Hitting Mesa 25.2-devel was a three month old merge request to enable a 64-bit memory structure mode for ray-tracing (RT).
This 64-bit memory structure mode for ray-tracing is just being enabled with the upcoming Xe3 graphics hardware and not for existing Intel graphics processors. As part of the merge is also adapting other changes in making way for Xe3.
Notable is that it's now compiling and adapting BHV shaders separately between Xe1/Xe2 and Xe3+ hardware. The BVH shaders for Xe1 and Xe2 graphics are treated the same while with Xe3 is now separate due to the 64-bit memory structure. Presumably this is part of a larger shift with Intel engineers working on further advancing the ray-tracing capabilities for Xe3 hardware to be found in integrated form with Panther Lake and then in discrete form with Arc Graphics C-Series "Celestial". Makes sense after all that they would be focusing more with their 2025+ products on ensuring a better ray-tracing experience for gamers.
This merge has all the details for those interested in this newest code to land.