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Subscription Billing Kit (for Stripe)
This skill fixes "they paid but can't log in", and the opposite problem.
It gives your agent a webhook-driven access model for SaaS: Checkout in subscription mode, the Customer Portal, an access policy for all 8 subscription statuses, protection against out-of-order events, trials, cancel-at-period-end, failed-payment hooks, and helpers for Stripe's 2025 "Basil" API changes.
Who it's for
Indie developers and SaaS teams adding paid plans. It pairs well with Webhooks Done Right (for Stripe).
What's tested
- 15 automated tests, all passing, plus a clean TypeScript typecheck
- 12 unit tests of the access and state logic
- 3 request-schema checks run against stripe-mock (Stripe's open-source mock server). If stripe-mock isn't running, those 3 are skipped, not failed
What isn't tested
- None of the tests run against real Stripe test mode
- Test clocks, Smart Retries and real webhook payloads were not exercised; lifecycle behaviour is covered by unit tests with Basil-shaped fixtures
What's in the download
- SKILL.md: instructions your agent follows
- src/entitlements.ts and src/checkout.ts: reference code
- tests/: unit tests and stripe-mock schema checks
- TEST-REPORT.md, LICENSE.txt, REFUND.txt
Requirements
Node 20+. You don't need a Stripe account. The optional schema checks need the free stripe-mock binary (github.com/stripe/stripe-mock).
How to use it
Copy the folder to .claude/skills/subscription-billing-kit-for-stripe/, then ask your agent to "add Stripe subscriptions with a free trial and gate the Pro features".