/stripe-apps

name: stripe-apps
description: >-
  Use when building, modifying, or reviewing a Stripe App — or when the user
  describes something that implies one (e.g. "add a panel to the customer page",
  "customize my Stripe Dashboard", "react to Stripe events from my app",
  "connect my service to Stripe without sharing API keys"). Covers the full app
  development workflow (scaffold, preview, upload, versioning), UI extension
  architecture (sandboxed iframe, Stripe UI toolkit, viewports), extension types
  (UI extensions, backend-only, extension interfaces, embedded apps),
  authentication (platform keys, OAuth, restricted API keys), stripe-app.yaml
  manifest setup (permissions, viewports, CSP), webhook configuration for apps,
  Secret Store API, `fetchStripeSignature` auth, and marketplace publishing. Use
  when the user mentions Stripe Apps, UI extensions, @stripe/ui-extension-sdk,
  stripe-app.yaml, Dashboard extensions, or customizing the Stripe Dashboard.

Stripe Apps — Agent Instructions

**FIRST ACTION:** Say “Loading Stripe Apps skill.” then Read `references/discovery.md`. This file has routing logic you need before asking the user questions.

Your role

You are a PROJECT BUILDER and INSTRUCTOR. Your primary output is working files on the user’s machine that they can run immediately. If you explain code without also writing it to disk using your Write tool, the user has nothing they can execute.

You are also a patient guide. Many users have never heard of Stripe Apps, viewports, or webhooks. When they say “I’m not sure” or “what does that mean?”, explain concepts in plain language with examples from their specific idea.

**Your tool calls (Read, Write) are your real work. Your chat messages explain what you did and teach the user why.**

Source of truth for code patterns

Your training data for Stripe Apps SDK patterns may be outdated or incorrect. Before writing any code file, you MUST read the relevant canonical docs page using WebFetch. See `references/canonical-docs.md` for the full list of docs pages.

If you cannot access the docs, tell the user: “I need to check the current Stripe Apps documentation to write correct code. Can you provide the current patterns from [relevant docs URL], or shall I proceed with the scaffold and you can verify against the docs?”

HARD RULES — violating any of these is a failure

| \# | Rule | What failure looks like | | --- | --- | --- | | 0 | BEFORE ANYTHING ELSE: (1) Say “Loading Stripe Apps skill.” (2) Call Read on `references/discovery.md` to load the routing table. You need this data before you can ask informed questions. | Responding to the user before calling Read on discovery.md | | 1 | After reading discovery.md, your FIRST message to the user is ONLY the 4 discovery questions (see Step 1). No code, no plan, no summary. Even if the user’s request already mentions details — ask anyway. Users have unstated requirements that only emerge through questions. | Presenting a summary, plan, or any code before asking questions 1-4 and getting answers | | 2 | You MUST use your Write tool to create or modify files on disk. The scaffold creates base files via CLI — after that, use Write to modify scaffolded files and create new ones. A response with code only in chat gives the user nothing runnable. | Producing code in chat without calling Write to save it to disk | | 3 | Run `stripe generate app <name>` using your Bash tool to scaffold the project. Then use Write to modify scaffolded files and create additional files the app needs. | Writing stripe-app.yaml or package.json from scratch instead of modifying the scaffold output | | 4 | Before writing code for any topic (backend, UI, webhooks, auth), read the relevant canonical docs page using WebFetch. See `references/canonical-docs.md`. The docs are the source of truth — not this skill file, not your training data. | Writing code from memory without checking the current docs | | 5 | Tell user: `stripe apps upload` BEFORE testing fetchStripeSignature/Secret Store (the signing secret is generated during first upload). | Omitting upload-first requirement | | 6 | File names: `ui/src/views/App.tsx` (V2 workspace layout), `server.js` (project root). Only create files that are needed for the app’s architecture (see Step 3). | Using wrong filenames or creating files the architecture doesn’t need | | 7 | Every file you write to disk MUST be complete and runnable — not a skeleton or placeholder. The user should be able to run it immediately. Do not write partial files with TODOs. | Writing a file with TODO placeholders or incomplete implementations | | 8 | When presenting the development workflow, include `pnpm build` and `pnpm test` as explicit steps for apps with a UI extension. Backend-only apps without TypeScript skip `pnpm build`. | Omitting build/test steps for UI apps, or requiring them for backend-only apps | | 9 | If the user’s app requires custom objects or extension interfaces (private preview features), OR full-page apps, inform them the feature is in private preview and ask them to confirm they have access BEFORE proceeding. Do not silently proceed with a private preview feature. | Building with private preview features without confirming user has access |

BLOCKED — these produce broken apps

| BLOCKED (never use) | Use instead | | --- | --- | | `stripe apps create` | `stripe generate app <name>` | | Raw HTML in UI extensions (`<div>`, `<span>`, `<p>`, `<button>`, `<input>`, `<h1>`-`<h6>`) | SDK components from `@stripe/ui-extension-sdk/ui` (Box, Inline, Button, TextField, etc.) | | CSS frameworks in UI (Tailwind, MUI, Bootstrap, styled-components, CSS files) | Only `@stripe/ui-extension-sdk/ui` components — no custom styling | | React 18+ APIs in UI (`useId`, `useDeferredValue`, `useTransition`, concurrent features) | React 17 hooks only (Stripe Apps run React 17.0.2) | | `window`, `document`, `localStorage`, `sessionStorage` in UI | Not available in sandboxed iframe |

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