People say SSR like it's a new concept, but this was how it worked for a long time.

Guess based on user agent (or other fingerprinting metric of choice), redirect to guessed site, provide user the option to override when the page appears, remember the choice in cookie (or local storage).

Though personally I think you can do a lot with responsive CSS if you try hard enough - that is my preferred option.

> redirect to guessed site

I always wondered about that. What's the point of redirecting instead of serving a different template on the same URL?

That works, you'd just have to put the setting in a cookie rather than local storage.

Why? If you can detect mobile user-agents on the first page load, can't you do it in the next page loads too?

Devices should be truthful in the type of content they request. If your phone somehow tells my website that it’s a tablet or a laptop then you should reconsider the intelligence of who has developed your software

> Devices should be truthful in the type of content they request.

I think that websites should assume that devices are being truthful. I should be able to request the desktop view on my phone or request the mobile view on my computer. The former I can do sometimes, the latter I can only do with developer tools (and usually doesn't work because the website detects that I'm on desktop!). Browsers could add a header to switch to the mode in which the website dynamically readjusts based on actual device parameters like window size, but by default I need the view to be what I requested regardless of my window size and device type.

You know how Wikipedia has no table of contents on mobile? I made my browser request the desktop site by default so that I could see the table of contents and don't have to tap to open the article sections. (Unfortunately, Wikipedia changed its desktop view UI by moving the table of contents into a hamburger button. On mobile the desktop view forces me to tap the hamburger button to view a blocking popout of the table of contents, while on desktop the contents are automatically opened in a sidebar.) If Wikipedia had forced a dynamic design on me to restrict me to the mobile view on mobile, then I would've wasted time opening article sections to decide whether I wanted to open them in the first place.

My phone often does tell remote sites it is a desktop because as bad as the desktop experience is, often that is the only way to get at something. (I don't want an app for my doctors office - I check it after my yearly physical and the rest of the time it takes up space I could use for another picture)

Does it do that automatically or does it have an option?

If you can't, give me at least a choice