If nopush also disables the 103 early hints, that would be a bad move IMO.

note that as Chrome indicates that it does not want pushed resources, servers won't push them those resources.

note that as Chrome indicates that it does not want pushed resources, servers won't push them those resources.

The question is: for people using Firefox, Safari, are those also indicating that they don't want pushed resources? I don't know the answer. And which web servers are pushing resources? Is this a real problem? Or in practice, is nothing being pushed already?

If nopush also disables the 103 early hints, that would be a bad move IMO.

I think you're correct that we would NOT want to include nopush in the Link headers of a 103 early-hint response. Currently, AssetMapper does not attempt to send a 103. So having the nopush on the main response shouldn't affect if a user DID try to send a 103. In the future, we could consider having AssetMapper send a 103. And in that case, indeed, we would want to use nopush.

AssetMapper is not the one sending the response at all when you render an import map. So early hints might still be used.

AssetMapper is not the one sending the response at all when you render an import map. So early hints might still be used

Hmm. Here is the only flow I can imagine:

A) User manually adds Link header and sends the 103. This does not include nopush
B) Request continues. When the importmap is rendered, AssetMapper adds a Link header for the same asset with nopush

I'm not entirely sure what happens in this case. The best I can tell, this would be ok - but it is a bit odd. However, closing this PR would be a bigger problem, assuming that server-push is actually something that's happening in practice with non-Chrome browsers.

The push attribute of the preload link type seems to have been removed from the specification: https://html.spec.whatwg.org/multipage/links.html#link-type-preload

As @stof pointed out, Chromium-based browsers no longer support Server Push, and although SP is still supported by Firefox and Safari, it can still bring some performance benefits in some cases (if the resource is already cached, the browser will cancel the download, and servers will only trigger the push if conditions are ideal).

AFAIK, all web servers supporting Server Push have a configuration option to disable it necessary.

TL;DR: I wouldn't bother adding this attribute, as it's no longer part of any standard anyway.

Regarding 103 Early Hints, I tried to use them in the original implementation of AssetMapper, unfortunately it's current not possible to use Early Hints to preload files used in importmap: #50476

However, now that the component supports CSS files, it should be possible to use Early Hints to preload CSS files.

Thank you for that detailed clarification! I'll close this

However, now that the component supports CSS files, it should be possible to use Early Hints to preload CSS files

Cool :). It won't be for 6.4, but we should think about this for the future.