Protected Structures

Structure Protection is a Fabric mod for Minecraft that stops players from breaking, exploding, or transforming blocks that were actually placed during structure generation — nothing more, nothing less. It works on both client and server: install it on a dedicated server to protect the world for everyone, or in singleplayer for the same protection locally. The optional Mod Menu screen adds a client-side configuration UI, but isn’t required to use the mod.

Instead of protecting a structure’s whole bounding box (which would also lock up caves, terrain, and anything built nearby), Structure Protection tags each individual block placed by StructureStart.placeInChunk with the ID of the structure that generated it. A player-placed block sitting right next to a Bastion looks the same but isn’t protected — only the Bastion’s own blackstone is.

• Configurable per structure — protect everything by default, or pick specific structures (vanilla, datapack, or modded) via commands or an in-game Mod Menu screen with collapsible Overworld/Nether/End/Modded groups.
• Covers the real threats — blocked player mining, explosion damage, piston/sticky-block movement, and tool-based block transformations (axe stripping, hoe tilling, etc.), while leaving normal interactions (chests, doors, furnaces, redstone) untouched.
• No scanning, no lag — protection state is stored as compact per-chunk bitmaps and checked with a direct lookup; there’s no tick handler or world scanner.
• Admin bypass — operators (or the singleplayer world owner) can toggle a personal bypass to edit protected structures when needed.

Structures generated before installing this mod can’t be retroactively identified at the block level.

Known Issues:
Villagers cannot pick the crops in villages when they are protected.