-- NO-FAIL UNIVERSAL PROPORTIONAL SIZE HUB
local Players = game:GetService("Players")
local CoreGui = game:GetService("CoreGui")
local UserInputService = game:GetService("UserInputService")
local Player = Players.LocalPlayer

-- Clean up existing UI if present
if CoreGui:FindFirstChild("UniversalSizeHubFixed") then CoreGui.UniversalSizeHubFixed:Destroy() end

-- 1. BUILD NATIVE UI
local ScreenGui = Instance.new("ScreenGui", CoreGui:FindFirstChild("RobloxGui") or CoreGui)
ScreenGui.Name = "UniversalSizeHubFixed"
ScreenGui.ResetOnSpawn = false

local MainFrame = Instance.new("Frame", ScreenGui)
MainFrame.Size = UDim2.new(0, 220, 0, 150)
MainFrame.Position = UDim2.new(0.3, 0, 0.3, 0)
MainFrame.BackgroundColor3 = Color3.fromRGB(28, 28, 30)
Instance.new("UICorner", MainFrame).CornerRadius = UDim.new(0, 8)
MainFrame.Active = true
MainFrame.Draggable = true

local Title = Instance.new("TextLabel", MainFrame)
Title.Size = UDim2.new(1, 0, 0, 35)
Title.Text = "Universal Size Hub (Fixed)"
Title.TextColor3 = Color3.fromRGB(255, 255, 255)
Title.BackgroundTransparency = 1

local SizeInput = Instance.new("TextBox", MainFrame)
SizeInput.Size = UDim2.new(0, 196, 0, 36)
SizeInput.Position = UDim2.new(0, 12, 0, 45)
SizeInput.PlaceholderText = "Multiplier (-Inf to Inf)"
SizeInput.BackgroundColor3 = Color3.fromRGB(44, 44, 46)
SizeInput.TextColor3 = Color3.fromRGB(48, 209, 88)
SizeInput.Text = "1"

local ApplyButton = Instance.new("TextButton", MainFrame)
ApplyButton.Size = UDim2.new(0, 196, 0, 36)
ApplyButton.Position = UDim2.new(0, 12, 0, 95)
ApplyButton.Text = "Resize & Connect"
ApplyButton.BackgroundColor3 = Color3.fromRGB(0, 122, 255)
ApplyButton.TextColor3 = Color3.fromRGB(255, 255, 255)
Instance.new("UICorner", ApplyButton).CornerRadius = UDim.new(0, 6)

-- Track baseline joints to keep structural integrity intact
local baselineC0 = {}
local baselineC1 = {}

-- 2. JOINT RE-ALIGNMENT ENGINE
local function applyConnectedSize(multiplier)
    local char = Player.Character
    if not char then return end
    local humanoid = char:FindFirstChildOfClass("Humanoid")
    if not humanoid then return end

    -- Turn off standard automatic scaling so it doesn't fight our script
    humanoid.AutomaticScalingEnabled = false

    -- Step A: Scale the actual physical parts
    for _, part in ipairs(char:GetChildren()) do
        if part:IsA("BasePart") and part.Name ~= "HumanoidRootPart" then
            -- Use internal values to check original size if Roblox supports it
            local origSizeObj = part:FindFirstChild("OriginalSize")
            local baseSize = origSizeObj and origSizeObj.Value or part.Size
            
            part.Size = baseSize * multiplier
        end
    end

    -- Step B: Recalculate and connect all limb joints securely
    for _, part in ipairs(char:GetChildren()) do
        if part:IsA("BasePart") then
            for _, joint in ipairs(part:GetChildren()) do
                if joint:IsA("Motor6D") then
                    -- Cache original bone anchors so we don't permanently break the avatar layout
                    if not baselineC0[joint] then baselineC0[joint] = joint.C0 end
                    if not baselineC1[joint] then baselineC1[joint] = joint.C1 end
                    
                    -- Rescale joint offsets proportionally so parts stay touching
                    joint.C0 = baselineC0[joint] * CFrame.new(baselineC0[joint].Position * (multiplier - 1))
                    joint.C1 = baselineC1[joint] * CFrame.new(baselineC1[joint].Position * (multiplier - 1))
                end
            end
        end
    end
end

ApplyButton.MouseButton1Click:Connect(function()
    local val = tonumber(SizeInput.Text)
    if val then 
        applyConnectedSize(val) 
    end
end)