Virtualization, imho. Every build gets its own virtual machine, and once the build is released to the public, the VM gets cloned for continued development and the released VM gets archived.

I do this git tags thing with my projects - it helps immensely if the end user can hover over the company logo and get a tooltip with the current version, git tag and hash, and any other relevant information to the build.

Then, if I need to triage something specific, I un-archive the virtualized build environment, and everything that was there in the original build is still there.

This is a very handy method for keeping large code bases under control, and has been very effective over the years in going back to triage new bugs found, fixing them, and so on.

Back in the PS2 era of game development, we didn't have much of virtual machines to work with. And, making a shippable build involved wacky custom hardware that wouldn't work in a VM anyway. So, instead we had The Build Machine.

The Build Machine would be used to make The Gold Master Disc. A physical DVD that would be shipped to the publisher to be reproduced hopefully millions of times. Getting The Gold Master Disc to a shippable state would usually take weeks because it involved burning a custom disc format for each build and there was usually no way to debug other than watching what happened on the game screen.

When The Gold Master Disc was finally finalized, The Build Machine would be powered down, unplugged, labeled "This is the machine that made The Gold Master Disc for Game XYZ. DO NOT DISCARD. Do not power on without express permission from the CTO." and archived in the basement forever. Or, until the company shut down. Then, who knows what happens to it.

But, there was always a chance that the publisher or Sony would come back and request to make a change for 1.0.1 version because of some subtle issue that was found later. You don't want to take any chances starting the build process over on a different machine. You make the minimal changes possible on The Build Machine and you get The Gold Master Disc 1.0.1 out ASAP.