Smoldot connection handling

[rosesopranodesertbat]

I switched to using Smoldot as looks like a lot of the RPC providers are shutting down. However noticed that a lot of queries are failing because of connection shutdowns. I vibe-coded a fix to reconnect/retry on failure but think it should probably be upstream.

class SafeSubstrate:
    def __init__(
        self,
        connection: SubstrateInterface,
        label: str,
        reconnect_fn: Optional[Callable[[], SubstrateInterface]] = None
    ) -> None:
        self._connection = connection
        self._label = label
        self._reconnect_fn = reconnect_fn

    def query(self, module: str, storage_function: str, params: Optional[List[Any]] = None, block_hash: Optional[str] = None):
        retries = int(os.environ.get('SMOLDOT_QUERY_RETRIES', '5'))
        base_delay = float(os.environ.get('SMOLDOT_QUERY_BASE_DELAY', '0.5'))
        params = params or []

        for attempt in range(1, retries + 1):
            try:
                return self._connection.query(module, storage_function, params=params, block_hash=block_hash)
            except SubstrateRequestException as exc:
                if not is_transient_smoldot_error(exc) or attempt == retries:
                    raise
                delay = base_delay * (2 ** (attempt - 1))
                name = f"{self._label}.{module}.{storage_function}" if self._label else f"{module}.{storage_function}"
                logger.warning(f"{name} failed with smoldot connection error (attempt {attempt}/{retries}); retrying in {delay:.2f}s")
                if self._reconnect_fn is not None:
                    self._connection = self._reconnect_fn()
                time.sleep(delay)

        return self._connection.query(module, storage_function, params=params, block_hash=block_hash)

    def __getattr__(self, name: str):
        return getattr(self._connection, name)

def is_transient_smoldot_error(exc: SubstrateRequestException) -> bool:
    error = exc.args[0] if exc.args else None
    if isinstance(error, dict):
        message = str(error.get('message', ''))
        code = error.get('code')
    else:
        message = str(exc)
        code = None
    if code == -32000 and ('NoConnection' in message or 'ConnectionShutdown' in message):
        return True
    return 'NoConnection' in message or 'ConnectionShutdown' in message