Edge case: duplicate taskId entries in one relayer_sendTransactionMultichain batch

[ch4r10t33r]

Summary

process_send_transaction_multichain validates each provided taskId against storage but does not detect duplicate task IDs within the same request array before processing (src/methods/send_tx/multi.rs).

Behavior

The first item succeeds and persists the id; a later item with the same taskId fails with duplicate (4214) after partial relay, leaving the batch in a partially applied state.

Suggested fix

Pre-scan the items slice for duplicate taskId values (when Some) and reject the entire request with -32602 or 4214 before mutating state.

References

• src/methods/send_tx/multi.rs