How to recreate history steps after closing PSD file.

[REN5252]

In PS I’m always using the History window. I love when I’m at state #43 (e.g.) and I want to go back to state #27 and restart from there, it’s just one click. Now I exit, save my work, and then re-open my psd file. My Layer window is there BUT the History window is empty and I want to go back to my old state #27.  It would be great if Adobe created a function in PS that would record every keystroke (like an action) which could be saved with the file then be run on the original file (hopefully unchanged) to get back to state #27. Since Adobe would be saving keystrokes, rather than large layers, the “action” shouldn’t (??) create too large a file. Would save HUGE amounts of time. 

[D Fosse]

It would eat up enormous amounts of disk space. It already does that, but it's freed up when you close Photoshop, so it doesn't pile up. But if you had 100 or 1000 saved files, it would be absolutely massive, terabytes upon terabytes. There's no way that's possible. Every history state potentially adds the full uncompressed file size.

Already the size of the scratch file (which is deleted when Photoshop closes) causes problems for many users.

[REN5252]

Wonder how much would a yottabyte cost (1 septillion bytes) and would it fit under my desk?

Thanks for your quick reply.

[c.pfaffenbichler]

A stringent use of non-destructive techniques (Smart Objects, Smart Filters instead of destructive Filters, Adjustment Layers instead of destructive Adjustments, …) and Layer Comps can help maintain the ability to roll back (some) changes – not to the extent you may prefer, naturally. 

What kind of editing steps are you talking about?

Painterly/illustrative work, photographic touch-up, montages, complete designs including graphics and type, …? 

[REN5252]

Photographic touch ups

[Per Berntsen]

Not quite what you're asking for, but there is the History log feature.

See https://helpx.adobe.com/photoshop/using/undo-history.html

Scroll down to Set Edit History Log options.

[Pete.Green]

Can you share one of your resulting PSD files?

We could take a look and see if there are ways you could infuse more non-destructive workflows into your editing style. 

I really feel the answer here is as c.pfaffenbichler mentions, utilize more non-destructive workflows to retain "history" (and ability to revert) within your layers panel. 

[REN5252]

I try to always use non-destructive methods. I was looking for the holy
grail. Thanks for all your help.

[Stephen Marsh]

Isn't this the idea behind parametric editing as in Lightroom?

[Per Berntsen]

Indeed it is, and in the Camera Raw plugin, which is an integrated part of Lightroom and Lightroom Classic.

For rendered files in PS one can use the Camera Raw filter on a smart object layer.

It is also possible to open jpg and tiff files in the Camera Raw plugin.

Unlike Camera Raw, Lightroom Classic has a history panel that lists every edit, and all the history steps are always visible.