docs(sandboxes): document non-interactive sbx login with PAT

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dvdksn

content/manuals/ai/sandboxes/get-started.md

@@ -123,6 +123,20 @@ option.
 > See the [FAQ](faq.md) for details on why sign-in is required and what
 > happens with your data.
 
+### Non-interactive login
+
+For CI environments and scripts where a browser is not available, use a
+Docker Personal Access Token (PAT) with `--username` and `--password-stdin`:
+
+```console
+$ echo "$DOCKER_PAT" | sbx login --username <your-docker-id> --password-stdin
+```
+
+`--password-stdin` reads the token from standard input to keep it out of
+your shell history. Generate a PAT from your
+[Docker account settings](https://app.docker.com/settings/personal-access-tokens)
+with at least **Read** scope.
+
 ## Authenticate your agent
 
 Agents need credentials for their model provider. How you provide them depends