feat(BT-002): add historical snapshot provider

app/services/backtesting/service.py

@@ -5,7 +5,7 @@ from math import isclose
 from app.backtesting.engine import SyntheticBacktestEngine
 from app.models.backtest import BacktestRunResult, BacktestScenario
 from app.models.strategy_template import StrategyTemplate
-from app.services.backtesting.historical_provider import SyntheticHistoricalProvider
+from app.services.backtesting.historical_provider import BacktestHistoricalProvider, SyntheticHistoricalProvider
 from app.services.strategy_templates import StrategyTemplateService
 
 
@@ -15,7 +15,7 @@ class BacktestService:
 
     def __init__(
         self,
-        provider: SyntheticHistoricalProvider | None = None,
+        provider: BacktestHistoricalProvider | None = None,
         template_service: StrategyTemplateService | None = None,
     ) -> None:
         self.provider = provider or SyntheticHistoricalProvider()
@@ -59,15 +59,15 @@ class BacktestService:
 
         return BacktestRunResult(scenario_id=scenario.scenario_id, template_results=tuple(template_results))
 
-    @staticmethod
-    def _validate_template_for_mvp(template: StrategyTemplate) -> None:
+    def _validate_template_for_mvp(self, template: StrategyTemplate) -> None:
+        provider_label = (
+            "historical snapshot engine" if self.provider.pricing_mode == "snapshot_mid" else "synthetic MVP engine"
+        )
         if template.contract_mode != "continuous_units":
-            raise ValueError(f"Unsupported contract_mode for synthetic MVP engine: {template.contract_mode}")
+            raise ValueError(f"Unsupported contract_mode for {provider_label}: {template.contract_mode}")
         if template.roll_policy.policy_type != "hold_to_expiry":
-            raise ValueError("Unsupported roll_policy for synthetic MVP engine: " f"{template.roll_policy.policy_type}")
+            raise ValueError(f"Unsupported roll_policy for {provider_label}: {template.roll_policy.policy_type}")
         if template.entry_policy.entry_timing != "scenario_start_close":
-            raise ValueError(
-                "Unsupported entry_timing for synthetic MVP engine: " f"{template.entry_policy.entry_timing}"
-            )
+            raise ValueError(f"Unsupported entry_timing for {provider_label}: {template.entry_policy.entry_timing}")
         if template.entry_policy.stagger_days is not None:
-            raise ValueError("Unsupported entry_policy configuration for synthetic MVP engine")
+            raise ValueError(f"Unsupported entry_policy configuration for {provider_label}")