It depends on your settings in the Exploration settings (Select results to save). You can choose to generate Quartus archive files (.qar) and .sof programming files. The generated reports will tell you what settings were used. Creating a .qar is probably the easiest because it includes everything.
My DSE is set to "save all results". I found this in my project directory
At this point I had already ran DSE with 6 seeds + base several time, changing a paramter in the project every time. I would have asumed that this folder is the collection of all compilations that were named DSE_1. However, the "dse" folder only contains "dse1", so if the previous assumption is correct, then I don't know where the compilation that were not called dse_1 went. In addition, this folder only contains one quar file, so I don't know which one of the many project versions in this folder get restored by it.
The name of "output" changed to "output_files" for some reason. I also gave the explorations different names but "timing_15_1" is the same as "dse1_1" in the screenshots I posted before.
I started a new DSE compilation and now the sub folder in dse_1 are empty. it seems they are overwritten whenever i start a new compilation. I also checked in the new compilation, all explorations are indeed called dse_1_x, so they correspond to the ones in the dse1 folder. I will follow with the content of the subfolders in dse1 as soon as the compilations are done (which will probably take a day), but for now I can confirm that there were no .qar files in those subfolders before they were overwritten.
Actually, I tried opening the .qsf files and that didn't help in the the way I hoped. When the project is opened, I automatically get warnings that none of .qip files can be found. Also, when I open the timing analyzer, it treats the project as uncompiled, so I cannot verify the results from DSE. I need the project to be fully functional because I need to recompile it with different timing constraints
I have selected the option to save all results, which should all files including .qar files if I understand correctly. But as I previously mentioned and is visible in the screenshots there is only one .qar file for all exploration points. I have never used a .qar file before so I don't know how they work, but it seems there should be one for every compilation.
The qar is created from the base project. It is used in each of the DSE compilation. To use the result in each of the DSE compilation, you can simply go to the dse > dse1 folder, apply the .qsf settings in your project file. dse1_x folders contain the result/reports for each of the DSE compilation.