In the Shop building, Stock says available but checkout blocks

[Pragya79645]

In the Shop building, Product shows in stock, but checkout rejects purchase.

[Sampurnasit]

Bug Report
Building: [ Shop House ] Difficulty (your estimate): [ Medium ]

What is broken?
Checkout fails with an "out of stock" error even when products are in stock, particularly if the user navigates away from the product's page or applies filters.

Steps to reproduce

1. Go to the Shop House.
2. Add a product to the cart (e.g., "Vector Cut Jacket").
3. Navigate to the next page of products or search for a different item so the added product is no longer visible in the main grid.
4. Click "Proceed To Checkout".
5. Observe the error: "Checkout blocked: one or more items are out of stock."

Expected behavior
The checkout process should verify the stock against the entire product database, not just the products currently rendered on the screen.

Actual behavior
The checkoutStockMap is derived only from renderedProducts. If a cart item's ID is not found in this map, the stock check defaults to 0, causing the checkout to be blocked.

Environment
Browser: Any Screen size: Desktop Mode: Dark (Debug Quest Mode)

[Soyam27]

Please provide Solution/Approach.

[Sampurnasit]

Fix: Validated checkout stock against the full product catalog
Closes #17

Bug found
The checkout process would incorrectly block purchases with an "out of stock" error for items that were clearly in stock. Visible symptom: If a user added an item to their cart, then searched for something else or moved to a different page in the shop, clicking "Proceed To Checkout" would trigger the error: "Checkout blocked: one or more items are out of stock."

Root cause
The checkout logic was relying on a stock map that only contained the products currently visible on the user's screen.

File: src/components/shop-house/hooks/useDebugQuestShop.js
Lines: ~162-164 and ~277
Logic: The checkoutStockMap was memoized using renderedProducts.map(...). Because renderedProducts only contains the 8 items on the current page, any item in the cart that was on a different page was missing from the map.
The "Zero" Fallback: In the checkout function, the code used checkoutStockMap.get(item.id) ?? 0. Since the item wasn't in the map, it defaulted to 0, causing the validation to fail even for items with plenty of stock.
Fix applied
I updated the stock validation to use the master product list instead of the filtered/paged view:

useDebugQuestShop.js: Modified the checkoutStockMap useMemo hook to map over the global products array instead of renderedProducts.

Logic Update: By using the full catalog for the stock map, the checkout function can now correctly verify the availability of any item in the cart, regardless of whether the user is currently looking at that item in the product grid.

Stability: This decouples the "Cart" logic from the "Grid" logic, ensuring that the checkout process remains reliable even as the user navigates through different categories and search results.

Testing done
Reproduced the bug by adding an item, searching for a different item, and attempting checkout. Confirmed fix resolves the issue (checkout now succeeds for all in-stock items). Verified no existing features are broken. Tested on: Chrome / Windows 11

[Soyam27]

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