Lighten Up, Chunks!

Server-side chunk relighting for existing Fabric worlds on Minecraft 26.1.2.

This mod is aimed at repairing broken saved lighting in bulk without asking admins to fly around and trigger chunk updates manually.

What It Does

• Scans existing chunks from region files instead of generating new terrain
• Relights whole dimensions, circular radii, or boxed regions
• Supports pause, resume, cancel, and crash-safe persistence through luc_state.json
• Shows progress in chat and on a boss bar
• Broadcasts a completion message to online players
• Optionally notifies Voxy and VoxyServer after relighting so LODs can refresh without a manual import

Commands

• /luc Shows the current selection and task status
• /luc dimensions Lists loaded dimensions and powers tab completion for custom dimensions
• /luc mode <missing-only|full|full-2-pass> Chooses how the next task should relight chunks
• /luc world [dimension] Configures a whole-dimension selection
• /luc radius <radius> [centerX centerZ] [dimension] Configures a circular selection in block coordinates
• /luc region <x1 z1 x2 z2> Configures a boxed selection in block coordinates
• /luc preview Scans the configured selection and shows how many chunks and relight steps would run before you start
• /luc estimate Alias for /luc preview
• /luc start Starts the configured task
• /luc pause
• /luc resume
• /luc cancel

You can also run preview, estimate, and start directly with world, radius, region, and explicit dimension arguments.

Relight Modes

• missing-only Only relights chunks whose saved light data appears to be missing
• full Performs a full relight pass on each matched chunk
• full-2-pass Queues two passes for each chunk, which can help more stubborn edge cases

Safety Notes

• The mod only targets chunks that already exist on disk
• It skips chunks whose 3x3 lighting neighborhood is incomplete on disk, which avoids accidental neighbor generation at world borders
• Radius selections are true circles now, not bounding squares
• /luc pause and /luc cancel release in-flight work immediately instead of waiting for chunk loads to drain

Voxy Integration

• When enableVoxyCompat is enabled, Lighten Up, Chunks tries to notify supported Voxy variants after saving relit chunks
• In singleplayer it attempts to use Voxy client's auto-ingest path
• On dedicated servers it attempts to mark VoxyServer sections dirty so they can rebuild
• If neither mod is present, or if Voxy is not ready yet, relighting still completes normally
• Debug logging will note when a supported Voxy integration is detected

Config

The config file lives at Fabric's config path as lighten-up-chunks.json.

Notable options:

• defaultRelightMode
• maxInFlightChunks
• maxRelightsPerTick
• saveFlushIntervalSeconds
• enableVoxyCompat
• Boss bar display toggles

Set them in-game with /luc config show, /luc config get <key>, and /luc config set <key> <value>, or through Mod Menu in singleplayer.