Here's a recommendation for the scenario:

*   **Outcome/State:** The client should not remove the pending entry for operation K upon local "Cancel." The server's status for K is unknown.
*   **Preserved Information:** The client must retain the original operation K's identity and payload, along with its "pending" status, even after local cancellation.
*   **Recovery Action and Rejected Alternative:** The user's request to submit the "same booking again" should be treated as a new, distinct operation with a fresh identity. Blindly retrying K with its original identity is rejected because the server lacks deduplication guarantees.
*   **Missing Contract or Clarification:** A critical missing contract is the server's behavior regarding duplicate submissions and its retention window for operation identities. Without this, the client cannot safely assume a new submission will not result in a duplicate booking if K was, in fact, accepted.