保存纪录：第一次认识 DataStore

local Players = game:GetService("Players")
local PRACTICE = true -- 先保持 true；内存练习不跨 Stop 保存
local store = nil
if not PRACTICE then
    store = game:GetService("DataStoreService"):GetDataStore("Lesson25_Best_v1")
end
local memory = {}
local ready, saving, lastSave, lastScore = {}, {}, {}, {}
local scoreStation = workspace:WaitForChild("ScoreStation")
local saveStation = workspace:WaitForChild("SaveStation")
local mode = PRACTICE and "[PRACTICE]" or "[DATASTORE]"

local function readValue(value)
    if value == nil then return 0 end
    assert(typeof(value) == "number" and value == value, "Invalid stored data")
    assert(value >= 0 and value < math.huge and value % 1 == 0, "Invalid score")
    return value
end
local function near(player, station)
    local character = player.Character
    local root = character and character:FindFirstChild("HumanoidRootPart")
    local hum = character and character:FindFirstChildOfClass("Humanoid")
    return root and hum and hum.Health > 0 and (root.Position - station.Position).Magnitude <= 12
end
local function setup(player)
    player:SetAttribute("RunScore", 0)
    local key = "u_" .. player.UserId
    local ok, value = pcall(function()
        if PRACTICE then return readValue(memory[key]) end
        return readValue(store:GetAsync(key))
    end)
    if player.Parent ~= Players then return end
    if not ok then warn(mode, "Load failed; saving disabled", value); return end
    ready[player] = true
    player:SetAttribute("BestScore", value)
    print(mode, player.Name, "loaded", value)
end
Players.PlayerAdded:Connect(setup)
for _, player in ipairs(Players:GetPlayers()) do task.spawn(setup, player) end

scoreStation.ProximityPrompt.Triggered:Connect(function(player)
    if not ready[player] or not near(player, scoreStation) then return end
    local now = os.clock()
    if now - (lastScore[player] or -math.huge) < 0.5 then return end
    lastScore[player] = now
    local score = math.min(9990, (player:GetAttribute("RunScore") or 0) + 10)
    player:SetAttribute("RunScore", score)
    print(mode, "RunScore", score)
end)

saveStation.ProximityPrompt.Triggered:Connect(function(player)
    if not ready[player] or saving[player] or not near(player, saveStation) then return end
    local now = os.clock()
    if now - (lastSave[player] or -math.huge) < 10 then return end
    lastSave[player] = now
    saving[player] = true
    local key = "u_" .. player.UserId
    local score = player:GetAttribute("RunScore") or 0
    local ok, result = pcall(function()
        if PRACTICE then
            memory[key] = math.max(readValue(memory[key]), score)
            return memory[key]
        end
        return store:UpdateAsync(key, function(old)
            return math.max(readValue(old), score)
        end)
    end)
    saving[player] = nil
    if not ok then warn(mode, "Save failed; try again later", result); return end
    if player.Parent == Players then player:SetAttribute("BestScore", result) end
    print(mode, "Saved best:", result)
end)
Players.PlayerRemoving:Connect(function(player)
    ready[player], lastSave[player], lastScore[player] = nil, nil, nil
end)