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Online store (Stripe) rules: AGENTS.md, CLAUDE.md & Cursor rules
Stores built with AI usually break in one of two spots: trusting the price from the browser, or skipping webhook checks. These rules cover the money parts.
Stack these rules assume: Any web front end, Stripe Checkout, a webhook endpoint for orders. Different stack? Customize it in the generator.
Want the full step-by-step kit?
MVP Spec-to-Build Pack ($7): A fill-in 1-page spec, a landing page prompt, a 7-prompt build sequence in the right order, a "did I leak user data?" checklist, and cheap fix-it prompts.
Get the kit for $7 on Gumroad → See what's inside
or get all 5 kits for $25 (save $14) →
One markdown file, instant download. 7-day refund, no questions asked.
Quick start
- Copy the
AGENTS.mdbelow into your project's root folder. - Fill in the three
[bracketed]lines under "Project". Delete any rule that doesn't fit. - Start your first chat with: "Read AGENTS.md and follow it for this whole session."
AGENTS.md (works across tools)
Read by OpenAI Codex, Cursor, GitHub Copilot, Claude Code (when there's no CLAUDE.md) and many other agents.
# AGENTS.md: Online store (Stripe)
Instructions for AI coding agents working on this project. Replace anything in [brackets].
## Project
- What it is: [one sentence: what you are building and who it is for]
- Stack: Any web front end, Stripe Checkout, a webhook endpoint for orders
- Version 1 only needs to: [the ONE thing it must do]
## Commands
- Forward Stripe webhooks to your local server (Stripe CLI): `stripe listen --forward-to localhost:3000/api/webhooks`
- Use test mode: Test keys (sk_test_… / pk_test_…) until launch day
## Project rules
- Use Stripe Checkout (Stripe-hosted). Never collect or store card numbers ourselves.
- Prices and products come from the server or from Stripe, never from the browser.
- Mark an order as paid only from a verified webhook event (check the signature), not from the success page redirect.
- Use test-mode keys during development. Ask before anything touches live keys.
- Handle the same webhook event arriving twice without creating two orders.
- The secret key and webhook signing secret live in environment variables only.
## How to work
- Do one task per request. If my request is really several tasks, list them and do only the first.
- Before writing code, give a 3-line plan: what you'll change, which files, and how I'll test it.
- Make the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.
- Ask before adding a dependency, deleting or moving files, changing the data/database structure, or touching more than 3 files.
- If you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.
- Never say something works unless you ran it or I confirmed it. Report errors exactly.
- Secrets (API keys, tokens, passwords) live only in environment variables or a .env file listed in .gitignore. Never print, hardcode, or commit them.
- Never run destructive commands (rm -rf, git reset --hard, force-push, dropping tables) without asking first.
## Finish every task with
1. What changed (list the files).
2. How to run or test it in under a minute, and what I should see.
3. A suggested git commit message.
Want the full step-by-step kit?
MVP Spec-to-Build Pack ($7): A fill-in 1-page spec, a landing page prompt, a 7-prompt build sequence in the right order, a "did I leak user data?" checklist, and cheap fix-it prompts.
Get the kit for $7 on Gumroad → See what's inside
or get all 5 kits for $25 (save $14) →
One markdown file, instant download. 7-day refund, no questions asked.
Why each rule exists
- Online store (Stripe) ruleUse Stripe Checkout (Stripe-hosted). Never collect or store card numbers ourselves.Why: Handling card data yourself pulls you into PCI compliance. Checkout keeps card details on Stripe's side.
- Online store (Stripe) rulePrices and products come from the server or from Stripe, never from the browser.Why: If the browser sends the price, a visitor can change it.
- Online store (Stripe) ruleMark an order as paid only from a verified webhook event (check the signature), not from the success page redirect.Why: Anyone can visit your success URL. Only the signed webhook proves payment.
- Online store (Stripe) ruleUse test-mode keys during development. Ask before anything touches live keys.Why: Test mode lets you run hundreds of fake orders for free.
- Online store (Stripe) ruleHandle the same webhook event arriving twice without creating two orders.Why: Stripe can retry webhook delivery, so duplicates happen.
- Online store (Stripe) ruleThe secret key and webhook signing secret live in environment variables only.Why: Those two strings control your money.
- How to workDo one task per request. If my request is really several tasks, list them and do only the first.Why: Big multi-part requests are where AI tools change 12 files and you can't tell which change broke things.
- How to workBefore writing code, give a 3-line plan: what you'll change, which files, and how I'll test it.Why: A plan you can read in 10 seconds catches the wrong approach before it costs you an hour or a pile of credits.
- How to workMake the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.Why: Drive-by "cleanups" are the #1 cause of "it was working yesterday".
- How to workAsk before adding a dependency, deleting or moving files, changing the data/database structure, or touching more than 3 files.Why: These are the changes that are hard to undo. One quick question is cheaper than a rollback.
- How to workIf you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.Why: AI tools confidently invent functions and config options. Making it check is the cure.
- How to workNever say something works unless you ran it or I confirmed it. Report errors exactly.Why: "Should work now" isn't a test result. You want facts, not optimism.
- How to workSecrets (API keys, tokens, passwords) live only in environment variables or a .env file listed in .gitignore. Never print, hardcode, or commit them.Why: Leaked keys get found by bots within minutes of a public push. This rule is the cheapest insurance you'll ever buy.
- How to workNever run destructive commands (rm -rf, git reset --hard, force-push, dropping tables) without asking first.Why: One bad command can delete the only copy of your work.
- Finish every task withWhat changed, how to test it, and a commit message.Why: This turns every task into a checkpoint: you test it, you commit it, and you always have a last good version to go back to.
Use it as CLAUDE.md (Claude Code)
Pick one:
- Do nothing. Current Claude Code versions read
AGENTS.mdwhen the project has noCLAUDE.md. Run/memoryin a session to check it loaded. - Import it (best if you want Claude-only extras, or you're on an older Claude Code). Create
CLAUDE.mdnext toAGENTS.md:
@AGENTS.md
## Claude Code
- Use plan mode before any change that touches more than 3 files.
- Claude only? Save the same AGENTS.md text as
CLAUDE.mdinstead. Don't keep two separate copies; they drift apart.
Heads-up: if a project has both files and CLAUDE.md doesn't import AGENTS.md, Claude Code reads only CLAUDE.md by default. More in AGENTS.md vs CLAUDE.md.
Use it as Cursor rules (.cursor/rules/*.mdc)
Cursor reads AGENTS.md too, so the file above already works. If you prefer Cursor's own Project Rules, split it into two .mdc files. The .mdc extension and frontmatter are required; Cursor ignores plain .md files in .cursor/rules.
---
description: Project overview and working rules for Online store (Stripe)
alwaysApply: true
---
# Online store (Stripe)
Instructions for AI coding agents working on this project. Replace anything in [brackets].
## Project
- What it is: [one sentence: what you are building and who it is for]
- Stack: Any web front end, Stripe Checkout, a webhook endpoint for orders
- Version 1 only needs to: [the ONE thing it must do]
## Commands
- Forward Stripe webhooks to your local server (Stripe CLI): `stripe listen --forward-to localhost:3000/api/webhooks`
- Use test mode: Test keys (sk_test_… / pk_test_…) until launch day
## How to work
- Do one task per request. If my request is really several tasks, list them and do only the first.
- Before writing code, give a 3-line plan: what you'll change, which files, and how I'll test it.
- Make the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.
- Ask before adding a dependency, deleting or moving files, changing the data/database structure, or touching more than 3 files.
- If you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.
- Never say something works unless you ran it or I confirmed it. Report errors exactly.
- Secrets (API keys, tokens, passwords) live only in environment variables or a .env file listed in .gitignore. Never print, hardcode, or commit them.
- Never run destructive commands (rm -rf, git reset --hard, force-push, dropping tables) without asking first.
## Finish every task with
1. What changed (list the files).
2. How to run or test it in under a minute, and what I should see.
3. A suggested git commit message.
The project rules only attach when a matching file is in the chat (globs with alwaysApply: false). Want them on all the time? Change it to alwaysApply: true.
---
globs: **/*.ts, **/*.tsx, **/*.js
alwaysApply: false
---
# Project rules: Online store (Stripe)
- Use Stripe Checkout (Stripe-hosted). Never collect or store card numbers ourselves.
- Prices and products come from the server or from Stripe, never from the browser.
- Mark an order as paid only from a verified webhook event (check the signature), not from the success page redirect.
- Use test-mode keys during development. Ask before anything touches live keys.
- Handle the same webhook event arriving twice without creating two orders.
- The secret key and webhook signing secret live in environment variables only.
Use either AGENTS.md or these .mdc files, not both, so you don't send the same rules twice. See Cursor rules vs AGENTS.md.
Use it in Lovable or Bolt
Browser builders don't read files from your computer, so paste the rules into the project's persistent instructions:
- Lovable: Project settings → Knowledge (up to 10,000 characters). This version is 1,988 characters. If your Lovable project is connected to GitHub, Lovable's docs say it also reads a root-level
AGENTS.md. - Bolt: Project settings → Knowledge.
This version drops the Commands section, since the builder runs the project for you.
# Project rules: Online store (Stripe)
Instructions for AI coding agents working on this project. Replace anything in [brackets].
## Project
- What it is: [one sentence: what you are building and who it is for]
- Stack: Any web front end, Stripe Checkout, a webhook endpoint for orders
- Version 1 only needs to: [the ONE thing it must do]
## Project rules
- Use Stripe Checkout (Stripe-hosted). Never collect or store card numbers ourselves.
- Prices and products come from the server or from Stripe, never from the browser.
- Mark an order as paid only from a verified webhook event (check the signature), not from the success page redirect.
- Use test-mode keys during development. Ask before anything touches live keys.
- Handle the same webhook event arriving twice without creating two orders.
- The secret key and webhook signing secret live in environment variables only.
## How to work
- Do one task per request. If my request is really several tasks, list them and do only the first.
- Before writing code, give a 3-line plan: what you'll change, which files, and how I'll test it.
- Make the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.
- Ask before adding a dependency, deleting or moving files, changing the data/database structure, or touching more than 3 files.
- If you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.
- Never say something works unless you ran it or I confirmed it. Report errors exactly.
- Secrets (API keys, tokens, passwords) live only in environment variables or a .env file listed in .gitignore. Never print, hardcode, or commit them.
- Never run destructive commands (rm -rf, git reset --hard, force-push, dropping tables) without asking first.
## Finish every task with
1. What changed (list the files).
2. How to run or test it in under a minute, and what I should see.
3. A suggested git commit message.
Building this in a browser app builder? These rules work as Project Knowledge in both. Try Lovable · Try Bolt
Disclosure: the Bolt link is an affiliate (referral) link. If you sign up or buy through it, VibeKits may earn a commission at no extra cost to you. The Lovable link is a plain link. It never changes our pick.
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- AGENTS.md, CLAUDE.md and Cursor rules formats explained