SQLite Forum

about "strict" mode
No, implicitly generated rowids are NOT stable. In particular, it has been mentioned that when you vacuum a table, IMPLICIT rowids might change, while explicitly generated columns of type PRIMARY INTEGER will be stable.

Not sure if there is an explicit promise of exactly how long an implicit key is promised to remain, and changing its value does require updating all the indexes for the table, so won't be don't lightly (so vacuuming is a good time to reset them to squeeze out spaces in the numbers since indexes are being regenerated anyway).