Replace Python numerical kernels with native C execution

app/simulation/results.py

@@ -0,0 +1,49 @@
+"""Backend-neutral simulation result and preparation error contracts."""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Literal
+from app.simulation.core.metadata import ResultVariableMetadata
+
+SimulationRunStatus = Literal["completed", "cancelled", "failed"]
+
+@dataclass(frozen=True)
+class SimulationPreparationIssue:
+    code: str
+    message: str
+
+    def as_dict(self) -> dict[str, str]:
+        return {"code": self.code, "message": self.message}
+
+
+class SimulationPreparationError(ValueError):
+    def __init__(self, issues: tuple[SimulationPreparationIssue, ...]) -> None:
+        super().__init__("The compiled model is not ready for simulation.")
+        self.issues = issues
+
+
+@dataclass(frozen=True)
+class GenericSimulationResult:
+    success: bool
+    status: SimulationRunStatus
+    message: str
+    simulated_until: float
+    requested_stop_time: float
+    variables: tuple[ResultVariableMetadata, ...]
+    series: dict[str, list[float]]
+    final: dict[str, float]
+    diagnostics: dict[str, object]
+
+    def as_dict(self) -> dict[str, object]:
+        return {
+            "success": self.success,
+            "status": self.status,
+            "partial": self.status != "completed",
+            "message": self.message,
+            "simulatedUntil": self.simulated_until,
+            "requestedStopTime": self.requested_stop_time,
+            "variables": [variable.as_dict() for variable in self.variables],
+            "series": self.series,
+            "final": self.final,
+            "diagnostics": self.diagnostics,
+        }