[Feature Request] Allow Codex CLI to automatically start Live Preview for a specified HTML file

Background

I frequently use Codex CLI inside VS Code, and it has become a very useful part of my workflow.

Recently, I noticed that the Claude Code team open-sourced a skill called eli5. It converts Markdown explanations into clearer and more readable HTML pages, then displays them beside the editor. This creates an experience similar to explaining a concept to a five-year-old with a visual artifact.

At the moment, neither Codex CLI nor Claude Code CLI appears to provide built-in Artifacts support. Since this project already provides Live Preview functionality, I would like to use it to create a similar automatic HTML preview workflow.

Current Problem

Live Preview does not currently appear to provide a documented way for an external tool, such as Codex CLI, to open the preview window for a specific HTML file.

The current workflow is:

1. Ask Codex CLI to generate an HTML file;

2. Run:

   code -r /path/to/index.html
   

3. Manually click the Live Preview button in VS Code.

This requires an extra manual step and prevents the workflow from being fully automated.

Expected Behavior

Live Preview should allow an external tool to specify an HTML file and:

• Automatically start Live Preview for that file without opening the corresponding HTML file in the editor;
• Open or focus the preview beside the current editor;
• Show a clear error when the file does not exist or cannot be previewed.

No source files or tests are named in the issue. Start by locating the Live Preview command and the extension entry point that starts a preview for an HTML file, then trace how an external file path could be supplied without opening the editor. Done means an external tool can start or focus the preview and receives clear errors for missing or unpreviewable files.