Pasted

-- bridge_and_stop.lua
-- Moves forward, checks below; if air then places stone bricks below and moves forward.
-- If below is NOT air, stops. Also stops if blocked ahead or out of bricks.
 local function selectStoneBricks()
  for slot = 1, 16 do
    local item = turtle.getItemDetail(slot)
    if item then
      if item.name == "minecraft:stone_bricks" then
        turtle.select(slot)
        return true
      end
      -- Fallback match by display name
      if item.displayName and item.displayName:lower():find("stone bricks") then
        turtle.select(slot)
        return true
      end
    end
  end
  return false
end
 while true do
  -- First forward; stop if blocked.
  if not turtle.forward() then
    print("Blocked ahead. Stopping.")
    break
  end
   -- Look down: if air, place bricks; else stop.
  if not turtle.detectDown() then
    if not selectStoneBricks() then
      print("Out of stone bricks. Stopping.")
      break
    end
    if not turtle.placeDown() then
      print("Failed to place block below. Stopping.")
      break
    end
  else
    print("Ground detected below. Stopping.")
    break
  end
end
 print("Done.")