diff --git a/crates/fidc-core/src/data.rs b/crates/fidc-core/src/data.rs
index 8c1b639..22e2731 100644
--- a/crates/fidc-core/src/data.rs
+++ b/crates/fidc-core/src/data.rs
@@ -161,6 +161,8 @@ impl DailyMarketSnapshot {
     }
 }
 
+pub type NumericFactorMap = BTreeMap<Cow<'static, str>, f64>;
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct DailyFactorSnapshot {
     #[serde(with = "date_format")]
@@ -172,7 +174,7 @@ pub struct DailyFactorSnapshot {
     pub turnover_ratio: Option<f64>,
     pub effective_turnover_ratio: Option<f64>,
     #[serde(default)]
-    pub extra_factors: BTreeMap<String, f64>,
+    pub extra_factors: NumericFactorMap,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -3264,11 +3266,15 @@ fn normalize_factor_snapshots(factors: Vec<DailyFactorSnapshot>) -> Vec<DailyFac
                 .extra_factors
                 .into_iter()
                 .filter_map(|(field, value)| {
-                    let normalized = normalize_field(&field);
-                    if normalized.is_empty() || !value.is_finite() {
+                    let trimmed = field.as_ref().trim().trim_matches('"').trim_matches('\'');
+                    if trimmed.is_empty() || !value.is_finite() {
                         None
+                    } else if trimmed == field.as_ref()
+                        && trimmed.bytes().all(|byte| !byte.is_ascii_uppercase())
+                    {
+                        Some((field, value))
                     } else {
-                        Some((normalized, value))
+                        Some((Cow::Owned(trimmed.to_ascii_lowercase()), value))
                     }
                 })
                 .collect();
@@ -3962,10 +3968,9 @@ mod tests {
                 .map(|(index, date)| {
                     let mut extra_factors = BTreeMap::new();
                     if let Some(values) = availability {
-                        extra_factors
-                            .insert("source_daily_volume_available".to_string(), values[index]);
+                        extra_factors.insert("source_daily_volume_available".into(), values[index]);
                         if values[index] >= 0.5 {
-                            extra_factors.insert("daily_volume".to_string(), volumes[index] as f64);
+                            extra_factors.insert("daily_volume".into(), volumes[index] as f64);
                         }
                     }
                     DailyFactorSnapshot {
@@ -4140,10 +4145,7 @@ mod tests {
                     pe_ttm: 10.0,
                     turnover_ratio: None,
                     effective_turnover_ratio: None,
-                    extra_factors: BTreeMap::from([(
-                        "adjustment_factor_backward1".to_string(),
-                        factor,
-                    )]),
+                    extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), factor)]),
                 })
                 .collect(),
             Vec::new(),
@@ -4243,7 +4245,7 @@ mod tests {
                     extra_factors: if *date == dates[3] {
                         BTreeMap::new()
                     } else {
-                        BTreeMap::from([("adjustment_factor_backward1".to_string(), 1.0)])
+                        BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)])
                     },
                 })
                 .collect(),
diff --git a/crates/fidc-core/src/lib.rs b/crates/fidc-core/src/lib.rs
index a2de0c6..957054c 100644
--- a/crates/fidc-core/src/lib.rs
+++ b/crates/fidc-core/src/lib.rs
@@ -31,8 +31,8 @@ pub use data::{
     BenchmarkSnapshot, CandidateEligibility, CorporateAction, DailyFactorSnapshot,
     DailyMarketSnapshot, DailySnapshotBundle, DataSet, DataSetError, DividendRecord,
     EligibleUniverseSnapshot, FactorTextValue, FactorValue, IntradayExecutionQuote,
-    IntradayOrderBookDepthLevel, PriceBar, PriceField, SecuritiesMarginRecord, SplitRecord,
-    YieldCurvePoint,
+    IntradayOrderBookDepthLevel, NumericFactorMap, PriceBar, PriceField, SecuritiesMarginRecord,
+    SplitRecord, YieldCurvePoint,
 };
 pub use engine::{
     AnalyzerMonthlyReturnRow, AnalyzerPositionRow, AnalyzerReport, AnalyzerRiskSummary,
diff --git a/crates/fidc-core/src/platform_expr_strategy.rs b/crates/fidc-core/src/platform_expr_strategy.rs
index 0ff1c64..1002c51 100644
--- a/crates/fidc-core/src/platform_expr_strategy.rs
+++ b/crates/fidc-core/src/platform_expr_strategy.rs
@@ -3669,7 +3669,7 @@ impl PlatformExprStrategy {
                 ctx.data
                     .factor_snapshots_on(date)
                     .into_iter()
-                    .flat_map(|row| row.extra_factors.keys().cloned())
+                    .flat_map(|row| row.extra_factors.keys().map(|key| key.to_string()))
                     .collect()
             } else {
                 BTreeSet::new()
@@ -3993,7 +3993,11 @@ impl PlatformExprStrategy {
         };
 
         let extra_factors = if self.stock_extra_factors_required {
-            factor.extra_factors.clone()
+            factor
+                .extra_factors
+                .iter()
+                .map(|(field, value)| (field.to_string(), *value))
+                .collect()
         } else {
             BTreeMap::new()
         };
@@ -13686,7 +13690,7 @@ mod tests {
                     pe_ttm: 8.0,
                     turnover_ratio: Some(1.0),
                     effective_turnover_ratio: Some(1.0),
-                    extra_factors: BTreeMap::from([("model_score".to_string(), 2.0)]),
+                    extra_factors: BTreeMap::from([("model_score".into(), 2.0)]),
                 },
             ],
             symbols
@@ -16173,10 +16177,7 @@ mod tests {
                     pe_ttm: 8.0,
                     turnover_ratio: Some(3.0),
                     effective_turnover_ratio: Some(3.0),
-                    extra_factors: BTreeMap::from([(
-                        "adjustment_factor_backward1".to_string(),
-                        1.0,
-                    )]),
+                    extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)]),
                 })
                 .collect(),
             vec![CandidateEligibility {
@@ -17125,7 +17126,7 @@ mod tests {
                     pe_ttm: 8.0,
                     turnover_ratio: Some(1.2),
                     effective_turnover_ratio: Some(1.2),
-                    extra_factors: BTreeMap::from([("touched_upper_limit".to_string(), 1.0)]),
+                    extra_factors: BTreeMap::from([("touched_upper_limit".into(), 1.0)]),
                 },
                 DailyFactorSnapshot {
                     date,
@@ -17239,7 +17240,7 @@ mod tests {
                 pe_ttm: 8.0,
                 turnover_ratio: Some(1.0),
                 effective_turnover_ratio: Some(1.0),
-                extra_factors: BTreeMap::from([("touched_upper_limit".to_string(), 1.0)]),
+                extra_factors: BTreeMap::from([("touched_upper_limit".into(), 1.0)]),
             }],
             vec![CandidateEligibility {
                 date,
@@ -17976,7 +17977,7 @@ mod tests {
                 pe_ttm: 8.0,
                 turnover_ratio: Some(1.0),
                 effective_turnover_ratio: Some(1.0),
-                extra_factors: BTreeMap::from([("adjustment_factor_backward1".to_string(), 1.0)]),
+                extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)]),
             })
             .collect();
         let benchmark_rows: Vec<BenchmarkSnapshot> = market_rows
@@ -20825,7 +20826,7 @@ mod tests {
                     pe_ttm: 8.0,
                     turnover_ratio: Some(1.0),
                     effective_turnover_ratio: Some(1.0),
-                    extra_factors: BTreeMap::from([("amount".to_string(), 30_000_000.0)]),
+                    extra_factors: BTreeMap::from([("amount".into(), 30_000_000.0)]),
                 },
                 DailyFactorSnapshot {
                     date: decision_date,
@@ -22054,17 +22055,17 @@ mod tests {
                 turnover_ratio: Some(22.0),
                 effective_turnover_ratio: Some(18.0),
                 extra_factors: BTreeMap::from([
-                    ("custom_alpha".to_string(), 7.0),
-                    ("margin_all".to_string(), 1.0),
-                    ("yield_curve_1y".to_string(), 0.02),
-                    ("total_shares".to_string(), 123.0),
-                    ("stock_connect_north_bound".to_string(), 1.0),
-                    ("industry_citics_l1".to_string(), 10.0),
-                    ("fundamental_net_profit".to_string(), 99.0),
-                    ("financial_revenue".to_string(), 188.0),
-                    ("pit_financial_eps".to_string(), 0.88),
-                    ("current_performance_roe".to_string(), 12.0),
-                    ("amount".to_string(), 12_345_678.0),
+                    ("custom_alpha".into(), 7.0),
+                    ("margin_all".into(), 1.0),
+                    ("yield_curve_1y".into(), 0.02),
+                    ("total_shares".into(), 123.0),
+                    ("stock_connect_north_bound".into(), 1.0),
+                    ("industry_citics_l1".into(), 10.0),
+                    ("fundamental_net_profit".into(), 99.0),
+                    ("financial_revenue".into(), 188.0),
+                    ("pit_financial_eps".into(), 0.88),
+                    ("current_performance_roe".into(), 12.0),
+                    ("amount".into(), 12_345_678.0),
                 ]),
             }],
             vec![CandidateEligibility {
@@ -22835,8 +22836,8 @@ mod tests {
                 turnover_ratio: Some(1.0),
                 effective_turnover_ratio: Some(1.0),
                 extra_factors: BTreeMap::from([
-                    ("Mixed_Factor".to_string(), index as f64 + 5.0),
-                    ("adjustment_factor_backward1".to_string(), 1.0),
+                    ("Mixed_Factor".into(), index as f64 + 5.0),
+                    ("adjustment_factor_backward1".into(), 1.0),
                 ]),
             })
             .collect::<Vec<_>>();
@@ -22989,7 +22990,7 @@ mod tests {
                 pe_ttm: 8.0,
                 turnover_ratio: Some(1.0),
                 effective_turnover_ratio: Some(1.0),
-                extra_factors: BTreeMap::from([("adjustment_factor_backward1".to_string(), 1.0)]),
+                extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)]),
             })
             .collect::<Vec<_>>();
         let candidate_rows = dates
@@ -25352,7 +25353,7 @@ mod tests {
                 pe_ttm: 8.0,
                 turnover_ratio: Some(1.0),
                 effective_turnover_ratio: Some(1.0),
-                extra_factors: BTreeMap::from([("adjustment_factor_backward1".to_string(), 1.0)]),
+                extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)]),
             })
             .chain(symbols.iter().map(|symbol| DailyFactorSnapshot {
                 date,
@@ -25368,7 +25369,7 @@ mod tests {
                 pe_ttm: 8.0,
                 turnover_ratio: Some(1.0),
                 effective_turnover_ratio: Some(1.0),
-                extra_factors: BTreeMap::from([("adjustment_factor_backward1".to_string(), 1.0)]),
+                extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)]),
             }))
             .collect(),
             symbols
@@ -26020,7 +26021,7 @@ mod tests {
             pe_ttm: 8.0,
             turnover_ratio: Some(1.0),
             effective_turnover_ratio: Some(1.0),
-            extra_factors: BTreeMap::from([("adjustment_factor_backward1".to_string(), 1.0)]),
+            extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)]),
         };
         let data = DataSet::from_components(
             vec![Instrument {
@@ -29884,7 +29885,7 @@ mod tests {
         let date = dates[5];
         let symbol = "300001.SZ";
         let mut extra_factors = BTreeMap::new();
-        extra_factors.insert("adjustment_factor_backward1".to_string(), 1.0);
+        extra_factors.insert("adjustment_factor_backward1".into(), 1.0);
         let data = DataSet::from_components(
             vec![Instrument {
                 symbol: symbol.to_string(),
@@ -29934,7 +29935,7 @@ mod tests {
                     extra_factors: if factor_date == date {
                         extra_factors.clone()
                     } else {
-                        BTreeMap::from([("adjustment_factor_backward1".to_string(), 1.0)])
+                        BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)])
                     },
                 })
                 .collect(),
@@ -30088,9 +30089,9 @@ mod tests {
                     turnover_ratio: None,
                     effective_turnover_ratio: None,
                     extra_factors: BTreeMap::from([
-                        ("adjustment_factor_backward1".to_string(), 1.0),
-                        ("ma5_current_back_adjusted_close".to_string(), current_close),
-                        ("avg_volume5_current".to_string(), current_volume),
+                        ("adjustment_factor_backward1".into(), 1.0),
+                        ("ma5_current_back_adjusted_close".into(), current_close),
+                        ("avg_volume5_current".into(), current_volume),
                     ]),
                 },
             )
@@ -30239,7 +30240,7 @@ mod tests {
                 pe_ttm: 0.0,
                 turnover_ratio: None,
                 effective_turnover_ratio: None,
-                extra_factors: BTreeMap::from([("ma5_prev_close".to_string(), 10.0)]),
+                extra_factors: BTreeMap::from([("ma5_prev_close".into(), 10.0)]),
             }],
             vec![CandidateEligibility {
                 date: current,
@@ -32539,10 +32540,7 @@ let target_exposure = csi_ready ? dynamic_exposure : 0.0;
                     pe_ttm: 8.0,
                     turnover_ratio: Some(22.0),
                     effective_turnover_ratio: Some(18.0),
-                    extra_factors: BTreeMap::from([(
-                        "adjustment_factor_backward1".to_string(),
-                        1.0,
-                    )]),
+                    extra_factors: BTreeMap::from([("adjustment_factor_backward1".into(), 1.0)]),
                 })
                 .collect(),
             dates
@@ -32755,7 +32753,7 @@ let target_exposure = csi_ready ? dynamic_exposure : 0.0;
                     extra_factors: if *symbol == "000002.SZ" {
                         BTreeMap::new()
                     } else {
-                        BTreeMap::from([("model_score".to_string(), 4.0 - index as f64)])
+                        BTreeMap::from([("model_score".into(), 4.0 - index as f64)])
                     },
                 })
                 .collect(),
diff --git a/crates/fidc-core/tests/engine_hooks.rs b/crates/fidc-core/tests/engine_hooks.rs
index 863010c..e2db4e3 100644
--- a/crates/fidc-core/tests/engine_hooks.rs
+++ b/crates/fidc-core/tests/engine_hooks.rs
@@ -10,11 +10,11 @@ use fidc_core::{
     ChinaEquityRuleHooks, DailyFactorSnapshot, DailyMarketSnapshot, DataSet, ExecutionQuoteRequest,
     FuturesAccountState, FuturesCommissionType, FuturesContractSpec, FuturesDirection,
     FuturesOrderIntent, FuturesPositionEffect, FuturesTradingParameter, FuturesValidationConfig,
-    Instrument, IntradayExecutionQuote, IntradayOrderBookDepthLevel, MatchingType, OpenOrderView,
-    OrderIntent, OrderSide, OrderStatus, PlatformExprStrategy, PlatformExprStrategyConfig,
-    PlatformTradeAction, PortfolioState, PriceField, ProcessEvent, ProcessEventBus,
-    ProcessEventKind, ScheduleRule, ScheduleStage, ScheduleTimeRule, Strategy, StrategyContext,
-    StrategyDecision,
+    Instrument, IntradayExecutionQuote, IntradayOrderBookDepthLevel, MatchingType,
+    NumericFactorMap, OpenOrderView, OrderIntent, OrderSide, OrderStatus, PlatformExprStrategy,
+    PlatformExprStrategyConfig, PlatformTradeAction, PortfolioState, PriceField, ProcessEvent,
+    ProcessEventBus, ProcessEventKind, ScheduleRule, ScheduleStage, ScheduleTimeRule, Strategy,
+    StrategyContext, StrategyDecision,
 };
 
 fn d(year: i32, month: u32, day: u32) -> NaiveDate {
@@ -133,7 +133,7 @@ fn market_row(date: NaiveDate, symbol: &str, open: f64, close: f64) -> DailyMark
 fn factor_row(
     date: NaiveDate,
     symbol: &str,
-    extra_factors: BTreeMap<String, f64>,
+    extra_factors: NumericFactorMap,
 ) -> DailyFactorSnapshot {
     DailyFactorSnapshot {
         date,
@@ -209,26 +209,26 @@ fn two_day_futures_data() -> DataSet {
                 d1,
                 "000001.SZ",
                 BTreeMap::from([
-                    ("custom_alpha".to_string(), 7.0),
-                    ("margin_all".to_string(), 1.0),
-                    ("yield_curve_1y".to_string(), 0.02),
-                    ("total_shares".to_string(), 123.0),
-                    ("stock_connect_north_bound".to_string(), 1.0),
-                    ("industry_citics_l1".to_string(), 10.0),
-                    ("fundamental_net_profit".to_string(), 99.0),
+                    ("custom_alpha".into(), 7.0),
+                    ("margin_all".into(), 1.0),
+                    ("yield_curve_1y".into(), 0.02),
+                    ("total_shares".into(), 123.0),
+                    ("stock_connect_north_bound".into(), 1.0),
+                    ("industry_citics_l1".into(), 10.0),
+                    ("fundamental_net_profit".into(), 99.0),
                 ]),
             ),
             factor_row(
                 d2,
                 "000001.SZ",
                 BTreeMap::from([
-                    ("custom_alpha".to_string(), 8.0),
-                    ("margin_all".to_string(), 1.0),
-                    ("yield_curve_1y".to_string(), 0.021),
-                    ("total_shares".to_string(), 124.0),
-                    ("stock_connect_north_bound".to_string(), 1.0),
-                    ("industry_citics_l1".to_string(), 10.0),
-                    ("fundamental_net_profit".to_string(), 101.0),
+                    ("custom_alpha".into(), 8.0),
+                    ("margin_all".into(), 1.0),
+                    ("yield_curve_1y".into(), 0.021),
+                    ("total_shares".into(), 124.0),
+                    ("stock_connect_north_bound".into(), 1.0),
+                    ("industry_citics_l1".into(), 10.0),
+                    ("fundamental_net_profit".into(), 101.0),
                 ]),
             ),
         ],