Just Compatible

Just Compatible

Server-side compatibility, safe world migration and preventive diagnostics for Minecraft 1.21.1 NeoForge. Install it only on the server together with Just Core; vanilla clients can connect normally.

Official downloads are available exclusively on CurseForge and Modrinth. GitHub contains source code, issues and changelogs, not mod binaries.

Three pillars

• World recovery: safely reconciles data after dimension or world-clock changes.
• Mod compatibility: targeted adapters for Waystones, Vinery, Starcatcher, Bountiful Baubles and vanilla Vaults.
• Server health: the early Mod Doctor reports explicit client-only JARs and conservative duplicate candidates before normal mod discovery.

Included integrations

• Waystones: repairs only unambiguous dimension references while preserving UUIDs and player discoveries. A backup is created first.
• Vinery: prevents existing wine age from going backwards when the primary world changes.
• Starcatcher: recognizes Overworld-, Nether- and End-like dimensions through vanilla dimension effects instead of hardcoded IDs.
• Bountiful Baubles: repairs stale attributes and migrated absolute clocks on supported artifacts after login, dimension travel or item use.
• Vanilla Vaults: diagnoses and repairs impossible absolute timers in loaded chunks while preserving keys, loot tables, state and rewarded players.

Mod Doctor safety

The Mod Doctor is conservative: it never deletes JARs, automatic quarantine is disabled by default, ambiguous findings are only reported, and Just Compatible, Just Core, Minecraft, NeoForge and language providers are protected. Every opt-in quarantine records the original and destination paths, SHA-256, version, reason and timestamp in an append-only manifest, and can be restored.

Commands

• /justcompatible scan — global read-only diagnostics.
• /justcompatible repair — applies only verified Waystones migrations after backup.
• /justcompatible doctor status — latest startup scan summary.
• /justcompatible doctor report — latest Mod Doctor report.
• /justcompatible doctor restore — restores available quarantined JARs; restart required.
• /justcompatible vaults scan|repair — loaded-chunk-only Vault timer tools.

Community and bug reports: https://discord.gg/cCHeBPKkD

Source and issue tracker: https://github.com/yofred09/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.