Matt Turley, Continuum. Updated November 5, 2026.
For founders building a two-sided marketplace (services, goods, bookings or rentals) with AI tools and Stripe Connect or a similar payments platform.
The money flow and the two sides. A marketplace must onboard sellers, take a payment, split it, pay out later and handle refunds and disputes, and each step has states AI-generated code skips. Test with a seller who has not finished onboarding, a refund after payout and a buyer reading a seller's private data.
A single-vendor shop has one payment path: customer to you. A marketplace has several: buyer to platform, platform to seller, fees withheld, refunds taken back and disputes decided by a bank weeks later. Each leg can fail on its own, and money is involved in all of them.
The hard part is state. A seller account is not simply "connected": it can be created and not yet verified, able to take payments but not receive payouts, or restricted until the platform collects more information. Code that assumes a connected account is a working one will accept an order it cannot pay for.
There are also two audiences with different rights. A buyer must see their own orders and a seller's public listing, and nothing else of the seller's. A seller must see their sales and not the buyer's other purchases.
How to tell A seller can list items before their account can receive payouts. Orders succeed and funds sit unreleased, or a charge fails because the seller account is restricted.
The fix Store the payment platform's account status from its webhook events, block or flag listings until the account can take payments and receive payouts and show sellers what information is still needed.
How to tell Rounding errors, fees calculated on the wrong base, taxes ignored or amounts computed in the browser. Totals differ by a cent in one currency or one case.
The fix Compute every amount on the server in the smallest currency unit, as integers, and keep one place where the split is defined and tested with real cases.
How to tell There is a "refund" button that changes your database but not the payment, or refunds happen after the seller has already been paid and the platform absorbs the loss. Nobody handles a chargeback.
The fix Write down who bears the cost in each case, reflect refunds and disputes from the payment provider's events and test a refund after payout on the test account.
How to tell An order endpoint returns the buyer's email and address to any seller, or a buyer can open a seller's dashboard URL. Messages between users are readable with a guessed id.
The fix Define for each record who may read which fields, enforce it on the server or in database policies and return only the fields each side needs.
How to tell Order state, payouts and seller status depend on events. A missed or repeated event leaves an order stuck or paid twice.
The fix Handle events idempotently, store the event ids, retry failures and reconcile your records against the payment provider on a schedule.
How to tell Fake listings, fake reviews, sellers who collect payment elsewhere and new accounts that behave oddly. AI-built apps usually have no moderation or limits.
The fix Rate limit new accounts and listings, add a report and review flow and decide in advance what you will do about each pattern.
If you are validating demand with a handful of manual transactions, run payments by hand and build the automation later. The risks on this page matter once real money flows between strangers automatically.
A Ship Check reads the payment, payout and permission code together and ranks what will break first. If the payment flow needs rebuilding, a Ship Fix is the fixed-scope job for it.
Ship Check, $299: A senior engineer reads your codebase and sends a written verdict (fine, fixable or rewrite), what will break first, a security and data read, and a costed plan, within 48 hours of repo access or it is free. It has a 7-day money-back and is credited against a Ship Fix. Or: See Ship Fix, $4,000 to $15,000.