--- title: Vercel Sandbox commands now support stdin | daily.dev description: Vercel Sandbox commands now accept input through standard input (stdin). This lets developers exchange messages with stdio MCP servers, such as agent-browser,... canonical: https://daily.dev/posts/vercel-sandbox-commands-now-support-stdin-kppx8dmkf twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Vercel Sandbox commands now support stdin | daily.dev og:description: Vercel Sandbox commands now accept input through standard input (stdin). This lets developers exchange messages with stdio MCP servers, such as agent-browser,... og:url: https://daily.dev/posts/vercel-sandbox-commands-now-support-stdin-kppx8dmkf og:image: https://api.daily.dev/og/posts/KPpX8DMKf.png og:image:alt: Vercel Sandbox commands now support stdin og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Vercel Sandbox commands now support stdin **[Vercel](https://daily.dev/sources/vercel)** · 2 min read · 0 upvotes · 0 comments ## Summary Vercel Sandbox commands now accept input through standard input (stdin). This lets developers exchange messages with stdio MCP servers, such as agent-browser, or send data to other command-line programs while they run. In the TypeScript SDK, you set stdin: true and detached: true in runCommand(), then call writeStdin() to send data and closeStdin() when finished. You can also pass a Node.js readable stream like process.stdin. In the Python SDK, set stdin=subprocess.PIPE and send input with server.stdin.send(), then call communicate() to close stdin and collect output. Python's run_process() also accepts an input argument for one-shot input. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I send input to a running command in Vercel Sandbox using the TypeScript SDK? Set stdin: true and detached: true when calling runCommand(), then use writeStdin() to send data and closeStdin() when done. You can also pass a Node.js readable stream, such as process.stdin, as the stdin value, and the SDK forwards the stream's data and closes the command's input automatically when the stream ends. _Developers wiring stdio-based tools into sandboxed environments can track SDK changes like this on daily.dev._ ### How do I write to a process's stdin in Vercel Sandbox using the Python SDK? Pass stdin=subprocess.PIPE when creating the process with create_process(), then call server.stdin.send() with bytes to write data. Call communicate() to close stdin, collect any remaining output, and wait for the process to exit. For input known entirely upfront, pass it directly via the input argument to run_process() instead. _Python developers automating sandboxed CLI workflows can follow SDK updates like this on daily.dev._ ### Can Vercel Sandbox run stdio-based MCP servers like agent-browser? Yes, because Vercel Sandbox commands now support stdin, you can exchange messages with stdio MCP servers such as agent-browser by writing to and reading from a running command's standard input and output streams inside the sandbox. _Teams running MCP servers in sandboxed infrastructure can keep tabs on platform updates via daily.dev._ ## Similar posts on daily.dev - [Vercel Sandbox tutorial: run untrusted code safely](https://daily.dev/posts/vercel-sandbox-tutorial-run-untrusted-code-safely-ycdiv657b) · Flavio Copes · 1 upvotes · 1 comments - [Vercel Launches v0 API for Headless App Building](https://daily.dev/posts/vercel-launches-v0-api-for-headless-app-building-cibatalc3) · InfoQ · 0 upvotes · 0 comments - [Getting started with the CircleCI CLI for coding agents](https://daily.dev/posts/getting-started-with-the-circleci-cli-for-coding-agents-z5nci5cdi) · CircleCI · 0 upvotes · 0 comments - [Vercel Sandbox supports forking](https://daily.dev/posts/vercel-sandbox-supports-forking-vv1osmj3n) · Vercel · 3 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python), [#typescript](https://daily.dev/tags/typescript), [#mcp](https://daily.dev/tags/mcp) [View this post on daily.dev](https://daily.dev/posts/vercel-sandbox-commands-now-support-stdin-kppx8dmkf) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Vercel Sandbox commands now support stdin","url":"https://daily.dev/posts/vercel-sandbox-commands-now-support-stdin-kppx8dmkf","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/vercel-sandbox-commands-now-support-stdin-kppx8dmkf"},"datePublished":"2026-10-26T17:35:44.596Z","dateModified":"2026-10-26T17:37:00.328Z","description":"Vercel Sandbox commands now accept input through standard input (stdin). 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You can also pass a Node.js readable stream, such as process.stdin, as the stdin value, and the SDK forwards the stream's data and closes the command's input automatically when the stream ends. Developers wiring stdio-based tools into sandboxed environments can track SDK changes like this on daily.dev."}},{"@type":"Question","name":"How do I write to a process's stdin in Vercel Sandbox using the Python SDK?","acceptedAnswer":{"@type":"Answer","text":"Pass stdin=subprocess.PIPE when creating the process with create_process(), then call server.stdin.send() with bytes to write data. Call communicate() to close stdin, collect any remaining output, and wait for the process to exit. For input known entirely upfront, pass it directly via the input argument to run_process() instead. 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