On the client, evoker installs a pack as a Prism Launcher instance and keeps it up to date: every time you launch the instance, evoker checks the pack for updates first. Prism does everything else (accounts, downloading Minecraft, launching).

Prism is the only launcher supported for now.

Install evoker (see Getting Started) and Prism Launcher. evoker finds Prism's data folder in its usual place, and reads Prism's own settings (prismlauncher.cfg: InstanceDir, IconsDir) for where instances and icons go:

If Prism isn't there (a portable install), tell evoker where its instances are once:

evoker config instanceDir "D:\Games\Prism\instances"

evoker install https://raw.githubusercontent.com/me/pack/main/
evoker install --local ./my-pack

1. Fetches evoker.json, evoker.lock and the icon (see Pack URLs). The pack's side must include client.
2. Creates a Prism instance named after the pack. An instance with that name already managed by evoker is an error (use client update); an unrelated one with the same name gets a number appended.
3. Sets the instance's Minecraft and loader versions to the pack's.
4. Downloads every entry whose sides include client into the instance, checking each file against its locked hash, and the pack's client overrides.
5. Asks about each optional entry, showing its title and description. Without a console to ask in, optional entries are left out.
6. Sets the instance's pre-launch command to evoker client update.

Then launch the instance from Prism. A running Prism picks the new instance up by itself.

Before every launch, Prism runs evoker client update:

1. Fetches the pack again from where it was installed from.
2. Nothing changed: the launch continues.
3. Content changed: downloads and deletes files to match, then the launch continues with the new content.
4. New optional entries: a window asks whether to install them. The answers are remembered.
5. The game version or loader changed: evoker updates the instance, then stops the launch (by exiting with an error, which Prism treats as "don't launch") and shows a message, e.g. "My Pack was updated to Minecraft 1.21.5. Press Launch again." Prism reads the instance's versions before it runs the pre-launch command, so the new ones only take effect on the next launch.

Prism saves its own copy of mmc-pack.json about five seconds after loading it, which would undo the change. So when the versions change, evoker keeps the launch waiting about seven seconds and redoes the change if Prism saved over it. Every update also compares the instance's versions with the pack, not only what changed upstream, so anything that slips through is corrected on the next launch.

Launching is never blocked by updates: if the pack can't be fetched (offline, the URL is gone) or a file can't be downloaded, evoker warns and the game launches with what's installed. A file that doesn't match its locked hash is never installed.

Run it yourself any time:

evoker client update "My Pack"

evoker client options "My Pack"

Asks about every optional entry again, and installs or removes files to match.

evoker only touches files it installed. Mods, resource packs and shaders you add to the instance yourself stay, and so do your options, keybinds, worlds and screenshots.

In the instance folder:

The pack icon is copied to Prism's icons folder as evoker-<instance>.png (icon key evoker-<instance>).

If evoker.jar moves (reinstalling evoker to a different folder), run evoker client update <pack> once to fix the pre-launch command.

Data packs and plugins are server-only.