Let's update the protos and add the following rpc and messages:

• New GetPendingTx rpc: allows users to recover an interrupted offchain spend by presenting a proof of ownership for any of the spent vtxos and returns the unsigned checkpoint and signed ark txs.
• New string version field in GetInfoResponse message: contains the current version of arkd
• New FeeInfo fees field in GetInfoResponse message: contains all fee params:

message FeeInfo {
   IntentFeeInfo intentFee = 1;
   string tx_fee_rate = 2;
}
message IntentFeeInfo  {
   string offchain_input = 1;
   string offchain_output = 2;
   string onchain_input = 3;
   string onchain_output = 4;
}

• New repeated string deprecated_signer_pubkeys field in GetInfoResponse message: contains the list of deprecated signers in case arkd migrated it and is now using a different signer key.
• New string digest field in GetInfoResponse message: contains the hash of the GetInfoResponse message to make it easier for clients to know if any param changed