fix(stock-pool): preserve exit roles and freeze relative reduction bases

crates/fidc-core/src/stock_pool_state.rs

@@ -24,6 +24,14 @@ pub struct StockPoolEntryProgress {
     pub completion_quantity: Option<Decimal>,
 }
 
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct StockPoolPositionActionBasis {
+    pub generation: String,
+    pub first_execution_date: NaiveDate,
+    pub quantity: Decimal,
+}
+
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct StockPoolExecutionState {
@@ -34,6 +42,10 @@ pub struct StockPoolExecutionState {
     pub last_target_weights: BTreeMap<String, i32>,
     /// First signal excluding an actually held member; not an acquisition date.
     pub removed_since: BTreeMap<String, NaiveDate>,
+    /// Signal progress, not a fill or holding-period fact. Kept across retries
+    /// and later execution sessions until a new generation supersedes it.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub position_action_bases: BTreeMap<String, StockPoolPositionActionBasis>,
 }
 
 pub struct StockPoolGoalObservation<'a> {
@@ -53,6 +65,7 @@ impl Default for StockPoolExecutionState {
             entries: BTreeMap::new(),
             last_target_weights: BTreeMap::new(),
             removed_since: BTreeMap::new(),
+            position_action_bases: BTreeMap::new(),
         }
     }
 }
@@ -62,6 +75,7 @@ impl StockPoolExecutionState {
         if self.schema_version != 1
             || self.entries.len() > 10000
             || self.removed_since.len() > 10000
+            || self.position_action_bases.len() > 10000
         {
             return Err("stock_pool_execution_state_invalid_schema_or_size".into());
         }
@@ -70,6 +84,7 @@ impl StockPoolExecutionState {
             .keys()
             .chain(self.removed_since.keys())
             .chain(self.last_target_weights.keys())
+            .chain(self.position_action_bases.keys())
         {
             if normalize_stock_symbol(symbol).as_ref() != Some(symbol) {
                 return Err("stock_pool_execution_state_invalid_symbol".into());
@@ -97,6 +112,12 @@ impl StockPoolExecutionState {
         {
             return Err("stock_pool_execution_state_invalid_goal_or_clock".into());
         }
+        if self.position_action_bases.values().any(|basis| {
+            basis.generation.trim().is_empty() || basis.quantity <= Decimal::ZERO
+                || self.last_execution_date.is_none_or(|date| basis.first_execution_date > date)
+        }) {
+            return Err("stock_pool_execution_state_invalid_action_basis".into());
+        }
         Ok(())
     }
 
@@ -186,7 +207,7 @@ impl StockPoolExecutionState {
         self.record_targets(
             decision_date,
             generation,
-            plan.rows.iter().map(|row| StockPoolGoalObservation {
+            plan.rows.iter().filter(|row| !plan.position_action_bases.contains_key(&row.symbol)).map(|row| StockPoolGoalObservation {
                 symbol: &row.symbol,
                 target_weight_bps: row.target_weight_bps,
                 target_value: row.target_value,
@@ -194,7 +215,67 @@ impl StockPoolExecutionState {
                 target_quantity: row.target_quantity,
                 status: &row.status,
             }),
-        )
+        )?.record_position_action_bases(generation, &plan.position_action_bases)
+    }
+
+    pub fn position_action_bases_for(&self, generation: &str) -> BTreeMap<String, Decimal> {
+        self.position_action_bases.iter()
+            .filter(|(_, basis)| basis.generation == generation)
+            .map(|(symbol, basis)| (symbol.clone(), basis.quantity))
+            .collect()
+    }
+
+    /// A verified split changes the share unit, not the intended reduction or
+    /// entry completion. Never infer a split from a changed holding quantity.
+    pub fn adjust_for_split(&self, symbol: &str, ratio: Decimal) -> Result<Self, String> {
+        self.validate()?;
+        if ratio <= Decimal::ZERO || normalize_stock_symbol(symbol).as_deref() != Some(symbol) {
+            return Err("stock_pool_execution_state_split_invalid".into());
+        }
+        let scale = |quantity: Decimal| quantity.checked_mul(ratio)
+            .map(|value| value.round_dp_with_strategy(0, rust_decimal::RoundingStrategy::MidpointAwayFromZero))
+            .ok_or_else(|| "stock_pool_execution_state_split_overflow".to_string());
+        let mut next = self.clone();
+        if let Some(entry) = next.entries.get_mut(symbol) {
+            if let Some(quantity) = entry.completion_quantity {
+                let quantity = scale(quantity)?;
+                entry.completion_quantity = (quantity > Decimal::ZERO).then_some(quantity);
+            }
+        }
+        if let Some(basis) = next.position_action_bases.get_mut(symbol) {
+            basis.quantity = scale(basis.quantity)?;
+            if basis.quantity == Decimal::ZERO { next.position_action_bases.remove(symbol); }
+        }
+        next.validate()?;
+        Ok(next)
+    }
+
+    pub fn record_position_action_bases(
+        &self,
+        generation: &str,
+        quantities: &BTreeMap<String, Decimal>,
+    ) -> Result<Self, String> {
+        self.validate()?;
+        if generation.trim().is_empty() {
+            return Err("stock_pool_execution_state_action_generation_missing".into());
+        }
+        let first_execution_date = self.last_execution_date
+            .ok_or("stock_pool_execution_state_action_clock_missing")?;
+        let mut next = self.clone();
+        next.position_action_bases.retain(|_, basis| basis.generation == generation);
+        for (symbol, quantity) in quantities {
+            if let Some(basis) = next.position_action_bases.get(symbol) {
+                if basis.quantity != *quantity {
+                    return Err(format!("stock_pool_execution_state_action_basis_changed:{symbol}"));
+                }
+            } else {
+                next.position_action_bases.insert(symbol.clone(), StockPoolPositionActionBasis {
+                    generation: generation.into(), first_execution_date, quantity: *quantity,
+                });
+            }
+        }
+        next.validate()?;
+        Ok(next)
     }
 
     pub fn record_targets<'a>(
@@ -213,6 +294,9 @@ impl StockPoolExecutionState {
         }
         let mut next = self.clone();
         for row in rows {
+            if row.status == "AUTOMATIC_TRADE_PROTECTED" {
+                continue;
+            }
             if row.target_weight_bps > 0 {
                 next.last_target_weights
                     .insert(row.symbol.into(), row.target_weight_bps);