Looking for a drag and drop granular synth with grain size sync to tempo

I think I understand what you mean.

Seems like an interesting, just not how granular is usually configured (in my limited experience anyway).

Most granular stuff uses short grains in the ms range, so maybe ranging from 50 to 300ms, but with more extreme setting possible. And they are usually (not always) played back overlapping each other. If you sync the grain playback to some tempo division, you would either have short clicks with lots of empty space, or very long grains to the point where it ceases to be a granular process and starts to be more like a regular sampler with some sort of envelope system and modulation of playback position.

Some granulators (like morphagene) allow you to split the audio up into slices that are then granulated.. so the grains are still very short, but you also have a higher level mechanism to chop up the audio in bigger chunks that can be synced in various ways. Not sure if there is anything like that publicly available for Reaktor.

different parts being read here and there with a bit of overlapping,short or long envelopes,usually with random option too,can create interesting textures and rythm

This sounds more familiar to me, longer grains, with overlapping, some randomness in playback position and/or timing… but I must still be missing something because surely syncing to the tempo would force grains to start together rather than allowing the overlapping offsets that provide that textural effect?

I suppose it is like what Mutuable Instruments Beads does in hardware form (with limited success IMO). In order to keep the GUI to a sane control count, user control over the way sync happens is quite heavily restricted. As as a result, what might have been a fantastically powerful granular processer turned out to be an OK granular processor and an OK delay type effect and real time sampler. Great for exploring what it can do, but not great for exploring ones own creative ideas about how to use granular synthesis.

Makes more sense in the context of a commercial VSTi - no massive penalty to complex code, more features = more sales… but not so much in Reaktor - big performance penalty for complex systems, no penalty for streamlined feature set, because just make two versions :)

It is interesting that the graincloud core engine in the Grain Sampler from the factory library doesn't provide any option that would make this feature possible.