ShipToPaid Lite

Free AI coding-agent skills to add Polar payments to a vibe-coded Next.js app, and to check it’s actually ready to take money. Works with Codex, Claude Code and Cursor.

Every gotcha in these skills was hit for real while building a working app: snake_case SDK fields, raw-body verification, example.com emails rejected with a 422, stale events restoring revoked access, and more.

Install

Codex / Cursor: copy skills/ into your app and add to AGENTS.md:

Skills live in skills//SKILL.md. Before relevant work, read the matching
skill and follow its procedure and verification checklist:
- Polar checkout: polar-checkout. Webhooks: polar-webhooks.
- Before going live: launch-audit-lite.

Claude Code: copy each folder to .claude/skills// in your app (or ~/.claude/skills/). Claude picks them up from their descriptions.

Then ask your agent: “Add a $9/month Pro plan with Polar” or “Am I ready to launch?”

Requirements: Node 22+ (required by @polar-sh/sdk), a Polar sandbox account.

Example

With the skills installed, type a plain request into Claude Code, Cursor or Codex:

Add a $9/month Pro plan with Polar. Only Pro users should be able to open /dashboard/pro.

The agent reads polar-checkout and polar-webhooks, then roughly:

1. Creates the Pro plan in your Polar sandbox with a small script you can re-run.
2. Adds an upgrade button that sends the signed-in user to Polar checkout and back to a success page.
3. Sets up the payment notifications Polar sends, checks each one really came from Polar, and turns Pro on (and off again when a subscription ends).
4. Locks /dashboard/pro so only Pro users can open it.
5. Writes a few sandbox tests into your app, runs them, and tells you what passed and what it couldn’t run.

Later, ask “Am I ready to launch?” and launch-audit-lite walks through the checklist, marking each item PASS, FAIL or NOT RUN.

Results depend on your app and your agent. Read the changes before you commit them.

Limits

• Written for Next.js App Router with TypeScript. Examples use Better Auth and Postgres + Drizzle; on another stack the agent has to adapt them.
• Polar only. There is no Stripe support in this repo.
• These are instructions for your coding agent, not a library. There is nothing to install from npm; the agent writes the code into your app.
• Test in the Polar sandbox before switching to production, and don’t test production with your own real card (Polar asks you not to; launch-audit-lite uses a 100% discount code instead).

Contributing / issues