The account+model transient breaker reset its failure streak whenever the
gap since the previous failure exceeded a one-minute window. That made the
breaker's sensitivity a function of request rate rather than upstream
health: a gateway called less often than once a minute never advanced past
streak 1, where the cooldown is zero, so a consistently broken account was
never blocked. Every request re-selected it, paid a full upstream attempt,
and only then failed over to a healthy account.
Observed on a low-traffic deployment: two accounts returning 500 and 503
stayed in rotation indefinitely, logging `failure_streak: 1, cooldown_ms: 0`
on every request and adding ~750ms to each one before a working account was
reached.
The streak is already cleared on success — recordSuccess deletes the entry,
and every OpenAI handler reports the schedule result — so the time-based
reset is not needed to recover a healthy account. Keep a TTL purely to bound
the map for account+model pairs that stopped being used, and raise it well
above the cooldowns so it no longer doubles as a streak reset.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
