v0.17.0 lets a game system arrive as a package rather than a built-in registry entry. A GM can inspect it, choose a world and review what it will add before the system runs.
Install a system
An installable system package can bring its own document types, sheets and starter content, plus the dependencies and services it needs. The listing and consent view show the package and its contents before world creation.
Required packages are checked before anything changes. A missing requirement stops the install instead of opening a partial world. Marketplace system code is not loaded into the world server.
Sheets and companion apps
The native path handles character and NPC sheets inside Aether's UI. A companion application can use a separate sandboxed frame for richer tools and import flows.
Native sheets keep Aether's rendering, focus, keyboard and permission behavior. The companion frame gets a typed bridge and only the access granted to it.
Upgrading a world
World Settings shows the installed system version and update state. Before an upgrade, the GM reviews what the new package will change.
Aether checkpoints the world, stages the new package, runs its migrations and checks the result before restarting it. A failed migration returns to the previous checkpoint. Startup refuses a missing or changed package until the exact installed version is restored.
Downgrades require a validated reverse migration. Existing worlds stay on their system; to use another one, create another world.