Every release bumped the balance version, so an account's own short-lived
holds (each realtime session probes one and releases it at once) could
keep its other reservations reading a stale version until they were
refused. The usage a hold stands for already bumps the version when it's
recorded, before the hold is released, and a release without usage
leaves the balance as it was, so releases no longer bump it.
The admission read also uses the cached add-ons record when it shows no
purchased credit left, which can only understate the balance; it reads
consistently only while credit remains.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>