hamshamb
all work

labMINECRAFT · NETWORKING · JAVA

Nexus

"send them a code and let them join my world" turned out to be a networking project.

an experimental Fabric mod for sharing a Minecraft Java single-player world through a short invite code.

the distance between "open to LAN" and "the internet" is apparently an architecture diagram.

Nexus wordmark: white italic letters with a blue swoosh, on black.
released
status
lab
what i did
Protocol design + Fabric development
links
read the code

what it is

Nexus is an experimental Fabric mod for sharing a Minecraft Java single-player world through a short invite code.

aug 31, 2026: Published the development build for invite-code hosting, local coordination, authenticated bridging, and explicit release gates.

why i made it

the annoying bit.

i wanted to send someone a code and have them join my minecraft world.

turns out that is not a small problem.

the problem

what was actually wrong.

Open to LAN works on a local network. The moment the other player is somewhere else, the simple idea turns into session discovery, admission, transport, authentication, expiry, abuse controls, and a lot of ways to get it wrong.

under the hood

what i actually built.

The code is split into session state machines, a versioned protocol, short-lived admission capabilities, coordination services, transport contracts, and a Fabric bridge that keeps normal Minecraft authentication in the loop.

important detailsthe technical bits.

  1. Host and join screens inside a Fabric mod
  2. Short-lived, single-use admission capabilities with replay protection
  3. Session creation, joining, heartbeats, expiry, and cleanup
  4. Reliable ordered transport contracts with backpressure and lifecycle handling
  5. Seven modules separating protocol, client, backend, transport, and Minecraft code
  6. Threat model, evidence ledger, and public release gates

countedactual numbers.

gradle modules
7
use per invite
1

what workedwhere it is now.

The local bridge and invite-code flow work as a development system. Internet transport and a verified two-account join are still blockers. It is a real experiment, not a finished product wearing a launch badge.

what is still not donethe honest bit.

statusInternet transport is not implemented yet. The full two-account join still needs manual verification.

stackbuilt with.

  • Java
  • Fabric
  • Gradle
  • TCP
  • protocol design
  • security
inspect the source