Function is_retryable_error

crates/openshell-sandbox/src/lib.rs:1296–1313

Returns `true` if the error is transient and worth retrying. Walks the `miette::Report` error chain looking for a `tonic::Status`. If found, only the gRPC codes that represent transient failures are retryable. If no `tonic::Status` is present (e.g. a raw connection error), assume the failure is transient.

(err: &miette::Report)

/// If no `tonic::Status` is present (e.g. a raw connection error), assume the
/// failure is transient.
fn is_retryable_error(err: &miette::Report) -> bool {
    let mut source: Option<&dyn std::error::Error> = Some(err.as_ref());
    while let Some(e) = source {
        if let Some(status) = e.downcast_ref::<tonic::Status>() {
            return matches!(
                status.code(),
                tonic::Code::Unavailable
                    | tonic::Code::DeadlineExceeded
                    | tonic::Code::ResourceExhausted
                    | tonic::Code::Aborted
                    | tonic::Code::Internal
                    | tonic::Code::Unknown
            );
        }
        source = e.source();
    }
    true
}

/// Retry a gRPC operation with exponential backoff (capped at 4 s).
///