openai/gpt-6-astra

**Choose C: rewrite the hot path.** Billing correctness is a hard constraint; stale-balance caching and lagging replicas introduce correctness risks when used for billing decisions. **Exactly what we give up:** immediate latency relief and six weeks of engineering capacity that could otherwise deliver features or fixes. We accept current latency during that period—not stale balances or weaker billing guarantees. Keep authoritative balance reads and transactional safeguards intact. Validate the rewrite with billing-invariant tests, production-like benchmarks, and a staged rollout with rollback. The 40% reduction is a release criterion, not an assumed outcome. If benchmarks miss it, revisit scope or timing rather than relax correctness.