preview

Installation
SKILL.md

Windmill Preview Workflow

Use this skill any time the user wants to see, open, navigate to, visualize, or preview a flow, script, or app — and any time you've just finished writing one and want to offer visual verification.

The Windmill dev page renders the flow graph / script editor, lets the user step through steps, and live-reloads on every save. It runs locally via wmill dev and is reached on a localhost port.

Two independent decisions

1. Mode: proxy or direct?

wmill dev runs in two modes; pick by asking what kind of URL whatever will display the preview needs.

  • Proxy (--proxy-port <port>) — exposes the dev page on http://localhost:<port>/. Use it when the embedder you'll hand the URL to only accepts localhost URLs (most in-IDE / in-chat preview embedders do, because they sandbox cross-origin loads).
  • Direct (default) — the user's browser loads the dev page from the remote workspace's HTTPS URL; the local wmill dev only runs the WebSocket back-channel for live reload. Use it when the URL will be opened in a regular browser tab.

Default to direct unless you have a specific embedder that needs localhost.

2. Who starts the server?

Installs
8
First Seen
Jun 9, 2026
preview — windmill-labs/windmill-cli-docs