Sorry if this gets a bit terse - I had a draft of a much longer one but it got lost because I threw together another one in a separate tab before finishing that 😕
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Basically we're running into two related issues with the history and parameteric modeling. We find it useful to make lots of intermediate sketches and when making a design and then clean those up when we're done with them (if only because the browser becomes unwieldy when there are hundreds of sketches and bodies).
The problem is that when we delete things, constraints and user defined parameters and equations that we spent a long time building in break, and deleting bodies or objects seems to delete them from history which can ruin designs that are based on boolean combinations of things that no longer exist.
The second issue can be easily fixed simply by adding an archive / recycle bin where things that the user deletes go rather than just destroying the data structures and leaving us with yellow tiles in the roll and warnings that Fusion is using a cache because something no longer exists (something that was particularly annoying and destructive before we realized what was happening).
The first (and really everything to do with parametric design) can and should be fixed by retaining every relationship that a user sets up and never breaking them unless the user explicitly and deliberately does that.
Minor anecdote but I spent a couple days building up a parameteric design and have a page full of user defined parameters that I thought would magically let me transform our design at will. That worked well at first so I trusted it would continue to function, kept building, and then after hours of additional work, I discovered that changing most of my parameters now does nothing. I understand that some relationships might be difficult to maintain but if I'm just specifying that the thickness of something be something like shell_wall_thickness, or some simple algebraic fomula (a + b/2) that should always just work and never be collapsed to whatever the numeric value of that value is (unless that's /really/ what I want.. and I honestly can't imagine a scenario when that would be what I'd want if I went to the trouble of setting it up in the first place so even doing it manually seems insane).
