Per-key credit limit
A spending cap set on one API key, separate from the account balance.
What it means
A budget on a key fences off a script, a staging environment or a customer-facing integration, so a bug or a runaway loop cannot drain the whole account.
How Onekey handles it
Any key can carry a credit_limit. Usage is counted per key and refunds are given back. The check happens before charging, in the same atomic step as the balance check. A call the limit cannot cover returns 402 KEY_BUDGET_EXCEEDED, distinct from INSUFFICIENT_CREDITS, and other keys keep working.