Scope code mode cell IDs to the host process

codex-rs/code-mode-host/src/main.rs

@@ -49,6 +49,7 @@ async fn run() -> Result<(), String> {
         sessions: Mutex::new(HashMap::new()),
         next_session_id: AtomicU64::new(1),
         peer,
+        host_id: std::process::id().to_string(),
     });
 
     let writer = tokio::spawn(async move {
@@ -110,8 +111,12 @@ impl HostState {
                 });
                 self.sessions.lock().await.insert(
                     session_id,
-                    Arc::new(CodeModeService::with_delegate(delegate)),
+                    Arc::new(CodeModeService::with_delegate_and_cell_id_prefix(
+                        delegate,
+                        self.host_id.clone(),
+                    )),
                 );
+    host_id: String,
                 self.respond(request_id, Ok(HostResponse::SessionCreated { session_id }))
                     .await;
             }

codex-rs/code-mode-host/tests/host.rs

@@ -25,6 +25,7 @@ async fn serves_code_mode_sessions_over_stdio() {
     .kill_on_drop(true)
     .spawn()
     .expect("spawn codex-code-mode-host");
+    let host_id = child.id().expect("host process id");
     let mut stdin = child.stdin.take().expect("host stdin");
     let mut stdout = child.stdout.take().expect("host stdout");
 
@@ -70,6 +71,7 @@ async fn serves_code_mode_sessions_over_stdio() {
         }) => cell_id,
         message => panic!("unexpected execute response: {message:?}"),
     };
+    assert_eq!(cell_id.as_str(), format!("{host_id}_1"));
     let response = match read_frame(&mut stdout)
         .await
         .expect("initial response frame")