ISBN links are autodetected on paste, so if you manually construct one by prepending ISBN to the number, it isn't going to get linked. The same would happen if you typed out an external link by hand backwards.

There are always going to be ways around auto-linking, and I'm not sure this use case is necessarily worth fixing.

I argued for this to be put in "Needs Discussion/Analysis" rather than "Freezer", but on a closer look, I agree with Ed – I'm not sure if this case is worth investigating. I think what I really wanted to discuss was T162291 (nowiki around ISBN caused by copy-paste of large blocks, e.g. copying citations from read mode).

Not sure I agree with @Esanders, this is detected, as it has nowiki added to *not* being linked. It should just be left alone.

@jeblad It is detected by Parsoid because it scans the entire document again. Similarly with links it would <nowiki> anything that might get autolinked by wikitext rules but was not linked by VE. Parsoid has no way to determine if the ISBN/link was no linked deliberately by the user so just respects what we send them (i.e. in this case, unlinked text).

Perhaps a regression of T117165.

This happened today in the Hebrew Wikipedia.