Synchronize world state across editor and room saves

level_editor/editor.lua

@@ -492,6 +492,7 @@ local function saveRoomFromEditor()
 	gameWorld:invalidatePreview(name)
 	if editorView == "world" then rebuildWorldRoomButtons() end
 	currentRoom.name = name
+	gameWorld:setLevel(currentRoom)
 	editorRoomName = name
 	roomNameField:editText(name)
 	activeField = nil
@@ -520,6 +521,7 @@ local function clearRuntimeSaves()
 	clearSaveConfirmationScope = nil
 	if roomName then
 		currentRoom = Room:new{ name = roomName }
+		gameWorld:setLevel(currentRoom)
 		setEditorRoomName(currentRoom.name)
 		editorStatus = "Cleared " .. removed .. " runtime save item(s) and reloaded '" .. roomName .. ".'"
 	else
@@ -905,6 +907,7 @@ local function openWorldRoom(cellX, cellY)
 		currentRoom = Room:new{ name = name }
 		editorStatus = "Editing '" .. name .. ".'"
 	end
+	gameWorld:setLevel(currentRoom)
 	gameWorld:setLastRoom(currentRoom.name)
 	setEditorRoomName(currentRoom.name)
 	assetsView()

main.lua

@@ -66,8 +66,12 @@ function love.quit()
 	-- An explicit editor save/clear removes the runtime copy intentionally;
 	-- don't immediately recreate it while shutting down.
 	if currentRoom and not suppressRuntimeAutosave then
-		currentRoom:save()
-		if gameWorld then gameWorld:setLastRoom(currentRoom.name) end
+		if gameWorld then
+			gameWorld:markDirty(currentRoom)
+			gameWorld:flushRuntime()
+		else
+			currentRoom:save()
+		end
 	end
 end
 

world.lua

@@ -12,15 +12,54 @@ function World:initialize()
 	self.previewCache = {}
 	self.lastRoom = nil
 	self:load()
+	self:loadRuntimeState()
 	self.levels = {}
 
 end
 
 function World:loadLevels()
-	for _, placed in ipairs(self.rooms) do self.levels[placed.name] = Room:new{name = placed.name} end
+	-- Gameplay saves go to LÖVE's runtime directory. Seed every world slice
+	-- through the same runtime-first loader, not just the initially visible one.
+	for _, placed in ipairs(self.rooms) do self.levels[placed.name] = Room:new{name = placed.name, runtime = true} end
 	self:rebuildCollision()
 end
 
+-- The editor can replace a level with a freshly loaded authored Room. Keep the
+-- global simulation pointing at that exact instance, not a stale preload.
+function World:setLevel(room)
+	if not room or not room.name or not self:roomLocation(room.name) then return false end
+	self.levels[room.name] = room
+	self:rebuildCollision()
+	return true
+end
+
+-- Runtime state is one logical world snapshot: each level slice is written to
+-- LÖVE's save directory, and this companion file says which slice was active.
+-- The authored world layout remains source-only for the editor.
+function World:loadRuntimeState()
+	local raw = love.filesystem.read("rooms/world.sav")
+	if not raw then return end
+	local ok, state = pcall(TSerial.unpack, raw)
+	if ok and type(state) == "table" and state.lastRoom and self:roomLocation(state.lastRoom) then
+		self.lastRoom = state.lastRoom
+	end
+end
+
+function World:saveRuntime(dirtyRooms)
+	for room in pairs(dirtyRooms or {}) do room:save() end
+	return love.filesystem.write("rooms/world.sav", TSerial.pack({lastRoom = currentRoom and currentRoom.name}, nil, true))
+end
+
+function World:markDirty(room)
+	self.dirtyRooms = self.dirtyRooms or {}
+	self.dirtyRooms[room] = true
+end
+
+function World:flushRuntime()
+	self:saveRuntime(self.dirtyRooms)
+	self.dirtyRooms = {}
+end
+
 function World:listRoomNames()
 	local names = {}
 	for _, file in ipairs(love.filesystem.getDirectoryItems("rooms")) do
@@ -120,7 +159,6 @@ end
 function World:setLastRoom(name)
 	if name and self.lastRoom ~= name then
 		self.lastRoom = name
-		return self:save()
 	end
 	return true
 end
@@ -310,8 +348,10 @@ function World:movePlayer(room, key)
 		current[color] = player:getGridPos()
 	end
 	if moved then
+		self:markDirty(room)
 		self:playerJoinCheck(room, previous, current)
 		self:tick(room)
+		self:flushRuntime()
 	end
 end
 
@@ -326,6 +366,7 @@ function World:switchPlayerColor(room, color)
 		end
 	end
 	player:playSwitchSound(canSwitch)
+	if canSwitch then self:markDirty(room); self:flushRuntime() end
 	return canSwitch
 end
 
@@ -353,19 +394,33 @@ function World:nextRoom(room, pos)
 	elseif pos.y < 1 then exit, entry.y = "top", gridHeight end
 	local nextName = self:getNeighbor(room.name, exit) or room.name
 	local activeColors = room:getActiveColors()
-	room:save()
-	room.activeColors = {red = false, green = false, blue = false}
-	currentRoom = self.levels[nextName]
+	self:markDirty(room)
+	local destination = self.levels[nextName]
 	for _, color in ipairs(activeColors) do
-		if currentRoom.player[color] then
-			currentRoom.player[color].x, currentRoom.player[color].y = entry.x, entry.y
-		else
-			currentRoom:registerPlayer(Player:new(entry.x, entry.y, color), color)
+		local player = room.player[color]
+		-- Active copies travel with the player. Inactive copies are deliberately
+		-- left in their room so World:playerJoinCheck can merge them later.
+		room.player[color] = nil
+		for i = #room.colorsPlayerHas, 1, -1 do
+			if room.colorsPlayerHas[i] == color then table.remove(room.colorsPlayerHas, i) end
 		end
+		if destination.player[color] then
+			for i = #destination.colorsPlayerHas, 1, -1 do
+				if destination.colorsPlayerHas[i] == color then table.remove(destination.colorsPlayerHas, i) end
+			end
+		end
+		destination.player[color] = player
+		table.insert(destination.colorsPlayerHas, color)
+	end
+	room.activeColors = {red = false, green = false, blue = false}
+	currentRoom = destination
+	self:markDirty(currentRoom)
+	for _, color in ipairs(activeColors) do
+		currentRoom.player[color].x, currentRoom.player[color].y = entry.x, entry.y
 		currentRoom:setActiveColor(color, true)
 	end
 	self:playerJoinCheck(currentRoom)
-	self:setLastRoom(currentRoom.name)
+	self.lastRoom = currentRoom.name
 	setEditorRoomName(currentRoom.name)
 end
 
@@ -397,7 +452,7 @@ function World:moveGroup(group, direction)
 	self:rebuildCollision()
 	for room in pairs(changed) do room:resolveSwitchesAndDoors() end
 	self:rebuildCollision()
-	for room in pairs(changed) do if room ~= currentRoom then room:save() end end
+	for room in pairs(changed) do self:markDirty(room) end
 end
 
 function World:drawOverlaps(room, color)