Oh that's very interesting. I am actually using a UI called "DB Browser for SQLite" and checking its logs shows that when I add a PK, it actually creates a new

Oh that's very interesting. I am actually using a UI called "DB Browser for SQLite" and checking its logs shows that when I add a PK, it actually creates a new temporary table, copies over all data from the old table, deletes the old table, and then renames the new table. So you were correct originally, it can't just add a PK. Thanks for following up!