Fix lpVec3 packet endianness

[GenerelSchwerz]

Problem

lpVec3 reads and writes its 32-bit word as little-endian, while Minecraft uses FriendlyByteBuf.readUnsignedInt / writeInt (big-endian). This silently corrupts nonzero entity velocity vectors on 1.21.9+.

Fix

• Read and write the packed 32-bit word as big-endian.
• Preserve the datatype’s native blocks-per-tick values; version-aware consumers can distinguish it from legacy vec3i16 using Add feature flag for lpVec3 entity velocity minecraft-data#1206.
• Add decode and byte-exact round-trip coverage using payloads captured from vanilla 1.21.11.

This is an alternative to #1494: it keeps protocol datatype units native instead of converting lpVec3 into legacy 1/8000 units.

Validation

• npx standard src/datatypes/lpVec3.js test/lpVec3Test.js
• npx mocha test/lpVec3Test.js

[Copilot]

Pull request overview

Fixes lpVec3 encoding/decoding to match Minecraft’s on-wire big-endian 32-bit word layout (preventing silent corruption of nonzero velocity vectors on 1.21.9+), and adds regression coverage using real 1.21.11 payloads.

Changes:

• Switch lpVec3 read/write of the 32-bit portion to big-endian and align byte layout with packed = c << 16 | b << 8 | a.
• Refactor packing/unpacking bit extraction to avoid 32-bit bitwise truncation.
• Add mocha tests covering zero-vector decoding and byte-exact round-trips of captured vanilla payloads.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/datatypes/lpVec3.js	Updates lpVec3 serialization/deserialization to big-endian and adjusts packing/unpacking implementation.
test/lpVec3Test.js	Adds targeted decode + exact round-trip tests using real 1.21.11 payloads.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[GenerelSchwerz]

Failing tests are redundant there, its the fault of the test, not me.