OpenAIVerified interview challenge
Investigate GPU credit balance drift
Trace why a completed compute job can leave an account with more credits than its ledger justifies.
Unlock with Full AccessThe challenge
Reservations, final charges and expiring holds update a ledger shared across regions, with a cached available balance. Callbacks can arrive repeatedly. Start from the accounting invariant and the supplied trace to identify evidence that separates incorrect state transitions from stale balance reads, before changing customer balances or redesigning the service.
What you'll practise
Accounting invariants
Reconstruct how one logical request changes holds, charges and available credits.
Distributed diagnosis
Distinguish repeated callbacks, concurrent writes and cached-state problems using evidence.
Ledger contract and incident traceCase materials included in the full challenge
Your investigation
Explain which evidence you would inspect and what each result would change.
The complete brief and feedback are included with Full Access.