class NotFoundError(Exception):
    def __init__(self, entity: str, entity_id: str) -> None:
        self.entity = entity
        self.entity_id = entity_id
        super().__init__(f"{entity} not found: {entity_id}")


class ValidationError(Exception):
    def __init__(self, message: str) -> None:
        self.message = message
        super().__init__(message)


class FileSystemError(Exception):
    def __init__(self, path: str, message: str) -> None:
        self.path = path
        self.message = message
        super().__init__(f"Filesystem error at {path}: {message}")