SpaceSimulation

Orbital mechanics (new orbital/ package + network package + mixin):

• Inverse-square gravitational field of the sun at the world origin, velocity Verlet numerical integration per tick, driving the player and all entities; μ defaults to 6.25e6 blocks³/tick² (circular orbit at 1 million blocks = 2.5 blocks/tick = 50 m/s), configurable, 0 disables.
• Server authoritative: the server integrates based on client input masks, ignores client position packets, and sends down authoritative state; the client predicts with the same integrator, reconciles by input sequence number, and only rolls back and replays when deviation exceeds orbitalCorrectionBlocks (default 1 block).
• No ticking while offline: on logout, osculating Keplerian elements are saved; on login, propagation is resolved according to server ticks (elliptical/hyperbolic).
• Initial orbit: remove the old 5,000,000–10,000,000-block safe ring; on first join and death respawn, assign to a random orbit at 1,000,000–1,500,000 blocks (inner asteroid belt), with inclination/eccentricity constrained to stay within the thin disk of the ring.
• New /orbit command (info / circular / mu); F3 displays radius, velocity, elements, and prediction correction count.
• Neutralize two vanilla traps: absMoveTo rollback on connection tick, and aiStep zeroing of velocity components <0.003.

Asteroid system:

• asteroid_type refactored into 15 types × 6 variants = 90 structure NBTs (10 in the inner belt, 11 in the outer belt, weights balanced), retiring the split core_*_1/2/3 naming.
• New asteroidMuFollowPlayerOrbital (default on), asteroid orbits follow player μ, allowing escort flight and landing.
• Materialization radius 1500→2000, cap 8→16, interval 100→40 ticks; staging area chunk radius tightened, unload logging added.

Other:

• Players are immune to void damage (fall speed cleared, can fly back on their own).
• Rapier rebase-based global chunk retransmission changed to frame-sliced (10 ms budget per physics frame), with precise self-checks and removal of per-frame magnitude false positives.
• New perfStatsEnabled: one line every 60 seconds with server tick time/TPS/entities/chunks/asteroids/heap memory.
• Clean up client test classes TestFlow, AimDiagTest, SphereVisualTest, AimDiagnostics mistakenly committed during 0.2.0, as well as the screenshot hook and captureScreenshot in WorldSphereRenderer.
• Docs: README.md / README_EN.md / MOD_INTRO.md upgraded to 0.3.1-beta, adding orbital mechanics, new commands, new config tables, and known issues; CI checkout adds fetch-depth: 0 to generate Release notes from tag annotations.