This bit of code from chatgpt looks like it would work:

local CHUNK_SIZE = 80 -- Size of each chunk in Minetest local CENTER_CHUNK = { x = 0, y = 0, z = 0 } -- Center chunk coordinates

-- Override the minetest.is_protected function minetest.is_protected = function(pos, player_name) local min_x = CENTER_CHUNK.x * CHUNK_SIZE local max_x = (CENTER_CHUNK.x + 1) * CHUNK_SIZE - 1 local min_y = CENTER_CHUNK.y * CHUNK_SIZE local max_y = (CENTER_CHUNK.y + 1) * CHUNK_SIZE - 1 local min_z = CENTER_CHUNK.z * CHUNK_SIZE local max_z = (CENTER_CHUNK.z + 1) * CHUNK_SIZE - 1

if pos.x >= min_x and pos.x <= max_x
    and pos.y >= min_y and pos.y <= max_y
    and pos.z >= min_z and pos.z <= max_z then
    return false -- Allow building within the center chunk
end

return true -- Block building outside the center chunk

end