Persistent preview

By default a preview container idles down when it is not in use. Persistent preview keeps it warm for as long as the workspace exists, so a web app, API, bot, or site stays reachable at a stable URL.

Turn it on

Open Workspace settings -> Preview and enable Persistent preview. While it is on:

• The container is not idle-evicted.
• Your startup command runs every time the container starts.

What persists and what does not

This is the most important thing to understand before you rely on it.

• Durable: your workspace files. They are stored independently of the container and rebuilt into it on every start. Edits survive restarts and recreations.
• Not durable: anything that exists only inside the running container - a local SQLite/Postgres file written at runtime, uploaded-at-runtime scratch files, in-memory state. These are lost when the container is recreated.

For data that must survive restarts, use an external database or store and connect to it from your app.

Startup command

Set what runs when the container boots. Examples:

# Serve a static site
typelets-static --dir /workspace --port 3000

# Start a Node app
npm install && npm run start

Output from the startup command is captured to /workspace/.typelets-startup.log. Tail it from the workspace terminal to debug a startup that is not coming up:

tail -f /workspace/.typelets-startup.log

If you change the startup command while persistent preview is on, Typelets restarts the preview so the new command takes effect.

Restarting the preview

If your app wedges, crashes into a bad state, or you have published new files, restart the preview from Workspace settings -> Preview -> Restart preview. This recreates the container from a clean state and rebuilds its filesystem from your stored files.

Your workspace files are preserved across a restart. Only in-container state is discarded, and the next load pays a short cold start.

Crash behavior

A persistent container is configured to restart on failure. If the whole container goes down it is brought back and the startup command runs again. Note that if your app process crashes but the container itself stays up, it is not automatically respawned - restart the preview, or have your startup command supervise the process.

Limits

Persistent workspaces run inside a sandboxed microVM with CPU and memory caps, the same as standard workspaces. The exact limits are shown in the workspace settings dialog.