Files
sub2api/backend/internal/config
William DrakeandClaude Opus 5.5 43f88c99aa fix(billing): reserve in-flight balance to prevent concurrent overdraft
Balance-mode admission only checked cached balance > threshold, so N
concurrent expensive requests could all pass and overdraw the user.
Add a Redis in-flight reservation: at admission estimate a conservative
per-request cost (input estimate + output price x max_tokens, times rate
multiplier) and atomically require cached_balance - inflight >= estimate
(first in-flight request always admitted). Reservations are released via
defer on every path and expire by TTL. Fails open on estimation / Redis
errors. Configurable via billing.inflight_reservation (enabled by default).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 14:20:49 -04:00
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