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@github-actions github-actions released this 28 Sep 15:29
· 21 commits to main since this release
v3.0.0
c15e7e1

ObserverLauncher 3.0.0

ObserverLauncher can now run without its window. That sounds strange for a desktop app, but it is the point: the same launcher that runs your server from the GUI can now run as a plain background program — started from a command line, or driven entirely by an AI assistant over the Model Context Protocol (MCP).

If you only ever use the window, nothing changes. Same screens, same buttons, same look. The new power sits underneath, and the window uses the exact same machinery.

This is the plain-English release note. Developers: see the full technical changelog in CHANGELOG.md.

You can now run a server from the command line

There is a new observer command. It gives you the everyday actions without opening the app:

observer status      # is the server running, where is the folder, which Java
observer start       # start the server
observer stop        # stop it gracefully
observer logs        # the last lines of the console
observer players     # who is online / whitelisted / banned
observer backup      # make a world backup
observer doctor      # a full health report
observer list        # all your server instances
observer install ... # install a plugin or mod from a marketplace

Add --json to any of them and the output becomes machine-readable, so you can script it. Add --instance <id> to target one specific server.

You can set a server up from a template

Instead of walking through the wizard and picking plugins by hand, you can start from a ready-made recipe:

observer templates                          # list the recipes
observer init --template survival-5         # show the steps to build it

Three ship today:

  • survival-5 — a Paper survival server, tuned for up to 5 players.
  • creative-build — a Paper creative world with WorldEdit for fast building.
  • modded-performance — a Fabric server with a performance mod set (lithium, ferritecore, krypton).

init prints the exact steps it would run; the same steps are the same actions the app already knows how to do, so nothing is magic.

The app can run with no window at all

A new background mode starts the whole backend — the server manager, metrics, backups, the scheduler and the MCP server — with no window. It is the same code the window uses, so your settings, your server folders and your instances all carry over. Close it with Ctrl+C and it shuts down cleanly.

This is what makes the next part possible.

An AI can now manage a headless server

The app has spoken MCP for a while. Until now that always meant the app was open. Now the MCP server can run in the background with no window, so an assistant can connect and manage a server on a machine that has no desktop at all.

The safety rules are unchanged and now explicit: with no one to click a confirmation box, write and destructive actions are refused by default (and recorded in the audit log). If you want to allow specific ones for automation, you can opt in.

A health check for unattended setups

When the MCP server is running, it answers a simple GET /health with “yes, I’m alive” plus the version — no password needed. That is what a container or a monitoring tool asks. Everything that can do something still needs the secret token.

A better record of what an assistant did

The audit log — the list of write and destructive actions an assistant performed — is now stored as structured entries and keeps its history: instead of throwing everything away when it gets large, it rolls over to older files, so you can still see what happened days ago.

Linux is now officially verified

For a long time the Linux build came with a caveat: it was written and reasoned about on Windows, but nobody had actually run it on a real Linux machine. That caveat is gone.

Every change is now checked on a real Linux kernel automatically — the unit tests, the full app test, and, for the first time, a test that downloads a real Paper server, boots it, waits for it to finish starting, and shuts it down cleanly. The Linux-specific parts (finding the server process, reading its memory and CPU, making and restoring a backup) are exercised for real rather than assumed. If a Linux-only problem ever slips in, the build turns red before it reaches you.

What did not change

  • The window. No new buttons, no moved screens, no colour or layout changes. If 3.0.0 looks identical to 2.6.0, that is on purpose.
  • Your settings and servers. They carry straight over; there is no migration and nothing to re-configure.
  • The confirmation rules. Write and destructive actions still need approval wherever a person is present.

What is coming next

3.0.0 is the foundation. On top of it:

  • 3.1.0 — Docker: package a headless server as a container.
  • 3.2.0 — CI/CD for modpacks: verify and boot-test a modpack automatically.
  • 3.3.0 — Remote management: check on your server from elsewhere, designed to be safe by default.

Developer notes: npm test (68 files) passes. New: a headless entry point, an observer CLI, server templates, an MCP /health endpoint, JSONL audit with rotation, an explicit headless confirm policy, and Linux verified on a real kernel (unit + E2E + a real server boot in CI). The GUI shares every line of backend code with the headless mode.

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