6822acc49c made tools.configure refuse with 4009 while the session is
running, because its agent reset bumps history_version and a live turn would
drop its reply. No test reached that guard: reverting the hunk left the suite
green. The existing manual-compaction test now calls tools.configure while the
compaction holds the busy claim and expects 4009 (4017 without the guard).
Gate finding: C04 r2 2ab [Low TOOTHLESS].
Refs #133504