💚 Slimefun Legacy 4.1.47

Migration Safety, Ticker Efficiency & Addon Compatibility

Slimefun Legacy 4.1.47 continues our goal of keeping the classic Slimefun experience alive on modern Minecraft servers while improving performance, administration tools, and compatibility with the enormous Slimefun addon ecosystem.

This release introduces a new guarded legacy-item migration framework, reduces unnecessary ticker and profiler overhead, and significantly expands the addon compatibility checks used before Slimefun Legacy releases are published.

🔄 Safer Legacy Item Migrations

A new migration system has been added to /sf doctor for addons and servers that need to move old Slimefun item IDs to newer replacements.

New commands include:

/sf doctor migrations status /sf doctor migrations list /sf doctor migrations unknown /sf doctor migrations plan /sf doctor migrations providers

Addon developers can now provide their own migration logic through the new LegacyItemMigrationProvider API.

Migration execution is intentionally conservative.

A provider must first complete a clean read-only scan:

/sf doctor migrations scan <plugin>

A successful scan creates a temporary migration fingerprint. Only the matching prepared plan can then be executed:

/sf doctor migrations execute <plugin> <fingerprint>

Prepared plans expire after 10 minutes.

Unknown IDs, missing targets, invalid mappings, expired plans, provider errors, or an incorrect fingerprint all fail closed rather than guessing.

Always make a full offline backup before executing a migration.

⚡ Lower Ticker & Profiler Overhead

4.1.47 also reduces background bookkeeping performed by Slimefun machines.

Ticker profiling is now more request-driven, with lightweight background telemetry instead of continuously paying the full profiling cost.

Additional optimizations include:

• Idle fast paths when no ticker failures are active
• Skipping circuit-breaker checks when no circuits are open
• Skipping targeted-pause lookups when none exist
• Reusing ticker-registration snapshots until registrations actually change
• Cleaning cached runtime state when registrations are removed
• Removing empty chunk ticker state after cleanup

Normal machine ticking behavior remains unchanged.

The goal is simple: spend less server time monitoring healthy machines and more time actually running them.

🧩 Stronger Addon Compatibility Testing

The Slimefun Legacy release pipeline now performs broader baseline-vs-candidate testing against maintained Slimefun addons.

This helps catch situations where an addon builds or links correctly against the previous Slimefun Legacy release but breaks against the new candidate.

Compatibility testing now better distinguishes:

PASS BASELINE_BUILD_FAILED LEGACY_COMPATIBILITY_FAILED INSTRUMENTATION_ERROR

Required Legacy addon forks remain release-blocking, while additional maintained addons and representative upstream/Gugu projects provide advisory compatibility coverage.

Compatibility work in this release also includes narrowly scoped support for the historical Gugu SlimeCustomizer Maven dependency used by older builds.

The SlimefunGuguProject SlimeCustomizer baseline/candidate compatibility job now completes successfully without requiring broad dependency rewriting.

🛡️ Existing Worlds & Gameplay

4.1.47 intentionally preserves established Slimefun behavior.

There are no intentional changes to the existing:

• Slimefun item IDs
• Storage schema
• Saved-world format
• Cargo behavior
• Energy behavior
• Machine gameplay
• Existing public compatibility boundaries

The migration framework does not automatically rewrite addon data, BlockStorage, Cargo data, or Energy data.

Migration remains explicit and provider-owned.

🖥️ Platform Support

Primary: Paper 26.2 Supported: Purpur 26.2 Experimental: Folia 26.2 Compatibility tested: Paper/Purpur 1.21.11 Runtime: Java 25 Slimefun-owned bytecode target: Java 21

Folia remains experimental and requires Folia-safe addons.

📦 Release Files

Slimefun-Legacy4.1.47.jar

The GitHub release also contains:

SFL_AddonsNDependencies.zip

The addon bundle is provided as a convenient validated starting point for Slimefun Legacy servers. You should still install only the addons you actually use and check individual addon repositories for newer releases.

⬆️ Updating

Fully stop your server before replacing Slimefun.

Make a backup of your worlds, Slimefun data, player data, databases, and addon data.

Replace the previous Slimefun Legacy JAR with:

Slimefun-Legacy4.1.47.jar

Then start the server normally.

Do not use /reload to update Slimefun.

After starting, server administrators can use /sf doctor and /sf versions to review the installation and addon environment.

❤️ Keeping Classic Slimefun Alive

Slimefun Legacy is an independently maintained continuation of the classic Slimefun 4 experience for modern Paper servers.

Machines. Electricity. Cargo. Automation. Reactors. Magic. Backpacks. Hundreds of items. Thousands of addon possibilities.

Classic Slimefun. Modern Minecraft. Better diagnostics. Less unnecessary overhead.

Thank you to everyone testing releases, reporting issues, profiling servers, maintaining addons, and helping keep the Slimefun ecosystem alive.

Stay slimy! 💚