Can reportaling happen if the portal was since navigated?

[jakearchibald]

I'm still keen on making the back button 'work' after activation. As in, if the previous page is still alive, due to bfcache or adopted portal, the current page is put back into its original portal, so a reverse transition can happen.

However, in the meantime, that portal may have had its src changed, creating a new browsing context.

Options:

---

The current browsing context in the portal is discarded, and replaced with the 'reportaled' context.

---

The page navigates, but no reportaling happens. The portal will display its latest browsing context.

---

Setting src on a portal is ignored between successful activation and reportaling.

I think I'm leaning towards "The current browsing context in the portal is discarded"

[jeremyroman]

Another option is to offer the context to the page if it qualifies but not do so automatically. This would have the downside that some simple cases that could have been automatic won't be, but it has the advantage that it would be possible to ship a version that didn't support readoption and add support later without breaking previous content.