Add realtime voice selection (#17176)

- Add realtime voice selection for realtime/start.
- Expose the supported v1/v2 voice lists and cover explicit, configured,
default, and invalid voice paths.

codex-rs/app-server/src/codex_message_processor.rs

@@ -144,6 +144,8 @@ use codex_app_server_protocol::ThreadRealtimeAppendAudioParams;
 use codex_app_server_protocol::ThreadRealtimeAppendAudioResponse;
 use codex_app_server_protocol::ThreadRealtimeAppendTextParams;
 use codex_app_server_protocol::ThreadRealtimeAppendTextResponse;
+use codex_app_server_protocol::ThreadRealtimeListVoicesParams;
+use codex_app_server_protocol::ThreadRealtimeListVoicesResponse;
 use codex_app_server_protocol::ThreadRealtimeStartParams;
 use codex_app_server_protocol::ThreadRealtimeStartResponse;
 use codex_app_server_protocol::ThreadRealtimeStartTransport;
@@ -279,6 +281,7 @@ use codex_protocol::protocol::McpAuthStatus as CoreMcpAuthStatus;
 use codex_protocol::protocol::McpServerRefreshConfig;
 use codex_protocol::protocol::Op;
 use codex_protocol::protocol::RateLimitSnapshot as CoreRateLimitSnapshot;
+use codex_protocol::protocol::RealtimeVoicesList;
 use codex_protocol::protocol::ReviewDelivery as CoreReviewDelivery;
 use codex_protocol::protocol::ReviewRequest;
 use codex_protocol::protocol::ReviewTarget as CoreReviewTarget;
@@ -839,6 +842,10 @@ impl CodexMessageProcessor {
                 self.thread_realtime_stop(to_connection_request_id(request_id), params)
                     .await;
             }
+            ClientRequest::ThreadRealtimeListVoices { request_id, params } => {
+                self.thread_realtime_list_voices(to_connection_request_id(request_id), params)
+                    .await;
+            }
             ClientRequest::ReviewStart { request_id, params } => {
                 self.review_start(to_connection_request_id(request_id), params)
                     .await;
@@ -6861,6 +6868,7 @@ impl CodexMessageProcessor {
                             ConversationStartTransport::Webrtc { sdp }
                         }
                     }),
+                    voice: params.voice,
                 }),
             )
             .await;
@@ -6987,6 +6995,21 @@ impl CodexMessageProcessor {
         }
     }
 
+    async fn thread_realtime_list_voices(
+        &mut self,
+        request_id: ConnectionRequestId,
+        _params: ThreadRealtimeListVoicesParams,
+    ) {
+        self.outgoing
+            .send_response(
+                request_id,
+                ThreadRealtimeListVoicesResponse {
+                    voices: RealtimeVoicesList::builtin(),
+                },
+            )
+            .await;
+    }
+
     fn build_review_turn(turn_id: String, display_text: &str) -> Turn {
         let items = if display_text.is_empty() {
             Vec::new()