Built-in tools›Preview

Group

Preview

Turned on by

Any other preview tool being on.

Approval

Reviewed: writes and open-ended actions ask for approval unless the security level or an earlier “Always allow” covers them.

Profile key

tool.preview_start.description

Starts a dev server from the workspace's .mework/launch.json and points the conversation's preview page at it.

A server already running for that entry is reused. Always set port in each launch.json entry; otherwise Mework takes it from a localhost url, PORT in env, or a --port or -p argument, and falls back to 3000.

Limits

• Up to 5 dev servers per workspace folder, across all conversations.
• A server that exits within 3 seconds has failed; its output is in the result.

Good to know

• The pane does not open by itself; open Preview in the top bar to see the page.
• On an SSH workspace the server runs on that machine, and localhost in the page means that machine. WSL workspaces have no previews.
• On macOS, a project in Documents, Desktop or Downloads may need Mework allowed in System Settings → Privacy & Security → Files and Folders.

Parameters