Implement cache persistence for inventory data and enhance loading mechanism

inventoryManager.lua

@@ -8,6 +8,7 @@ local MONITOR_SIDE  = "left"
 local SCAN_INTERVAL = 3    -- seconds between background scans
 local SMELT_INTERVAL = 3   -- seconds between furnace checks
 local SMELT_RESERVE  = 64  -- keep at least 1 stack of each raw material
+local CACHE_FILE     = ".inventory_cache"  -- persistent cache file
 
 -------------------------------------------------
 -- Furnace types to manage
@@ -239,6 +240,58 @@ local function refreshCache(onProgress)
     cache.furnaceCount = furnaceCount
 
     activity.scanning = false
+
+    -- Persist cache to disk
+    pcall(function()
+        local data = {
+            catalogue  = cache.catalogue,
+            itemList   = cache.itemList,
+            grandTotal = cache.grandTotal,
+            chestCount = cache.chestCount,
+            totalSlots = cache.totalSlots,
+            usedSlots  = cache.usedSlots,
+            freeSlots  = cache.freeSlots,
+            usedRatio  = cache.usedRatio,
+            dropperOk  = cache.dropperOk,
+            barrelOk   = cache.barrelOk,
+            furnaceCount = cache.furnaceCount,
+            savedAt    = os.epoch("utc"),
+        }
+        local f = fs.open(CACHE_FILE, "w")
+        f.write(textutils.serialise(data))
+        f.close()
+    end)
+end
+
+-- Load cache from disk (returns true if loaded)
+local function loadCacheFromDisk()
+    if not fs.exists(CACHE_FILE) then return false end
+    local ok, err = pcall(function()
+        local f = fs.open(CACHE_FILE, "r")
+        local raw = f.readAll()
+        f.close()
+        local data = textutils.unserialise(raw)
+        if data and data.catalogue and data.itemList then
+            cache.catalogue    = data.catalogue
+            cache.itemList     = data.itemList
+            cache.grandTotal   = data.grandTotal   or 0
+            cache.chestCount   = data.chestCount   or 0
+            cache.totalSlots   = data.totalSlots   or 0
+            cache.usedSlots    = data.usedSlots    or 0
+            cache.freeSlots    = data.freeSlots    or 0
+            cache.usedRatio    = data.usedRatio    or 0
+            cache.dropperOk    = data.dropperOk    or false
+            cache.barrelOk     = data.barrelOk     or false
+            cache.furnaceCount = data.furnaceCount or 0
+        else
+            error("invalid cache data")
+        end
+    end)
+    if not ok then
+        print("[WARN] Could not load cache: " .. tostring(err))
+        return false
+    end
+    return true
 end
 
 -------------------------------------------------
@@ -1079,8 +1132,14 @@ local function main()
     print("Console shows log. Use the monitor to interact.")
     print("")
 
-    -- Initial scan with progress bar on monitor
+    -- Try loading cached inventory from disk for instant startup
-    print("[INIT] Scanning inventories...")
+    local cacheLoaded = loadCacheFromDisk()
+    if cacheLoaded then
+        print("[INIT] Loaded cached inventory (" .. #cache.itemList .. " types)")
+        print("[INIT] Background refresh starting...")
+    else
+        -- No cache: do full scan with progress bar
+        print("[INIT] No cache found. Scanning inventories...")
         if mon then
             local w, h = mon.getSize()
             local buf = window.create(mon, 1, 1, w, h, false)
@@ -1146,11 +1205,18 @@ local function main()
             refreshCache()
         end
         print("[INIT] Done. Found " .. #cache.itemList .. " item types.")
+    end
     print("")
 
     parallel.waitForAny(
         -- Task 1: Background inventory scanner
         function()
+            -- If we loaded from disk cache, refresh immediately in background
+            if cacheLoaded then
+                pcall(refreshCache)
+                needsRedraw = true
+                print("[INIT] Background refresh complete. " .. #cache.itemList .. " types.")
+            end
             while true do
                 sleep(SCAN_INTERVAL)
                 pcall(refreshCache)