The persisted pre-vibe snapshot was applied on every reconciliation that
re-entered vibe mode, including cold resumes and switches in from a non-vibe
session. Those paths build their toolset from the current CLI flags and
settings, so replacing it with a historical snapshot silently drops tools the
session was started with: resuming a session that entered vibe under
--tools read with --tools read,bash restored only read on exit.
Gate the override on the one case the snapshot exists for: the vibe -> vibe
switch, where #clearTransientModeState kept the already-reduced live set.