I was thinking you could just set a web cookie that records the last known resolution value and when the user visits the site again, it will read the resolution from the cookie and apply it to the settings?
And just to clarify if I didn’t make sense with the original setup:
My Comet Pro KVM is connected to my work PC and this will does not change.
When I connect from either of these two devices below to access my KVM, I would like the KVM to resize the resolution accordingly.
Desktop PC → 2560×1440
Personal Laptop → 1900×1200
I think this can be done via cookies, but let me know. It’s a convenience feature like how Remote Desktop (RDP) works. It resizes to the appropriate (best fit?) resolution when you connect automatically.
This might not work well, especially when the controlled device is a laptop. It's possible that you configure EDID A on the controlled computer for screen mirroring, and then the KVM might automatically switch to EDID B. Your controlled computer might then recognize the KVM as a secondary display.