diff --git a/.gitignore b/.gitignore
index 0b82408..2ec20ac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
-Packages/
\ No newline at end of file
+Packages/
+ServerPackages/
\ No newline at end of file
diff --git a/ReplicatedStorage/Shared/ClientState.lua b/ReplicatedStorage/Shared/ClientState.lua
new file mode 100644
index 0000000..bfc8a0b
--- /dev/null
+++ b/ReplicatedStorage/Shared/ClientState.lua
@@ -0,0 +1,128 @@
+--!native
+--!optimize 2
+
+local RunService = game:GetService("RunService")
+
+if RunService:IsServer() then
+	error("ClientState can only be required on the client")
+end
+
+local Players = game:GetService("Players")
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+local Replica = require(ReplicatedStorage.Packages.replica)
+
+local ClientState = {}
+
+local HOTBAR_SIZE = 10
+
+local localPlayer = Players.LocalPlayer
+local replicaForPlayer = nil
+local changed = Instance.new("BindableEvent")
+
+local function fireChanged()
+	changed:Fire()
+end
+
+local function onReplicaNew(replica)
+	local tags = replica.Tags or {}
+	if tags.UserId ~= localPlayer.UserId and tags.Player ~= localPlayer then
+		return
+	end
+
+	replicaForPlayer = replica
+	replica:OnChange(fireChanged)
+	fireChanged()
+end
+
+Replica.OnNew("ClientState", onReplicaNew)
+Replica.RequestData()
+
+function ClientState:IsReady(): boolean
+	return replicaForPlayer ~= nil
+end
+
+function ClientState:GetReplica()
+	return replicaForPlayer
+end
+
+function ClientState:GetSelectedSlot(): number?
+	if not replicaForPlayer then
+		return nil
+	end
+	return replicaForPlayer.Data.selectedSlot
+end
+
+local function getInventory()
+	return replicaForPlayer and replicaForPlayer.Data.inventory or nil
+end
+
+function ClientState:GetItemInfo(blockId: any)
+	if not replicaForPlayer or not blockId then
+		return nil
+	end
+	local inv = getInventory()
+	local entry = inv and inv[tostring(blockId)]
+	if not entry then
+		return nil
+	end
+
+	return {
+		id = tostring(blockId),
+		name = entry.name or tostring(blockId),
+		count = entry.count,
+	}
+end
+
+function ClientState:GetHotbarSlots(): {string}
+	if not replicaForPlayer then
+		local slots = table.create(HOTBAR_SIZE)
+		for i = 1, HOTBAR_SIZE do
+			slots[i] = ""
+		end
+		return slots
+	end
+
+	return replicaForPlayer.Data.hotbar or {}
+end
+
+function ClientState:GetSlotInfo(slot: number)
+	if not replicaForPlayer then
+		return nil
+	end
+	local hotbar = replicaForPlayer.Data.hotbar
+	if not hotbar then
+		return nil
+	end
+	local id = hotbar[slot]
+	if not id then
+		return nil
+	end
+	return ClientState:GetItemInfo(id)
+end
+
+function ClientState:GetSelectedBlock()
+	if not replicaForPlayer then
+		return nil
+	end
+	local slot = ClientState:GetSelectedSlot()
+	if not slot then
+		return nil
+	end
+	return ClientState:GetSlotInfo(slot)
+end
+
+function ClientState:SetSelectedSlot(slot: number)
+	if not replicaForPlayer then
+		return
+	end
+	local hotbar = replicaForPlayer.Data.hotbar
+	if not hotbar or not hotbar[slot] then
+		return
+	end
+	replicaForPlayer:FireServer("SelectHotbarSlot", slot)
+end
+
+ClientState.Changed = changed.Event
+
+return ClientState
diff --git a/ServerScriptService/Actor/ClientState.lua b/ServerScriptService/Actor/ClientState.lua
new file mode 100644
index 0000000..378a68c
--- /dev/null
+++ b/ServerScriptService/Actor/ClientState.lua
@@ -0,0 +1,198 @@
+--!native
+--!optimize 2
+
+local Players = game:GetService("Players")
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+local Replica = require(ReplicatedStorage.Packages.replica)
+
+local ClientStateService = {}
+
+local HOTBAR_SIZE = 10
+
+local token = Replica.Token("ClientState")
+
+local blockCatalog = {}
+local playerReplicas = {} :: {[Player]: any}
+local blocksFolder: Folder? = nil
+local readyConnections = {} :: {[Player]: RBXScriptConnection}
+
+local function sortBlocks()
+	table.sort(blockCatalog, function(a, b)
+		local na = tonumber(a.id)
+		local nb = tonumber(b.id)
+		if na and nb then
+			return na < nb
+		end
+		if na then
+			return true
+		end
+		if nb then
+			return false
+		end
+		return a.id < b.id
+	end)
+end
+
+local function rebuildBlockCatalog()
+	table.clear(blockCatalog)
+	if not blocksFolder then
+		return
+	end
+
+	for _, block in ipairs(blocksFolder:GetChildren()) do
+		local id = block:GetAttribute("n")
+		if id ~= nil then
+			table.insert(blockCatalog, {
+				id = tostring(id),
+				name = block:GetAttribute("displayName") or block:GetAttribute("dn") or block.Name,
+			})
+		end
+	end
+	sortBlocks()
+end
+
+local function makeBaseState()
+	local inventory = {}
+	local hotbar = {}
+
+	for _, entry in ipairs(blockCatalog) do
+		inventory[entry.id] = {
+			name = entry.name,
+			count = 999999,
+		}
+		if #hotbar < HOTBAR_SIZE then
+			table.insert(hotbar, entry.id)
+		end
+	end
+
+	return {
+		inventory = inventory,
+		hotbar = hotbar,
+		selectedSlot = #hotbar > 0 and 1 or 0,
+	}
+end
+
+local function sanitizeSelection(hotbar, selectedSlot)
+	if type(selectedSlot) ~= "number" then
+		return (#hotbar > 0) and 1 or 0
+	end
+	if selectedSlot < 1 or selectedSlot > HOTBAR_SIZE then
+		return (#hotbar > 0) and 1 or 0
+	end
+	if not hotbar[selectedSlot] then
+		return (#hotbar > 0) and 1 or 0
+	end
+	return selectedSlot
+end
+
+local function refreshReplica(replica)
+	local state = makeBaseState()
+	replica:Set({"inventory"}, state.inventory)
+	replica:Set({"hotbar"}, state.hotbar)
+	replica:Set({"selectedSlot"}, sanitizeSelection(state.hotbar, replica.Data.selectedSlot))
+end
+
+function ClientStateService:SetBlocksFolder(folder: Folder?)
+	blocksFolder = folder
+	rebuildBlockCatalog()
+	for _, replica in pairs(playerReplicas) do
+		refreshReplica(replica)
+	end
+end
+
+function ClientStateService:GetReplica(player: Player)
+	return playerReplicas[player]
+end
+
+function ClientStateService:GetSelectedBlockId(player: Player)
+	local replica = playerReplicas[player]
+	if not replica then
+		return nil
+	end
+	local data = replica.Data
+	local hotbar = data.hotbar or {}
+	local selectedSlot = sanitizeSelection(hotbar, data.selectedSlot)
+	return hotbar[selectedSlot]
+end
+
+function ClientStateService:HasInInventory(player: Player, blockId: any): boolean
+	local replica = playerReplicas[player]
+	if not replica or not blockId then
+		return false
+	end
+	local inv = replica.Data.inventory
+	return inv and inv[tostring(blockId)] ~= nil or false
+end
+
+local function handleReplicaEvents(player: Player, replica)
+	replica.OnServerEvent:Connect(function(plr, action, payload)
+		if plr ~= player then
+			return
+		end
+
+		if action == "SelectHotbarSlot" then
+			local slot = tonumber(payload)
+			local hotbar = replica.Data.hotbar
+			if not hotbar then
+				return
+			end
+			if slot and slot >= 1 and slot <= HOTBAR_SIZE and hotbar[slot] then
+				replica:Set({"selectedSlot"}, slot)
+			end
+		end
+	end)
+end
+
+local function onPlayerAdded(player: Player)
+	local replica = Replica.New({
+		Token = token,
+		Tags = {
+			UserId = player.UserId,
+			Player = player,
+		},
+		Data = makeBaseState(),
+	})
+
+	if Replica.ReadyPlayers[player] then
+		replica:Subscribe(player)
+	else
+		readyConnections[player] = Replica.NewReadyPlayer:Connect(function(newPlayer)
+			if newPlayer ~= player then
+				return
+			end
+			if readyConnections[player] then
+				readyConnections[player]:Disconnect()
+				readyConnections[player] = nil
+			end
+			replica:Subscribe(player)
+		end)
+	end
+
+	handleReplicaEvents(player, replica)
+	playerReplicas[player] = replica
+end
+
+local function onPlayerRemoving(player: Player)
+	local replica = playerReplicas[player]
+	if replica then
+		replica:Destroy()
+		playerReplicas[player] = nil
+	end
+	if readyConnections[player] then
+		readyConnections[player]:Disconnect()
+		readyConnections[player] = nil
+	end
+end
+
+function ClientStateService:Init()
+	rebuildBlockCatalog()
+
+	for _, player in ipairs(Players:GetPlayers()) do
+		onPlayerAdded(player)
+	end
+	Players.PlayerAdded:Connect(onPlayerAdded)
+	Players.PlayerRemoving:Connect(onPlayerRemoving)
+end
+
+return ClientStateService
diff --git a/ServerScriptService/Actor/ServerChunkManager/init.server.lua b/ServerScriptService/Actor/ServerChunkManager/init.server.lua
index 62198c7..0848a8e 100644
--- a/ServerScriptService/Actor/ServerChunkManager/init.server.lua
+++ b/ServerScriptService/Actor/ServerChunkManager/init.server.lua
@@ -2,15 +2,39 @@
 --!optimize 2
 
 local ReplicatedStorage = game:GetService("ReplicatedStorage")
-
+local ServerStorage = game:GetService("ServerStorage")
+local ClientStateService = require(script.Parent.ClientState)
 
 local Shared = ReplicatedStorage:WaitForChild("Shared")
 local ModsFolder = ReplicatedStorage:WaitForChild("Mods")
+local BlocksFolderRS = ReplicatedStorage:FindFirstChild("Blocks") or Instance.new("Folder")
+BlocksFolderRS.Name = "Blocks"
+BlocksFolderRS.Parent = ReplicatedStorage
+local BlocksFolderSS = ServerStorage:FindFirstChild("Blocks") or Instance.new("Folder")
+BlocksFolderSS.Name = "Blocks"
+BlocksFolderSS.Parent = ServerStorage
 
 local Util = require(Shared.Util)
-local TG = require("./ServerChunkManager/TerrainGen")
+local TG = require(script.TerrainGen)
 local Players = game:GetService("Players")
 
+local blockIdMap = {}
+local rebuildBlockIdMap
+
+local function syncBlocksToServerStorage()
+	BlocksFolderSS:ClearAllChildren()
+	for _, child in ipairs(BlocksFolderRS:GetChildren()) do
+		child:Clone().Parent = BlocksFolderSS
+	end
+	ClientStateService:SetBlocksFolder(BlocksFolderSS)
+	if rebuildBlockIdMap then
+		rebuildBlockIdMap()
+	end
+end
+
+BlocksFolderRS.ChildAdded:Connect(syncBlocksToServerStorage)
+BlocksFolderRS.ChildRemoved:Connect(syncBlocksToServerStorage)
+
 do
 	local workspaceModFolder = game:GetService("Workspace"):WaitForChild("mods")
 
@@ -22,6 +46,8 @@ end
 
 local ML = require(Shared.ModLoader)
 ML.loadModsS()
+syncBlocksToServerStorage()
+ClientStateService:Init()
 
 do
 	local bv = Instance.new("BoolValue")
@@ -67,7 +93,7 @@ local tickRemote = ReplicatedStorage.Tick
 local remotes = ReplicatedStorage:WaitForChild("Remotes")
 local placeRemote = remotes:WaitForChild("PlaceBlock")
 local breakRemote = remotes:WaitForChild("BreakBlock")
-local blocksFolder = ReplicatedStorage:WaitForChild("Blocks")
+local blocksFolder = BlocksFolderSS
 local function propogate(a, cx, cy, cz, x, y, z, bd)
 	task.synchronize()
 	tickRemote:FireAllClients(a, cx, cy, cz, x, y, z, bd)
@@ -75,9 +101,8 @@ local function propogate(a, cx, cy, cz, x, y, z, bd)
 end
 
 local MAX_REACH = 512
-local blockIdMap = {}
 
-local function rebuildBlockIdMap()
+rebuildBlockIdMap = function()
 	table.clear(blockIdMap)
 	for _, block in ipairs(blocksFolder:GetChildren()) do
 		local id = block:GetAttribute("n")
@@ -113,6 +138,17 @@ local function resolveBlockId(blockId: any): string | number | nil
 	return blockIdMap[blockId]
 end
 
+local function playerCanUseBlock(player: Player, resolvedId: any): boolean
+	if not ClientStateService:HasInInventory(player, resolvedId) then
+		return false
+	end
+	local selected = ClientStateService:GetSelectedBlockId(player)
+	if not selected then
+		return false
+	end
+	return tostring(selected) == tostring(resolvedId)
+end
+
 local function getServerChunk(cx: number, cy: number, cz: number)
 	task.desynchronize()
 	local chunk = TG:GetChunk(cx, cy, cz)
@@ -176,6 +212,9 @@ placeRemote.OnServerEvent:Connect(function(player, cx, cy, cz, x, y, z, blockId)
 	if not resolvedId then
 		return reject("invalid id")
 	end
+	if not playerCanUseBlock(player, resolvedId) then
+		return reject("not in inventory/hotbar")
+	end
 
 	local blockPos = Util.ChunkPosToCFrame(Vector3.new(cx, cy, cz), Vector3.new(x, y, z)).Position
 	if isBlockInsidePlayer(blockPos) then
diff --git a/StarterGui/Hotbar/LocalScript.client.lua b/StarterGui/Hotbar/LocalScript.client.lua
index 756c6d1..b8dbbaf 100644
--- a/StarterGui/Hotbar/LocalScript.client.lua
+++ b/StarterGui/Hotbar/LocalScript.client.lua
@@ -18,8 +18,7 @@ local PM = require(ReplicatedStorage.Shared.PlacementManager)
 local BlockManager = require(ReplicatedStorage.Shared.ChunkManager.BlockManager)
 local PlacementState = require(ReplicatedStorage.Shared.PlacementState)
 local Util = require(ReplicatedStorage.Shared.Util)
-
-local blocksFolder = ReplicatedStorage:WaitForChild("Blocks")
+local ClientState = require(ReplicatedStorage.Shared.ClientState)
 
 local HOTBAR_SIZE = 10
 
@@ -53,33 +52,34 @@ local function isTextInputFocused(): boolean
 	return config ~= nil and config.IsFocused
 end
 
-local function buildHotbarIds(): {string}
-	local ids = {}
-	local names = {}
-	for _, block in ipairs(blocksFolder:GetChildren()) do
-		local id = block:GetAttribute("n")
-		if id ~= nil then
-			local n = tonumber(id)
-			if n and n > 0 then
-				local idStr = tostring(n)
-				table.insert(ids, idStr)
-				names[idStr] = block:GetAttribute("displayName") or block:GetAttribute("dn") or block.Name
-			end
-		end
+local function resolveSelectedSlot(slots, desired)
+	if desired and desired >= 1 and desired <= HOTBAR_SIZE and slots[desired] ~= "" then
+		return desired
 	end
-	table.sort(ids, function(a, b)
-		local na = tonumber(a)
-		local nb = tonumber(b)
-		if na and nb then
-			return na < nb
-		end
-		return a < b
-	end)
-	local slots = table.create(HOTBAR_SIZE)
 	for i = 1, HOTBAR_SIZE do
-		slots[i] = ids[i] or ""
+		if slots[i] and slots[i] ~= "" then
+			return i
+		end
 	end
-	return slots, names
+	return desired or 1
+end
+
+local function buildHotbarFromState()
+	local slots = table.create(HOTBAR_SIZE)
+	local names = {}
+
+	for i = 1, HOTBAR_SIZE do
+		local info = ClientState:GetSlotInfo(i)
+		if info then
+			slots[i] = tostring(info.id)
+			names[slots[i]] = info.name or slots[i]
+		else
+			slots[i] = ""
+		end
+	end
+
+	local selected = resolveSelectedSlot(slots, ClientState:GetSelectedSlot())
+	return slots, names, selected
 end
 
 local function ensurePreviewRig(part: Instance)
@@ -131,40 +131,43 @@ end
 local Hotbar = Roact.Component:extend("Hotbar")
 
 function Hotbar:init()
+	local slots, names, selected = buildHotbarFromState()
 	self.state = {
-		slots = nil,
-		names = nil,
-		selected = 1,
+		slots = slots,
+		names = names,
+		selected = selected,
 	}
-	local slots, names = buildHotbarIds()
-	self.state.slots = slots
-	self.state.names = names
-	local initialId = slots and slots[1] or ""
-	if initialId and initialId ~= "" then
-		local initialName = names and (names[initialId] or initialId) or initialId
-		PlacementState:SetSelected(initialId, initialName)
-	end
 
-	self._updateSlots = function()
-		local nextSlots, nextNames = buildHotbarIds()
+	self._syncFromClientState = function()
+		local nextSlots, nextNames, nextSelected = buildHotbarFromState()
+		nextSelected = resolveSelectedSlot(nextSlots, nextSelected or self.state.selected)
 		self:setState({
 			slots = nextSlots,
 			names = nextNames,
+			selected = nextSelected,
 		})
+		local id = nextSlots[nextSelected] or ""
+		local name = ""
+		if id ~= "" then
+			name = nextNames[id] or id
+		end
+		PlacementState:SetSelected(id, name)
 	end
 
 	self._setSelected = function(slot: number)
 		if slot < 1 or slot > HOTBAR_SIZE then
 			return
 		end
+		local info = ClientState:GetSlotInfo(slot)
+		if not info then
+			return
+		end
+		ClientState:SetSelectedSlot(slot)
 		self:setState({
 			selected = slot,
 		})
-		local id = self.state.slots and self.state.slots[slot] or ""
-		local name = ""
-		if id ~= "" and self.state.names then
-			name = self.state.names[id] or id
-		end
+		local id = tostring(info.id)
+		local name = info.name or id
 		Util.StudioLog("[PLACE][CLIENT][SELECT]", "slot", slot, "id", id, "name", name)
 		PlacementState:SetSelected(id, name)
 	end
@@ -258,11 +261,11 @@ end
 
 function Hotbar:didMount()
 	self._connections = {
-		blocksFolder.ChildAdded:Connect(self._updateSlots),
-		blocksFolder.ChildRemoved:Connect(self._updateSlots),
+		ClientState.Changed:Connect(self._syncFromClientState),
 		UIS.InputBegan:Connect(self._handleInput),
 		UIS.InputChanged:Connect(self._handleScroll),
 	}
+	self._syncFromClientState()
 	self:_refreshViewports()
 	-- initialize selection broadcast
 	local id = self.state.slots and self.state.slots[self.state.selected] or ""
diff --git a/ThirdParty/Character-Realism b/ThirdParty/Character-Realism
new file mode 160000
index 0000000..14021f7
--- /dev/null
+++ b/ThirdParty/Character-Realism
@@ -0,0 +1 @@
+Subproject commit 14021f7c4d0c89dd99d5a5af5f64b363c903767c
diff --git a/wally.lock b/wally.lock
index 28a443c..4e49274 100644
--- a/wally.lock
+++ b/wally.lock
@@ -7,10 +7,15 @@ name = "evaera/cmdr"
 version = "1.12.0"
 dependencies = []
 
+[[package]]
+name = "ivasmigins/replica"
+version = "0.1.0"
+dependencies = []
+
 [[package]]
 name = "ocbwoy3-development-studios/minecraft-roblox"
 version = "0.1.0"
-dependencies = [["cmdr", "evaera/cmdr@1.12.0"], ["roact", "roblox/roact@1.4.4"]]
+dependencies = [["cmdr", "evaera/cmdr@1.12.0"], ["replica", "ivasmigins/replica@0.1.0"], ["roact", "roblox/roact@1.4.4"]]
 
 [[package]]
 name = "roblox/roact"
diff --git a/wally.toml b/wally.toml
index 47b8c51..fdbb37a 100644
--- a/wally.toml
+++ b/wally.toml
@@ -7,3 +7,4 @@ realm = "shared"
 [dependencies]
 cmdr = "evaera/cmdr@1.12.0"
 roact = "roblox/roact@1.4.4"
+replica = "ivasmigins/replica@0.1.0"
\ No newline at end of file