Thank you.
Keep bays as square as possible, ideally 1:1 to 1:1.5 and no worse than 1:2. UFH pipes stapled to insulation are common and fine, but they do not control cracking. Saw-cut joints to about one-third depth and cut early so the slab cracks where you want it to.
Avoid adding water on site, over-trowelling or closing the surface too early, delaying saw cuts, skipping curing, or pouring long thin bays. Get the joint layout, timing, and curing right and the UFH will cope with normal movement without issue.
You could use a macro fibre but it will not fix the basics. Used correctly, they are a support measure, not a solution.