Sync the page shown on each quick bar row

player_sync restored the content of the quick bar slots but not which
page each row shows, which every save keeps per player on its own. After
switching servers the rows could show other pages, and with them another
set of slots.

Fixes #1201

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JyNnVzRW4jPWaoWTxCyhM7

plugins/player_sync/module/serialize.lua

@@ -713,6 +713,30 @@ function serialize.deserialize_quick_bar(player, serialized)
 	end
 end
 
+--- Quick bar page shown on each quick bar row of the screen, kept by every save on its own
+--- @param player LuaPlayer
+--- @return integer[]?
+function serialize.serialize_quick_bar_pages(player)
+	local pages = {}
+	for screen = 1, 10 do
+		-- pcall: the number of rows the API knows is not documented for older versions
+		local ok, page = pcall(player.get_active_quick_bar_page, screen)
+		if not ok or not page then
+			break
+		end
+		pages[screen] = page
+	end
+	return pages[1] and pages or nil
+end
+
+--- @param player LuaPlayer
+--- @param pages integer[]? Absent in data from before pages were synced, the rows then stay as they are here
+function serialize.deserialize_quick_bar_pages(player, pages)
+	for screen, page in ipairs(pages or {}) do
+		player.set_active_quick_bar_page(screen, page)
+	end
+end
+
 -- Crafting queue is a table with the following fields:
 --  crafting_queue
 --  ingredients
@@ -974,6 +998,7 @@ end
 --- @field inventories table<string, table>?
 --- @field hotbar table<string, string>?
 --- @field quick_bar table<string, QuickBarSlotEncoded>?
+--- @field quick_bar_pages integer[]? Page shown on each quick bar row
 --- @field personal_logistic_slots table?
 --- @field crafting_queue table?
 --- @field recipe_notifications string?
@@ -1178,6 +1203,7 @@ function serialize.serialize_player(player, failed_deserialization, components)
 	-- Serialize quick bar
 	if syncs(components, "quick_bar") then
 		serialized.quick_bar = serialize.serialize_quick_bar(player)
+		serialized.quick_bar_pages = serialize.serialize_quick_bar_pages(player)
 	end
 
 	-- Serialize crafting queue
@@ -1444,6 +1470,7 @@ function serialize.deserialize_player(player, serialized, components, local_cont
 	-- Deserialize quick bar (named hotbar in old data)
 	if syncs(components, "quick_bar") then
 		serialize.deserialize_quick_bar(player, serialized.quick_bar or serialized.hotbar)
+		serialize.deserialize_quick_bar_pages(player, serialized.quick_bar_pages)
 	end
 
 	-- Deserialize recipe notifications