Stripe idempotency key length (255) and Sume's key rules

Stripe says idempotency keys are "up to 255 characters long". Sume's generation key accepts the same upper bound, 1 to 255 characters, but only printable ASCII, and the crawl endpoint requires a key capped at 200. A Stripe-style key such as a UUID fits all of them.

Stripe's figures come from its idempotent requests page; Sume's from the OpenAPI parameter definitions, both read 2026-09-30.

What are the limits side by side?

What happens when I reuse a Sume key?

On paid creates, reusing the same key with the same operation and normalized payload returns the original job with idempotency_hit: true. A different operation or payload under the same key returns 409 idempotency_conflict. Crawl keys follow the same adopt-or-conflict rule. The retry pattern itself is in idempotency keys for AI video APIs.

Do keys expire?

Stripe says it may remove keys once they are at least 24 hours old. The Sume parameter text I read gives no expiry, so do not assume a window either way; generate a new key for a new intent.

What should I do when porting a Stripe client?

Keep keys to printable ASCII and under 200 characters so one generator works for both. Avoid emoji or accented characters in a key derived from user text. If you hit a conflict, see idempotency conflict versus key in use.