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Roll out product credits in stages: configure, shadow, test, canary, monitor, and expand. Use separate sandbox customers and deterministic identifiers so every result is reproducible.

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1. Validate configuration

Before mutation traffic:
  • confirm the Feature is classified for credit consumption;
  • verify one effective conversion rate for the intended Credit System;
  • verify plan grants and paid top-ups create separate balance sources;
  • verify Entity pool policy where Entity attribution is used; and
  • confirm the backend key has only the required permissions.

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2. Shadow with advisory checks

Call usage.check() using representative production-shaped properties. Compare the exact-decimal metric amount, credits required, total availability, and projected source deductions with your expected fixtures. Advisory checks do not mutate balances and are safe for shadow evaluation.

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3. Test idempotency and concurrency

In a sandbox customer, confirm:
  • same-key retries return one logical result;
  • the same key with a different payload is rejected;
  • concurrent requests cannot overdraw a source;
  • denied operations create no allocations or billing-event outbox row;
  • successful operations reconcile to one billing event; and
  • source expiry, top-ups, and subscription grants retain expected priority.
Use fixed timestamps and deterministic keys in repeatable test fixtures.

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4. Canary one workflow

Enable one application workflow for a small set of non-production or internal customers. Monitor:
  • allow and denial rates;
  • request latency;
  • balance and operation history;
  • outbox publication delay and failures;
  • reconciliation status; and
  • support or application errors caused by changed denial behavior.

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5. Audit acceptance

Use Nozle’s read-only credit audit tooling when available. At minimum, verify:
  • source balances equal initial amounts plus immutable allocations;
  • successful consumes have exact deductions and one durable outbox event;
  • denied consumes have no side effects;
  • paid top-ups and subscription grants materialize once; and
  • customer and organization ownership remain consistent.
Retain the audit output with release evidence.

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6. Expand gradually

Expand by workflow, metric, or customer cohort only after the canary window is clean. Keep a dashboard for denial changes, reconciliation lag, and publication failures.

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Rollback

Stop sending new usage.track() requests for the affected workflow and fall back to your previous authorization path. Do not delete ledger rows. If a committed operation must be reversed, use an explicit compensating operation so financial history remains auditable.