
+    }
+    let free_original = original.iter().filter(|symbol| !result.contains_key(*symbol)).collect::<BTreeSet<_>>();
+    let free_total = (base * Decimal::from(free_original.len() as u64)).min((Decimal::ONE - frozen_total).max(Decimal::ZERO));
+    let share = if free_original.is_empty() { Decimal::ZERO } else { free_total / Decimal::from(free_original.len() as u64) };
+    let free = active.iter().filter(|symbol| !constraints.frozen_positions.contains_key(*symbol)).collect::<Vec<_>>();
+    let promoted = free.iter().filter(|symbol| !free_original.contains(**symbol)).copied().collect::<Vec<_>>();
+    for symbol in &free { result.insert((*symbol).clone(), if free_original.contains(*symbol) { share } else { Decimal::ZERO }); }
+    let assigned = free.iter().map(|symbol| result[*symbol]).sum::<Decimal>();
+    let missing = (free_total - assigned).max(Decimal::ZERO);
+    let recipients = if promoted.is_empty() { &free } else { &promoted };
+    if !recipients.is_empty() {
+        let addition = missing / Decimal::from(recipients.len() as u64);
+        for symbol in recipients { *result.entry((*symbol).clone()).or_default() += addition; }
+    }
+    Ok(result)
+}
+
 pub(super) fn valuation(
     symbol: &str,
     quotes: &HashMap<String, &MarketSnapshot>,
@@ -42,6 +91,48 @@ pub(super) fn valuation(
         .ok_or_else(|| format!("{symbol} confirmed holding valuation missing"))
 }
 
+#[cfg(test)]
+mod ratio_tests {
+    use super::*;
+    fn configuration() -> (Vec<String>, StockPoolDecisionConstraints, BTreeMap<String,i32>) {
+        let symbols = vec!["000001.SZ".into(),"000002.SZ".into(),"000003.SZ".into()];
+        let paused = FrozenStockPoolPosition { trade_date: NaiveDate::from_ymd_opt(2026,9,3).unwrap(), reason:"paused".into(), valuation_price:Decimal::from(10) };
+        let constraints = StockPoolDecisionConstraints { frozen_positions:BTreeMap::from([(symbols[0].clone(),paused)]),
+            prior_target_weights:BTreeMap::from([(symbols[0].clone(),3334)]), ..Default::default() };
+        let display = BTreeMap::from([(symbols[0].clone(),3334),(symbols[1].clone(),3333),(symbols[2].clone(),3333)]);
+        (symbols,constraints,display)
+    }
+    #[test]
+    fn precise_paused_budget_survives_replacement_and_zero_targets() {
+        let (symbols,mut constraints,display)=configuration();
+        let third=Decimal::ONE/Decimal::from(3);
+        constraints.prior_target_weight_ratios.insert(symbols[0].clone(),third);
+        let mut active=symbols.clone();active[2]="000004.SZ".into();
+        let ratios=sizing_ratios(&symbols,&active,&BTreeMap::new(),&constraints,0,&display).unwrap();
+        assert_eq!(ratios[&symbols[0]],third);
+        assert_eq!(ratios[&symbols[1]],third);
+        assert!((ratios["000004.SZ"]-third).abs()<Decimal::new(1,24));
+        assert!(!ratios.contains_key(&symbols[2]));
+        assert!((ratios.values().copied().sum::<Decimal>()-Decimal::ONE).abs()<Decimal::new(1,24));
+    }
+    #[test]
+    fn legacy_paused_and_explicit_partial_budgets_are_not_reinterpreted() {
+        let (symbols,constraints,display)=configuration();
+        let ratios=sizing_ratios(&symbols,&symbols,&BTreeMap::new(),&constraints,0,&display).unwrap();
+        assert_eq!(ratios[&symbols[0]],Decimal::new(3334,4));
+        assert!((ratios[&symbols[1]]-Decimal::new(3333,4)).abs()<Decimal::new(1,24));
+        let partial=BTreeMap::from([(symbols[0].clone(),2000),(symbols[1].clone(),0)]);
+        assert_eq!(sizing_ratios(&symbols,&symbols,&partial,&constraints,0,&partial).unwrap(),
+            BTreeMap::from([(symbols[0].clone(),Decimal::new(2,1)),(symbols[1].clone(),Decimal::ZERO)]));
+    }
+    #[test]
+    fn precision_is_checked_before_frozen_budget_is_allocated() {
+        let (symbols,mut constraints,display)=configuration();
+        constraints.prior_target_weight_ratios.insert(symbols[0].clone(),Decimal::new(1001,3));
+        assert!(sizing_ratios(&symbols,&symbols,&BTreeMap::new(),&constraints,0,&display).is_err());
+    }
+}
+
 pub(super) fn weights(
     original: &[String],
     active: &[String],