CityWorld ReForged

Fixed

• Biome mods on CityWorld's land, on 1.21.1 and 1.20.1. The TerraBlender bridge (Biomes O' Plenty, Nyctophobia, VanillaBackport, Regions Unexplored, Oh The Biomes We've Gone…) was silently off on those two lines from the day they shipped: it needed the frozen biome registry, and on 1.21.1/1.20.1 the biome source's codec hands a wrapper that is not one. The server's registry is the fallback. Measured on 1.21.1 with Nyctophobia + VanillaBackport: 0 modded biome columns of 140,625 sampled → Nyctophobia 2.8%, and 1,229 pale oak logs where there were none. 1.21.11 and 26.x were never affected.
• TerraBlender's deferred_placeholder is never a biome to place. A region's "vanilla's biome goes here" marker; it took 15.5% of the columns the moment the bridge worked on 1.21.1.
• A backport's vanilla-named biome counts as a mod's. "Modded" meant "not minecraft:", so VanillaBackport's minecraft:pale_garden could never stand on CityWorld land. A biome is now foreign when vanilla itself does not define it, whatever its namespace.

Added

• Datapack biome mods — Terralith, Dreamwoods' Grand Terrain — reach both lands. They rewrite the minecraft:normal world preset and write their biomes inline in it, nowhere else, so CityWorld never saw them. world.packPreset (default minecraft:normal) names the preset CityWorld reads the pack's overworld from: vanilla land takes its terrain noise and biome source from it, and CityWorld's land offers the foreign biomes it declares through moddedBiomeShare, exactly as TerraBlender's. Measured with Dreamwoods + Grand Terrain on 1.21.1: 0 → 18.9% of vanilla-land columns and 0 → 39.8% of CityWorld-land columns, trees included.
• A mod's biome comes in patches, not slivers. It is decided per cell (world.moddedBiomeGrain, 64 blocks, at a warped centre so edges are not a grid) instead of per column, where a narrow climate box won for a few blocks at its edges. Measured over 4 km on 1.21.1: patches of two chunks or less fell from 38% to 4% (Dreamwoods) and 36% to 4% (Nyctophobia), median patch 4 → 28 chunks, total coverage unchanged. 1 restores the old look.
• A river freezes by the biome on its banks, not by CityWorld's temperature number: a snowy Dreamwoods grove had an open river through it.
• A quay on frozen water freezes. The rustic and natural quay kinds left their own top-layer freeze to vanilla's decoration, which never runs on a structure lot: open squares of water beside a frozen ocean.
• 1.21.1 and 1.20.1: the Customize Style button no longer ping-pongs. After one style change the reopened screen's button sat on the first entry whatever it showed — one click swallowed, then Apocalypse ↔ Classic forever. Those two lines' button builder wants its values before its initial value.
• Lithostitched mods (Regions Unexplored) on vanilla land. Lithostitched patches surface rules and wraps the biome source of every vanilla noise generator at server start and skipped CityWorld's; vanilla land's generator now goes through the same two passes. Measured with Regions Unexplored on 1.21.1: 0 → 14.5% of vanilla-land columns. Its biomes are density layouts, not climate points, so CityWorld's own land cannot offer them.
• Structures only in the wild. structures.wildernessOnly (Customize: "Structures: only in the wild") keeps every placed structure set out of any platmap the city plans to build (judged by a dry plan without structure reservations, so the planner and vanilla's placement agree and nothing reserves a hole for a structure that is then removed; strongholds are never touched); set by set, a datapack tags #cityworld:wilderness_only (structure sets). Arboria's lake sets ship in it: its ponds are structures, and each one cut a city in two.