Export "create a new top-level browsing context"?

[alancutter]

Would it be reasonable to export https://html.spec.whatwg.org/multipage/browsers.html#creating-a-new-top-level-browsing-context for use by W3C specs? This is referenced by a handful of web app related algorithms:
https://www.w3.org/TR/appmanifest/#launching-a-shortcut
https://w3c.github.io/web-share-target/#launching-the-web-share-target
https://wicg.github.io/manifest-incubations/index.html#dfn-launch-a-web-app
https://wicg.github.io/manifest-incubations/index.html#handling-a-protocol-launch
https://wicg.github.io/manifest-incubations/index.html#launching-the-new_note_url
https://wicg.github.io/web-app-launch/#preparing-a-new-web-app-launch-client

(Context: w3c/manifest#1056 (comment))

[domenic]

Well, maybe. In #6315, scheduled to land on Monday, we're largely replacing the top-level browsing context concept with "top-level traversable". What you've provided is a good list of specs that we'll need to help you all update.

I'll add in the export to that PR, and in particular I'll ensure "create a new top-level traversable"'s arguments are both optional.

[domenic]

I've added create a fresh top-level traversable, which is exported and takes no arguments.

There's a remaining problem where none of those specs pass a sourceDocument to the new navigate. Which makes sense, because there is no source... Hmm. We could go a few routes here:

1. Require calling specs to understand what to do here, which is to pass the traversable's active document as the source document. I.e., treat the traversable as if it is navigating itself, from the initial about:blank document.

2. Generally allow no sourceDocument to be passed in to navigate. In this case we can use the current active document of the navigable as the sourceDocument automatically.

3. Have "create a fresh top-level traversable" also take a URL and optional POST resource argument, and let it wrap up this process.

(1) is annoying but most flexible. (2) is dangerous; it'll be too easy for people to forget to pass a sourceDocument when they really need to do so. (3) is most appealing, but it doesn't seem to work well for https://wicg.github.io/web-app-launch/#preparing-a-new-web-app-launch-client which has an intermediate step .

How important is that intermediate step? Could it happen after navigation has started?

[alancutter]

Oh awesome, thanks for rationalising this with what's going on in WHATWG land, I would have had no idea.

How important is that intermediate step? Could it happen after navigation has started?

Yep, it can happen after navigation. It mainly applies fairly cosmetic things like window decorations.

[domenic]

OK, sweet! So after that is merged and indexed by the various spec cross-referencing databases (say, Tuesday-ish), you should be able to replace all of those with [=create a fresh top-level traversable=] given |url|. The https://w3c.github.io/web-share-target/#launching-the-web-share-target case will need a bit more work to move from constructing a request to instead construct a POST resource.

[alancutter]

The https://w3c.github.io/web-share-target/#launching-the-web-share-target case will need a bit more work to move from constructing a request to instead construct a POST resource.

Can [=create a fresh top-level traversable=] take a POST resource instead of a URL for that case?

[domenic]

It will take a URL and an optional POST resource: https://whatpr.org/html/6315/document-sequences.html#create-a-fresh-top-level-traversable