Idempotency checker
Same tenant + Idempotency-Key returns the original event. Hard caps are a predictable 4xx (429). No account required.
Product rule: same tenant + Idempotency-Key (or idempotency_key) returns the original event. We do not double-count. This checker never leaves the browser.
Paste two keys. Empty keys are not idempotent — they count as two events.
Hard cap: a new distinct event after the monthly ceiling is a predictable 4xx (429). We do not silently drop it.
Illustrative / not tax or legal advice.