Refund the buyer and the seller keeps the money, unless two flags default the other way

reverse_transfer and refund_application_fee are real POST /v1/refunds parameters that both default to false -- forgetting them refunds the buyer while the seller keeps their payout and the platform keeps its fee (D10).

This is one of the things Marketplace Payouts & Connected Accounts already handles. Take payment from buyers and pay out sellers, with the onboarding and identity checks Stripe requires.

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Is this you?

Issuing a refund on a charge whose funds have already been transferred to a seller, without also reversing that transfer, refunds the buyer while the seller's payout stays exactly where it is -- the platform now owes the buyer money it doesn't have, having already moved the seller's share out. The refund API call itself doesn't error; it does exactly what was asked, silently leaving the money three-way inconsistent.

Why this one is easy to get wrong

A refund reads as a single, self-contained operation -- call the refunds endpoint, the buyer gets their money back, done -- and reverse_transfer / refund_application_fee are parameters that only matter under destination-style charge models most tutorials describe, both defaulting to false with no error if left unset. The API succeeds either way, so there's no failure to notice locally.

What you get instead

Under this pack's separate-charges-and-transfers model, D10's refundAction() never emits reverse_transfer or refund_application_fee at all -- there is no ApplicationFee object under this charge model, and a HELD order's refund needs no reversal because nothing was transferred yet. A RELEASED order's refund instead issues a separate POST /v1/transfers/{id}/reversals for the proportional seller amount, with the platform explicitly absorbing any rounding remainder on a partial refund -- asserted, not incidental.

Source: ARCHITECTURE.md D10 — checkable in the pack you receive

How you actually use this

You don’t install a library or wire up an SDK. Your own coding agent builds the code in your project, and you keep it — no runtime dependency on us.

Step 1
Download and unzip
You get a folder: the docs that tell an agent what to build, a starting skeleton, and the test suite that decides when it's done.
Step 2
Open it in Claude Code or Cursor
Point your coding agent at the folder. Nothing to install, no account with us, no API key.
Step 3
Paste one prompt
The pack contains the exact prompt. Paste it as your first message and leave it alone — it works through the build itself, choosing a cheaper or stronger model per task.
Step 4
Run ./verify.sh
One command. It prints a pass or fail for every check. Green means the build is done — the same script we ran to produce the receipt on this page.

Typical build: about 25 minutes of your agent working, mostly unattended. Then you integrate the working module into your app the way you would any code you’d written yourself.

Why you can believe this

3 of 3 runs passed

We ran this pack from an empty folder 3 times and published exactly what happened — every check, the model, the token cost, the wall time. Not a testimonial, and not our opinion: the same verify.sh you run yourself. Read the full receipt →

Buy for $199 14-day refund if verify.sh fails →