[Proposal][WEB]: Ability to skip loading auto-generated manifest files.

[luckydaemon]

I'm want to release my app as embedded web app on social network platform (namely VK.com). Theirs documentation says, that in order for my app to be visible in apps catalog for end users who uses iOS client of this platform, I have to prepare app as an ODR archive and I have problem running my app in this form. Unfortunately, I cannot access any debug information on their iOS client. Documentation says, that I should try to open app as local web page (without using any web server). In browser console I'm getting next error:

Access to XMLHttpRequest at 'file:///home/web/assets/FontManifest.json' from origin 'null' has been blocked by CORS policy: 
Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, chrome-untrusted, https.

And, I think that exact same error happens in platform client app.
Is there any way to change, how flutter loads its manifests on application start or maybe disable this function at all, so I can load any necessary assets some other way?
I saw this issue, but there is not much details about whats going on, and linked issue describes different use case.

[darshankawar]

Can you check if this helps ?

[luckydaemon]

I think this is not exactly what is needed for me. It sure will help, but first, I need to overcome initialization step.
After I wrote this issue, I digged in a bit more and found out that flutter engine generates and tries to load FontManifest.json and AssetManifest.json even if I remove every asset and font from pubspec.yaml and code will contain single print() function (even without calling runApp()). The resulting json files are empty, but generated main.dart.js still tries to load them, and fails to do this due to CORS policy.
Also, I only now noticed that with flutter 3.0 there is now exist an option to customize web initialization with _flutter.loader JS API (for which I unfortunately cannot find any documentation). So now I'm preparing a test environment in virtual machine, to try out flutter 3.0 and maybe I can do something with initialization on this version.

[luckydaemon]

So, I tried latest stable version of flutter, and, sadly, I don't see any way to affect engine initialization in web build and force it to skip loading of auto-generated manifest files (or at least I can't figure out how to do so). Can this be added as feature request? Not sure, what will be the best way to describe it, but maybe something like: "Ability to skip loading auto-generated manifest files, so developers will be able to manually register and load any necessary file after engine initialized"?

[darshankawar]

Thanks for the update. Updating the issue title and will label as proposal and for further insights from the team.

[yjbanov]

Currently the engine makes certain assumption, which is probably something we should relax. I'll take it as a feature request.