Fourth item of the v1.0.6 backlog, and the structuring one — the pre-
v1.0.6 RefundOrder wrote `status='refunded'` to the DB and called
Hyperswitch synchronously in the same transaction, treating the API
ack as terminal confirmation. In reality Hyperswitch returns `pending`
and only finalizes via webhook. Customers could see "refunded" in the
UI while their bank was still uncredited, and the seller balance
stayed credited even on successful refunds.
v1.0.6 flow
Phase 1 — open a pending refund (short row-locked transaction):
* validate permissions + 14-day window + double-submit guard
* persist Refund{status=pending}
* flip order to `refund_pending` (not `refunded` — that's the
webhook's job)
Phase 2 — call PSP outside the transaction:
* Provider.CreateRefund returns (refund_id, status, err). The
refund_id is the unique idempotency key for the webhook.
* on PSP error: mark Refund{status=failed}, roll order back to
`completed` so the buyer can retry.
* on success: persist hyperswitch_refund_id, stay in `pending`
even if the sync status is "succeeded". The webhook is the only
authoritative signal. (Per customer guidance: "ne jamais flipper
à succeeded sur la réponse synchrone du POST".)
Phase 3 — webhook drives terminal state:
* ProcessRefundWebhook looks up by hyperswitch_refund_id (UNIQUE
constraint in the new `refunds` table guarantees idempotency).
* terminal-state short-circuit: IsTerminal() returns 200 without
mutating anything, so a Hyperswitch retry storm is safe.
* on refund.succeeded: flip refund + order to succeeded/refunded,
revoke licenses, debit seller balance, mark every SellerTransfer
for the order as `reversed`. All within a row-locked tx.
* on refund.failed: flip refund to failed, order back to
`completed`.
Seller-side reconciliation
* SellerBalance.DebitSellerBalance was using Postgres-only GREATEST,
which silently failed on SQLite tests. Ported to a portable
CASE WHEN that clamps at zero in both DBs.
* SellerTransfer.Status = "reversed" captures the refund event in
the ledger. The actual Stripe Connect Transfers:reversal call is
flagged TODO(v1.0.7) — requires wiring through TransferService
with connected-account context that the current transfer worker
doesn't expose. The internal balance is corrected here so the
buyer and seller views match as soon as the PSP confirms; the
missing piece is purely the money-movement round-trip at Stripe.
Webhook routing
* HyperswitchWebhookPayload extended with event_type + refund_id +
error_message, with flat and nested (object.*) shapes supported
(same tolerance as the existing payment fields).
* New IsRefundEvent() discriminator: matches any event_type
containing "refund" (case-insensitive) or presence of refund_id.
routes_webhooks.go peeks the payload once and dispatches to
ProcessRefundWebhook or ProcessPaymentWebhook.
* No signature-verification changes — the same HMAC-SHA512 check
protects both paths.
Handler response
* POST /marketplace/orders/:id/refund now returns
`{ refund: { id, status: "pending" }, message }` so the UI can
surface the in-flight state. A new ErrRefundAlreadyRequested maps
to 400 with a "already in progress" message instead of silently
creating a duplicate row (the double-submit guard checks order
status = `refund_pending` *before* the existing-row check so the
error is explicit).
Schema
* Migration 978_refunds_table.sql adds the `refunds` table with
UNIQUE(hyperswitch_refund_id). The uniqueness constraint is the
load-bearing idempotency guarantee — a duplicate PSP notification
lands on the same DB row, and the webhook handler's
FOR UPDATE + IsTerminal() check turns it into a no-op.
* hyperswitch_refund_id is nullable (NULL between Phase 1 and
Phase 2) so the UNIQUE index ignores rows that haven't been
assigned a PSP id yet.
Partial refunds
* The Provider.CreateRefund signature carries `amount *int64`
already (nil = full), but the service call-site passes nil. Full
refunds only for v1.0.6 — partial-refund UX needs a product
decision and is deferred to v1.0.7. Flagged in the ErrRefund*
section.
Tests (15 cases, all sqlite-in-memory + httptest-style mock provider)
* RefundOrder phase 1
- OpensPendingRefund: pending state, refund_id captured, order
→ refund_pending, licenses untouched
- PSPErrorRollsBack: failed state, order reverts to completed
- DoubleRequestRejected: second call returns
ErrRefundAlreadyRequested, not a generic ErrOrderNotRefundable
- NotCompleted / NoPaymentID / Forbidden / SellerCanRefund
- ExpiredRefundWindow / FallbackExpiredNoDeadline
* ProcessRefundWebhook
- SucceededFinalizesState: refund + order + licenses + seller
balance + seller transfer all reconciled in one tx
- FailedRollsOrderBack: order returns to completed for retry
- IsRefundEventIdempotentOnReplay: second webhook asserts
succeeded_at timestamp is *unchanged*, proving the second
invocation bailed out on IsTerminal (not re-ran)
- UnknownRefundIDReturnsOK: never-issued refund_id → 200 silent
(avoids a Hyperswitch retry storm on stale events)
- MissingRefundID: explicit 400 error
- NonTerminalStatusIgnored: pending/processing leave the row
alone
* HyperswitchWebhookPayload.IsRefundEvent: 6 dispatcher cases
(flat event_type, mixed case, payment event, refund_id alone,
empty, nested object.refund_id)
Backward compat
* hyperswitch.Provider still exposes the old Refund(ctx,...) error
method for any call-site that only cared about success/failure.
* Old mockRefundPaymentProvider replaced; external mocks need to
add CreateRefund — the interface is now (refundID, status, err).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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