Source code
Security & compliance
Stability
Missing idempotency
Part of the Payment safety check · fix arrives as a guide
What it is
A charge, subscription change, or refund is created without an idempotency key.
Why it matters
Networks retry and users double-click. Without a key, the second identical request creates a second charge, and the customer is billed twice for one intent.
How to fix it
Generate a stable key per logical operation — derived from your own order id, not from a timestamp — and pass it on every mutating call. Store it so a retry after a crash reuses the same key.
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