Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add finsilabs/awesome-ecommerce-skills --skill cart-logicgit clone --depth 1 https://github.com/finsilabs/awesome-ecommerce-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/finsilabs/awesome-ecommerce-skills/cart-logic)<a href="https://agentmods.dev/skills/finsilabs/awesome-ecommerce-skills/cart-logic"><img src="https://agentmods.dev/badge/skills/finsilabs/awesome-ecommerce-skills/cart-logic/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/finsilabs/awesome-ecommerce-skills/cart-logic"><img src="https://agentmods.dev/badge/skills/finsilabs/awesome-ecommerce-skills/cart-logic.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00028 | $0.02208 |
| Opus 5 | $0.00014 | $0.01104 |
| Sonnet 5 | $0.00006 | $0.00442 |
| Haiku 4.5 | $0.00003 | $0.00221 |
Grade A, and why
cart-logic scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Cart Logic
Overview
Cart logic covers how your store manages items a shopper intends to buy: adding, removing, and updating items; persisting the cart across page loads and devices; and merging a guest cart into an account when the customer logs in. On Shopify, WooCommerce, and BigCommerce, the cart is built into the platform — the goal is to configure it correctly and extend it when needed. Custom code is only required for headless storefronts.
When to Use This Skill
- When cart state is lost when users navigate between pages (missing persistence)
- When guest cart items disappear after login (missing merge logic)
- When implementing real-time cart price updates (coupons, quantity changes, shipping estimates)
- When building a headless storefront that needs a custom cart implementation
Core Instructions
Step 1: Understand how your platform handles cart logic
| Platform | Cart Behavior | Where to Configure |
|---|---|---|
| Shopify | Built-in cart with automatic persistence; uses cookies/localStorage | Theme Liquid templates + Cart API; extend with Cart Transform Shopify Function |
| WooCommerce | Built-in cart with session persistence; configures via PHP hooks | WooCommerce settings + woocommerce_add_cart_item_data and woocommerce_cart_item_price filters |
| BigCommerce | Built-in Storefront Cart API; cart persists via cookie | BigCommerce Stencil theme + Storefront Cart API |
| Custom / Headless | Must build from scratch using platform APIs or Shopify/BigCommerce Storefront API | See Custom / Headless section below |
Step 2: Configure and extend cart behavior
Shopify
Shopify's cart is managed automatically. To extend it:
Customize the cart drawer or page:
- Go to Online Store → Themes → Customize
- Select the cart section and configure: cart type (drawer vs. page), item display, quantity controls
- Enable Cart notes and Shipping estimate in the cart settings if needed
What ships with it
7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- evals/cart-data-model-upsert-price-capture-ser/criteria.json 2.6 KB
- evals/cart-data-model-upsert-price-capture-ser/task.md 1.7 KB
- evals/guest-cart-persistence-and-react-cart-co/criteria.json 2.5 KB
- evals/guest-cart-persistence-and-react-cart-co/task.md 1.4 KB
- evals/guest-to-user-cart-merge-on-login/criteria.json 2.4 KB
- evals/guest-to-user-cart-merge-on-login/task.md 1.5 KB
- tile.json 225 B
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 201 lines · 28 tokens per session scan A e022412bc995
cart-logic is a skill published in the GitHub repository finsilabs/awesome-ecommerce-skills (52 stars, last pushed 6mo ago), licensed MIT. It adds 28 tokens to every session and 2,208 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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