feat: Square 3DS2 SCA primary authorisation for saved-card charges; 2FA demoted to audited backup
SCA is now the PRIMARY authorisation for saved-card (ccof) charges (PSR 2017 /
chargeback liability shift); the homegrown 2FA becomes a BACKUP used only when
SCA is unavailable (e.g. a bank without in-app approval), with a strict audit
trail. The 'approve in your banking app' UX comes from Square buyer
verification. Email/SMS remains the intended 2FA delivery channel; the [2FA]
stdout-log relay (TWO_FACTOR_ALLOW_LOG_DELIVERY=true) is the explicit-insecure
pre-email/SMS stopgap.
BACKEND:
- CreateTerminalPaymentRequest gains VerificationToken (forwarded to Square in
the admin saved-card branch; validated like the other charge handlers)
- Structured SCA-required error surfacing: isVerificationRequiredError +
writeVerificationRequiredResponse (HTTP 402 with {code:'verification_required'})
at all 5 charge error sites — the frontend keys on it to trigger the challenge
- requireTwoFactorForCardAccess reworked: SCA token present => 2FA skipped
(SCA primary); no token => 2FA fallback requires delivery channel + consume +
insertTwoFAFallbackAudit (admin_audit_log reason 2fa_fallback_charge,
{sca_performed:false,...}); TWO_FACTOR_FALLBACK env flag (default true) gates
the fallback; false => SCA-only posture
- MIT vs CIT: admin till saved-card + admin booking saved-card charges now flag
customer_initiated=false (merchant-initiated, no SCA, no liability shift);
customer-initiated online flows keep true
FRONTEND:
- square_card_id threaded through SavedCard/SelectableCard + admin lists
- isVerificationRequiredSignal + shouldFallbackTo2FA helpers (402 + code / text
fallback); VERIFICATION_REQUIRED_MESSAGE
- tokenizeSavedCardWithVerification (Square SDK tokenize(details, squareCardId))
with verified/challenge-cancelled/sca-unavailable/sca-failed outcomes
- Per-surface SCA retry with the SAME idempotency key + fresh verification_token
(booking/tip/till/gift-card/admin); 'waiting for approval in your banking
app' state on admin surfaces; 2FA backup-only UX in the shared composable
MOCK PARITY:
- SimulateSavedCardVerificationRequired toggle (default off) + grandfathering
- Challenge state (ApprovePendingVerification/DenyPendingVerification,
ChallengeResult config, token-encoded _ok|_deny outcome)
- One-time-use verify_mock_ token ledger + amount/source binding
- MockCardForm saved-card verification simulation + mock Approve button
- Tests: saved-card SCA gate, one-time-use, denied, amount-mismatch,
grandfathered; frontend helper tests
DOCS: payments-doc SCA appendix, Technical Manual 2FA section, README,
Overview, Feature Catalog updated to SCA-primary + 2FA-backup; env-var
documented (42/42).
26/26 backend packages; 95/95 frontend tests + build; env-docs 42/42.
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