Implement Engine HTTP interfaces for health, enrollment, and tokens

Data/Engine/services/enrollment/errors.py

@@ -0,0 +1,26 @@
+"""Error types shared across enrollment components."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Optional
+
+__all__ = ["EnrollmentValidationError"]
+
+
+@dataclass(frozen=True, slots=True)
+class EnrollmentValidationError(Exception):
+    """Raised when enrollment input fails validation."""
+
+    code: str
+    http_status: int = 400
+    retry_after: Optional[float] = None
+
+    def to_response(self) -> dict[str, object]:
+        payload: dict[str, object] = {"error": self.code}
+        if self.retry_after is not None:
+            payload["retry_after"] = self.retry_after
+        return payload
+
+    def __str__(self) -> str:  # pragma: no cover - debug helper
+        return f"{self.code} (status={self.http_status})"