What to try — b10-low-stock

# WHAT TO TRY — B10 Low-Stock Button ("Shelf Tag Yellow")

Open `index.html` in any modern browser (double-click the file, or serve the folder). No install, no account — and no sharing either, on purpose: the page says on its face that this is **one list on this device**, and that is literally true. It makes no network calls.

1. **Read the two halves.** Top: **The List** ("Pantry," stamped SAMPLE). Below: **The Shelf Sheet** — big yellow tiles, one per shelf item, each with a short code: `MILK-1` · `EGGS-6` · `RICE-5` · `COFFEE-4` · `DISH-2` · `PAPER-3`.
2. **See both list states at once.** The SAMPLE list starts with Milk ×2 and Rice ×1 *still to get*, and Eggs ×1 already *ticked off* — so you can try Restore before you change anything.
3. **The one-tap path:** in the "Add by shelf code" box, type `RICE-5` (lowercase works too) and tap **Add to list — one tap**. Rice is now ×2 — the quantity went up instead of a second Rice row appearing. That increment-instead-of-duplicate is the core behavior.
4. **Tap a tile.** Scroll to the shelf sheet and tap the **Coffee** tile itself. Coffee lands on the list without any typing — the on-screen version of the printed marker.
5. **Tick off and restore.** Tick off Milk, watch it move to "Ticked off" struck through, then Restore it — it comes back with its quantity intact.
6. **Reload the page.** Your list and shelf are exactly as you left them (that's localStorage, this device only). Then hit **Remove SAMPLE list items**, reload again — the samples stay gone, and anything you added yourself stays.
7. **Print the sheet.** Tap **Print the shelf sheet** — the printout is the tiles alone, three to a row. Read the note printed under them before you tape anything up: **codes today; QR tiles are the upgrade when the house adopts a QR library** — there is deliberately no QR-looking square on the sheet, because a code that doesn't scan would be a lie in a costume.
8. **Make it yours:** add a shelf item of your own (say, "Olive oil") — it gets its own tile and code instantly, and its code works in step 3's box right away.

The real test this prototype is staging for, in the sweep's own words: one real kitchen and one real supply shelf, one week — does the printed code get tapped at the moment someone notices the empty shelf? That run is a separate commission.