ICrudService

using System.Threading.Tasks;

using Cosmos.Common.Contracts;
using System;


// fixme
namespace Cosmos.Services
{


    public interface ICrudGetService<T> : ICosmosService where T : IHasId, IIsModifyable
    {
        // get
        Task<long> Count(); //200
        Task<T> Get(Guid id , bool includeDeleted = false); //200 , 404
        Task<Guid[]> GetAllIds(); //200 , 404

        Task<T[]> GetAll(bool includeDeleted = false); //200 , 404

        Task<T[]> GetAll(Guid[] ids); //200 , 404
        Task<NameValue[]> GetAllNames(); //200 , 404

        Task Delete(Guid id); //200 , 404

    }

    public interface ICrudPostService<T> : ICosmosService where T : IHasId//, IIsModifyable
    {
        ////post we skip the mosts 
        Task AddOrUpdate(T record); // 204 , 400 
        Task AddOrUpdateMany(T[] records); // 204 , 400 

    }


    // we may need more than T[] but that could be a different method.
    public interface IVersionedService<T> : ICosmosService where T : IHasVer
    {
        Task<T[]> GetByVer(long position , int maxCount); //200 , 404
    }



    // while simpler to use this contract will expose some extra fields that are ignored 
    public interface ICrudService<T> : ICrudGetService<T>  , ICrudPostService<T> where T : IHasId , IIsModifyable
    {

    }

}

Aaron Wyatt suggest getting a list of names as objects could be deep HDS. I have added returning NameValue..

Should arrays be replaced with IEnumerable ? I think so... the reason for arrays is serialisation behaviour but most serializers are pretty good these days in terms of mapping collections to arrays.