048-the-coockie-factory/docs/wiki/Step-4-Buy-Upgrades.md

Step 4: buy upgrades

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get_store_items reads the 20 store products, choose_upgrade picks the most expensive one the bot can afford, and buy_upgrade clicks it. The screenshot shows the first cursor bought.

Screenshot

Function

def choose_upgrade(items: Sequence[StoreItem]) -> StoreItem | None:
    affordable = [item for item in items if item.is_affordable]
    if not affordable:
        return None
    return max(affordable, key=lambda item: (item.price, item.index))

What we gained

• Keep the decision pure. choose_upgrade takes plain StoreItem values and returns one, so it is tested with no game at all (ties, none affordable, empty list).
• Confirm the result, do not assume it. buy_upgrade checks that the owned amount (productOwned<N>) went up. Checking the cookie count first was wrong: the count keeps rising while the bot clicks.
• The page lags behind. The first release lost about 40 percent of its purchases: the game updates the price and owned text at once but the affordable flag only at its next redraw, so a second purchase in the same visit used a stale flag. Buying at most one product per store visit cut the failures to 1 of 49.
• The real game finds what fakes cannot. The stale-element retry and the owned-amount check both came from running in Docker.

Next: Step 5: the five-minute run