Add PWA functionality

[gdbing]

Describe the bug.

https://twinery.org/reference/en/getting-started/installing.html#ios-browsers

The policy it enforces that if a week passes where you do not visit a web site, Safari will erase all of its storage. This means that if you do not use Twine for a week, everything you create in it will be lost.

The one exception to this policy is if you add a web site to your Home Screen. Sites that are added as Home Screen shortcuts will not have their storage deleted.

This is not accurate, it is not enough to add a web site to the Home Screen, only progressive web apps are exempted from the 7 day cache limit.

Either twinery.org needs to be updated to fulfill the PWA requirements (web app manifest, service worker) or this page should be updated, and the MacOS browser warning should be applied to iOS browsers as well.

Steps to reproduce:

• Open twinery.org on an iPad
• Add it to home screen following linked instructions: https://support.apple.com/en-ca/guide/iphone/iph42ab2f3a7/ios#iph4f9a47bbc
• create a project
• wait 7 days

Expected behavior:

• project data persists

Additional context on this problem.

No response

Twine version number

2.8.1

Does this problem occur with the web version of Twine or the desktop app?

Web

What operating system does this problem occur on?

iOS

If this problem is occurring with the web version of Twine, what browser does it occur on?

Safari

Presubmission checklist

• [X] I am interested in working on code that would fix this bug. (This is not required to submit a bug report.)
• [X] I have done a search and believe that an issue does not already exist for this bug in the GitHub repository.
• [X] If this problem is occurring with the app version of Twine, it still happens after I remove the user.css file from my Twine folder. (You would've added this file yourself. If you don't understand this question, you can safely check this box.)
• [X] I have read and agree to abide by this project's Code of Conduct.

[klembot]

Thanks for reporting this! I'm going to try to repro the problem myself and, assuming I see the same issue, we should fix this. You checked the box that you would like to work on code for this... what did you have in mind?

[klembot]

I wasn't able to repro this; after adding Twine to my home screen on my phone and waiting 12 days, it still had my story. That said, it seems reasonable enough to add basic PWA functionality, so I'll make this an enhancement request.

[gdbing]

You checked the box that you would like to work on code for this... what did you have in mind?

When i checked that box I had been poking around and investigating PWAs and was thinking I might try putting together a bare bones manifest and service worker to make twine function as a web app.

I’ve been sidetracked by some other projects though, so I’m no actively working on that at the moment, but if I turn my attention back towards it I’ll comment here

[klembot]

FWIW, my first guess is to try using vite-plugin-pwa since all we want is to cache assets so it can run offline.

[david-donachie]

I wasn't able to repro this; after adding Twine to my home screen on my phone and waiting 12 days, it still had my story. That said, it seems reasonable enough to add basic PWA functionality, so I'll make this an enhancement request.

It seems quite variable. General "received wisdom" is that you can't guarantee local storage being persisted past 7 days, but it doesn't seem to be a hard cap.