feat(rust-client): operator credentials on acknowledge-alarm

Claude-Session: https://claude.ai/code/session_016J6isfcgqy4SB2RK3ZvFvT

clients/rust/tests/client_behavior.rs

@@ -229,6 +229,8 @@ async fn acknowledge_alarm_returns_reply_with_native_status() {
             alarm_full_reference: "Tank01.Level.HiHi".to_owned(),
             comment: "investigating".to_owned(),
             operator_user: "alice".to_owned(),
+            operator_password: String::new(),
+            operator_domain: String::new(),
         })
         .await
         .unwrap();
@@ -1036,6 +1038,30 @@ async fn stream_alarms_emits_snapshot_then_complete_then_transition_in_order() {
     ));
 }
 
+#[tokio::test]
+async fn acknowledge_alarm_error_does_not_leak_operator_password() {
+    let state = Arc::new(FakeState::default());
+    let endpoint = spawn_fake_gateway(state.clone()).await;
+    let client = GatewayClient::connect(ClientOptions::new(endpoint))
+        .await
+        .unwrap();
+
+    let err = client
+        .acknowledge_alarm(AcknowledgeAlarmRequest {
+            client_correlation_id: "corr-pw".to_owned(),
+            alarm_full_reference: "Tank01.Level.HiHi".to_owned(),
+            comment: String::new(),
+            operator_user: "alice".to_owned(),
+            operator_password: "pw-secret".to_owned(),
+            operator_domain: String::new(),
+        })
+        .await
+        .unwrap_err();
+
+    assert!(!format!("{err:?}").contains("pw-secret"));
+    assert!(!err.to_string().contains("pw-secret"));
+}
+
 #[tokio::test]
 async fn cli_subcommands_propagate_unique_correlation_ids_from_next_correlation_id() {
     // The CLI's `stream-alarms` and `acknowledge-alarm` paths used to
@@ -1073,6 +1099,8 @@ async fn cli_subcommands_propagate_unique_correlation_ids_from_next_correlation_
             alarm_full_reference: "Tank01.Level.HiHi".to_owned(),
             comment: String::new(),
             operator_user: String::new(),
+            operator_password: String::new(),
+            operator_domain: String::new(),
         })
         .await
         .unwrap();
@@ -1424,8 +1452,11 @@ impl MxAccessGateway for FakeGateway {
         &self,
         request: Request<AcknowledgeAlarmRequest>,
     ) -> Result<Response<AcknowledgeAlarmReply>, Status> {
-        *self.state.last_correlation_id.lock().await =
-            Some(request.into_inner().client_correlation_id);
+        let request = request.into_inner();
+        if request.operator_password == "pw-secret" {
+            return Err(Status::internal("boom pw-secret"));
+        }
+        *self.state.last_correlation_id.lock().await = Some(request.client_correlation_id);
         Ok(Response::new(AcknowledgeAlarmReply {
             correlation_id: "corr-1".to_owned(),
             protocol_status: Some(ok_status("ack ok")),