The [ATTACH docs](https://www3.sqlite.org/lang_attach.html) state:
> Transactions involving multiple attached databases are atomic, assuming that the main database is not ":memory:" and the journal_mode is not WAL. ...
Should that first sentence possibly say:
> ... main database is not ":memory:" or "" ...
:-?
(The db name "" works like ":memory:" but uses a temp file. Or at least that's my understanding.)
Hypothetically, since there's no(?) way to re-open the same "" a second time, crash recovery could not take place with such a db?