First make sure the development server is actually running. A preview displays that server; it does not start your application by itself.
Use the entry you already have
| Starting point | Action |
|---|---|
| Terminal output contains a recognized development URL | Use the terminal's preview button. |
| A saved project action starts the server | Open its preview, or enable its automatic preview option. |
| You want to enter another address | Open the session menu and choose Open browser panel. |
The browser-panel action is a menu item, not a permanent globe button in the header. Electron direct connections can use the native browser; Relay and other supported hosts use the preview proxy/iframe path.
Attach evidence from the loaded page
For a loopback development page, the preview toolbar offers inspection and console controls once the page bridge is ready. Select an element or relevant console output and attach it to the current conversation. These controls are not promised for arbitrary third-party pages. They give the Agent a concrete target instead of a description such as “the button over there.”
For remote development, confirm whose localhost the address refers to. An SSH forward is an option for desktop connections when the service needs a local port.