{"id":207,"date":"2026-02-09T00:00:00","date_gmt":"2026-02-09T00:00:00","guid":{"rendered":"https:\/\/wordpress.securinsight.ca\/index.php\/2026\/02\/09\/agents-interactive-browser-terminals-in-sandboxes-2\/"},"modified":"2026-02-09T00:00:00","modified_gmt":"2026-02-09T00:00:00","slug":"agents-interactive-browser-terminals-in-sandboxes-2","status":"publish","type":"post","link":"https:\/\/wordpress.securinsight.ca\/index.php\/2026\/02\/09\/agents-interactive-browser-terminals-in-sandboxes-2\/","title":{"rendered":"Agents &#8211; Interactive browser terminals in Sandboxes"},"content":{"rendered":"<p>The <a href=\"https:\/\/github.com\/cloudflare\/sandbox-sdk\" target=\"_blank\">Sandbox SDK<\/a> now supports PTY (pseudo-terminal) passthrough, enabling browser-based terminal UIs to connect to sandbox shells via WebSocket.<\/p>\n<h4><code>sandbox.terminal(request)<\/code><\/h4>\n<p>The new <code>terminal()<\/code> method proxies a WebSocket upgrade to the container&#8217;s PTY endpoint, with output buffering for replay on reconnect.<\/p>\n<ul>\n<li>\n<p>JavaScript<\/p>\n<div>\n<div>\n<figure>\n<pre data-language=\"js\"><code class=\"language-js\"><div><div><span>\/\/ Worker: proxy WebSocket to container terminal<\/span><\/div><\/div><div><div><span>return<\/span><span> <\/span><span>sandbox<\/span><span>.<\/span><span>terminal<\/span><span>(<\/span><span>request<\/span><span>,<\/span><span> <\/span><span>{<\/span><span> cols<\/span><span>:<\/span><span> <\/span><span>80<\/span><span>,<\/span><span> rows<\/span><span>:<\/span><span> <\/span><span>24<\/span><span> <\/span><span>}<\/span><span>)<\/span><span>;<\/span><\/div><\/div><\/code><\/pre>\n<div>\n<div><\/div>\n<\/div>\n<\/figure>\n<\/div><\/div>\n<\/li>\n<li>\n<p>TypeScript<\/p>\n<div>\n<div>\n<figure>\n<pre data-language=\"ts\"><code class=\"language-ts\"><div><div><span>\/\/ Worker: proxy WebSocket to container terminal<\/span><\/div><\/div><div><div><span>return<\/span><span> <\/span><span>sandbox<\/span><span>.<\/span><span>terminal<\/span><span>(<\/span><span>request<\/span><span>,<\/span><span> <\/span><span>{<\/span><span> cols<\/span><span>:<\/span><span> <\/span><span>80<\/span><span>,<\/span><span> rows<\/span><span>:<\/span><span> <\/span><span>24<\/span><span> <\/span><span>}<\/span><span>)<\/span><span>;<\/span><\/div><\/div><\/code><\/pre>\n<div>\n<div><\/div>\n<\/div>\n<\/figure>\n<\/div><\/div>\n<\/li>\n<\/ul>\n<h4>Multiple terminals per sandbox<\/h4>\n<p>Each session can have its own terminal with an isolated working directory and environment, so users can run separate shells side-by-side in the same container.<\/p>\n<ul>\n<li>\n<p>JavaScript<\/p>\n<div>\n<div>\n<figure>\n<pre data-language=\"js\"><code class=\"language-js\"><div><div><span>\/\/ Multiple isolated terminals in the same sandbox<\/span><\/div><\/div><div><div><span>const<\/span><span> <\/span><span>dev<\/span><span> <\/span><span>=<\/span><span> <\/span><span>await<\/span><span> <\/span><span>sandbox<\/span><span>.<\/span><span>getSession<\/span><span>(<\/span><span>\"dev\"<\/span><span>)<\/span><span>;<\/span><\/div><\/div><div><div><span>return<\/span><span> <\/span><span>dev<\/span><span>.<\/span><span>terminal<\/span><span>(<\/span><span>request<\/span><span>)<\/span><span>;<\/span><\/div><\/div><\/code><\/pre>\n<div>\n<div><\/div>\n<\/div>\n<\/figure>\n<\/div><\/div>\n<\/li>\n<li>\n<p>TypeScript<\/p>\n<div>\n<div>\n<figure>\n<pre data-language=\"ts\"><code class=\"language-ts\"><div><div><span>\/\/ Multiple isolated terminals in the same sandbox<\/span><\/div><\/div><div><div><span>const<\/span><span> <\/span><span>dev<\/span><span> <\/span><span>=<\/span><span> <\/span><span>await<\/span><span> <\/span><span>sandbox<\/span><span>.<\/span><span>getSession<\/span><span>(<\/span><span>\"dev\"<\/span><span>)<\/span><span>;<\/span><\/div><\/div><div><div><span>return<\/span><span> <\/span><span>dev<\/span><span>.<\/span><span>terminal<\/span><span>(<\/span><span>request<\/span><span>)<\/span><span>;<\/span><\/div><\/div><\/code><\/pre>\n<div>\n<div><\/div>\n<\/div>\n<\/figure>\n<\/div><\/div>\n<\/li>\n<\/ul>\n<h4>xterm.js addon<\/h4>\n<p>The new <code>@cloudflare\/sandbox\/xterm<\/code> export provides a <code>SandboxAddon<\/code> for <a href=\"https:\/\/xtermjs.org\/\" target=\"_blank\">xterm.js<\/a> with automatic reconnection (exponential backoff + jitter), buffered output replay, and resize forwarding.<\/p>\n<ul>\n<li>\n<p>JavaScript<\/p>\n<div>\n<div>\n<figure>\n<pre data-language=\"js\"><code class=\"language-js\"><div><div><span>import <\/span><span>{<\/span><span><span> <\/span><span>SandboxAddon<\/span><span> <\/span><\/span><span>}<\/span><span> from <\/span><span>\"@cloudflare\/sandbox\/xterm\"<\/span><span>;<\/span><\/div><\/div><div><div>\n<\/div><\/div><div><div><span>const<\/span><span> <\/span><span>addon<\/span><span> <\/span><span>=<\/span><span> <\/span><span>new<\/span><span> <\/span><span>SandboxAddon<\/span><span>(<\/span><span>{<\/span><\/div><\/div><div><div><span>  <\/span><span>getWebSocketUrl<\/span><span>:<\/span><span> <\/span><span>({<\/span><span> <\/span><span>sandboxId<\/span><span>,<\/span><span> <\/span><span>origin<\/span><span> <\/span><span>})<\/span><span> <\/span><span>=&gt;<\/span><\/div><\/div><div><div><span>    <\/span><span>`<\/span><span>${<\/span><span>origin<\/span><span>}<\/span><span>\/ws\/terminal?id=<\/span><span>${<\/span><span>sandboxId<\/span><span>}<\/span><span>`<\/span><span>,<\/span><\/div><\/div><div><div><span>  <\/span><span>onStateChange<\/span><span>:<\/span><span> <\/span><span>(<\/span><span>state<\/span><span>,<\/span><span> <\/span><span>error<\/span><span>)<\/span><span> <\/span><span>=&gt;<\/span><span> <\/span><span>updateUI<\/span><span>(<\/span><span>state<\/span><span>)<\/span><span>,<\/span><\/div><\/div><div><div><span>}<\/span><span>)<\/span><span>;<\/span><\/div><\/div><div><div><span>terminal<\/span><span>.<\/span><span>loadAddon<\/span><span>(<\/span><span>addon<\/span><span>)<\/span><span>;<\/span><\/div><\/div><div><div><span>addon<\/span><span>.<\/span><span>connect<\/span><span>(<\/span><span>{<\/span><span> sandboxId<\/span><span>:<\/span><span> <\/span><span>\"my-sandbox\"<\/span><span> <\/span><span>}<\/span><span>)<\/span><span>;<\/span><\/div><\/div><\/code><\/pre>\n<div>\n<div><\/div>\n<\/div>\n<\/figure>\n<\/div><\/div>\n<\/li>\n<li>\n<p>TypeScript<\/p>\n<div>\n<div>\n<figure>\n<pre data-language=\"ts\"><code class=\"language-ts\"><div><div><span>import <\/span><span>{<\/span><span><span> <\/span><span>SandboxAddon<\/span><span> <\/span><\/span><span>}<\/span><span> from <\/span><span>\"@cloudflare\/sandbox\/xterm\"<\/span><span>;<\/span><\/div><\/div><div><div>\n<\/div><\/div><div><div><span>const<\/span><span> <\/span><span>addon<\/span><span> <\/span><span>=<\/span><span> <\/span><span>new<\/span><span> <\/span><span>SandboxAddon<\/span><span>(<\/span><span>{<\/span><\/div><\/div><div><div><span>  <\/span><span>getWebSocketUrl<\/span><span>:<\/span><span> <\/span><span>({<\/span><span> <\/span><span>sandboxId<\/span><span>,<\/span><span> <\/span><span>origin<\/span><span> <\/span><span>})<\/span><span> <\/span><span>=&gt;<\/span><\/div><\/div><div><div><span>    <\/span><span>`<\/span><span>${<\/span><span>origin<\/span><span>}<\/span><span>\/ws\/terminal?id=<\/span><span>${<\/span><span>sandboxId<\/span><span>}<\/span><span>`<\/span><span>,<\/span><\/div><\/div><div><div><span>  <\/span><span>onStateChange<\/span><span>:<\/span><span> <\/span><span>(<\/span><span>state<\/span><span>,<\/span><span> <\/span><span>error<\/span><span>)<\/span><span> <\/span><span>=&gt;<\/span><span> <\/span><span>updateUI<\/span><span>(<\/span><span>state<\/span><span>)<\/span><span>,<\/span><\/div><\/div><div><div><span>}<\/span><span>)<\/span><span>;<\/span><\/div><\/div><div><div><span>terminal<\/span><span>.<\/span><span>loadAddon<\/span><span>(<\/span><span>addon<\/span><span>)<\/span><span>;<\/span><\/div><\/div><div><div><span>addon<\/span><span>.<\/span><span>connect<\/span><span>(<\/span><span>{<\/span><span> sandboxId<\/span><span>:<\/span><span> <\/span><span>\"my-sandbox\"<\/span><span> <\/span><span>}<\/span><span>)<\/span><span>;<\/span><\/div><\/div><\/code><\/pre>\n<div>\n<div><\/div>\n<\/div>\n<\/figure>\n<\/div><\/div>\n<\/li>\n<\/ul>\n<h4>Upgrade<\/h4>\n<p>To update to the latest version:<\/p>\n<div>\n<figure>\n<pre data-language=\"sh\"><code class=\"language-sh\"><div><div><span>npm<\/span><span> <\/span><span>i<\/span><span> <\/span><span>@cloudflare\/sandbox@latest<\/span><\/div><\/div><\/code><\/pre>\n<div>\n<div><\/div>\n<\/div>\n<\/figure>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>The Sandbox SDK now supports PTY (pseudo-terminal) passthrough, enabling browser-based terminal UIs to connect to sandbox shells via WebSocket. sandbox.terminal(request) The new terminal() method proxies a WebSocket upgrade to the container&#8217;s PTY endpoint, with output buffering for replay on reconnect. JavaScript \/\/ Worker: proxy WebSocket to container terminalreturn sandbox.terminal(request, { cols: 80, rows: 24 }); [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-207","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/posts\/207","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/comments?post=207"}],"version-history":[{"count":0,"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/posts\/207\/revisions"}],"wp:attachment":[{"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/media?parent=207"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/categories?post=207"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wordpress.securinsight.ca\/index.php\/wp-json\/wp\/v2\/tags?post=207"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}