Add cross-mod recent items panel in titlebar

control.lua

@@ -8,7 +8,7 @@ Search = require "scripts.search"
 SearchResults = require "scripts.search-results"
 ResultLocation = require "scripts.result-location"
 SearchGui = require "scripts.search-gui"
-require "scripts.remote"
+Interop = require "scripts.remote"
 
 ---@alias ItemName string
 ---@alias EntityName string
@@ -36,6 +36,7 @@ require "scripts.remote"
 ---@field searching_label LuaGuiElement label
 ---@field search_progressbar LuaGuiElement progressbar
 ---@field result_flow LuaGuiElement flow
+---@field recent_items_flow LuaGuiElement flow
 ---@field highlighted_button? LuaGuiElement sprite-button
 
 ---@class (exact) PlayerData
@@ -237,15 +238,37 @@ local function generate_item_to_entity_table()
   storage.item_to_entities = item_to_entities
 end
 
+local function setup_interop_callback()
+  Interop.set_on_external_item_callback(function(player_index, item_name, source)
+    Interop.add_recent_item(player_index, item_name, source)
+    local player = game.get_player(player_index)
+    if player then
+      local player_data = storage.players[player_index]
+      if player_data and player_data.refs.frame.valid and player_data.refs.frame.visible then
+        SearchGui.update_recent_panel(player_data)
+      end
+    end
+  end)
+end
+
 local function on_init()
   ---@type table<PlayerIndex, PlayerData>
   storage.players = {}
   ---@type table<PlayerIndex, SearchData>
   storage.current_searches = {}
   ---@type boolean
   storage.multiple_surfaces = false
+  ---@type table<PlayerIndex, {item_name: string, source: string}[]>
+  storage.recent_external_items = {}
   update_surface_count()
   generate_item_to_entity_table()
+  Interop.subscribe_to_events()
+  setup_interop_callback()
+end
+
+local function on_load()
+  Interop.subscribe_to_events()
+  setup_interop_callback()
 end
 
 local function on_configuration_changed()
@@ -263,11 +286,17 @@ local function on_configuration_changed()
   storage.current_searches = {}
 
   storage.multiple_surfaces = false
+  if not storage.recent_external_items then
+    storage.recent_external_items = {}
+  end
   update_surface_count()
   generate_item_to_entity_table()
+  Interop.subscribe_to_events()
+  setup_interop_callback()
 end
 
 Control.on_init = on_init
+Control.on_load = on_load
 Control.on_configuration_changed = on_configuration_changed
 Control.events = {
   [defines.events.on_surface_created] = update_surface_count,

scripts/remote.lua

@@ -1,10 +1,92 @@
-remote.add_interface("factory-search", {
-  ---@param player LuaPlayer
-  ---@param search_value SignalID
-  search = function(player, search_value)
-    SearchGui.open(player, storage.players[player.index])
-    local player_data = storage.players[player.index]
-    player_data.refs.item_select.elem_value = search_value
-    SearchGui.start_search(player, player_data)
-  end
-})
+local remote_interface = {}
+
+local on_item_selected = script.generate_event_name()
+
+local on_external_item_callback = nil
+
+--- Open the search GUI for a player with the given item pre-selected.
+---@param player LuaPlayer
+---@param search_value SignalID
+function remote_interface.search(player, search_value)
+  SearchGui.open(player, storage.players[player.index])
+  local player_data = storage.players[player.index]
+  player_data.refs.item_select.elem_value = search_value
+  SearchGui.start_search(player, player_data)
+end
+
+function remote_interface.get_on_item_selected()
+  return on_item_selected
+end
+
+function remote_interface.interop_version()
+  return 1
+end
+
+remote.add_interface("factory-search", remote_interface)
+
+local function raise_item_selected(player_index, item_name)
+  script.raise_event(on_item_selected, {
+    player_index = player_index,
+    item_name = item_name,
+  })
+end
+
+local function subscribe_to_events()
+  for iface, functions in pairs(remote.interfaces) do
+    if iface == "factory-search" then goto continue end
+
+    if functions["get_on_item_selected"] then
+      local event_id = remote.call(iface, "get_on_item_selected")
+      if event_id then
+        local source_iface = iface
+        script.on_event(event_id, function(e)
+          local player = game.get_player(e.player_index)
+          if not player then return end
+          local item_name = e.item_name
+          if item_name and (prototypes.item[item_name] or prototypes.fluid[item_name]) then
+            if on_external_item_callback then
+              on_external_item_callback(e.player_index, item_name, source_iface)
+            end
+          end
+        end)
+        log("FactorySearch: subscribed to " .. iface .. ".get_on_item_selected")
+      end
+    end
+
+    ::continue::
+  end
+end
+
+local function add_recent_item(player_index, item_name, source)
+  if not storage.recent_external_items then
+    storage.recent_external_items = {}
+  end
+  local list = storage.recent_external_items[player_index]
+  if not list then
+    list = {}
+    storage.recent_external_items[player_index] = list
+  end
+
+  -- Deduplicate: remove existing entry for this item
+  for i = #list, 1, -1 do
+    if list[i].item_name == item_name then
+      table.remove(list, i)
+    end
+  end
+
+  table.insert(list, 1, { item_name = item_name, source = source })
+  if #list > 5 then
+    list[6] = nil
+  end
+end
+
+local function set_on_external_item_callback(cb)
+  on_external_item_callback = cb
+end
+
+return {
+  raise_item_selected = raise_item_selected,
+  subscribe_to_events = subscribe_to_events,
+  add_recent_item = add_recent_item,
+  set_on_external_item_callback = set_on_external_item_callback,
+}

scripts/search-gui.lua

@@ -1,3 +1,5 @@
+local interop = require("scripts.remote")
+
 local SearchGui = {}
 
 ---@param signal SignalID
@@ -390,6 +392,12 @@ function SearchGui.build(player)
               ignored_by_interaction = true,
             },
             {type = "empty-widget", style = "fs_flib_titlebar_drag_handle", ignored_by_interaction = true},
+            {
+              type = "flow",
+              direction = "horizontal",
+              ref = {"recent_items_flow"},
+              style_mods = {horizontal_spacing = 2},
+            },
             {
               type = "sprite-button",
               style = "frame_action_button",
@@ -668,6 +676,7 @@ function SearchGui.open(player, player_data)
   refs.frame.visible = true
   refs.frame.bring_to_front()
   player.set_shortcut_toggled("search-factory", true)
+  SearchGui.update_recent_panel(player_data)
 end
 
 ---@param player LuaPlayer
@@ -791,6 +800,10 @@ function SearchGui.start_search(player, player_data, _, _, immediate)
   local elem_button = refs.item_select
   local item = elem_button.elem_value --[[@as SignalID]]
   if item then
+    -- Broadcast item/fluid selection to other mods (interop spec v1)
+    if item.name and (item.type == "item" or item.type == "fluid") then
+      interop.raise_item_selected(player.index, item.name)
+    end
     local force = player.force --[[@as LuaForce]]
     local state = generate_state(refs)
     local state_valid = is_valid_state(state)
@@ -836,6 +849,61 @@ function SearchGui.sort_results_dropdown_changed(player, player_data)
   player_data.sort_results_by = sort_results_by_options[dropdown.selected_index]
 end
 
+---@param player_data PlayerData
+function SearchGui.update_recent_panel(player_data)
+  local flow = player_data.refs.recent_items_flow
+  if not flow or not flow.valid then return end
+
+  flow.clear()
+
+  local items = storage.recent_external_items and storage.recent_external_items[player_data.refs.frame.player_index]
+  if not items or #items == 0 then return end
+
+  for _, entry in ipairs(items) do
+    local sprite_path
+    if prototypes.item[entry.item_name] then
+      sprite_path = "item/" .. entry.item_name
+    elseif prototypes.fluid[entry.item_name] then
+      sprite_path = "fluid/" .. entry.item_name
+    end
+
+    if sprite_path then
+      local proto = prototypes.item[entry.item_name] or prototypes.fluid[entry.item_name]
+      local tooltip = proto and proto.localised_name or entry.item_name
+      gui.add(flow, {
+        {
+          type = "sprite-button",
+          sprite = sprite_path,
+          tooltip = tooltip,
+          style = "frame_action_button",
+          tags = { fs_recent_item_name = entry.item_name },
+          handler = {[defines.events.on_gui_click] = SearchGui.on_recent_item_clicked},
+        }
+      })
+    end
+  end
+end
+
+---@param player LuaPlayer
+---@param player_data PlayerData
+---@param element LuaGuiElement
+function SearchGui.on_recent_item_clicked(player, player_data, element)
+  local item_name = element.tags.fs_recent_item_name
+  if not item_name then return end
+
+  local sig_type
+  if prototypes.item[item_name] then
+    sig_type = "item"
+  elseif prototypes.fluid[item_name] then
+    sig_type = "fluid"
+  else
+    return
+  end
+
+  player_data.refs.item_select.elem_value = { type = sig_type, name = item_name }
+  SearchGui.start_search(player, player_data)
+end
+
 gui.add_handlers(SearchGui,
   function(event, handler)
     local player = game.get_player(event.player_index)  ---@cast player -?