Cart
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Cart page decisions for ecommerce teams: work out what each addition is worth against the friction it adds, then set the upsell, the shipping bar, the warranty or nothing.
The cart is where everything gets added: an upsell, a free shipping progress bar, a warranty offer, a discount field, a trust badge row, a last-chance bundle. Each was justified on its own and none was measured against what it costs in abandonment. The cart is also the highest intent page on the site, which makes friction there the most expensive friction you can add. This skill works out what each addition is worth against the friction it introduces, and sets the upsell, the shipping bar, the warranty, or strips the cart back.
What It Does
- Measures abandonment against each element currently in the cart.
- Prices what an upsell earns net of the orders it costs.
- Reads how far baskets sit from your shipping threshold before adding a bar.
- Checks whether the discount field is prompting customers to leave and search.
- Picks the one addition worth making rather than stacking several.
- Sets the upsell, the bar, the warranty, or strips the cart, with the reason.
Use Cases
- Find the cart element costing more in abandonment than it earns.
- Choose between an upsell and a shipping bar instead of running both.
- See whether the discount code field is sending customers off-site.
- Strip a cart that has accumulated five years of additions.
Example Session
Our cart converts worse than it used to. What should be on it?
Remove two things, add one. The discount field is the expensive one.
- Element | Earns | Costs in abandonment | Net | Action
- Discount code field | $0 | $61,000 per quarter | -$61,000 | Move behind a link
- Warranty upsell | $18,400 | $22,100 | -$3,700 | Remove
- Free shipping progress bar | $31,000 | $2,400 | +$28,600 | Keep
- Related product upsell | Not present | n/a | +$19,000 est | Add
An open discount field tells every customer a code exists and sends a share of them to a coupon site, where a third do not come back. Moving it behind a small link keeps it available and stops advertising it. The warranty upsell earns real money and costs slightly more in abandonment at this price point. The shipping bar works because 38% of your baskets sit within $12 of the threshold.
Why This Beats Prompting It Yourself
Each Addition On Its Own vs The Cart As One Page: The Hidden Risk
A generic prompt evaluates the upsell as an upsell and the trust badges as trust badges, each of which is defensible. What it cannot see is that the cart now has eleven elements on the highest intent page of the site, and the compound friction costs more than any single element earns. Carts get worse one reasonable addition at a time.
When You Still Need The Discount Field Priced
The discount code field is the most expensive element in most carts and almost never gets measured, because it does not earn anything to compare against. Its cost is the customers who leave to look for a code and do not return: $61,000 a quarter here. Putting it behind a link keeps it usable and stops it advertising itself to everyone.
Known Limitations
Attributing abandonment to a specific element is inference from behavior patterns and comparable carts, not a controlled test, and the output labels the confidence per element. The discount field estimate depends on being able to see exit behavior, which some analytics setups do not capture. It sets the recommendation and does not change your cart.
Install It
- Download the ZIP.
It is free and there is no account to create. - Unzip it into your agent's skills folder.
Claude Code reads ~/.claude/skills/, which is hidden by default: the command in the folder block opens it. Other agents scan their own directory, so drop the same folder there instead. - Ask your agent to use it.
Restart the agent if it was already running, then it picks the skill up with no config.
skills folder
Copy
~/.claude/skills/cart/
SKILL.md
references/cart-elements.md
recommendations/
# one file per review, with the net per element
# macOS: create the folder and open it in Finder
mkdir -p ~/.claude/skills && open ~/.claude/skills
# Windows: paste in the Explorer address bar
%USERPROFILE%\.claude\skills\Frequently asked questions
How is this different from cart optimization advice?
Generic advice adds elements: an upsell, a badge, a countdown. This prices what each existing element costs in abandonment against what it earns, which for most carts means removing more than adding. The net column is what changes the conversation.
Which agents does the skill run in?
Any agent that supports the open SKILL.md format: Claude Code, Cursor, Codex CLI, GitHub Copilot, Gemini CLI, Manus, Grok and others load it unmodified. The format is portable, the location is not. Each agent scans its own skills directory, so you drop the same folder into whichever one yours uses. There is no config file to edit and no API key to provision.
What does it need connected to work?
Cart and checkout funnel data, order lines, product margin, and your current cart configuration. Exit behavior data improves the discount field estimate noticeably.
Is the discount field really worth $61,000?
For a cart with this traffic and this abandonment pattern, yes, and it is the number most teams find hardest to believe. The mechanism is simple: an open field tells people a code exists, and a share of them leave to find one. Hiding it behind a link keeps it for the customers who have a code.
Why only add one upsell?
Because the second one earns less than the first and costs the same friction, and the third is usually negative. The cart has a budget of attention and spending it on a single well-chosen addition beats spreading it.
What is included with the skill?
The skill itself, the cart element reference, the recommendation format, and the friction estimates. It is free and security scanned. We re-publish the ZIP when the estimates change, so download it again if your nets start shifting.
An upsell that kills margin is not an upsell.
Polar folds product cost, shipping and returns into contribution margin, so adding a warranty, a bar or a bundle is judged on what the cart leaves behind.
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