Preview Dev Servers

    Use this guide to start a project dev server, register it with Sero, and open the preview URL.

    This page is task-focused. To choose Host, Apple Container, or Docker / Podman first, see Choose a Workspace Runtime. For the exact support matrix, see Support Scope.

    Before you start

    • Open the project as a Sero workspace.
    • Confirm which runtime the workspace uses.
    • Use the path style for that runtime:
      • Host: commands run in the real workspace folder on your computer.
      • Container runtimes: commands run inside the selected container, where the primary project is mounted at /workspace.

    Host path caveat: /workspace is for container runtimes except Sero compatibility aliases. Do not use /workspace as a Host shell path.

    Start and register a Host dev server

    Host is the default on supported platforms. Start the server normally from your project folder:

    npm run dev

    Register the port and command Sero should show:

    sero devserver register --name "Web app" --port 3000 --command "npm run dev" --framework vite

    Open the registered 127.0.0.1 URL from Dev Servers in Explorer, or ask the agent to preview it.

    Start and register a container dev server

    For Apple Container or Docker / Podman, start the server inside the workspace runtime. Many frameworks need the server to bind to all interfaces inside the container:

    npm run dev -- --host 0.0.0.0

    Register the same port and command:

    sero devserver register --name "Web app" --port 3000 --command "npm run dev -- --host 0.0.0.0" --framework vite

    Open the forwarded loopback URL from Dev Servers in Explorer, or ask the agent to preview the registered URL. Do not use a container IP.

    List and stop registered servers

    sero devserver list
sero devserver stop <id>
    CommandUse it for
    sero devserver listList registered servers for the current workspace.
    sero devserver register --name <name> --port <port> --command <cmd> [--framework <name>]Add a server entry with the command Sero can show or restart.
    sero devserver stop <id>Stop the entry through the active workspace runtime. For a Host server that you started outside Sero, this marks the entry stopped but does not kill your process.

    The registry is in memory. Re-register servers after restarting the app if the entry is gone or the URL changed.

    Preview the app

    Use one of these paths:

    • Open the server from Dev Servers in Explorer.
    • Run sero devserver list and open the current URL.
    • Ask the agent to preview the registered URL.
    • Use the CLI preview command when you already have a URL:
    sero app preview <registered-url>

    Troubleshooting quick checks

    • Server works in the terminal but preview fails in a container: restart it with a 0.0.0.0 bind option if your framework requires one.
    • Host preview fails: confirm the reported 127.0.0.1 URL opens in your normal browser.
    • URL stopped working after a restart: run sero devserver list, then open the fresh URL or register the server again.
    • A Host process continues after stop: stop it in the terminal where you started it. Sero does not kill a Host process that it only registered.
    • Selected container runtime is unavailable: fix Apple Container, Docker, or Podman, or explicitly choose another supported runtime. Sero does not silently switch a selected container workspace to Host.