refactor: extract useStockAdjustment hook from page.tsx

frontend/app/page.tsx

@@ -5,6 +5,7 @@ import { db, Item } from '@/lib/db';
 import { inventoryApi } from '@/lib/api';
 import { fetchAndCacheItems, syncOfflineOperations } from '@/lib/sync';
 import { useScanner } from '@/hooks/useScanner';
+import { useStockAdjustment } from '@/hooks/useStockAdjustment';
 import Scanner from '@/components/Scanner';
 import AIOnboarding from '@/components/AIOnboarding';
 import PageShell from '@/components/PageShell';
@@ -53,8 +54,6 @@ export default function Home() {
   const [boxMatches, setBoxMatches] = useState<Item[]>([]);
   const [isEditing, setIsEditing] = useState(false);
   const [editedItem, setEditedItem] = useState<Partial<Item>>({});
-  const [adjustQty, setAdjustQty] = useState<number>(1);
-  const [adjustType, setAdjustType] = useState<'ADD' | 'REMOVE' | 'TRASH'>('ADD');
   const [trashReason, setTrashReason] = useState('Damaged');
   const [syncing, setSyncing] = useState(false);
   const [currentUser, setCurrentUser] = useState<any | null>(null);
@@ -91,6 +90,22 @@ export default function Home() {
     }
   });
 
+  const {
+    adjustQty,
+    setAdjustQty,
+    adjustType,
+    setAdjustType,
+    handleAdjustStock
+  } = useStockAdjustment({
+    selectedItem,
+    isOnline,
+    currentUser,
+    onAdjustmentComplete: () => {
+      setSelectedItem(null);
+    },
+    onInventoryUpdate: setInventory
+  });
+
   useEffect(() => {
     if (!localStorage.getItem('inventory_token')) {
       window.location.href = '/login';
@@ -291,50 +306,6 @@ export default function Home() {
     }
   };
 
-  const handleAdjustStock = async () => {
-    if (!selectedItem) return;
-
-    const toastId = toast.loading("Processing...");
-
-    try {
-      const finalAdjustQty = adjustQty;
-      const newQty = selectedItem.quantity + (adjustType === 'ADD' ? adjustQty : -adjustQty);
-
-      // 1. Create a unique ID for this operation to prevent double-counting on server
-      const operationId = crypto.randomUUID();
-
-      // 2. Queue local operation
-      const opType = adjustType === 'ADD' ? 'CHECK_IN' : (adjustType === 'TRASH' ? 'TRASH' : 'CHECK_OUT');
-
-      await db.pendingOperations.add({
-        type: opType as any,
-        barcode: selectedItem.barcode,
-        quantity: finalAdjustQty,
-        timestamp: Date.now(),
-        synced: 0,
-        // We add this to our DB even if it doesn't have it yet, Dexie handles it
-        uuid: operationId
-      } as any);
-
-      // 3. Update local UI & DB
-      await db.items.update(selectedItem.id!, { quantity: newQty });
-      setInventory(prev => prev.map(i => i.id === selectedItem.id ? { ...i, quantity: newQty } : i));
-
-      // 4. Trigger Sync
-      if (isOnline) {
-        await handleSync();
-        toast.success("Inventory updated & synced", { id: toastId });
-      } else {
-        toast.success("Saved locally (Offline)", { id: toastId });
-      }
-
-      setSelectedItem(null);
-      setAdjustQty(1);
-    } catch (error: any) {
-      console.error("Adjustment failure:", error);
-      toast.error("Error saving operation", { id: toastId });
-    }
-  };
 
   const [searchQuery, setSearchQuery] = useState('');
 

frontend/hooks/useStockAdjustment.ts

@@ -0,0 +1,86 @@
+import { useState, useCallback } from 'react';
+import { db, Item } from '@/lib/db';
+import { toast } from 'react-hot-toast';
+import { syncOfflineOperations } from '@/lib/sync';
+
+interface UseStockAdjustmentOptions {
+  selectedItem: Item | null;
+  isOnline: boolean;
+  currentUser: any;
+  onAdjustmentComplete?: () => void;
+  onInventoryUpdate?: (items: Item[]) => void;
+}
+
+export function useStockAdjustment(options: UseStockAdjustmentOptions) {
+  const { selectedItem, isOnline, currentUser, onAdjustmentComplete, onInventoryUpdate } = options;
+  const [adjustQty, setAdjustQty] = useState<number>(1);
+  const [adjustType, setAdjustType] = useState<'ADD' | 'REMOVE' | 'TRASH'>('ADD');
+
+  const handleAdjustStock = useCallback(async () => {
+    if (!selectedItem) return;
+
+    const toastId = toast.loading("Processing...");
+
+    try {
+      const finalAdjustQty = adjustQty;
+      const newQty = selectedItem.quantity + (adjustType === 'ADD' ? adjustQty : -adjustQty);
+
+      // Create a unique ID for this operation to prevent double-counting on server
+      const operationId = crypto.randomUUID();
+
+      // Queue local operation
+      const opType = adjustType === 'ADD' ? 'CHECK_IN' : (adjustType === 'TRASH' ? 'TRASH' : 'CHECK_OUT');
+
+      await db.pendingOperations.add({
+        type: opType as any,
+        barcode: selectedItem.barcode,
+        quantity: finalAdjustQty,
+        timestamp: Date.now(),
+        synced: 0,
+        uuid: operationId
+      } as any);
+
+      // Update local UI & DB
+      await db.items.update(selectedItem.id!, { quantity: newQty });
+
+      // Get updated inventory
+      const updated = await db.items.toArray();
+      if (onInventoryUpdate) {
+        onInventoryUpdate(updated);
+      }
+
+      // Trigger Sync
+      if (isOnline && currentUser) {
+        try {
+          const result = await syncOfflineOperations(currentUser.id);
+          if (result.success > 0) {
+            toast.success("Inventory updated & synced", { id: toastId });
+          } else {
+            toast.success("Saved locally", { id: toastId });
+          }
+        } catch (syncError) {
+          console.error("Sync failed:", syncError);
+          toast.success("Saved locally (Sync pending)", { id: toastId });
+        }
+      } else {
+        toast.success("Saved locally (Offline)", { id: toastId });
+      }
+
+      setAdjustQty(1);
+      if (onAdjustmentComplete) {
+        onAdjustmentComplete();
+      }
+    } catch (error: any) {
+      console.error("Adjustment failure:", error);
+      toast.error("Error saving operation", { id: toastId });
+    }
+  }, [selectedItem, adjustQty, adjustType, isOnline, currentUser, onAdjustmentComplete, onInventoryUpdate]);
+
+  return {
+    adjustQty,
+    setAdjustQty,
+    adjustType,
+    setAdjustType,
+    handleAdjustStock
+  };
+}