update /docs to new slash command arch (#4133)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/cli/src/ui/commands/docsCommand.ts

@@ -0,0 +1,37 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import open from 'open';
+import process from 'node:process';
+import { type CommandContext, type SlashCommand } from './types.js';
+import { MessageType } from '../types.js';
+
+export const docsCommand: SlashCommand = {
+  name: 'docs',
+  description: 'open full Gemini CLI documentation in your browser',
+  action: async (context: CommandContext): Promise<void> => {
+    const docsUrl = 'https://goo.gle/gemini-cli-docs';
+
+    if (process.env.SANDBOX && process.env.SANDBOX !== 'sandbox-exec') {
+      context.ui.addItem(
+        {
+          type: MessageType.INFO,
+          text: `Please open the following URL in your browser to view the documentation:\n${docsUrl}`,
+        },
+        Date.now(),
+      );
+    } else {
+      context.ui.addItem(
+        {
+          type: MessageType.INFO,
+          text: `Opening documentation in your browser: ${docsUrl}`,
+        },
+        Date.now(),
+      );
+      await open(docsUrl);
+    }
+  },
+};