Developer Getting Started

Who this is for: programmers who want to write Data Center mods on gregCore. Players start at Player Getting Started.

Which language?

Language	Extension	Runtime	Status	Pick it when…
Lua	.lua	MoonSharp 2.0.0 (soft sandbox)	Production Ready, full API	You start fresh — biggest API, examples, REPL, hot-reload
JavaScript/TypeScript	.js (+ .ts via tsc)	Jint 4.8.0	UI-focused SDK (toasts, panels, menus, settings, hooks) + main-menu HotLoad	You prefer JS/TS and build UI mods fast
Python	.py	pythonnet 3.0.5	Beta, basic	You prefer Python and need only the small bridge surface
C#	.dll / .cs	MelonLoader + Harmony	Production Ready	You edit the world (spawn, cables, patches), need max power
Rust	.dll (from .rs via cargo)	Native cdylib (RustFFIBridge)	Native SDK (economy, world, tech, time, game, UI, events, hooks, config)	You ship native logic with a safe bindings layer
Go	FFI	C ABI (GameApiTable)	Alpha	You ship native logic via the FFI bridge

Lua is the recommended default. C# is required for world editing (spawning, cable ops, custom Harmony patches) — Lua deliberately cannot do those (see Core Events “Out of scope”).

The mod contract (all languages)

Every mod honors the same lifecycle + registry contract (docs/modding/gregcore-vertrag.md):

• Register what you are: GregModRegistry.Register(id, name, version, menus) (C#) or mod.json (id, name, version, entry, min_framework_version) for Lua.
• Report UI honestly: GregMenuRegistry.RegisterOpener / RegisterCloser / SetOpen, HUD rows via GregHudRegistry.Register(modId, key, label). The F1 Hub renders exactly what you report — no opener, no Open button.
• Respect saves: user settings → config, runtime state → save/sidecar, never vanilla structures directly (Core Save Engine).
• Respect co-op: local-only, no second transport (Developer Native Coop).
• Soft dependency: C# mods probe GregHost.HasCore with a JIT-split so they load (degraded, not crash) without gregCore.

Learning path

1. Developer Environment — SDK, references, build, test (once).
2. Developer First Lua Mod or Developer First CSharp Mod — your first working mod.
3. Developer Events Hooks Guide + Developer Timers Coroutines — react to the game + schedule work.
4. Developer Data Storage + Developer UI Panels HUD — persist + show.
5. Specialty: Developer Shop Items, Developer Hardware IDs Inventory, Developer Harmony IL2CPP, Developer Scripting Bridges.
6. Ship: Developer Best Practices → Developer Publishing.

Conventions you must follow from day one

• Conventional Commits (feat:, fix:, docs:, chore: …), one logical change per commit; never push --force or rewrite history unasked.
• Docs sync: new features update README.md + docs/ + CHANGELOG.md (Unreleased).
• No secrets in repos (keys/tokens/.env — env vars only); no generated artifacts (bin/, obj/, dist/) in commits.
• Verify before declaring done: build + test what the repo offers (QUICKSTART.md: dotnet build -c Release, DOTNET_ROLL_FORWARD=Major dotnet test, python3 scripts/validate_version.py <VERSION>).