Extensions

Extensions add features without touching the launcher binary: custom pages, batch operations on instances, third-party integrations, multiplayer helpers.

Want to start from code?

Template repos for six languages are ready: Language templates. Clone one, change the id, and ship.

Layout

my-ext/
├─ manifest.json     id, name, version, runtime, entry, permissions
├─ main.jar          entry point (.py / .js / .exe also fine)
└─ lib/              optional dependencies

Drop it into extensions/ inside the data directory and it shows up under Settings → Extensions.

See Import & manage for importing, permissions and the per-extension buttons.

Trust

The first load hashes the whole package and records it in extensions/trusted.json:

{
  "hello-go": { "sha": "9f2c…", "enabled": true }
}

• Any change to the package breaks the hash, and the launcher refuses to load it.
• This is tamper detection, not antivirus. Do not install extensions from untrusted sources.
• Disabling only flips enabled to false; files stay untouched.

Lifecycle

scan → read manifest → validate → compare trusted.json
  → check runtime → extract to temp (chmod +x for native)
  → spawn entry process → stdio channel → hello
  → runtime messages
  → exit / disable → cleanup

Extensions run as separate processes. A crash never takes the launcher down, and the launcher reaps child processes when it exits.

Permissions

Permission	Meaning
fs.read	Read the data directory
fs.write	Write the data directory
net	Network requests
process	Spawn child processes
ui	Dialogs, notifications, custom pages
launch	Trigger a game launch

Undeclared calls are rejected and logged.

Size limits

Item	Limit
Single file	8 MiB
Extracted package	16 MiB
manifest.json	64 KiB

Native binaries hit the limit quickly — strip before packing:

go build -ldflags "-s -w" -o main.exe .
cargo build --release && strip target/release/my-ext

Next

• Import & manage
• Runtimes and packing
• Host API