From eb34d12151f0d71c878fdd9e25705907299a6556 Mon Sep 17 00:00:00 2001
From: Takayuki Maeda <takoyaki0316@gmail.com>
Date: Wed, 1 Oct 2025 22:54:28 +0900
Subject: [PATCH] [`ty`] Reject renaming files to start with slash in
 Playground (#20666)

---
 playground/ty/src/Playground.tsx | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/playground/ty/src/Playground.tsx b/playground/ty/src/Playground.tsx
index e0e600c5ed..5ace4b9134 100644
--- a/playground/ty/src/Playground.tsx
+++ b/playground/ty/src/Playground.tsx
@@ -96,6 +96,11 @@ export default function Playground() {
     file: FileId,
     newName: string,
   ) => {
+    if (newName.startsWith("/")) {
+      setError("File names cannot start with '/'.");
+      return;
+    }
+
     const handle = files.handles[file];
     let newHandle: FileHandle | null = null;
     if (handle == null) {