Horizon no longer fetches anything of Minecraft from Mojang's servers. The
client jar, version JSON, libraries and assets come from the user's official
launcher install, and the server jar is one they downloaded themselves
(--server-jar or HORIZON_SERVER_JAR). Every file is checked against checksums
pinned in research-lock.json, and the prepared .local/ layout is byte-identical
to the old downloads, so the harnesses and the native client are unchanged.
CI keeps the offline checks on GitHub's runners; the vanilla comparisons and
the mod build need the game, so they move to a manual job on a self-hosted
runner that holds the maintainer's own copy.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Ludovic Marie