Auto-Cart Shopping Assistant by xaviesteve

Paste your weekly shopping list, one item per line, with as much or as
little detail as you want — quantities, brand preferences, size ranges,
dietary notes ("no added sugar", "sin gluten") — and the assistant searches
each store, picks the best-matching product for every line, and adds it to
your cart. You always place the order yourself; the extension never
completes a purchase.


Doing the same weekly supermarket order by hand — searching the same 20-30
items, picking the right pack size, adding each to cart — is repetitive.
This extension automates the tedious middle part (search → match → add) and
leaves the part that should stay a deliberate human decision (reviewing the
cart and paying) exactly where it belongs: with you, on the store's own
site.

• Plain-text shopping lists. Write your list the way you'd write it for
  yourself — 2x Yogur natural, Salmón congelado (sin piel, 250-500 g),
  # meat section as a comment to organize the list. Bullets (-, *,
  1.), blank lines, and # comment lines are all handled automatically.
• Fuzzy, constraint-aware matching. Weight/size ranges and simple
  keyword constraints ("no added sugar", "sin gluten") are matched directly
  against each store's product data — including correctly distinguishing
  "250-500 g" for one yogurt from "250-500 g" for a whole multi-pack.
• AI disambiguation, only when genuinely needed. Most items resolve with
  plain rule-based matching. When a search returns several similarly-good
  candidates, one batched request (using your own Anthropic API key)
  disambiguates them using the item's own notes and any general shopping
  preferences you've set — never a per-item AI call.
• General shopping preferences. A separate notes field ("prefer the
  cheapest equivalent", "avoid products with additives") applies to every
  item in the run, not just one line.
• Multi-store in one run. Mercadona, Bonpreu/Esclat, and Día side by
  side — pick which stores to run against each time.
• Optional cart clearing. Empty each store's existing cart before adding
  your list, for a clean weekly re-run — using each store's own native
  "empty cart" mechanism, not slow one-by-one removal.
• Live progress and a clear results table. Every item's outcome is
  reported — added (with the actual product and price that landed in your
  cart), needs manual review, or failed — with the reason, so nothing
  silently disappears. Progress is also mirrored in the browser tab's
  title, so you can check how a run is going while browsing another tab.
• Cross-store comparison. Running against two or more stores in one go
  adds one extra, automatic summary at the end pointing out where the two
  carts differ — a cheaper match at one store, or an item that only one
  store's search could find.
• Daily health checks. A background check flags a red badge on the
  toolbar icon if a store's search stops working, so you find out before
  you start shopping, not partway through.
• Runs in your own logged-in session. No separate login, no credential
  storage — the extension acts inside your existing, already-logged-in
  browser tabs for each store.

1. Open the extension (toolbar icon) and paste your list.
2. Pick which stores to run against, and optionally check "Empty each
   store's cart first."
3. Hit Run. The assistant opens a background tab per store if needed,
   searches for each item, filters by your constraints, and adds matches to
   cart — asking an AI model to pick between close candidates only when the
   rule-based match is genuinely ambiguous.
4. If you ran 2+ stores, a short AI-written comparison appears once
   everything's done, calling out anything worth a second look between the
   carts.
5. Review the results table, switch to each store's tab, and check out
   yourself whenever you're ready.

• The extension never completes checkout or handles payment. It only
  ever searches for products and adds them to cart — the final review and
  purchase step is always yours, on the store's own site.
• No data is collected by, or sent to, this extension's developer.
  There is no backend server owned by this project. All persistent data
  (your list text, store selection, preferences, and a small cache of past
  item→product matches) is stored locally via the browser's own
  storage.local/storage.sync, the same mechanism any extension uses to
  remember its settings.
• AI disambiguation is opt-in and limited. If you set an Anthropic API
  key in the extension's settings, the item text and a short list of
  candidate product names/prices/sizes are sent directly from your browser
  to Anthropic's API for genuinely ambiguous items only — never for every
  item, and never to any server other than Anthropic's own API. Leave the
  key blank and no data leaves your browser at all; ambiguous items are
  simply flagged for you to resolve by hand.
• The cross-store comparison uses the same key and the same direct
  browser→Anthropic connection. When 2+ stores are run, one extra request
  sends that run's own results — item names, the product name/price/size
  that landed in each cart, and any failure reasons — so the model can
  summarize where the stores diverged. No new information is gathered for this beyond what
  the run already produced, and it's skipped entirely (silently, not a
  failure) without an API key.
• No credentials are touched. The extension relies entirely on your
  existing, already-logged-in session in your own browser tabs. It never
  asks for, stores, or transmits a password, payment method, or other
  account credential for any store.

• Mercadona (tienda.mercadona.es)
• Bonpreu / Esclat (compraonline.bonpreuesclat.cat)
• Día (dia.es)

More Spanish supermarket chains may be added if they support a compatible
online cart. (Some chains — Lidl, at the time of writing — don't offer
online grocery ordering at all, only in-store pickup for non-food goods, and
so can't be supported.)