{"slug": "vercel-sandbox-commands-now-support-stdin", "title": "Vercel Sandbox commands now support stdin", "summary": "Vercel added standard input (stdin) support to commands in Vercel Sandbox, letting developers send input to running commands, including exchanging messages with stdio MCP servers such as agent-browser. In the TypeScript SDK, developers set `stdin: true` and `detached: true` in `runCommand()`, then use `writeStdin()` to send input and `closeStdin()` when finished, or pass a Node.js readable stream like `process.stdin`. In the Python SDK, developers set `stdin=subprocess.PIPE`, send input with `server.stdin.send()`, and call `communicate()` to close stdin, collect remaining output and wait for the process to exit.", "body_md": "[Vercel Sandbox](https://vercel.com/sandbox) now lets you send input to running commands through standard input (stdin). Use it to exchange messages with stdio MCP servers such as [agent-browser](https://github.com/vercel-labs/agent-browser#mcp-server), or send data to other command-line programs while they run.\n\nIn the TypeScript SDK, set `stdin: true` and `detached: true` in `runCommand()`. Use `writeStdin()` to send input and `closeStdin()` when you’re done:\n\nYou can also set `stdin` to a Node.js readable stream, such as `process.stdin`. The SDK forwards the stream’s data and closes the command’s standard input when the stream ends.\n\nIn the Python SDK, set `stdin=subprocess.PIPE` and send input with `server.stdin.send()`. Call `communicate()` to close stdin, collect remaining output, and wait for the process to exit:\n\nFor commands that receive all their input at once, you can pass `input` directly to Python’s `run_process()`.\n\nRead the [Sandbox documentation](https://vercel.com/docs/sandbox/sdk-reference#writestdin) to get started.", "url": "https://wpnews.pro/news/vercel-sandbox-commands-now-support-stdin", "canonical_source": "https://vercel.com/changelog/vercel-sandbox-commands-now-support-stdin", "published_at": "2026-10-26 06:00:00+00:00", "updated_at": "2026-10-26 17:44:30.482620+00:00", "lang": "en", "topics": ["developer-tools", "ai-agents", "agent-protocols", "ai-tools"], "entities": ["Vercel", "Vercel Sandbox", "agent-browser", "TypeScript", "Python", "Node.js"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/vercel-sandbox-commands-now-support-stdin", "markdown": "https://wpnews.pro/news/vercel-sandbox-commands-now-support-stdin.md", "text": "https://wpnews.pro/news/vercel-sandbox-commands-now-support-stdin.txt", "jsonld": "https://wpnews.pro/news/vercel-sandbox-commands-now-support-stdin.jsonld"}}