WorldRewild

A Paper plugin for rewilding resource worlds.

What it does

WorldRewild keeps a resource world fresh by continuously regenerating the chunks nobody has touched for a while:

1. It sweeps a world one region file at a time (a "tile" = 32×32 chunks), nearest-to-spawn first. A chunk is eligible when its last-saved time (the region file's per-chunk timestamp — bumped when the chunk is modified and saved, not by merely loading it) is older than the world's min-age.
2. Each tile is regenerated two-phase: first it deletes every eligible chunk's block/entity/POI data through Paper's Moonrise chunk system, then it reloads them so the server regenerates each from scratch with the current generator — terrain, structures and structure mobs — and saves them.
3. Work is TPS-gated and capped to a few concurrent regenerations, so it runs quietly in the background and players never trigger a burst of on-demand generation.
4. After sweeping every configured world it waits sweep-interval and repeats.

No FAWE / WorldEdit required. The resident sweep is off by default (enabled: false) — it's the heavy part, so start it on demand with /wr start. The lightweight structure reset below runs on its own schedule regardless.

Skip chunks nothing has changed

By default (skip-unchanged-chunks: true) a chunk is regenerated again only once it has changed since the last time WorldRewild reset it — detected by the region file's per-chunk timestamp advancing past the "reset stamp" recorded right after our own reset (stamps kept in plugins/WorldRewild/stamps/). Without this, our own regen keeps bumping that timestamp, so a chunk nobody has touched would be re-regenerated on every cycle forever — most wastefully in the End, whose vast empty void would otherwise be re-reset daily. Chunks we have never reset have no stamp and stay eligible, so the first-pass cross-version conversion still sweeps the whole map once; after that, untouched wilderness goes dormant and only the areas players actually change keep refreshing (on the min-age cycle).

Renewing the End dragon

Set respawn-dragon: true on the End world and the age sweep renews the dragon too. The central arena can't be chunk-regenerated in place, so instead the ordinary sweep regenerates the End's central island — once a kill has changed it and it goes idle — removing the old exit portal and end gateways. Only the pass that actually regenerates the central-island chunk (0,0) then resets the fight's saved state (via NMS); a pass that touches nothing there — nobody visited, so skip-unchanged skips it — leaves the fight alone, so an unbeaten dragon is never disturbed. Because the fight re-derives "previously killed" from whether an exit portal / gateway still exists, a fresh dragon spawns on the next entry. So the end-game journey (stronghold → portal → dragon → end city → elytra) renews. Because it rides the age sweep, it only happens while the sweep is enabled; /wr end reset forces a fight-state reset on demand.

Rare structures on a fast cycle

Alongside the slow wilderness refresh, WorldRewild resets specific rare structures on a much faster cycle (default every 6 hours, aligned to the wall clock at 00:00/06:00/12:00/18:00) so their loot, mobs and build come back for the next player. Structures are found automatically by reading each chunk's stored structures.starts straight from the region files — no in-game marking. Each configured type (by default the rare, high-value, low-count ones: woodland mansion, stronghold, jungle/desert pyramid, pillager outpost, bastion remnant) has its footprint regenerated with the same two-phase core, skipping any structure a player is currently inside — and, with skip-unchanged-chunks on, any that has not changed since its last reset, so only raided structures are refreshed. Very numerous types like ancient cities and end cities are left off this fast cycle and refresh via the slower age sweep.

Guarding reset structures from land claims (Residence)

WorldRewild soft-depends on Residence: when that plugin is installed, structure-reset.block-residence-claims (default on) refuses any residence claim — new residence, subzone, area add, or resize — that would cover a chunk of a reset structure's footprint. Without this, a player could fence off a stronghold or mansion so no one else can use it (and lose their build to the next reset anyway). The blocked region is the whole footprint bounding box, i.e. exactly what the reset regenerates, so a large sparse structure such as a stronghold blocks claims across its bbox. Existing residences are left untouched, and only rewilded worlds have reset structures, so permanent worlds are unaffected. Players with worldrewild.bypass.structureclaim (op by default) are exempt. With Residence absent, the setting does nothing.

Why whole tiles, not one chunk at a time

On a cross-version map (e.g. a 1.21.11 world opened under 26.2), the worldgen Blender blends a regenerating chunk toward its old neighbours' terrain and biomes. Regenerating chunks one-by-one therefore just reproduces the old world. Deleting a whole tile first means its interior chunks regenerate with no old neighbours, so they come out as genuine current-version terrain (verified: an old forested-land chunk became the correct 26.2 ocean + sulfur_caves). Only a thin biome-only rim on tile edges that still border old chunks is blended, and that rim heals the next time that area is swept, once those neighbours have themselves been converted (with skip-unchanged-chunks on, once a player has been back through it). The delete itself is a synchronous Moonrise RegionFileStorage.clear (via RegionDataController.startWrite(x,z,null)/finishWrite); the older scheduleSave(..., null, ...) path does not delete, so the chunk would only be DataFixer-upgraded, never truly regenerated.

Commands

/worldrewild (alias /wr), permission worldrewild.admin (default: op):

Command	Description
/wr start / pause / resume / stop	Control the resident sweeper
/wr status	Current state, world, progress, TPS
/wr count	Dry run: how many chunks are eligible right now (per world)
/wr reset	Clear saved progress and the reset-stamp cache
/wr reload	Reload config.yml
/wr region <world> <cx1> <cz1> <cx2> <cz2>	Manually regenerate a chunk rectangle now, two-phase (refuses if players are inside)
/wr vanillaregen <world> <cx> <cz>	Regenerate a single chunk now (subject to edge blending on a cross-version map — use region to convert an area)
/wr struct status	Structure-reset registry: counts per type, scan state
/wr struct scan	(Re)scan region files for structures (incremental after the first pass)
/wr struct reset [type]	Regenerate all registered structures now (optionally just one type)
/wr end reset	Reset the End dragon fight state now (a fresh dragon spawns after the central island is next regenerated by the sweep)
/wr probe <world> <cx> <cz> <material>	Count a material in a chunk (diagnostic)
/wr entities <world> <cx> <cz> [type]	List entities in a chunk (diagnostic)

Configuration

See config.yml. Time values are durations — 90d / 6h / 10m / 1d12h (units d/h/m/s, concatenable). Both features share a top-level worlds list — each entry is a name plus a required min-age duration (a world missing or malforming it is skipped), optionally with a region-dir override (else derived from the loaded world).

resident-sweep: enabled (default false), skip-unchanged-chunks (default true; see above), respawn-dragon (renew the End dragon after its sweep pass), sweep-interval, tps-pause / tps-resume, interval-ticks / per-tick / max-concurrent-regens, player-safe-radius-chunks, protect-spawn-radius-chunks, max-consecutive-failures, auto-resume.

structure-reset: enabled, interval (default 6h, wall-clock aligned), rescan (registry refresh), footprint-margin-chunks, block-residence-claims (Residence soft-depend; default true), types.

Building

./gradlew build   # outputs build/libs/WorldRewild-<version>.jar

Requires JDK 25 (Paper 26.2's API needs Java 25). The Paper API is resolved from Maven, so no local server is needed to compile.

Notes

• Requires Paper (uses the Moonrise chunk system via reflection). Tested on Paper 26.1.2 and 26.2.
• A classic cobblestone dungeon whose spawner sits exactly on a chunk border may generate without its spawner (the room and chest still generate). Structure spawners (trial chambers, etc.) regenerate correctly.
• Deleting chunk data bypasses block-logging plugins (e.g. CoreProtect) for the regenerated area.
• Loot chests refill on reset, but their contents are deterministic per seed + position — the same structure yields the same loot each time it is reset.