Just Compatible

Just Compatible

Just Compatible is a server-side compatibility and safe migration framework for Minecraft 1.21.1 on NeoForge. Install it on the server together with Just Core; vanilla clients can connect normally.

The mod helps other mods keep working when a server changes dimensions or uses multiple Overworld-like worlds. Integrations activate automatically only when their target mods are present, and use capability detection instead of fixed dependency version ranges.

Included integrations

• Waystones: safely repairs dimension references after a world migration while preserving waystone UUIDs and player discoveries. Repairs require matching UUID and position evidence, create a backup first, and roll back the entire in-memory batch if index rebuilding fails.
• Vinery: uses the greatest active server-dimension clock so existing wine does not lose its aging progress when the primary world changes.
• Starcatcher: recognizes Overworld-, Nether-, and End-like dimensions from their vanilla dimension effects instead of hardcoded world identifiers.
• Bountiful Baubles: reconciles stale Bountiful Baubles player attributes after login or dimension travel and reapplies rolls from currently equipped curios.

Safety

The mod does not hardcode dimension names and does not rewrite chunks, inventories, or level.dat. Unknown or ambiguous migration records are reported and left untouched. Waystones is the only integration that performs persistent migration, and it always creates a JSON backup before applying verified changes.

Use /justcompatible scan for diagnostics and a Waystones dry run. Use /justcompatible repair to apply only unambiguous Waystones migrations.