GET /__spool?op=cursor and ?op=diff&from=N: the version vector spool syncs from. Internal: the front worker asks it for a /.spool/sync and a visitor cannot reach a __ path. Reads memory and the generation, so it writes no row.
GET /__spool?op=cursor
?op=diff&from=N
/.spool/sync
__
GET /__spool?op=cursorand?op=diff&from=N: the version vector spool syncs from. Internal: the front worker asks it for a/.spool/syncand a visitor cannot reach a__path. Reads memory and the generation, so it writes no row.