Opening a world saved by an older version runs the file fixes, level.dat and
the DataFixers upgrades of every file instead of refusing it. The save
round-trip harness treats a lit campfire's cooking progress as a timer in the
vanilla views: Horizon saves it as loaded (stage 3 checks it exactly), and it
moves on by however many ticks each vanilla server ran before data get.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The vanilla differential run showed Horizon writing fields vanilla leaves out: empty scoreboard parts, recipe book settings at their default, an empty warden anger list. These are now omitted, and mobs loaded without saved equipment no longer receive the default bow. Opening a world whose level.dat is older than 26.3 now fails with a message naming tools/upgrade_world.py, which runs vanilla's own forceUpgrade on a copy. The roundtrip harness lists the timing-dependent differences it tolerates, and horizon-ctl waits up to five minutes for the control socket on a loaded machine.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Add version-bound core, world data, geometry, generation and feature implementations with native client/server comparison tools and scoped evidence reports. Apply Horizon project branding.
Workspace tests, Clippy and 147 Python tests passed. Full 51-family survival and expanded provider comparisons are still running; complete gameplay parity and a playable Rust client remain unfinished. Private game artifacts and the isolated simple-block placement work are excluded.
Ludovic Marie