ReplayPaymentByKey (POST /v2/payments re-issue with the same idempotency key
and a synthetic probe source token that can never process a real charge):
Square returns the ORIGINAL payment for a retained key and definitively
rejects an unknown/expired one, so the stale-pending sweep can rescue
lost-response charges without ever issuing a second payment. ErrReplayKeyNotRetained
marks a probe rejection as proof the charge never happened.
Refund classification: zero-amount refunds are now rejected (Square requires
amount_money) instead of lenient full-refund; REFUND_ALREADY_PENDING is
classified as already-processed to match the real contract.
Dev mock parity: SquarePayID == payment ID (was fabricated 'sqp_' prefix),
ForceCheckoutState for IN_PROGRESS/CANCEL_REQUESTED terminal states,
replay-by-key support, aligned refund error codes.
Adds SquareClient.DeleteCustomer for GDPR erasure (DELETE /v2/customers/{id}, NOT_FOUND as no-op), bounds doJSON response reads to 1 MiB with rune-safe 500-byte error snippets, adds validCardID guard to the disable-card URL, makes paymentFromSquare card fields consistent when the card ID is empty, redacts ccof/cnon tokens in all log paths, and fixes the idempotency-key-length comment (45 chars for payments/refunds/cards, 64 only for terminal checkouts).
Refund system (Round 3 fixes + follow-up + alignment):
- Serialize cancellation refunds against the manual handler via
per-payment advisory locks taken before the prior-refunds read
(pg_advisory_xact_lock, ascending, same crussell:refund: key space)
- Aggregate pending cancellation refunds into ONE Square refund per
charge (stable charge-level -square-agg key); atomic group UPDATE
keeps crash-retry amounts identical for Square key-dedup
- Persist paymentID-square-amount idempotency keys on cancellation
refunds; scheduler reads the stored key (legacy fallback for old rows)
- Add sweep-pending-square-refunds cron (*/5, concurrency 1) with
refund_attempts cap; sweep retries stale manual pending refunds with
each row's own stored idempotency key
- Reconcile at Square (GET /v2/refunds ListPaymentRefunds) before every
terminal failed transition: tri-state result leaves rows pending on
reconcile error instead of false-failing; PAYMENT_ALREADY_REFUNDED
resolves to completed
- Move over-refund guard inside the lock, counting completed + pending
(excluding failed); ErrRefundDeclined distinguishes definitive vs
ambiguous outcomes
- forgiveFees now executes a real full refund (forceFullRefund override)
with admin_forgiven_fees reason threaded to Square
- Surface failed card refunds in the admin notification centre
(refund_failed enum, RETURNING-id pre-pass inserts, NOT EXISTS dedup)
- Dedup double-cancel refund inserts via ON CONFLICT (idempotency_key)
DO NOTHING without consuming refundRemaining
Frontend:
- Remove all raw-PAN card entry: zero card_number/card_cvc/new_card_token
in request bodies; gate new-card entry behind CardEntryUnavailable
notice + newCardDisabled prop across all 8 flows
- Delete hand-rolled CardInput.svelte; keep CardSelection saved-card UI
and CardEntryUnavailable fallback
- Update cancellation-policy page to in-person cash pickup wording
Tests:
- Rewrite the two amount-blind dedup tests to assert real money movement
(single call, aggregated amount, shared refund ID)
- Add coverage: manual refund vs cancellation serialization (concurrent
goroutines), reconcile error vs no-match branches, stale manual retry,
forgive-fees real refund row + reason, double-cancel dedup, mock refund
key dedup, ListPaymentRefunds filtering
- Fix time-dependent booking flakes with fixtures.NextWorkingDayAt
- 25/25 packages pass; -race clean on payments/square/db/jobs/bookings
P0 — float truncation: applied math.Round to all remaining int64(x*100)
sites (till penceAmount, refund over-refund guard, GetAlreadyRefundedAmount,
payment summary conversions). A £1.14 till sale previously charged 113p.
P0 — raw PAN stopped at the API edge:
- Deleted CardNumber/CardExpMonth/CardExpYear/CardCVC from TillSaleRequest
and CardNumber/Expiry/CVC from CreatePaymentMethodRequest. Both now accept
card_token (Square nonce) and return 400 when absent. PAN+CVV no longer
transit the application server (PCI-DSS SAQ-A scope).
- Deleted CreateCardOnFileRaw from the SquareClient interface and all
implementations (MockClient, ProdClient, devProdClient).
- Added idempotency_key column to refunds table (UNIQUE).
P0 — RefundPayment hardened: advisory lock on payment ID (prevents two
concurrent refunds passing the over-refund guard), pending-refund-record-
then-Square pattern (scheduler reprocesses on failure), same-key dedup.
P1 — till sale pending-retry now re-attempts the Square charge instead of
returning the stale 'pending' status (gift card was already funded in the
committed tx — silent money loss otherwise). Sale row reused, not duplicated.
P1 — idempotency key caching in frontend: BuyGiftCard and
UserPaymentModal/BookingFlow now cache the key per amount+card, regenerated
on change and cleared on success — matches the tip-flow pattern so a
lost-response retry dedups instead of double-charging.
P1 — CreateTerminalPayment cash/giftcard INSERTs now persist idempotency_key.
Key is unique per payment (booking+type+amount would wrongly dedup two
legitimate identical payments, e.g. two £50 cash receipts).
P1 — gift-card codes no longer logged (spendable credential; value+recipient
only).
Tests: till pending-retry re-attempt, refund same-key dedup, mock CreatePayment
idempotency dedup, CreatePaymentMethod nonce happy path + raw-PAN rejection,
till online_square card_token required/valid.
popertots
