feat: /resume per ID/name (#17222)

Support `/resume 00000-0000-0000-00000000` from the TUI (equivalent for
the name)

codex-rs/tui/src/chatwidget/tests/slash_commands.rs

@@ -447,6 +447,24 @@ async fn slash_resume_opens_picker() {
     assert_matches!(rx.try_recv(), Ok(AppEvent::OpenResumePicker));
 }
 
+#[tokio::test]
+async fn slash_resume_with_arg_requests_named_session() {
+    let (mut chat, mut rx, mut op_rx) = make_chatwidget_manual(/*model_override*/ None).await;
+
+    chat.bottom_pane.set_composer_text(
+        "/resume my-saved-thread".to_string(),
+        Vec::new(),
+        Vec::new(),
+    );
+    chat.handle_key_event(KeyEvent::from(KeyCode::Enter));
+
+    assert_matches!(
+        rx.try_recv(),
+        Ok(AppEvent::ResumeSessionByIdOrName(id_or_name)) if id_or_name == "my-saved-thread"
+    );
+    assert_matches!(op_rx.try_recv(), Err(TryRecvError::Empty));
+}
+
 #[tokio::test]
 async fn slash_fork_requests_current_fork() {
     let (mut chat, mut rx, _op_rx) = make_chatwidget_manual(/*model_override*/ None).await;