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 localhost URL from Explorer's dev-server panel, 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 preview URL from Explorer's dev-server panel, or ask the agent to preview the registered URL.

List and stop registered servers#

sero devserver list
sero devserver stop <id>

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 Explorer's dev-server panel.
• 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 same localhost URL opens in your normal browser on the host.
• URL stopped working after a restart: run sero devserver list, then open the fresh URL or register the server again.
• Stop does nothing: copy the exact server id from sero devserver list and run sero devserver stop <id>.
• 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.

Related docs#

• Choose a Workspace Runtime
• Explorer
• Browser and Capture
• Container Isolation
• Sero CLI
• Troubleshooting