Apply recipe notification deltas directly in Lua

Review feedback: the download field now always carries the delta and the deserializer applies it against the current state instead of rebuilding the full list first. The previous failed recipe names are passed in so they survive the round trip. The version check moved to the call site.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

plugins/inventory_sync/module/serialize.lua

@@ -545,95 +545,54 @@ function serialize.serialize_crafting_notifications(player, failed)
 	return helpers.encode_string(helpers.table_to_json(recipe_names))
 end
 
---- Current notification state, sent with download requests so the instance plugin only returns the difference
---- @param player LuaPlayer
---- @param failed FailedDeserializationPlayerData?
---- @return string?
-function serialize.crafting_notification_snapshot(player, failed)
-	if not recipe_notifications_api then
-		return nil
-	end
-	return serialize.serialize_crafting_notifications(player, failed and failed.recipe_notifications)
-end
-
 --- @class CraftingNotificationDelta
---- @field add string[]? Recipe names to add to the cleared list
---- @field remove string[]? Recipe names to remove from the cleared list
-
---- Rebuild the full serialized form from the snapshot the delta was computed against
---- @param snapshot string
---- @param serialized_delta string
---- @return string?
-function serialize.apply_crafting_notification_delta(snapshot, serialized_delta)
-	local recipe_names = helpers.json_to_table(assert(helpers.decode_string(snapshot)))
-	assert(type(recipe_names) == "table", "wrong type decoded from json_to_table")
-	--- @type CraftingNotificationDelta
-	local delta = helpers.json_to_table(assert(helpers.decode_string(serialized_delta)))
-	assert(type(delta) == "table", "wrong type decoded from json_to_table")
-	local cleared = {}
-	for _, name in pairs(recipe_names) do
-		cleared[name] = true
-	end
-	for _, name in pairs(delta.remove or {}) do
-		cleared[name] = nil
-	end
-	for _, name in pairs(delta.add or {}) do
-		cleared[name] = true
-	end
-
-	local merged = {}
-	for name in pairs(cleared) do
-		merged[#merged + 1] = name
-	end
-	return helpers.encode_string(helpers.table_to_json(merged))
-end
+--- @field add string[]? Recipes cleared elsewhere that still have a notification here
+--- @field remove string[]? Recipes with a notification elsewhere that are cleared here
 
 --- @param player LuaPlayer
---- @param serialized string
+--- @param serialized string Encoded delta against the state sent with the download request
+--- @param previous_failed string[]? Recipe names that did not exist at the last deserialization
 --- @return string[]? failed Recipe names that do not exist
-function serialize.deserialize_crafting_notifications(player, serialized)
-	-- Decode the recipe name strings
-	local recipe_names = helpers.json_to_table(assert(helpers.decode_string(serialized)))
-	assert(type(recipe_names) == "table", "wrong type decoded from json_to_table")
-	local clear_notification = player.clear_recipe_notification
-	local add_notification = player.add_recipe_notification
-	local notifications = {}
+function serialize.deserialize_crafting_notifications(player, serialized, previous_failed)
+	--- @type CraftingNotificationDelta
+	local delta = helpers.json_to_table(assert(helpers.decode_string(serialized)))
+	assert(type(delta) == "table", "wrong type decoded from json_to_table")
 	local failed = {}
+	for _, recipe_name in pairs(previous_failed or {}) do
+		failed[recipe_name] = true
+	end
 
-	-- Assume all recipes need a notification
+	-- Recipes which can have a notification on this server
+	local enabled = {}
 	for _, recipe in pairs(player.force.recipes) do
 		if recipe.enabled and not recipe.hidden then
-			notifications[recipe.name] = true
+			enabled[recipe.name] = true
 		end
 	end
 
-	-- Remove recipes the player has cleared
-	for _, recipe_name in pairs(recipe_names) do
-		if notifications[recipe_name] then
-			notifications[recipe_name] = false
+	-- Clear notifications the player has cleared elsewhere
+	for _, recipe_name in pairs(delta.add or {}) do
+		if enabled[recipe_name] then
+			player.clear_recipe_notification(recipe_name)
 		else
-			-- Recipe does not exist on this server
-			failed[#failed+1] = recipe_name
+			failed[recipe_name] = true -- Recipe does not exist on this server
 		end
 	end
 
-	-- Clear ones which are ones which are not required
-	for _, recipe in pairs(player.get_recipe_notifications()) do
-		if notifications[recipe.name] == false then
-			clear_notification(recipe.name)
-		end
-		notifications[recipe.name] = nil -- Prevents double add below
-	end
-
-	-- Add any which the player did not have
-	for recipe_name, should_add in pairs(notifications) do
-		if should_add then
-			add_notification(recipe_name)
+	-- Add notifications the player has elsewhere
+	for _, recipe_name in pairs(delta.remove or {}) do
+		if enabled[recipe_name] then
+			player.add_recipe_notification(recipe_name)
+		else
+			failed[recipe_name] = nil
 		end
 	end
 
-	-- Return failed recipes if any
-	return next(failed) and failed or nil
+	local failed_names = {}
+	for recipe_name in pairs(failed) do
+		failed_names[#failed_names + 1] = recipe_name
+	end
+	return next(failed_names) and failed_names or nil
 end
 
 local controller_to_name = {}
@@ -839,8 +798,9 @@ end
 
 --- @param player LuaPlayer
 --- @param serialized SerializedPlayerData
+--- @param previous_failed FailedDeserializationPlayerData?
 --- @return FailedDeserializationPlayerData?
-function serialize.deserialize_player(player, serialized)
+function serialize.deserialize_player(player, serialized, previous_failed)
 	local failed_deserialization = {}
 
 	local target_controller = defines.controllers[serialized.controller]
@@ -927,8 +887,9 @@ function serialize.deserialize_player(player, serialized)
 
 	-- Deserialize recipe notifications
 	if recipe_notifications_api and serialized.recipe_notifications then
-		failed_deserialization.recipe_notifications =
-			serialize.deserialize_crafting_notifications(player, serialized.recipe_notifications)
+		failed_deserialization.recipe_notifications = serialize.deserialize_crafting_notifications(
+			player, serialized.recipe_notifications, previous_failed and previous_failed.recipe_notifications
+		)
 	end
 
 	return next(failed_deserialization) and failed_deserialization or nil