Ship a pricing feature flag only after idempotency makes retries converge on one result instead of creating duplicate writes, and expose that operation identity in traces, logs, and cost records. The deciding constraint is attribution: if a media purchase can be charged twice while the telemetry shows two unrelated requests, nobody can prove whether the new rule, the retry policy, or a downstream timeout caused the extra spend. TL;DR: evaluate the flag once, create an immutable rollout operat...