idempotency_key_reused

This `Idempotency-Key` was used before, for a request with a different body.

• A key was reused across two genuinely different calls.
• A retry mutated the payload — a regenerated timestamp or a re-ordered array is enough, because the guard hashes the whole body.
• A key was derived from something not unique per operation, such as a user id.

• Generate a fresh key per logical operation — a UUID v4 is the right shape.
• When retrying, send the byte-identical body you sent the first time. That is what makes the replay safe.
• Never derive keys from mutable data.

This code carries a details object with more than the message can say:

{
  "error": {
    "code": "idempotency_key_reused",
    "message": "This `Idempotency-Key` was used before, for a request with a different body",
    "details": { ... },
    "request_id": "7cb7f7862a82425d8e4c3fb8a497dfe6"
  },
  "type": "https://integrable.cloud/docs/errors/idempotency_key_reused",
  "title": "Idempotency Key Reused",
  "status": 422,
  "detail": "This `Idempotency-Key` was used before, for a request with a different body",
  "instance": "/api/bots/01a0652b-3713-7ea1-a6c9-2e895389ec34"
}

Branch on error.code, not on the message — the code is stable, the sentence is not. Log request_id either way.

Codes that are easy to confuse with this one, or that show up alongside it:

• idempotency_in_progress
• conflict

Quote the request_id from the response — hello@integrable.cloud. It is what lets us find the exact request. The full list of codes is at Error codes, and the conventions every endpoint shares are in Retries, versioning and limits.