IHttpRestClientAsync exposes various method-specific async methods as well as SendAsync.

SendAsync has a cancellation token parameter in its signature:

Task<TResponse> SendAsync<TResponse>(string httpMethod, string absoluteUrl, object request, CancellationToken token = default);

while other methods (GetAsync, PostAsync etc) don't

https://github.com/ServiceStack/ServiceStack/blob/6366ba9316d1380b920cd854042bef8649f630c5/src/ServiceStack.Interfaces/IHttpRestClientAsync.cs

Implementations of IHttpRestClientAsync (like JsonHttpClient) do have the methods which support then token:

    public Task<TResponse> GetAsync<TResponse>(IReturn<TResponse> requestDto, CancellationToken token) =>
        SendAsync<TResponse>(HttpMethods.Get, ResolveTypedUrl(HttpMethods.Get, requestDto), null, token);

https://github.com/ServiceStack/ServiceStack/blob/9de810436e0a589be002dff5bdfcf203081e6a0b/src/ServiceStack.HttpClient/JsonHttpClient.cs#L699

and in fact all the method-specific implementations just call SendAsync under the hood.

Without token-aware methods exposed through an interface I cannot use them in a depencency-injected IServiceClient and its derivatives. They are only usable if you access JsonHttpClient directly and not through its interfaces.

Right now I'm using this workaround in my DI setup:

public interface ICancellableHttpRestClientAsync : IHttpRestClientAsync
{
    Task<TResponse> GetAsync<TResponse>(IReturn<TResponse> requestDto, CancellationToken token);

    Task<TResponse> PostAsync<TResponse>(IReturn<TResponse> requestDto, CancellationToken token);

    Task<TResponse> PutAsync<TResponse>(IReturn<TResponse> requestDto, CancellationToken token);

    Task PatchAsync(IReturnVoid requestDto, CancellationToken token);

    Task DeleteAsync(IReturnVoid requestDto, CancellationToken token);
}

    private class CancellableJsonHttpRestClientAsync : JsonHttpClient, ICancellableHttpRestClientAsync
    {
        public CancellableJsonHttpRestClientAsync(string baseUrl) : base(baseUrl)
        {
        }
    }

    services.AddSingleton<ICancellableHttpRestClientAsync>(new CancellableJsonHttpRestClientAsync(myEndpoint));

Why not expose these methods in a library-provided interface?