Here is the whole thing, in the order it happens. There is no feed to scroll and no dashboard you need to keep open.
Step 1
Show it the thing
Three ways in. Pick whichever is in front of you.
Photo. Snap the item, the box, or the shelf tag in a store. Nab Price reads it and guesses the name, brand, model, and barcode if one is visible. You confirm or correct the guess.
Name. Type what it is. "Sony WH-1000XM5" is enough.
Link. Paste a product page from a store. This is the one Nab Price will recheck, so a link is the most exact.
With a link, you see the current price before you arm anything, so you know what you are arming against.
Step 2
It works out what the object is
Store titles are messy. The same headphones can be "WH-1000XM5", "wh1000xm5", or "Sony Noise Cancelling Over-Ear (Black)". Nab Price turns whatever you gave it into a stable identity: the product codes it can find (a UPC, a model number, a store's own item id) plus the words that actually tell one product from another.
That identity is what the watch is attached to. Not the URL. Not the title. So when a store rewrites the page, the watch still knows what it is looking for.
Step 3
Arm a target
One target per item. Say what would make you act.
Under a price. "Under $40."
Down a percentage from where it is now. "Down 15%."
Back in stock. It is sold out today. Tell me when it is not.
Any real move. Up or down. You just want to know.
Optional filters, if they matter to you: distance, budget, "I already own one", and whether you are buying, selling, or just researching.
Step 4
The quiet recheck
You leave. Nab Price rechecks the listing on a schedule, using only the page you gave it. It does not crawl the open web looking for the item somewhere else.
Every check saves two things: the price it saw and a fingerprint of the listing. That history is what the next step uses.
If a store blocks the check or the page stops loading, the watch backs off and tries again later, less often. If it keeps failing, the watch shows as quiet in your list and says why. A watch that silently never pings would look exactly like a broken app, so we do not do that.
Step 5
What counts as a real move
A ping has to pass two tests. The line you set was crossed, and the move is real. Real means:
It is measured against our own readings, not the store's "was" price. The baseline is the middle of the prices Nab Price has seen itself. A crossed-out number the store made up does not count.
A "down 15%" line never drifts up. If a store sits inflated for weeks and then returns to normal, that is not a sale. The drop line is capped at the price you armed against.
It is the same item. A store can put a different product in the same catalogue slot. Before pinging, Nab Price compares the listing fingerprint: a product code like a UPC or model number is decisive, and a store's slot id has to be backed up by the title. If the identifiers conflict, it refuses to ping.
Wobble is ignored. A change under 1% or under a dollar is noise, not a move.
Unknown beats wrong. If the page can be read but the price cannot be read with confidence, the reading is shown as unverified and is never acted on.
Armed: under $300 · Store shows "was $449, now $329" · Our readings: $329, $329, $335 · Verdict: no ping. Not under $300, and the "was" price is not ours.
Step 6
The single ping
When both tests pass, you get one message. Email or push at first. Text later. It says what the item is, what it was, what it is now, and where.
One ping per watch, then quiet. It will not nag you about the same move again. If the price keeps sliding, you hear from it again only after a long cool-down, not every hour.
Step 7
You reply
BUY — you nabbed it. The watch closes and is marked nabbed.
SKIP — not interested any more. The watch is dropped.
HOLD — not yet. The watch stays on and keeps checking.
Nab Price never places the order. It has no card, no cart, and no checkout. The reply is a note to yourself and to the watch. The buying is yours.