fix: include rollout_path in NewConversationResponse (#3352)

Adding the `rollout_path` to the `NewConversationResponse` makes it so a
client can perform subsequent operations on a `(ConversationId,
PathBuf)` pair. #3353 will introduce support for `ArchiveConversation`.

---
[//]: # (BEGIN SAPLING FOOTER)
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with [ReviewStack](https://reviewstack.dev/openai/codex/pull/3352).
* #3353
* __->__ #3352

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

@@ -528,6 +528,7 @@ impl CodexMessageProcessor {
                 let response = NewConversationResponse {
                     conversation_id,
                     model: session_configured.model,
+                    rollout_path: session_configured.rollout_path,
                 };
                 self.outgoing.send_response(request_id, response).await;
             }

codex-rs/mcp-server/src/outgoing_message.rs

@@ -262,6 +262,7 @@ mod tests {
     use codex_protocol::mcp_protocol::LoginChatGptCompleteNotification;
     use pretty_assertions::assert_eq;
     use serde_json::json;
+    use tempfile::NamedTempFile;
     use uuid::Uuid;
 
     use super::*;
@@ -272,6 +273,7 @@ mod tests {
         let outgoing_message_sender = OutgoingMessageSender::new(outgoing_tx);
 
         let conversation_id = ConversationId::new();
+        let rollout_file = NamedTempFile::new().unwrap();
         let event = Event {
             id: "1".to_string(),
             msg: EventMsg::SessionConfigured(SessionConfiguredEvent {
@@ -280,6 +282,7 @@ mod tests {
                 history_log_id: 1,
                 history_entry_count: 1000,
                 initial_messages: None,
+                rollout_path: rollout_file.path().to_path_buf(),
             }),
         };
 
@@ -305,12 +308,14 @@ mod tests {
         let outgoing_message_sender = OutgoingMessageSender::new(outgoing_tx);
 
         let conversation_id = ConversationId::new();
+        let rollout_file = NamedTempFile::new().unwrap();
         let session_configured_event = SessionConfiguredEvent {
             session_id: conversation_id,
             model: "gpt-4o".to_string(),
             history_log_id: 1,
             history_entry_count: 1000,
             initial_messages: None,
+            rollout_path: rollout_file.path().to_path_buf(),
         };
         let event = Event {
             id: "1".to_string(),
@@ -340,6 +345,7 @@ mod tests {
                 "history_log_id": session_configured_event.history_log_id,
                 "history_entry_count": session_configured_event.history_entry_count,
                 "type": "session_configured",
+                "rollout_path": rollout_file.path().to_path_buf(),
             }
         });
         assert_eq!(params.unwrap(), expected_params);