Record quotation and payment integration delivery links

README.md

@@ -9,11 +9,11 @@ The consumer app includes responsive login/signup, English and Russian
 localization, email verification and recovery screens, and URL-based navigation
 with `go_router`. Its interface uses the shared theme's colors and typography.
 
-**Authentication, email verification and analytics use dummy services.** No real
+The default preview uses dummy services. Configuring the existing backend URL
-account or session is created, no email is delivered, and no analytics data is
+and client ID selects authenticated BFF adapters for auth, identity, limits and
-transmitted by those app services. The backend now contains locally owned copies
+wallet quotations/payment execution. Optional Sendico configuration and dedicated
-of Sendico’s BFF runtime, auth/session stack and account service. The app is not
+customer financial resources are required for real operations; analytics still
-connected to that backend or to Sendico yet.
+defaults to an in-memory sink. See [payment setup and rollout](docs/payments.md).
 
 ## Repository structure
 
@@ -256,7 +256,9 @@ gaps and delivery phases. Selected Sendico code has been adapted with recorded
 [provenance](backend/PROVENANCE.md); the projects share no runtime modules.
 
 Run `make test-backend`, `make lint-backend` or `make run-backend` from the root.
-The copied runtime installs local authentication transport and initializes its
+The runtime installs local authentication, verification delivery, identity and
-account service. Signup/profile endpoints, verification delivery/completion,
+wallet transports. Public Sendico adapters support independent customer facts,
-Flutter HTTP adapters and live Sendico operations remain to be wired. See the
+reviewed identity/limits and quotation/execution through the BFF. Deployment and
-[backend run guide](backend/README.md) for local MongoDB configuration.
+financial-resource provisioning are separate; backend account-language saving
+and additional funding/recipient onboarding remain follow-up work. See the
+[backend run guide](backend/README.md) and [payment integration](docs/payments.md).

backend/product/README.md

@@ -43,3 +43,10 @@ contracts; local customers retain no platform tenancy. See
 `go test -race ./...` and `go vet ./...` validate this module. Tests require Docker
 for disposable Mongo replica sets. Root `make test` and `make lint-backend` also
 validate `shared`. See [source provenance](../PROVENANCE.md).
+
+## Customer quotations and payments
+
+With `api.sendico`, runtime composes the customer-scoped payment service and
+public HTTP provider adapter. Flutter backend mode selects this path automatically;
+missing provider configuration never returns demo money. See
+[contracts, provisioning, authorization and rollout](../../docs/payments.md).

backend/product/app/api/api.go

@@ -6,6 +6,8 @@ import (
 	"git.sendico.io/tech/sxchnge/product/auth/flow"
 	"git.sendico.io/tech/sxchnge/product/auth/storage"
 	"git.sendico.io/tech/sxchnge/product/customers"
+	"git.sendico.io/tech/sxchnge/product/identity"
+	"git.sendico.io/tech/sxchnge/product/payments"
 	"git.sendico.io/tech/sxchnge/product/twofactor"
 	"git.sendico.io/tech/sxchnge/shared/logging"
 	"github.com/go-chi/chi/v5"
@@ -17,6 +19,8 @@ type Dependencies struct {
 	Customers   accountservice.AccountService
 	Auth        *flow.Service
 	Factors     *twofactor.Service
+	Identity    *identity.Service
+	Payments    *payments.Service
 	Token       middleware.TokenConfig
 	Signature   middleware.Signature
 	LoginLimits middleware.LoginRateLimits

backend/product/app/api/v1/install.go

@@ -5,6 +5,8 @@ import (
 	"git.sendico.io/tech/sxchnge/product/app/api"
 	auth "git.sendico.io/tech/sxchnge/product/auth/http/v1"
 	"git.sendico.io/tech/sxchnge/product/auth/http/v1/public"
+	identity "git.sendico.io/tech/sxchnge/product/identity/http/v1"
+	paymenthttp "git.sendico.io/tech/sxchnge/product/payments/http/v1"
 	factors "git.sendico.io/tech/sxchnge/product/twofactor/http/v1"
 	"git.sendico.io/tech/sxchnge/shared/errors"
 )
@@ -22,5 +24,7 @@ func Install(scope api.Scope, deps *api.Dependencies) error {
 	if deps.Factors != nil {
 		factors.Install(routes, deps.Factors, scope.Logger)
 	}
+	identity.Install(routes, deps.Identity, scope.Logger)
+	paymenthttp.Install(routes, deps.Payments, scope.Logger)
 	return nil
 }

backend/product/app/runtime/services.go

@@ -10,6 +10,7 @@ import (
 	"git.sendico.io/tech/sxchnge/product/customers"
 	"git.sendico.io/tech/sxchnge/product/identity"
 	"git.sendico.io/tech/sxchnge/product/notifications"
+	"git.sendico.io/tech/sxchnge/product/payments"
 	"git.sendico.io/tech/sxchnge/product/providers/sendico"
 	"git.sendico.io/tech/sxchnge/product/twofactor"
 	"git.sendico.io/tech/sxchnge/product/twofactor/delivery"
@@ -67,7 +68,13 @@ func OpenDependencies(_ context.Context, logger mlogger.Logger, config *api.Conf
 			if err != nil {
 				return nil, nil, err
 			}
-			deps.Auth.Facts = &identity.Service{Store: bindings, Provider: provider, Logger: logger.Named("signup_facts")}
+			deps.Identity = &identity.Service{Store: bindings, Provider: provider, Logger: logger.Named("identity")}
+			deps.Auth.Facts = deps.Identity
+			paymentStore, err := payments.OpenStore(db)
+			if err != nil {
+				return nil, nil, err
+			}
+			deps.Payments = &payments.Service{Store: paymentStore, Provider: provider, Identity: deps.Identity, Logger: logger.Named("payments")}
 			logger.Info("Sendico sign-up facts integration enabled")
 		}
 		records, err := factorstore.Open(logger, db)
@@ -79,6 +86,9 @@ func OpenDependencies(_ context.Context, logger mlogger.Logger, config *api.Conf
 			return nil, nil, err
 		}
 	}
+	if deps.Payments != nil {
+		deps.Payments.Factors = deps.Factors
+	}
 	if config.Sendico != nil && deps.Auth == nil {
 		return nil, nil, merrors.InvalidArgument("Sendico sign-up facts require notifications configuration")
 	}

backend/product/identity/http/v1/dto.go

@@ -0,0 +1,48 @@
+package identityhttp
+
+import "git.sendico.io/tech/sxchnge/product/identity"
+
+type profileDTO struct {
+	FullName         string `json:"fullName"`
+	DateOfBirth      string `json:"dateOfBirth"`
+	ResidenceCountry string `json:"residenceCountry"`
+}
+
+func (p profileDTO) model() identity.Profile {
+	return identity.Profile{FullName: p.FullName, DateOfBirth: p.DateOfBirth, ResidenceCountry: p.ResidenceCountry}
+}
+
+type verificationDTO struct {
+	Status         string     `json:"status"`
+	UpgradePending bool       `json:"upgradePending"`
+	Reason         string     `json:"reason,omitempty"`
+	SubmissionID   string     `json:"submissionId,omitempty"`
+	Profile        profileDTO `json:"profile"`
+}
+
+func mapVerification(v identity.Verification) verificationDTO {
+	return verificationDTO{Status: v.Status, UpgradePending: v.UpgradePending, Reason: v.Reason, SubmissionID: v.SubmissionID, Profile: profileDTO{FullName: v.Profile.FullName, DateOfBirth: v.Profile.DateOfBirth, ResidenceCountry: v.Profile.ResidenceCountry}}
+}
+
+type limitDTO struct {
+	Operation string `json:"operation"`
+	Period    string `json:"period"`
+	Currency  string `json:"currency"`
+	Cap       string `json:"cap"`
+	Remaining string `json:"remaining"`
+	Used      string `json:"used"`
+	Reserved  string `json:"reserved"`
+}
+type limitsDTO struct {
+	Tier       string     `json:"tier"`
+	ProfileRef string     `json:"profileRef"`
+	Entries    []limitDTO `json:"entries"`
+}
+
+func mapLimits(v identity.Limits) limitsDTO {
+	entries := make([]limitDTO, 0, len(v.Entries))
+	for _, r := range v.Entries {
+		entries = append(entries, limitDTO{Operation: r.Operation, Period: r.Period, Currency: r.Currency, Cap: r.Cap, Remaining: r.Remaining, Used: r.Used, Reserved: r.Reserved})
+	}
+	return limitsDTO{Tier: v.Tier, ProfileRef: v.ProfileRef, Entries: entries}
+}

backend/product/identity/http/v1/router.go

@@ -0,0 +1,107 @@
+package identityhttp
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strconv"
+
+	sresponse "git.sendico.io/tech/sxchnge/product/auth/http/v1/response"
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	"git.sendico.io/tech/sxchnge/product/identity"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	api "git.sendico.io/tech/sxchnge/shared/http"
+	"git.sendico.io/tech/sxchnge/shared/http/response"
+	mlogger "git.sendico.io/tech/sxchnge/shared/logging"
+	mservice "git.sendico.io/tech/sxchnge/shared/service"
+)
+
+type Registrar interface {
+	AccountHandler(mservice.Type, string, api.HTTPMethod, sresponse.AccountHandlerFunc)
+}
+type router struct {
+	service *identity.Service
+	logger  mlogger.Logger
+}
+
+func Install(reg Registrar, service *identity.Service, logger mlogger.Logger) {
+	h := &router{service, logger.Named("identity_http")}
+	reg.AccountHandler(mservice.Accounts, "/identity", api.Get, h.get)
+	reg.AccountHandler(mservice.Accounts, "/identity", api.Post, h.submit)
+	reg.AccountHandler(mservice.Accounts, "/limits", api.Get, h.limits)
+}
+
+func (h *router) limits(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	v, err := h.service.Limits(r.Context(), a)
+	return h.result(mapLimits(v), err)
+}
+func (h *router) result(data any, err error) http.HandlerFunc {
+	if err == nil {
+		return response.Ok(h.logger, data)
+	}
+	if throttle, ok := merrors.ThrottleDetailsFrom(err); ok {
+		return func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Retry-After", strconv.Itoa(max(1, int(throttle.RetryAfter.Seconds()))))
+			response.TooManyRequests(h.logger, mservice.Accounts, "Wait before retrying identity submission")(w, r)
+		}
+	}
+	switch {
+	case errors.Is(err, merrors.ErrInvalidArg):
+		return response.BadRequest(h.logger, mservice.Accounts, "invalid_request", "Check profile and use readable JPEG/PNG photos, 600×600 minimum, 10 MiB maximum each")
+	case errors.Is(err, merrors.ErrDataConflict):
+		return response.DataConflict(h.logger, mservice.Accounts, "Identity submission changed; refresh its status")
+	case errors.Is(err, merrors.ErrAccessDenied):
+		return response.AccessDenied(h.logger, mservice.Accounts, "Identity submission is unavailable")
+	default:
+		return response.Error(h.logger, mservice.Accounts, http.StatusServiceUnavailable, "unavailable", "Identity verification is temporarily unavailable; retry")
+	}
+}
+func (h *router) get(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	v, err := h.service.Verification(r.Context(), a)
+	return h.result(mapVerification(v), err)
+}
+func (h *router) submit(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	// Read multipart as a bounded stream. Never spill identity documents to disk.
+	r.Body = http.MaxBytesReader(nil, r.Body, 2*identity.MaxPhotoBytes+16384)
+	reader, err := r.MultipartReader()
+	if err != nil {
+		return h.result(nil, merrors.InvalidArgument("multipart required"))
+	}
+	fields := map[string][]byte{}
+	for {
+		part, readErr := reader.NextPart()
+		if readErr == io.EOF {
+			break
+		}
+		if readErr != nil {
+			return h.result(nil, merrors.InvalidArgument("invalid multipart"))
+		}
+		name := part.FormName()
+		limit := int64(8192)
+		switch name {
+		case "document", "selfie":
+			limit = identity.MaxPhotoBytes
+		case "profile", "idempotencyKey":
+		default:
+			_ = part.Close()
+			return h.result(nil, merrors.InvalidArgument("unexpected field"))
+		}
+		if _, exists := fields[name]; exists {
+			_ = part.Close()
+			return h.result(nil, merrors.InvalidArgument("duplicate field"))
+		}
+		data, readErr := io.ReadAll(io.LimitReader(part, limit+1))
+		_ = part.Close()
+		if readErr != nil || int64(len(data)) > limit {
+			return h.result(nil, merrors.InvalidArgument("field too large"))
+		}
+		fields[name] = data
+	}
+	var p profileDTO
+	if err = json.Unmarshal(fields["profile"], &p); err != nil {
+		return h.result(nil, merrors.InvalidArgument("profile required"))
+	}
+	v, err := h.service.SubmitVerification(r.Context(), a, string(fields["idempotencyKey"]), p.model(), fields["document"], fields["selfie"])
+	return h.result(mapVerification(v), err)
+}

backend/product/identity/http/v1/router_test.go

@@ -0,0 +1,20 @@
+package identityhttp
+
+import (
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
+)
+
+func TestThrottleDoesNotBecomeGenericUnavailable(t *testing.T) {
+	h := router{logger: zap.NewNop()}
+	w := httptest.NewRecorder()
+	r := httptest.NewRequest("POST", "/accounts/identity", nil)
+	h.result(nil, merrors.WithThrottle(merrors.ErrServiceUnavailable, "identity", 120*time.Second, "temporary limit"))(w, r)
+	require.Equal(t, 429, w.Code)
+	require.Equal(t, "120", w.Header().Get("Retry-After"))
+}

backend/product/identity/photo.go

@@ -0,0 +1,31 @@
+package identity
+
+import (
+	"bytes"
+	"image"
+	_ "image/jpeg"
+	_ "image/png"
+
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+)
+
+const MaxPhotoBytes = 10 << 20
+
+// ValidatePhoto repeats client checks at the trust boundary and bounds decoder
+// memory before decoding pixels. File names and client MIME types are ignored.
+func ValidatePhoto(data []byte) error {
+	if len(data) == 0 || len(data) > MaxPhotoBytes {
+		return merrors.InvalidArgument("photo must be between 1 byte and 10 MiB")
+	}
+	config, format, err := image.DecodeConfig(bytes.NewReader(data))
+	if err != nil || (format != "jpeg" && format != "png") {
+		return merrors.InvalidArgument("readable JPEG or PNG required")
+	}
+	if config.Width < 600 || config.Height < 600 || int64(config.Width)*int64(config.Height) > 40000000 {
+		return merrors.InvalidArgument("photo dimensions must be at least 600 by 600 and at most 40 megapixels")
+	}
+	if _, _, err = image.Decode(bytes.NewReader(data)); err != nil {
+		return merrors.InvalidArgument("readable JPEG or PNG required")
+	}
+	return nil
+}

backend/product/identity/store.go

@@ -7,6 +7,8 @@ import (
 	db "git.sendico.io/tech/sxchnge/shared/database"
 	deps "git.sendico.io/tech/sxchnge/shared/database/dependencies"
 	"git.sendico.io/tech/sxchnge/shared/database/repository"
+	"git.sendico.io/tech/sxchnge/shared/database/repository/builder"
+	ri "git.sendico.io/tech/sxchnge/shared/database/repository/index"
 	"git.sendico.io/tech/sxchnge/shared/database/source"
 	"go.mongodb.org/mongo-driver/v2/bson"
 )
@@ -26,7 +28,11 @@ func OpenStore(factory db.Factory) (Store, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &mongoStore{records: repository.CreateRepository(source.Majority(d.Database), "signup_facts")}, nil
+	records := repository.CreateRepository(source.Majority(d.Database), "signup_facts")
+	if err = records.CreateIndex(&ri.Definition{Name: "provider_subject_unique", Unique: true, Keys: []ri.Key{{Field: "namespace", Sort: ri.Asc}, {Field: "subjectRef", Sort: ri.Asc}}, PartialFilter: repository.Query().Comparison(repository.Field("subjectRef"), builder.Gt, "")}); err != nil {
+		return nil, err
+	}
+	return &mongoStore{records: records}, nil
 }
 
 func (s *mongoStore) Get(ctx context.Context, id bson.ObjectID) (*Binding, error) {

backend/product/identity/store_test.go

@@ -62,6 +62,13 @@ func TestDurableBindingClaimsAndIsolation(t *testing.T) {
 	require.False(t, stored.RegisteringAt.IsZero())
 	require.Error(t, store.Bind(ctx, b.ID, "other-source", "subject"))
 	require.NoError(t, store.Bind(ctx, b.ID, b.Namespace, "subject"))
+	duplicate := &Binding{Namespace: b.Namespace}
+	duplicate.SetID(bson.NewObjectID())
+	require.NoError(t, store.Create(ctx, duplicate))
+	claimedDuplicate, err := store.Claim(ctx, duplicate.ID, duplicate.Namespace)
+	require.NoError(t, err)
+	require.True(t, claimedDuplicate)
+	require.ErrorIs(t, store.Bind(ctx, duplicate.ID, duplicate.Namespace, "subject"), merrors.ErrDataConflict)
 	require.Error(t, store.Bind(ctx, b.ID, b.Namespace, "different-subject"))
 	receipt := Receipt{SubjectRef: "other-subject", SubmissionRef: "submission", AcceptedAt: time.Now().UTC().Truncate(time.Millisecond)}
 	require.Error(t, store.Accept(ctx, b.ID, b.Namespace, receipt))

backend/product/identity/verification.go

@@ -0,0 +1,159 @@
+package identity
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"strings"
+	"time"
+
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"go.uber.org/zap"
+)
+
+// Profile holds unverified customer assertions. Email and customer reference are
+// always supplied by the authenticated backend, never accepted from the browser.
+type Profile struct {
+	FullName         string
+	DateOfBirth      string
+	ResidenceCountry string
+}
+
+func (p Profile) Validate() error {
+	birth, err := time.Parse("2006-01-02", p.DateOfBirth)
+	if strings.TrimSpace(p.FullName) == "" || len(p.FullName) > 800 || err != nil || !birth.Before(time.Now()) || len(p.ResidenceCountry) != 2 || p.ResidenceCountry[0] < 'A' || p.ResidenceCountry[0] > 'Z' || p.ResidenceCountry[1] < 'A' || p.ResidenceCountry[1] > 'Z' {
+		return merrors.InvalidArgument("complete identity profile required")
+	}
+	return nil
+}
+
+type Verification struct {
+	Status         string
+	UpgradePending bool
+	Reason         string
+	SubmissionID   string
+	Profile        Profile
+}
+
+// VerificationProvider consumes reviewed state through the platform public API.
+// It cannot accept a browser-selected subject, policy profile or approval.
+type VerificationProvider interface {
+	Verification(context.Context, string) (Verification, error)
+	SubmitVerification(context.Context, string, string, Profile, Facts, []byte, []byte) (Verification, error)
+}
+
+// Decimal amounts are transported losslessly in their currency's major unit.
+// No fiat scale or illustrative client caps are applied to provider policy.
+type Limit struct {
+	Operation string
+	Period    string
+	Currency  string
+	Cap       string
+	Remaining string
+	Used      string
+	Reserved  string
+}
+type Limits struct {
+	Tier       string
+	ProfileRef string
+	Entries    []Limit
+}
+type LimitsProvider interface {
+	Limits(context.Context, string) (Limits, error)
+}
+
+func (s *Service) Limits(ctx context.Context, a *customer.Account) (Limits, error) {
+	b, err := s.binding(ctx, a)
+	if err != nil {
+		return Limits{}, err
+	}
+	p, ok := s.Provider.(LimitsProvider)
+	if !ok {
+		return Limits{}, unavailable()
+	}
+	return p.Limits(ctx, b.SubjectRef)
+}
+
+func (s *Service) binding(ctx context.Context, a *customer.Account) (*Binding, error) {
+	if s == nil || s.Provider == nil || s.Store == nil {
+		return nil, merrors.ServiceUnavailable("identity verification unavailable")
+	}
+	if a == nil || a.ID.IsZero() {
+		return nil, merrors.InvalidArgument("customer required")
+	}
+	b, err := s.Store.Get(ctx, a.ID)
+	if errors.Is(err, merrors.ErrNoData) || err == nil && b.Receipt == nil {
+		if err = s.Ensure(ctx, a); err != nil {
+			return nil, err
+		}
+		b, err = s.Store.Get(ctx, a.ID)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if b.Namespace != s.Provider.Namespace() || b.SubjectRef == "" || b.Receipt == nil || b.Receipt.SubjectRef != b.SubjectRef {
+		return nil, merrors.FailedPrecondition("identity binding requires reconciliation")
+	}
+	return b, nil
+}
+
+func (s *Service) Verification(ctx context.Context, a *customer.Account) (Verification, error) {
+	b, err := s.binding(ctx, a)
+	if err != nil {
+		return Verification{}, err
+	}
+	provider, ok := s.Provider.(VerificationProvider)
+	if !ok {
+		return Verification{}, unavailable()
+	}
+	v, err := provider.Verification(ctx, b.SubjectRef)
+	if err == nil && v.Profile.FullName == "" {
+		v.Profile.FullName = a.Name
+	}
+	return v, err
+}
+
+func (s *Service) SubmitVerification(ctx context.Context, a *customer.Account, key string, p Profile, document, selfie []byte) (Verification, error) {
+	if len(key) < 16 || len(key) > 128 {
+		return Verification{}, merrors.InvalidArgument("valid idempotency key required")
+	}
+	if err := p.Validate(); err != nil {
+		return Verification{}, err
+	}
+	for _, photo := range [][]byte{document, selfie} {
+		if err := ValidatePhoto(photo); err != nil {
+			return Verification{}, err
+		}
+	}
+	b, err := s.binding(ctx, a)
+	if err != nil {
+		return Verification{}, err
+	}
+	provider, ok := s.Provider.(VerificationProvider)
+	if !ok {
+		return Verification{}, unavailable()
+	}
+	digest := sha256.Sum256([]byte(a.ID.Hex() + "\x00" + key))
+	facts := b.Facts
+	facts.Email = a.Login
+	facts.CustomerRef = a.ID.Hex()
+	v, err := provider.SubmitVerification(ctx, b.SubjectRef, "sxchnge:identity:"+hex.EncodeToString(digest[:]), p, facts, document, selfie)
+	if err != nil {
+		s.Logger.Warn("Identity proof submission incomplete", zap.String("account_ref", a.ID.Hex()))
+		return Verification{}, err
+	}
+	s.Logger.Info("Identity proofs accepted for review", zap.String("account_ref", a.ID.Hex()), zap.String("submission_ref", v.SubmissionID))
+	return v, nil
+}
+
+// Subject resolves the authenticated customer's confirmed provider binding.
+// Only server-side services may use this resource; clients cannot select it.
+func (s *Service) Subject(ctx context.Context, a *customer.Account) (string, error) {
+	b, err := s.binding(ctx, a)
+	if err != nil {
+		return "", err
+	}
+	return b.SubjectRef, nil
+}

backend/product/identity/verification_test.go

@@ -0,0 +1,84 @@
+package identity
+
+import (
+	"bytes"
+	"context"
+	"image"
+	"image/png"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type proofProvider struct {
+	*providerStub
+	subject, key string
+	profile      Profile
+	facts        Facts
+	calls        int
+}
+
+func (p *proofProvider) Verification(_ context.Context, subject string) (Verification, error) {
+	p.subject = subject
+	return Verification{Status: "unverified"}, nil
+}
+func (p *proofProvider) SubmitVerification(_ context.Context, subject, key string, profile Profile, facts Facts, _, _ []byte) (Verification, error) {
+	p.subject = subject
+	p.key = key
+	p.profile = profile
+	p.facts = facts
+	p.calls++
+	return Verification{Status: "pending", SubmissionID: "receipt"}, nil
+}
+func proofImage(t *testing.T, width, height int) []byte {
+	t.Helper()
+	var body bytes.Buffer
+	require.NoError(t, png.Encode(&body, image.NewNRGBA(image.Rect(0, 0, width, height))))
+	return body.Bytes()
+}
+func TestVerificationUsesBoundSubjectAndStableCustomerKey(t *testing.T) {
+	s, _, base, a := fixture()
+	p := &proofProvider{providerStub: base}
+	s.Provider = p
+	ctx := t.Context()
+	result, err := s.Verification(ctx, a)
+	require.NoError(t, err)
+	require.Equal(t, a.Name, result.Profile.FullName)
+	require.Equal(t, "subject-1", p.subject)
+	photo := proofImage(t, 600, 600)
+	profile := Profile{FullName: "Legal Customer Name", DateOfBirth: "1990-04-23", ResidenceCountry: "PL"}
+	_, err = s.SubmitVerification(ctx, a, "0123456789012345", profile, photo, photo)
+	require.NoError(t, err)
+	key := p.key
+	require.Equal(t, a.ID.Hex(), p.facts.CustomerRef)
+	require.Equal(t, a.Login, p.facts.Email)
+	require.Equal(t, profile, p.profile)
+	_, err = s.SubmitVerification(ctx, a, "0123456789012345", profile, photo, photo)
+	require.NoError(t, err)
+	require.Equal(t, key, p.key)
+	require.Equal(t, 1, base.registrations)
+	other := a.Copy()
+	other.ID[0]++
+	_, err = s.SubmitVerification(ctx, other, "0123456789012345", profile, photo, photo)
+	require.NoError(t, err)
+	require.NotEqual(t, key, p.key)
+}
+func TestVerificationValidationBeforeExternalHandoff(t *testing.T) {
+	s, _, base, a := fixture()
+	p := &proofProvider{providerStub: base}
+	s.Provider = p
+	photo := proofImage(t, 600, 600)
+	for _, profile := range []Profile{{}, {FullName: "Name", DateOfBirth: "1990-02-30", ResidenceCountry: "PL"}, {FullName: "Name", DateOfBirth: "2990-04-23", ResidenceCountry: "PL"}, {FullName: "Name", DateOfBirth: "1990-04-23", ResidenceCountry: "USA"}} {
+		_, err := s.SubmitVerification(t.Context(), a, "0123456789012345", profile, photo, photo)
+		require.Error(t, err)
+	}
+	require.Zero(t, p.calls)
+	require.Zero(t, base.registrations)
+	require.Error(t, ValidatePhoto([]byte("not an image")))
+	require.Error(t, ValidatePhoto(proofImage(t, 599, 600)))
+	require.Error(t, ValidatePhoto(photo[:len(photo)-20]))
+	require.Error(t, ValidatePhoto(make([]byte, MaxPhotoBytes+1)))
+	var unavailableService *Service
+	_, err := unavailableService.Verification(t.Context(), a)
+	require.Error(t, err)
+}

backend/product/payments/http/v1/dto.go

@@ -0,0 +1,84 @@
+package paymenthttp
+
+import (
+	"git.sendico.io/tech/sxchnge/product/payments"
+	factor "git.sendico.io/tech/sxchnge/product/twofactor/model"
+	"time"
+)
+
+type requestDTO struct {
+	Kind        string `json:"kind"`
+	Source      string `json:"source"`
+	Destination string `json:"destination"`
+	Recipient   string `json:"recipient"`
+	Amount      int64  `json:"amount"`
+}
+
+func (d requestDTO) model() payments.Request {
+	return payments.Request{Kind: d.Kind, Source: d.Source, Destination: d.Destination, Recipient: d.Recipient, Amount: d.Amount}
+}
+func fromRequest(r payments.Request) requestDTO {
+	return requestDTO{r.Kind, r.Source, r.Destination, r.Recipient, r.Amount}
+}
+
+type quoteDTO struct {
+	ID          string     `json:"id"`
+	Request     requestDTO `json:"request"`
+	Fee         int64      `json:"fee"`
+	Debit       int64      `json:"debit"`
+	Credit      int64      `json:"credit"`
+	ExpiresAt   time.Time  `json:"expiresAt"`
+	Numerator   int64      `json:"rateNumerator"`
+	Denominator int64      `json:"rateDenominator"`
+}
+
+func fromQuote(q payments.Quote) quoteDTO {
+	return quoteDTO{q.ID, fromRequest(q.Request), q.Fee, q.Debit, q.Credit, q.ExpiresAt, q.RateNumerator, q.RateDenominator}
+}
+
+type operationDTO struct {
+	ID        string    `json:"id"`
+	Quote     quoteDTO  `json:"quote"`
+	Status    string    `json:"status"`
+	CreatedAt time.Time `json:"createdAt"`
+}
+
+func fromOperation(o payments.Operation) operationDTO {
+	return operationDTO{o.ID, fromQuote(o.Quote), o.Status, o.CreatedAt}
+}
+
+type accountDTO struct {
+	ID           string `json:"id"`
+	Currency     string `json:"currency"`
+	Precision    int    `json:"precision"`
+	Available    int64  `json:"available"`
+	PayoutMethod string `json:"payoutMethod"`
+	PayoutLabel  string `json:"payoutLabel"`
+	CanFund      bool   `json:"canFund"`
+}
+type snapshotDTO struct {
+	Accounts   []accountDTO   `json:"accounts"`
+	Operations []operationDTO `json:"operations"`
+}
+
+func fromSnapshot(s payments.Snapshot) snapshotDTO {
+	v := snapshotDTO{Accounts: []accountDTO{}, Operations: []operationDTO{}}
+	for _, a := range s.Accounts {
+		v.Accounts = append(v.Accounts, accountDTO{a.ID, a.Currency, a.Precision, a.Available, a.PayoutMethod, a.PayoutLabel, a.FundingMethod != ""})
+	}
+	for i := len(s.Operations) - 1; i >= 0; i-- {
+		v.Operations = append(v.Operations, fromOperation(s.Operations[i]))
+	}
+	return v
+}
+
+type challengeDTO struct {
+	ID        string    `json:"challengeId"`
+	Target    string    `json:"target"`
+	ExpiresAt time.Time `json:"expiresAt"`
+	ResendAt  time.Time `json:"resendAt"`
+}
+
+func fromChallenge(c factor.Challenge) challengeDTO {
+	return challengeDTO{c.ID, c.Target, c.ExpiresAt, c.ResendAt}
+}

backend/product/payments/http/v1/router.go

@@ -0,0 +1,164 @@
+package paymenthttp
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strconv"
+
+	sresponse "git.sendico.io/tech/sxchnge/product/auth/http/v1/response"
+	"git.sendico.io/tech/sxchnge/product/auth/ipguard"
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	"git.sendico.io/tech/sxchnge/product/payments"
+	verification "git.sendico.io/tech/sxchnge/product/verification/store"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	api "git.sendico.io/tech/sxchnge/shared/http"
+	"git.sendico.io/tech/sxchnge/shared/http/response"
+	mlogger "git.sendico.io/tech/sxchnge/shared/logging"
+	mservice "git.sendico.io/tech/sxchnge/shared/service"
+)
+
+type Registrar interface {
+	AccountHandler(mservice.Type, string, api.HTTPMethod, sresponse.AccountHandlerFunc)
+}
+type router struct {
+	service *payments.Service
+	logger  mlogger.Logger
+}
+
+func Install(reg Registrar, s *payments.Service, logger mlogger.Logger) {
+	h := &router{s, logger.Named("payment_http")}
+	reg.AccountHandler(mservice.Accounts, "/wallet/profile", api.Get, h.profile)
+	reg.AccountHandler(mservice.Accounts, "/wallet", api.Get, h.fetch)
+	reg.AccountHandler(mservice.Accounts, "/wallet/quote", api.Post, h.quote)
+	reg.AccountHandler(mservice.Accounts, "/wallet/submit", api.Post, h.submit)
+	reg.AccountHandler(mservice.Accounts, "/wallet/submission", api.Post, h.reconcile)
+	reg.AccountHandler(mservice.Accounts, "/wallet/challenge", api.Post, h.challenge)
+	reg.AccountHandler(mservice.Accounts, "/wallet/resend", api.Post, h.resend)
+	reg.AccountHandler(mservice.Accounts, "/wallet/verify", api.Post, h.verify)
+}
+func decode(r *http.Request, dst any) error {
+	d := json.NewDecoder(io.LimitReader(r.Body, 8193))
+	d.DisallowUnknownFields()
+	if d.Decode(dst) != nil {
+		return payments.InvalidAmount
+	}
+	var extra any
+	if d.Decode(&extra) != io.EOF {
+		return payments.InvalidAmount
+	}
+	return nil
+}
+func (h *router) result(data any, err error) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-store")
+		if err == nil {
+			response.Ok(h.logger, data)(w, r)
+			return
+		}
+		code := "unavailable"
+		status := http.StatusServiceUnavailable
+		var f payments.Failure
+		if errors.As(err, &f) {
+			code = string(f)
+			if f != payments.Unavailable && f != payments.Uncertain {
+				status = http.StatusBadRequest
+			}
+		}
+		switch {
+		case errors.Is(err, verification.ErrTokenExpired):
+			code = "factorExpired"
+			status = 400
+		case errors.Is(err, verification.ErrTokenAttemptsExceeded):
+			code = "factorLocked"
+			status = 400
+		case errors.Is(err, verification.ErrTokenNotFound), errors.Is(err, verification.ErrTokenAlreadyUsed), errors.Is(err, merrors.ErrUnauthorized):
+			code = "factorInvalid"
+			status = 400
+		}
+		if throttle, ok := verification.Throttle(err); ok {
+			w.Header().Set("Retry-After", strconv.Itoa(max(1, int(throttle.RetryAfter.Seconds()))))
+			code = "factorCooldown"
+			status = 429
+		}
+		response.Error(h.logger, mservice.Accounts, status, code, "Unable to complete wallet operation")(w, r)
+	}
+}
+func (h *router) fetch(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	v, e := h.service.Fetch(r.Context(), a)
+	return h.result(fromSnapshot(v), e)
+}
+func (h *router) quote(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	var d requestDTO
+	if e := decode(r, &d); e != nil {
+		return h.result(nil, e)
+	}
+	v, e := h.service.Quote(r.Context(), a, d.model())
+	return h.result(fromQuote(v), e)
+}
+
+type actionDTO struct {
+	Quote     string `json:"quoteId"`
+	Key       string `json:"idempotencyKey"`
+	Challenge string `json:"challengeId"`
+	Code      string `json:"code"`
+}
+
+func (h *router) submit(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	var d actionDTO
+	if e := decode(r, &d); e != nil {
+		return h.result(nil, e)
+	}
+	v, e := h.service.Submit(r.Context(), a, d.Quote, d.Key)
+	return h.result(fromOperation(v), e)
+}
+func (h *router) reconcile(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	var d actionDTO
+	if e := decode(r, &d); e != nil {
+		return h.result(nil, e)
+	}
+	v, e := h.service.Reconcile(r.Context(), a, d.Key)
+	if v == nil {
+		return h.result(nil, e)
+	}
+	return h.result(fromOperation(*v), e)
+}
+func requestIP(r *http.Request) string {
+	if ip := ipguard.ClientIP(r); ip != nil {
+		return ip.String()
+	}
+	return "unresolved"
+}
+func (h *router) challenge(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	var d actionDTO
+	if e := decode(r, &d); e != nil {
+		return h.result(nil, e)
+	}
+	v, e := h.service.Challenge(r.Context(), a, d.Quote, requestIP(r))
+	return h.result(fromChallenge(v), e)
+}
+func (h *router) resend(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	var d actionDTO
+	if e := decode(r, &d); e != nil {
+		return h.result(nil, e)
+	}
+	v, e := h.service.Resend(r.Context(), a, d.Quote, d.Challenge, d.Key, requestIP(r))
+	return h.result(fromChallenge(v), e)
+}
+func (h *router) verify(r *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	var d actionDTO
+	if e := decode(r, &d); e != nil {
+		return h.result(nil, e)
+	}
+	e := h.service.Authorize(r.Context(), a, d.Quote, d.Challenge, d.Code, d.Key)
+	return h.result(struct {
+		Key string `json:"idempotencyKey"`
+	}{d.Key}, e)
+}
+
+func (h *router) profile(_ *http.Request, a *customer.Account, _ *sresponse.TokenData) http.HandlerFunc {
+	return h.result(struct {
+		Locale string `json:"locale"`
+	}{a.Locale}, nil)
+}

backend/product/payments/http/v1/router_test.go

@@ -0,0 +1,36 @@
+package paymenthttp
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	"github.com/stretchr/testify/require"
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.uber.org/zap"
+)
+
+func TestUnconfiguredWalletCannotReturnDemoFunds(t *testing.T) {
+	h := &router{logger: zap.NewNop()}
+	a := &customer.Account{}
+	a.ID = bson.NewObjectID()
+	request := httptest.NewRequest(http.MethodGet, "/accounts/wallet", nil)
+	recorder := httptest.NewRecorder()
+	h.fetch(request, a, nil)(recorder, request)
+	require.Equal(t, http.StatusServiceUnavailable, recorder.Code)
+	require.Equal(t, "no-store", recorder.Header().Get("Cache-Control"))
+	require.NotContains(t, recorder.Body.String(), "7500")
+}
+func TestQuoteRejectsUnknownFieldsAndTrailingRequests(t *testing.T) {
+	h := &router{logger: zap.NewNop()}
+	a := &customer.Account{}
+	a.ID = bson.NewObjectID()
+	for _, body := range []string{`{"kind":"payout","subject":"foreign"}`, `{"amount":10} {"amount":20}`, `{"amount":1.2}`} {
+		request := httptest.NewRequest(http.MethodPost, "/accounts/wallet/quote", strings.NewReader(body))
+		recorder := httptest.NewRecorder()
+		h.quote(request, a, nil)(recorder, request)
+		require.Equal(t, http.StatusBadRequest, recorder.Code)
+	}
+}

backend/product/payments/model.go

@@ -0,0 +1,83 @@
+// Package payments owns customer quotation ownership and durable execution intent.
+// Money and settlement remain authoritative in the provider.
+package payments
+
+import (
+	"context"
+	"time"
+
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	"git.sendico.io/tech/sxchnge/shared/database/record"
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+type Account struct {
+	ID, Currency                             string
+	Precision                                int
+	Available                                int64
+	PayoutMethod, PayoutLabel, FundingMethod string
+}
+type Request struct {
+	Kind, Source, Destination, Recipient string
+	Amount                               int64
+}
+type Quote struct {
+	ID                             string
+	Request                        Request
+	Fee, Debit, Credit             int64
+	ExpiresAt                      time.Time
+	RateNumerator, RateDenominator int64
+}
+type Operation struct {
+	ID        string
+	Quote     Quote
+	Status    string
+	CreatedAt time.Time
+}
+type Snapshot struct {
+	Accounts   []Account
+	Operations []Operation
+}
+type Record struct {
+	storable.Base `bson:",inline"`
+	Customer      bson.ObjectID `bson:"customer"`
+	Namespace     string        `bson:"namespace"`
+	Subject       string        `bson:"subject"`
+	Quote         Quote         `bson:"quote"`
+	ProviderQuote string        `bson:"providerQuote"`
+	Key           string        `bson:"key"`
+	Payment       string        `bson:"payment"`
+}
+
+func (*Record) Collection() string { return "payment_quotes" }
+
+type Provider interface {
+	Namespace() string
+	Accounts(context.Context, string) ([]Account, error)
+	Quote(context.Context, string, Request, []Account) (Quote, error)
+	Execute(context.Context, string, string) (RemoteOperation, error)
+	Payment(context.Context, string) (RemoteOperation, error)
+}
+type RemoteOperation struct {
+	ID, QuoteRef, Status string
+	CreatedAt            time.Time
+}
+type Identity interface {
+	Subject(context.Context, *customer.Account) (string, error)
+}
+type Failure string
+
+func (e Failure) Error() string { return string(e) }
+
+const (
+	Unavailable       Failure = "unavailable"
+	InvalidAmount     Failure = "invalidAmount"
+	InvalidRecipient  Failure = "invalidRecipient"
+	InsufficientFunds Failure = "insufficientFunds"
+	LimitExceeded     Failure = "limitExceeded"
+	ExpiredQuote      Failure = "expiredQuote"
+	Unsupported       Failure = "unsupported"
+	NotFound          Failure = "notFound"
+	Uncertain         Failure = "uncertain"
+	FactorRequired    Failure = "factorRequired"
+)

backend/product/payments/service.go

@@ -0,0 +1,237 @@
+package payments
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	"git.sendico.io/tech/sxchnge/product/twofactor"
+	factor "git.sendico.io/tech/sxchnge/product/twofactor/model"
+	verification "git.sendico.io/tech/sxchnge/product/verification/model"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	mlogger "git.sendico.io/tech/sxchnge/shared/logging"
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.uber.org/zap"
+)
+
+type Service struct {
+	Store    Store
+	Provider Provider
+	Identity Identity
+	Factors  twofactor.API
+	Logger   mlogger.Logger
+}
+
+func (s *Service) ready() error {
+	if s == nil || s.Store == nil || s.Provider == nil || s.Identity == nil || s.Factors == nil {
+		return Unavailable
+	}
+	return nil
+}
+func (s *Service) record(ctx context.Context, a *customer.Account, id string) (*Record, error) {
+	if err := s.ready(); err != nil {
+		return nil, err
+	}
+	if a == nil || a.ID.IsZero() {
+		return nil, NotFound
+	}
+	ref, err := bson.ObjectIDFromHex(id)
+	if err != nil {
+		return nil, NotFound
+	}
+	r, err := s.Store.Get(ctx, ref, a.ID, s.Provider.Namespace())
+	if errors.Is(err, merrors.ErrNoData) {
+		return nil, NotFound
+	}
+	if err != nil {
+		return nil, err
+	}
+	subject, err := s.Identity.Subject(ctx, a)
+	if err != nil {
+		return nil, err
+	}
+	if subject != r.Subject {
+		return nil, Unavailable
+	}
+	return r, nil
+}
+func (s *Service) Quote(ctx context.Context, a *customer.Account, request Request) (Quote, error) {
+	if err := s.ready(); err != nil {
+		return Quote{}, err
+	}
+	subject, err := s.Identity.Subject(ctx, a)
+	if err != nil {
+		return Quote{}, err
+	}
+	accounts, err := s.Provider.Accounts(ctx, subject)
+	if err != nil {
+		return Quote{}, err
+	}
+	q, err := s.Provider.Quote(ctx, subject, request, accounts)
+	if err != nil {
+		return Quote{}, err
+	}
+	providerRef := q.ID
+	q.ID = bson.NewObjectID().Hex()
+	r := &Record{Customer: a.ID, Namespace: s.Provider.Namespace(), Subject: subject, Quote: q, ProviderQuote: providerRef}
+	r.SetID(mustID(q.ID))
+	if err = s.Store.Create(ctx, r); err != nil {
+		return Quote{}, err
+	}
+	s.Logger.Info("Customer quotation stored", zap.String("quote_ref", q.ID), zap.String("kind", request.Kind))
+	return q, nil
+}
+func mustID(id string) bson.ObjectID { value, _ := bson.ObjectIDFromHex(id); return value }
+func operationScope(r *Record) factor.Scope {
+	return factor.Scope{Purpose: verification.PurposePayment, ContextRef: r.Quote.ID}
+}
+func (s *Service) Challenge(ctx context.Context, a *customer.Account, id, ip string) (factor.Challenge, error) {
+	r, err := s.record(ctx, a, id)
+	if err != nil {
+		return factor.Challenge{}, err
+	}
+	if !time.Now().Before(r.Quote.ExpiresAt) || r.Key != "" {
+		return factor.Challenge{}, ExpiredQuote
+	}
+	return s.Factors.Begin(ctx, factor.Request{Subject: a.ID, Scope: operationScope(r), Deadline: r.Quote.ExpiresAt, IdempotencyKey: "payment:" + r.Quote.ID, IP: ip})
+}
+func (s *Service) Resend(ctx context.Context, a *customer.Account, id, challenge, key, ip string) (factor.Challenge, error) {
+	r, err := s.record(ctx, a, id)
+	if err != nil {
+		return factor.Challenge{}, err
+	}
+	if !time.Now().Before(r.Quote.ExpiresAt) || r.Key != "" {
+		return factor.Challenge{}, ExpiredQuote
+	}
+	if !validKey(key) {
+		return factor.Challenge{}, InvalidAmount
+	}
+	return s.Factors.Resend(ctx, factor.Request{Subject: a.ID, Scope: operationScope(r), Deadline: r.Quote.ExpiresAt, IdempotencyKey: key, IP: ip}, challenge)
+}
+func validKey(key string) bool {
+	if len(key) < 16 || len(key) > 128 {
+		return false
+	}
+	for _, c := range key {
+		if !(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9' || c == '-' || c == '_') {
+			return false
+		}
+	}
+	return true
+}
+
+// Authorize consumes the challenge atomically with a durable execution intent.
+// No upstream I/O occurs inside the transaction. Replaying the same authorization
+// recovers a lost response without reusing the one-use verification code.
+func (s *Service) Authorize(ctx context.Context, a *customer.Account, id, challenge, code, key string) error {
+	r, err := s.record(ctx, a, id)
+	if err != nil {
+		return err
+	}
+	if !validKey(key) {
+		return InvalidAmount
+	}
+	if r.Key != "" {
+		if r.Key == key {
+			return nil
+		}
+		return ExpiredQuote
+	}
+	return s.Factors.Complete(ctx, a.ID, operationScope(r), challenge, code, func(tx context.Context) error {
+		if !time.Now().Before(r.Quote.ExpiresAt) {
+			return ExpiredQuote
+		}
+		return s.Store.Authorize(tx, r, key)
+	})
+}
+func (s *Service) execute(ctx context.Context, r *Record) (Operation, error) {
+	var remote RemoteOperation
+	var err error
+	if r.Payment != "" {
+		remote, err = s.Provider.Payment(ctx, r.Payment)
+	} else {
+		remote, err = s.Provider.Execute(ctx, r.ProviderQuote, "sxchnge:payment:"+r.ID.Hex())
+	}
+	if err != nil {
+		s.Logger.Warn("Payment execution needs reconciliation", zap.String("quote_ref", r.Quote.ID))
+		return Operation{}, merrors.OpaqueWrap(Uncertain, err, "provider payment outcome unknown")
+	}
+	if remote.QuoteRef != r.ProviderQuote || remote.ID == "" || (r.Payment != "" && r.Payment != remote.ID) {
+		return Operation{}, Uncertain
+	}
+	if r.Payment == "" {
+		if err = s.Store.Attach(ctx, r, remote.ID); err != nil {
+			return Operation{}, merrors.OpaqueWrap(Uncertain, err, "persist provider payment reference")
+		}
+	}
+	s.Logger.Info("Payment execution reconciled", zap.String("quote_ref", r.Quote.ID), zap.String("payment_ref", remote.ID), zap.String("state", remote.Status))
+	return Operation{ID: r.Quote.ID, Quote: r.Quote, Status: remote.Status, CreatedAt: remote.CreatedAt}, nil
+}
+func (s *Service) Submit(ctx context.Context, a *customer.Account, id, key string) (Operation, error) {
+	r, err := s.record(ctx, a, id)
+	if err != nil {
+		return Operation{}, err
+	}
+	if !validKey(key) || r.Key == "" || r.Key != key {
+		return Operation{}, FactorRequired
+	}
+	return s.execute(ctx, r)
+}
+
+// Reconcile replays the already authorized durable intent with the same provider
+// key. A timeout or an empty upstream list is never treated as proof of absence.
+func (s *Service) Reconcile(ctx context.Context, a *customer.Account, key string) (*Operation, error) {
+	if err := s.ready(); err != nil {
+		return nil, err
+	}
+	if !validKey(key) {
+		return nil, NotFound
+	}
+	r, err := s.Store.ByKey(ctx, a.ID, s.Provider.Namespace(), key)
+	if errors.Is(err, merrors.ErrNoData) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	r, err = s.record(ctx, a, r.ID.Hex())
+	if err != nil {
+		return nil, err
+	}
+	op, err := s.execute(ctx, r)
+	return &op, err
+}
+func (s *Service) Fetch(ctx context.Context, a *customer.Account) (Snapshot, error) {
+	if err := s.ready(); err != nil {
+		return Snapshot{}, err
+	}
+	subject, err := s.Identity.Subject(ctx, a)
+	if err != nil {
+		return Snapshot{}, err
+	}
+	rows, err := s.Store.List(ctx, a.ID, s.Provider.Namespace())
+	if err != nil {
+		return Snapshot{}, err
+	}
+	result := Snapshot{Operations: []Operation{}}
+	for _, r := range rows {
+		if r.Subject != subject {
+			return Snapshot{}, Unavailable
+		}
+		op, err := s.execute(ctx, &r)
+		if errors.Is(err, Uncertain) {
+			// A durable authorization with an unknown provider outcome remains
+			// pending. It must not hide unrelated balances or report failure.
+			op = Operation{ID: r.Quote.ID, Quote: r.Quote, Status: "pending", CreatedAt: r.CreatedAt}
+		} else if err != nil {
+			return Snapshot{}, err
+		}
+		result.Operations = append(result.Operations, op)
+	}
+	result.Accounts, err = s.Provider.Accounts(ctx, subject)
+	if err != nil {
+		return Snapshot{}, err
+	}
+	return result, nil
+}

backend/product/payments/service_test.go

@@ -0,0 +1,189 @@
+package payments
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	factor "git.sendico.io/tech/sxchnge/product/twofactor/model"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"github.com/stretchr/testify/require"
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.uber.org/zap"
+)
+
+type memoryStore struct {
+	mu      sync.Mutex
+	records map[bson.ObjectID]Record
+}
+
+func (s *memoryStore) Create(_ context.Context, r *Record) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.records[r.ID] = *r
+	return nil
+}
+func (s *memoryStore) Get(_ context.Context, id, customer bson.ObjectID, namespace string) (*Record, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	r, ok := s.records[id]
+	if !ok || r.Customer != customer || r.Namespace != namespace {
+		return nil, merrors.ErrNoData
+	}
+	return &r, nil
+}
+func (s *memoryStore) ByKey(_ context.Context, customer bson.ObjectID, namespace, key string) (*Record, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for _, r := range s.records {
+		if r.Customer == customer && r.Namespace == namespace && r.Key == key {
+			return &r, nil
+		}
+	}
+	return nil, merrors.ErrNoData
+}
+func (s *memoryStore) List(_ context.Context, customer bson.ObjectID, namespace string) ([]Record, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	rows := []Record{}
+	for _, r := range s.records {
+		if r.Customer == customer && r.Namespace == namespace && r.Key != "" {
+			rows = append(rows, r)
+		}
+	}
+	return rows, nil
+}
+func (s *memoryStore) Authorize(_ context.Context, r *Record, key string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	current := s.records[r.ID]
+	if current.Key != "" {
+		return Uncertain
+	}
+	current.Key = key
+	s.records[r.ID] = current
+	return nil
+}
+func (s *memoryStore) Attach(_ context.Context, r *Record, id string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	current := s.records[r.ID]
+	current.Payment = id
+	s.records[r.ID] = current
+	return nil
+}
+
+type provider struct {
+	mu        sync.Mutex
+	accepted  int
+	lost      bool
+	status    string
+	key       string
+	namespace string
+}
+
+func (p *provider) Namespace() string { return p.namespace }
+func (p *provider) Accounts(context.Context, string) ([]Account, error) {
+	return []Account{{ID: "ledger", Currency: "EUR", Precision: 2, Available: 5000}}, nil
+}
+func (p *provider) Quote(_ context.Context, _ string, r Request, _ []Account) (Quote, error) {
+	return Quote{ID: "provider-quote", Request: r, ExpiresAt: time.Now().Add(time.Minute)}, nil
+}
+func (p *provider) Execute(_ context.Context, quote, key string) (RemoteOperation, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.key == "" {
+		p.accepted++
+		p.key = key
+	}
+	if p.key != key {
+		return RemoteOperation{}, Unavailable
+	}
+	if p.lost {
+		p.lost = false
+		return RemoteOperation{}, Unavailable
+	}
+	return RemoteOperation{ID: "payment", QuoteRef: quote, Status: p.status, CreatedAt: time.Now()}, nil
+}
+func (p *provider) Payment(context.Context, string) (RemoteOperation, error) {
+	return RemoteOperation{ID: "payment", QuoteRef: "provider-quote", Status: p.status, CreatedAt: time.Now()}, nil
+}
+
+type identity struct{}
+
+func (identity) Subject(context.Context, *customer.Account) (string, error) { return "subject", nil }
+
+type factors struct {
+	calls   int
+	subject bson.ObjectID
+	scope   factor.Scope
+}
+
+func (f *factors) Begin(_ context.Context, r factor.Request) (factor.Challenge, error) {
+	f.subject = r.Subject
+	f.scope = r.Scope
+	return factor.Challenge{ID: "challenge"}, nil
+}
+func (f *factors) Resend(ctx context.Context, r factor.Request, _ string) (factor.Challenge, error) {
+	return f.Begin(ctx, r)
+}
+func (f *factors) Complete(ctx context.Context, subject bson.ObjectID, scope factor.Scope, id, code string, action func(context.Context) error) error {
+	if subject != f.subject || scope != f.scope || id != "challenge" || code != "123456" {
+		return FactorRequired
+	}
+	f.calls++
+	return action(ctx)
+}
+func TestCustomerExecutionOwnershipAndLostResponse(t *testing.T) {
+	ctx := context.Background()
+	a := &customer.Account{}
+	a.ID = bson.NewObjectID()
+	other := &customer.Account{}
+	other.ID = bson.NewObjectID()
+	store := &memoryStore{records: map[bson.ObjectID]Record{}}
+	p := &provider{lost: true, status: "pending", namespace: "provider"}
+	f := &factors{}
+	s := &Service{Store: store, Provider: p, Identity: identity{}, Factors: f, Logger: zap.NewNop()}
+	q, err := s.Quote(ctx, a, Request{Kind: "payout", Source: "ledger", Amount: 1000})
+	require.NoError(t, err)
+	_, err = s.Submit(ctx, a, q.ID, "unapproved-key-123")
+	require.ErrorIs(t, err, FactorRequired)
+	require.Zero(t, p.accepted)
+	_, err = s.Challenge(ctx, other, q.ID, "")
+	require.ErrorIs(t, err, NotFound)
+	_, err = s.Challenge(ctx, a, q.ID, "")
+	require.NoError(t, err)
+	require.ErrorIs(t, s.Authorize(ctx, a, q.ID, "challenge", "bad-code", "authorized-key-123"), FactorRequired)
+	require.NoError(t, s.Authorize(ctx, a, q.ID, "challenge", "123456", "authorized-key-123"))
+	require.NoError(t, s.Authorize(ctx, a, q.ID, "challenge", "123456", "authorized-key-123"))
+	require.Equal(t, 1, f.calls)
+	_, err = s.Submit(ctx, a, q.ID, "authorized-key-123")
+	require.ErrorIs(t, err, Uncertain)
+	op, err := s.Reconcile(ctx, other, "authorized-key-123")
+	require.NoError(t, err)
+	require.Nil(t, op)
+	op, err = s.Reconcile(ctx, a, "authorized-key-123")
+	require.NoError(t, err)
+	require.Equal(t, "pending", op.Status)
+	require.Equal(t, 1, p.accepted)
+	p.status = "completed"
+	snapshot, err := s.Fetch(ctx, a)
+	require.NoError(t, err)
+	require.Equal(t, "completed", snapshot.Operations[0].Status)
+	require.ErrorIs(t, s.Authorize(ctx, a, q.ID, "challenge", "123456", "different-key-1234"), ExpiredQuote)
+	// A changed provider namespace cannot execute the old quote.
+	p.namespace = "rotated-provider"
+	_, err = s.Submit(ctx, a, q.ID, "authorized-key-123")
+	require.ErrorIs(t, err, NotFound)
+}
+func TestExpiredQuoteCannotAuthorize(t *testing.T) {
+	a := &customer.Account{}
+	a.ID = bson.NewObjectID()
+	r := Record{Customer: a.ID, Namespace: "p", Subject: "subject", Quote: Quote{ID: bson.NewObjectID().Hex(), ExpiresAt: time.Now().Add(-time.Second)}}
+	r.SetID(mustID(r.Quote.ID))
+	s := &Service{Store: &memoryStore{records: map[bson.ObjectID]Record{r.ID: r}}, Provider: &provider{namespace: "p"}, Identity: identity{}, Factors: &factors{}, Logger: zap.NewNop()}
+	_, err := s.Challenge(context.Background(), a, r.Quote.ID, "")
+	require.ErrorIs(t, err, ExpiredQuote)
+}

backend/product/payments/store.go

@@ -0,0 +1,88 @@
+package payments
+
+import (
+	"context"
+
+	db "git.sendico.io/tech/sxchnge/shared/database"
+	deps "git.sendico.io/tech/sxchnge/shared/database/dependencies"
+	"git.sendico.io/tech/sxchnge/shared/database/repository"
+	"git.sendico.io/tech/sxchnge/shared/database/repository/builder"
+	ri "git.sendico.io/tech/sxchnge/shared/database/repository/index"
+	"git.sendico.io/tech/sxchnge/shared/database/source"
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+type Store interface {
+	Create(context.Context, *Record) error
+	Get(context.Context, bson.ObjectID, bson.ObjectID, string) (*Record, error)
+	ByKey(context.Context, bson.ObjectID, string, string) (*Record, error)
+	List(context.Context, bson.ObjectID, string) ([]Record, error)
+	Authorize(context.Context, *Record, string) error
+	Attach(context.Context, *Record, string) error
+}
+type mongoStore struct{ records repository.Repository }
+
+func OpenStore(factory db.Factory) (Store, error) {
+	d, err := deps.ResolveDependencies(factory)
+	if err != nil {
+		return nil, err
+	}
+	r := repository.CreateRepository(source.Majority(d.Database), "payment_quotes")
+	err = r.CreateIndex(&ri.Definition{Name: "customer_execution_key", Unique: true, Keys: []ri.Key{{Field: "customer", Sort: ri.Asc}, {Field: "namespace", Sort: ri.Asc}, {Field: "key", Sort: ri.Asc}}, PartialFilter: repository.Query().Comparison(repository.Field("key"), builder.Gt, "")})
+	if err != nil {
+		return nil, err
+	}
+	if err = r.CreateIndex(&ri.Definition{Name: "provider_quote_unique", Unique: true, Keys: []ri.Key{{Field: "namespace", Sort: ri.Asc}, {Field: "providerQuote", Sort: ri.Asc}}, PartialFilter: repository.Query().Comparison(repository.Field("providerQuote"), builder.Gt, "")}); err != nil {
+		return nil, err
+	}
+	return &mongoStore{r}, nil
+}
+func scope(customer bson.ObjectID, namespace string) repository.FilterQuery {
+	return repository.Query().Filter(repository.Field("customer"), customer).Filter(repository.Field("namespace"), namespace)
+}
+func (s *mongoStore) Create(ctx context.Context, r *Record) error {
+	return s.records.Insert(ctx, r, nil)
+}
+func (s *mongoStore) Get(ctx context.Context, id, customer bson.ObjectID, namespace string) (*Record, error) {
+	r := &Record{}
+	err := s.records.FindOneByFilter(ctx, scope(customer, namespace).Filter(repository.IDField(), id), r)
+	return r, err
+}
+func (s *mongoStore) ByKey(ctx context.Context, customer bson.ObjectID, namespace, key string) (*Record, error) {
+	r := &Record{}
+	err := s.records.FindOneByFilter(ctx, scope(customer, namespace).Filter(repository.Field("key"), key), r)
+	return r, err
+}
+func (s *mongoStore) List(ctx context.Context, customer bson.ObjectID, namespace string) ([]Record, error) {
+	var rows []Record
+	err := s.records.FindAllByFilter(ctx, scope(customer, namespace).Comparison(repository.Field("key"), builder.Gt, "").Sort(repository.Field("createdAt"), true), &rows)
+	return rows, err
+}
+func (s *mongoStore) Authorize(ctx context.Context, r *Record, key string) error {
+	matched, err := s.records.PatchOneByFilter(ctx, scope(r.Customer, r.Namespace).Filter(repository.IDField(), r.ID).Filter(repository.Field("key"), ""), repository.Patch().Set(repository.Field("key"), key), &Record{})
+	if err != nil {
+		return err
+	}
+	if !matched {
+		return Uncertain
+	}
+	return nil
+}
+
+func (s *mongoStore) Attach(ctx context.Context, r *Record, id string) error {
+	matched, err := s.records.PatchOneByFilter(ctx, scope(r.Customer, r.Namespace).Filter(repository.IDField(), r.ID).Filter(repository.Field("payment"), ""), repository.Patch().Set(repository.Field("payment"), id), &Record{})
+	if err != nil {
+		return err
+	}
+	if matched {
+		return nil
+	}
+	current, err := s.Get(ctx, r.ID, r.Customer, r.Namespace)
+	if err != nil {
+		return err
+	}
+	if current.Payment != id {
+		return Uncertain
+	}
+	return nil
+}

backend/product/payments/store_test.go

@@ -0,0 +1,66 @@
+package payments
+
+import (
+	"context"
+	"net/url"
+	"testing"
+	"time"
+
+	db "git.sendico.io/tech/sxchnge/shared/database"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	sharedmodel "git.sendico.io/tech/sxchnge/shared/model"
+	"github.com/stretchr/testify/require"
+	"github.com/testcontainers/testcontainers-go/modules/mongodb"
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.uber.org/zap"
+)
+
+func TestDurableAuthorizationTransactionAndCustomerIsolation(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+	container, err := mongodb.Run(ctx, "mongo:latest", mongodb.WithReplicaSet("rs"))
+	require.NoError(t, err)
+	t.Cleanup(func() { require.NoError(t, container.Terminate(context.Background())) })
+	uri, err := container.ConnectionString(ctx)
+	require.NoError(t, err)
+	u, err := url.Parse(uri)
+	require.NoError(t, err)
+	q := u.Query()
+	q.Set("directConnection", "true")
+	u.RawQuery = q.Encode()
+	factory, err := db.NewConnection(zap.NewNop(), &db.Config{Driver: db.Mongo, Settings: sharedmodel.SettingsT{"uri": u.String(), "database": "payments"}})
+	require.NoError(t, err)
+	t.Cleanup(factory.CloseConnection)
+	store, err := OpenStore(factory)
+	require.NoError(t, err)
+	customer := bson.NewObjectID()
+	r := &Record{Customer: customer, Namespace: "provider", Subject: "subject"}
+	r.SetID(bson.NewObjectID())
+	require.NoError(t, store.Create(ctx, r))
+	_, err = store.Get(ctx, r.ID, bson.NewObjectID(), r.Namespace)
+	require.ErrorIs(t, err, merrors.ErrNoData)
+	_, err = factory.TransactionFactory().CreateTransaction().Execute(ctx, func(tx context.Context) (any, error) {
+		require.NoError(t, store.Authorize(tx, r, "authorized-key-123"))
+		return nil, Uncertain
+	})
+	require.ErrorIs(t, err, Uncertain)
+	stored, err := store.Get(ctx, r.ID, customer, r.Namespace)
+	require.NoError(t, err)
+	require.Empty(t, stored.Key)
+	require.NoError(t, store.Authorize(ctx, r, "authorized-key-123"))
+	require.ErrorIs(t, store.Authorize(ctx, r, "other-key-123456"), Uncertain)
+	another := &Record{Customer: customer, Namespace: r.Namespace}
+	another.SetID(bson.NewObjectID())
+	require.NoError(t, store.Create(ctx, another))
+	require.ErrorIs(t, store.Authorize(ctx, another, "authorized-key-123"), merrors.ErrDataConflict)
+	require.NoError(t, store.Attach(ctx, r, "payment-1"))
+	require.NoError(t, store.Attach(ctx, r, "payment-1"))
+	require.ErrorIs(t, store.Attach(ctx, r, "different-payment"), Uncertain)
+	reopened, err := OpenStore(factory)
+	require.NoError(t, err)
+	stored, err = reopened.ByKey(ctx, customer, r.Namespace, "authorized-key-123")
+	require.NoError(t, err)
+	require.Equal(t, "payment-1", stored.Payment)
+	_, err = reopened.ByKey(ctx, customer, "other-provider", "authorized-key-123")
+	require.ErrorIs(t, err, merrors.ErrNoData)
+}

backend/product/providers/sendico/payments.go

@@ -0,0 +1,110 @@
+package sendico
+
+import (
+	"context"
+	"net/http"
+
+	"git.sendico.io/tech/sxchnge/product/payments"
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+// Accounts exposes only dedicated, organization-owned customer ledgers tagged by
+// trusted platform provisioning. The integration login's personal/pooled ledgers
+// never become customer balances. Method bindings are provisioned on that ledger.
+func (c *Client) Accounts(ctx context.Context, subject string) ([]payments.Account, error) {
+	if !validRef(subject) {
+		return nil, payments.Unavailable
+	}
+	var currencies struct {
+		Rows []currencyDTO `json:"currencies"`
+	}
+	if err := c.paymentRequest(ctx, http.MethodGet, "/payments/fx/currencies/"+c.config.OrganizationID, nil, &currencies); err != nil {
+		return nil, err
+	}
+	scales := map[string]int{}
+	for _, row := range currencies.Rows {
+		if row.Scale != nil && *row.Scale >= 0 && *row.Scale <= 8 {
+			scales[row.Code] = *row.Scale
+		}
+	}
+	var data struct {
+		Accounts []accountDTO `json:"accounts"`
+	}
+	root := "/ledger_accounts/" + c.config.OrganizationID
+	if err := c.paymentRequest(ctx, http.MethodGet, root, nil, &data); err != nil {
+		return nil, err
+	}
+	accounts := []payments.Account{}
+	for _, row := range data.Accounts {
+		if row.Metadata["sxchnge_subject_ref"] != subject {
+			continue
+		}
+		if !validRef(row.ID) || row.ScopeRef != c.config.OrganizationID || row.Owner != "" || row.Status != "ACCOUNT_STATUS_ACTIVE" || row.Type != "ACCOUNT_TYPE_ASSET" || row.LedgerRole != "ACCOUNT_ROLE_OPERATING" {
+			return nil, payments.Unavailable
+		}
+		scale, ok := scales[row.Currency]
+		if !ok {
+			return nil, payments.Unsupported
+		}
+		var balance struct {
+			Value balanceDTO `json:"balance"`
+		}
+		if err := c.paymentRequest(ctx, http.MethodGet, root+"/"+row.ID+"/balance", nil, &balance); err != nil {
+			return nil, err
+		}
+		account, err := mapAccount(row, balance.Value, scale)
+		if err != nil {
+			return nil, err
+		}
+		accounts = append(accounts, account)
+	}
+	return accounts, nil
+}
+func (c *Client) Quote(ctx context.Context, subject string, r payments.Request, accounts []payments.Account) (payments.Quote, error) {
+	mapped, err := mapIntent(subject, r, accounts)
+	if err != nil {
+		return payments.Quote{}, err
+	}
+	var response struct {
+		Quote   paymentQuoteDTO `json:"quote"`
+		Subject string          `json:"externalSubjectRef"`
+	}
+	err = c.paymentRequest(ctx, http.MethodPost, "/payments/quote/"+c.config.OrganizationID, quoteRequestDTO{Key: "sxchnge:quote:" + bson.NewObjectID().Hex(), Intent: mapped.wire}, &response)
+	if err != nil {
+		return payments.Quote{}, err
+	}
+	if response.Subject != subject {
+		return payments.Quote{}, payments.Unavailable
+	}
+	return mapPaymentQuote(response.Quote, mapped.request, mapped.source, mapped.destination)
+}
+func (c *Client) Execute(ctx context.Context, quote, key string) (payments.RemoteOperation, error) {
+	if !safePaymentRef(quote) {
+		return payments.RemoteOperation{}, payments.Unavailable
+	}
+	var result struct {
+		Payment paymentDTO `json:"payment"`
+	}
+	payload := struct {
+		Quote string `json:"quoteRef"`
+		Key   string `json:"idempotencyKey"`
+	}{quote, key}
+	err := c.paymentRequest(ctx, http.MethodPost, "/payments/by-quote/"+c.config.OrganizationID, payload, &result)
+	if err != nil {
+		return payments.RemoteOperation{}, err
+	}
+	return mapPayment(result.Payment)
+}
+func (c *Client) Payment(ctx context.Context, id string) (payments.RemoteOperation, error) {
+	if !safePaymentRef(id) {
+		return payments.RemoteOperation{}, payments.Unavailable
+	}
+	var result struct {
+		Payment paymentDTO `json:"payment"`
+	}
+	err := c.paymentRequest(ctx, http.MethodGet, "/payments/by-ref/"+id, nil, &result)
+	if err != nil {
+		return payments.RemoteOperation{}, err
+	}
+	return mapPayment(result.Payment)
+}

backend/product/providers/sendico/payments_mapper.go

@@ -0,0 +1,211 @@
+package sendico
+
+import (
+	"math/big"
+	"strconv"
+	"strings"
+	"time"
+
+	"git.sendico.io/tech/sxchnge/product/payments"
+)
+
+const maxMinor int64 = 9007199254740991
+
+func safePaymentRef(value string) bool {
+	if len(value) == 0 || len(value) > 200 {
+		return false
+	}
+	for _, c := range value {
+		if !(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9' || c == '-' || c == '_' || c == ':') {
+			return false
+		}
+	}
+	return true
+}
+
+// Decimal parsing never rounds provider values or converts money through floats.
+func minorMoney(m moneyDTO, currency string, scale int) (int64, error) {
+	if m.Currency != currency || scale < 0 || scale > 8 {
+		return 0, payments.Unavailable
+	}
+	parts := strings.Split(m.Amount, ".")
+	if len(parts) > 2 || parts[0] == "" {
+		return 0, payments.Unavailable
+	}
+	digits := parts[0]
+	if len(parts) == 2 {
+		if parts[1] == "" || len(parts[1]) > scale {
+			return 0, payments.Unavailable
+		}
+		digits += parts[1] + strings.Repeat("0", scale-len(parts[1]))
+	} else {
+		digits += strings.Repeat("0", scale)
+	}
+	for _, r := range digits {
+		if r < '0' || r > '9' {
+			return 0, payments.Unavailable
+		}
+	}
+	value, err := strconv.ParseInt(digits, 10, 64)
+	if err != nil || value > maxMinor {
+		return 0, payments.Unavailable
+	}
+	return value, nil
+}
+func majorMoney(minor int64, scale int) string {
+	digits := strconv.FormatInt(minor, 10)
+	if scale == 0 {
+		return digits
+	}
+	if len(digits) <= scale {
+		digits = strings.Repeat("0", scale+1-len(digits)) + digits
+	}
+	return digits[:len(digits)-scale] + "." + digits[len(digits)-scale:]
+}
+func mapPaymentQuote(dto paymentQuoteDTO, r payments.Request, source, destination payments.Account) (payments.Quote, error) {
+	if !dto.Executable || dto.State != "executable" {
+		switch dto.BlockReason {
+		case "limit_blocked":
+			return payments.Quote{}, payments.LimitExceeded
+		case "amount_too_small", "amount_too_large":
+			return payments.Quote{}, payments.InvalidAmount
+		default:
+			return payments.Quote{}, payments.Unsupported
+		}
+	}
+	if !safePaymentRef(dto.ID) || !dto.Expires.After(time.Now()) {
+		return payments.Quote{}, payments.ExpiredQuote
+	}
+	debit, err := minorMoney(dto.Amounts.Debit, source.Currency, source.Precision)
+	if err != nil {
+		return payments.Quote{}, err
+	}
+	principal, err := minorMoney(dto.Amounts.Principal, source.Currency, source.Precision)
+	if err != nil {
+		return payments.Quote{}, err
+	}
+	credit, err := minorMoney(dto.Amounts.Credit, destination.Currency, destination.Precision)
+	if err != nil {
+		return payments.Quote{}, err
+	}
+	if principal != r.Amount || debit < principal || credit <= 0 {
+		return payments.Quote{}, payments.Unavailable
+	}
+	if r.Kind != "topUp" && debit > source.Available {
+		return payments.Quote{}, payments.InsufficientFunds
+	}
+	num, den := big.NewInt(credit), big.NewInt(principal)
+	num.Mul(num, new(big.Int).Exp(big.NewInt(10), big.NewInt(int64(source.Precision)), nil))
+	den.Mul(den, new(big.Int).Exp(big.NewInt(10), big.NewInt(int64(destination.Precision)), nil))
+	gcd := new(big.Int).GCD(nil, nil, num, den)
+	num.Quo(num, gcd)
+	den.Quo(den, gcd)
+	if !num.IsInt64() || !den.IsInt64() || num.Int64() > maxMinor || den.Int64() > maxMinor {
+		return payments.Quote{}, payments.Unsupported
+	}
+	return payments.Quote{ID: dto.ID, Request: r, Fee: debit - principal, Debit: debit, Credit: credit, ExpiresAt: dto.Expires, RateNumerator: num.Int64(), RateDenominator: den.Int64()}, nil
+}
+func mapPayment(dto paymentDTO) (payments.RemoteOperation, error) {
+	if !safePaymentRef(dto.ID) || !safePaymentRef(dto.Quote.ID) || dto.Created.IsZero() {
+		return payments.RemoteOperation{}, payments.Unavailable
+	}
+	status := "pending"
+	switch dto.State {
+	case "orchestration_state_settled":
+		status = "completed"
+	case "orchestration_state_failed":
+		status = "failed"
+	case "orchestration_state_created", "orchestration_state_executing", "orchestration_state_needs_attention":
+	default:
+		return payments.RemoteOperation{}, payments.Unavailable
+	}
+	return payments.RemoteOperation{ID: dto.ID, QuoteRef: dto.Quote.ID, Status: status, CreatedAt: dto.Created}, nil
+}
+
+func accountByID(accounts []payments.Account, id string) (payments.Account, error) {
+	for _, a := range accounts {
+		if a.ID == id {
+			return a, nil
+		}
+	}
+	return payments.Account{}, payments.NotFound
+}
+func ledgerEndpoint(id string) endpointDTO {
+	return endpointDTO{Type: "ledger", Data: map[string]string{"account_ref": id}}
+}
+func methodEndpoint(id string) endpointDTO {
+	return endpointDTO{Type: "paymentMethod", Data: map[string]string{"ref": id}}
+}
+
+type mappedIntent struct {
+	wire                paymentIntentDTO
+	request             payments.Request
+	source, destination payments.Account
+}
+
+func mapIntent(subject string, r payments.Request, accounts []payments.Account) (mappedIntent, error) {
+	source, err := accountByID(accounts, r.Source)
+	if err != nil {
+		return mappedIntent{}, err
+	}
+	if r.Amount <= 0 || r.Amount > maxMinor {
+		return mappedIntent{}, payments.InvalidAmount
+	}
+	intent := paymentIntentDTO{Subject: subject, Source: ledgerEndpoint(source.ID), Amount: moneyDTO{Amount: majorMoney(r.Amount, source.Precision), Currency: source.Currency}, FeeTreatment: "add_to_source"}
+	destination := source
+	switch r.Kind {
+	case "payout":
+		r.Destination = ""
+		if source.PayoutMethod == "" || r.Recipient != source.PayoutMethod {
+			return mappedIntent{}, payments.InvalidRecipient
+		}
+		intent.Kind = "payout"
+		intent.Destination = methodEndpoint(source.PayoutMethod)
+		// Store the safe provisioned display label, never present an opaque method ID.
+		r.Recipient = source.PayoutLabel
+	case "exchange":
+		r.Recipient = ""
+		destination, err = accountByID(accounts, r.Destination)
+		if err != nil {
+			return mappedIntent{}, err
+		}
+		if source.ID == destination.ID || source.Currency == destination.Currency {
+			return mappedIntent{}, payments.Unsupported
+		}
+		intent.Kind = "fx_conversion"
+		intent.Destination = ledgerEndpoint(destination.ID)
+	case "topUp":
+		r.Destination = ""
+		r.Recipient = ""
+		if source.FundingMethod == "" {
+			return mappedIntent{}, payments.Unsupported
+		}
+		intent.Kind = "internal_transfer"
+		intent.Source = methodEndpoint(source.FundingMethod)
+		intent.Destination = ledgerEndpoint(source.ID)
+	default:
+		return mappedIntent{}, payments.Unsupported
+	}
+
+	return mappedIntent{intent, r, source, destination}, nil
+}
+
+func mapAccount(row accountDTO, balance balanceDTO, scale int) (payments.Account, error) {
+	if balance.ID != row.ID {
+		return payments.Account{}, payments.Unavailable
+	}
+	minor, err := minorMoney(balance.Money, row.Currency, scale)
+	if err != nil {
+		return payments.Account{}, err
+	}
+	account := payments.Account{ID: row.ID, Currency: row.Currency, Precision: scale, Available: minor, PayoutMethod: row.Metadata["sxchnge_payout_method_ref"], PayoutLabel: row.Metadata["sxchnge_payout_label"], FundingMethod: row.Metadata["sxchnge_funding_method_ref"]}
+	for _, ref := range []string{account.PayoutMethod, account.FundingMethod} {
+		if ref != "" && !validRef(ref) {
+			return payments.Account{}, payments.Unavailable
+		}
+	}
+	if account.PayoutMethod != "" && (strings.TrimSpace(account.PayoutLabel) == "" || len(account.PayoutLabel) > 140) {
+		return payments.Account{}, payments.Unavailable
+	}
+	return account, nil
+}

backend/product/providers/sendico/payments_test.go

@@ -0,0 +1,103 @@
+package sendico
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"git.sendico.io/tech/sxchnge/product/payments"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPaymentPublicWireAndExactMoney(t *testing.T) {
+	ctx := context.Background()
+	ledger := "507f1f77bcf86cd799439015"
+	method := "507f1f77bcf86cd799439016"
+	calls := 0
+	acknowledge := true
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.NotEmpty(t, r.Header.Get("Authorization"))
+		var result any
+		switch r.URL.Path {
+		case "/api/v1/payments/fx/currencies/" + org:
+			result = map[string]any{"currencies": []any{map[string]any{"code": "EUR", "accountingScale": 2}}}
+		case "/api/v1/ledger_accounts/" + org:
+			result = map[string]any{"accounts": []any{
+				map[string]any{"ledgerAccountRef": source, "organizationRef": org, "ownerRef": source, "currency": "EUR", "accountType": "ACCOUNT_TYPE_ASSET", "role": "ACCOUNT_ROLE_OPERATING", "status": "ACCOUNT_STATUS_ACTIVE"},
+				map[string]any{"ledgerAccountRef": ledger, "organizationRef": org, "currency": "EUR", "accountType": "ACCOUNT_TYPE_ASSET", "role": "ACCOUNT_ROLE_OPERATING", "status": "ACCOUNT_STATUS_ACTIVE", "metadata": map[string]string{"sxchnge_subject_ref": subject, "sxchnge_payout_method_ref": method, "sxchnge_payout_label": "Saved bank ending 1234"}},
+			}}
+		case "/api/v1/ledger_accounts/" + org + "/" + ledger + "/balance":
+			result = map[string]any{"balance": map[string]any{"ledgerAccountRef": ledger, "balance": moneyDTO{"75.00", "EUR"}}}
+		case "/api/v1/payments/quote/" + org:
+			var request quoteRequestDTO
+			require.NoError(t, json.NewDecoder(r.Body).Decode(&request))
+			require.Equal(t, subject, request.Intent.Subject)
+			require.Equal(t, "20.01", request.Intent.Amount.Amount)
+			require.Equal(t, ledger, request.Intent.Source.Data["account_ref"])
+			require.Equal(t, method, request.Intent.Destination.Data["ref"])
+			confirmedSubject := subject
+			if !acknowledge {
+				confirmedSubject = ""
+			}
+			result = map[string]any{"externalSubjectRef": confirmedSubject, "quote": paymentQuoteDTO{ID: "quote:1", State: "executable", Executable: true, Expires: time.Now().Add(time.Minute), Amounts: quoteAmountsDTO{Principal: moneyDTO{"20.01", "EUR"}, Debit: moneyDTO{"21.01", "EUR"}, Credit: moneyDTO{"20.01", "EUR"}}}}
+		case "/api/v1/payments/by-quote/" + org:
+			calls++
+			var payload map[string]string
+			require.NoError(t, json.NewDecoder(r.Body).Decode(&payload))
+			require.Equal(t, "stable-execution", payload["idempotencyKey"])
+			require.Equal(t, "quote:1", payload["quoteRef"])
+			result = map[string]any{"payment": paymentDTO{ID: "payment:1", State: "orchestration_state_needs_attention", Quote: paymentQuoteDTO{ID: "quote:1"}, Created: time.Now()}}
+		case "/api/v1/payments/by-ref/payment:1":
+			result = map[string]any{"payment": paymentDTO{ID: "payment:1", State: "orchestration_state_settled", Quote: paymentQuoteDTO{ID: "quote:1"}, Created: time.Now()}}
+		default:
+			t.Errorf("unexpected path: %s", r.URL.Path)
+			w.WriteHeader(404)
+			return
+		}
+		require.NoError(t, json.NewEncoder(w).Encode(map[string]any{"status": "success", "data": result}))
+	}))
+	defer server.Close()
+	client, err := Open(config(t, server.URL))
+	require.NoError(t, err)
+	accounts, err := client.Accounts(ctx, subject)
+	require.NoError(t, err)
+	require.Len(t, accounts, 1)
+	require.EqualValues(t, 7500, accounts[0].Available)
+	q, err := client.Quote(ctx, subject, payments.Request{Kind: "payout", Source: ledger, Amount: 2001, Recipient: method}, accounts)
+	require.NoError(t, err)
+	require.EqualValues(t, 100, q.Fee)
+	require.EqualValues(t, 2101, q.Debit)
+	require.Equal(t, "Saved bank ending 1234", q.Request.Recipient)
+	_, err = client.Quote(ctx, subject, payments.Request{Kind: "payout", Source: source, Amount: 2001, Recipient: method}, accounts)
+	require.ErrorIs(t, err, payments.NotFound)
+	_, err = client.Quote(ctx, subject, payments.Request{Kind: "payout", Source: ledger, Amount: 2001, Recipient: "foreign-method"}, accounts)
+	require.ErrorIs(t, err, payments.InvalidRecipient)
+	acknowledge = false
+	_, err = client.Quote(ctx, subject, payments.Request{Kind: "payout", Source: ledger, Amount: 2001, Recipient: method}, accounts)
+	require.ErrorIs(t, err, payments.Unavailable)
+	acknowledge = true
+	op, err := client.Execute(ctx, q.ID, "stable-execution")
+	require.NoError(t, err)
+	require.Equal(t, "pending", op.Status)
+	require.Equal(t, 1, calls)
+	op, err = client.Payment(ctx, op.ID)
+	require.NoError(t, err)
+	require.Equal(t, "completed", op.Status)
+}
+func TestPaymentMappingRejectsUnsafeOrUnexecutableValues(t *testing.T) {
+	for _, amount := range []string{"1e3", "0.001", "-2", "NaN", "90071992547409.92", ""} {
+		_, err := minorMoney(moneyDTO{amount, "EUR"}, "EUR", 2)
+		require.Error(t, err, amount)
+	}
+	_, err := minorMoney(moneyDTO{"10.00", "USD"}, "EUR", 2)
+	require.Error(t, err)
+	_, err = mapPayment(paymentDTO{ID: "p", State: "new_unknown_state", Quote: paymentQuoteDTO{ID: "q"}, Created: time.Now()})
+	require.Error(t, err)
+	_, err = mapPaymentQuote(paymentQuoteDTO{State: "blocked", BlockReason: "limit_blocked"}, payments.Request{}, payments.Account{}, payments.Account{})
+	require.ErrorIs(t, err, payments.LimitExceeded)
+	_, err = mapPaymentQuote(paymentQuoteDTO{State: "executable", Executable: false}, payments.Request{}, payments.Account{}, payments.Account{})
+	require.Error(t, err)
+}

backend/product/providers/sendico/payments_transport.go

@@ -0,0 +1,123 @@
+package sendico
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"time"
+
+	"git.sendico.io/tech/sxchnge/product/payments"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+)
+
+type moneyDTO struct {
+	Amount   string `json:"amount"`
+	Currency string `json:"currency"`
+}
+type endpointDTO struct {
+	Type string            `json:"type"`
+	Data map[string]string `json:"data"`
+}
+
+// Explicit wire fields avoid coupling local domain models to provider JSON.
+type quoteRequestDTO struct {
+	Key    string           `json:"idempotencyKey"`
+	Intent paymentIntentDTO `json:"intent"`
+}
+type paymentIntentDTO struct {
+	Kind         string      `json:"kind"`
+	Source       endpointDTO `json:"source"`
+	Destination  endpointDTO `json:"destination"`
+	Amount       moneyDTO    `json:"amount"`
+	Subject      string      `json:"external_subject_ref"`
+	FeeTreatment string      `json:"fee_treatment"`
+}
+type quoteAmountsDTO struct {
+	Principal moneyDTO `json:"sourcePrincipal"`
+	Debit     moneyDTO `json:"sourceDebitTotal"`
+	Credit    moneyDTO `json:"destinationSettlement"`
+}
+type paymentQuoteDTO struct {
+	ID          string          `json:"quoteRef"`
+	State       string          `json:"state"`
+	Executable  bool            `json:"executable"`
+	BlockReason string          `json:"blockReason"`
+	Expires     time.Time       `json:"expiresAt"`
+	Amounts     quoteAmountsDTO `json:"amounts"`
+}
+type paymentDTO struct {
+	ID      string          `json:"paymentRef"`
+	State   string          `json:"state"`
+	Quote   paymentQuoteDTO `json:"lastQuote"`
+	Created time.Time       `json:"createdAt"`
+}
+type accountDTO struct {
+	ID         string            `json:"ledgerAccountRef"`
+	ScopeRef   string            `json:"organizationRef"`
+	Owner      string            `json:"ownerRef"`
+	Currency   string            `json:"currency"`
+	Type       string            `json:"accountType"`
+	LedgerRole string            `json:"role"`
+	Status     string            `json:"status"`
+	Metadata   map[string]string `json:"metadata"`
+}
+type currencyDTO struct {
+	Code  string `json:"code"`
+	Scale *int   `json:"accountingScale"`
+}
+type balanceDTO struct {
+	ID    string   `json:"ledgerAccountRef"`
+	Money moneyDTO `json:"balance"`
+}
+
+func (c *Client) paymentRequest(ctx context.Context, method, path string, payload, dst any) error {
+	token, err := c.token()
+	if err != nil {
+		return err
+	}
+	var body []byte
+	if payload != nil {
+		body, err = json.Marshal(payload)
+		if err != nil {
+			return merrors.OpaqueWrap(payments.Unavailable, err, "encode Sendico payment request")
+		}
+	}
+	req, err := http.NewRequestWithContext(ctx, method, c.base+path, bytes.NewReader(body))
+	if err != nil {
+		return merrors.OpaqueWrap(payments.Unavailable, err, "create Sendico payment request")
+	}
+	req.Header.Set("Authorization", "Bearer "+token)
+	req.Header.Set("Content-Type", "application/json")
+	client := *c.http
+	client.Timeout = 30 * time.Second
+	res, err := client.Do(req)
+	if err != nil {
+		return merrors.OpaqueWrap(payments.Unavailable, err, "Sendico payment request failed")
+	}
+	defer func() { _ = res.Body.Close() }()
+	// Never forward upstream errors, credentials, or arbitrary error bodies.
+	if res.StatusCode != http.StatusOK {
+		return payments.Unavailable
+	}
+	var envelope struct {
+		Status string          `json:"status"`
+		Data   json.RawMessage `json:"data"`
+	}
+	d := json.NewDecoder(io.LimitReader(res.Body, 4*1024*1024+1))
+	if err = d.Decode(&envelope); err != nil {
+		return merrors.OpaqueWrap(payments.Unavailable, err, "decode Sendico payment envelope")
+	}
+	if envelope.Status != "success" {
+		return payments.Unavailable
+	}
+	var extra any
+	if d.Decode(&extra) != io.EOF {
+		return payments.Unavailable
+	}
+	if err = json.Unmarshal(envelope.Data, dst); err != nil {
+		return merrors.OpaqueWrap(payments.Unavailable, err, "decode Sendico payment payload")
+	}
+	return nil
+}

backend/product/providers/sendico/verification.go

@@ -0,0 +1,184 @@
+package sendico
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"io"
+	"mime/multipart"
+	"net/http"
+	"strconv"
+	"time"
+
+	"git.sendico.io/tech/sxchnge/product/identity"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+)
+
+type profileDTO struct {
+	FullName         string `json:"full_name"`
+	DateOfBirth      string `json:"date_of_birth"`
+	ResidenceCountry string `json:"residence_country"`
+	Email            string `json:"email"`
+	CustomerRef      string `json:"external_customer_ref"`
+}
+type verificationDTO struct {
+	SubjectRef     string     `json:"subject_ref"`
+	SubmissionRef  string     `json:"submission_ref"`
+	Status         string     `json:"status"`
+	Reason         string     `json:"reason"`
+	Profile        profileDTO `json:"profile"`
+	UpgradePending bool       `json:"upgrade_pending"`
+}
+type policyDTO struct {
+	Tier       string     `json:"tier"`
+	ProfileRef string     `json:"profile_ref"`
+	Entries    []limitDTO `json:"entries"`
+}
+type limitDTO struct {
+	Operation string `json:"operation"`
+	Period    string `json:"period"`
+	Currency  string `json:"currency"`
+	Cap       string `json:"cap"`
+	Remaining string `json:"remaining"`
+	Used      string `json:"used"`
+	Reserved  string `json:"reserved"`
+}
+
+func (c *Client) identityRequest(ctx context.Context, subject, suffix, method, contentType string, body []byte, dst any) error {
+	if !validRef(subject) {
+		return merrors.InvalidArgument("invalid bound subject")
+	}
+	token, err := c.token()
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequestWithContext(ctx, method, c.base+"/identity_facts/"+c.config.OrganizationID+"/proofs/"+subject+suffix, bytes.NewReader(body))
+	if err != nil {
+		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "create identity request")
+	}
+	req.Header.Set("Authorization", "Bearer "+token)
+	if contentType != "" {
+		req.Header.Set("Content-Type", contentType)
+	}
+	// Uploads need a longer bound than small sign-up receipts. The base client is
+	// copied so concurrent sign-up operations keep their own four-second timeout.
+	client := *c.http
+	client.Timeout = 60 * time.Second
+	res, err := client.Do(req)
+	if err != nil {
+		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "identity provider request failed")
+	}
+	defer func() { _ = res.Body.Close() }()
+	switch res.StatusCode {
+	case http.StatusOK:
+	case http.StatusBadRequest, http.StatusRequestEntityTooLarge:
+		return merrors.InvalidArgument("identity profile or photos were not accepted")
+	case http.StatusConflict:
+		return merrors.DataConflict("identity submission changed; refresh")
+	case http.StatusForbidden:
+		return merrors.PermissionDenied("identity resource unavailable")
+	case http.StatusTooManyRequests:
+		retry := 60
+		if seconds, parseErr := strconv.Atoi(res.Header.Get("Retry-After")); parseErr == nil && seconds > 0 && seconds <= 86400 {
+			retry = seconds
+		}
+		return merrors.WithThrottle(merrors.ErrServiceUnavailable, "identity", time.Duration(retry)*time.Second, "identity submission temporarily limited")
+	default:
+		return merrors.ServiceUnavailable("identity provider unavailable")
+	}
+	var envelope struct {
+		Status string          `json:"status"`
+		Data   json.RawMessage `json:"data"`
+	}
+	decoder := json.NewDecoder(io.LimitReader(res.Body, 256*1024+1))
+	if err := decoder.Decode(&envelope); err != nil {
+		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "decode identity response")
+	}
+	var extra any
+	if decoder.Decode(&extra) != io.EOF || envelope.Status != "success" {
+		return merrors.ServiceUnavailable("invalid identity response")
+	}
+	if err := json.Unmarshal(envelope.Data, dst); err != nil {
+		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "decode identity payload")
+	}
+	return nil
+}
+func mapVerification(dto verificationDTO, subject string) (identity.Verification, error) {
+	if dto.SubjectRef != subject {
+		return identity.Verification{}, merrors.ServiceUnavailable("identity response scope mismatch")
+	}
+	switch dto.Status {
+	case "unverified", "pending", "approved", "changesRequested", "denied":
+	default:
+		return identity.Verification{}, merrors.ServiceUnavailable("invalid identity status")
+	}
+	if dto.Status == "approved" && dto.UpgradePending {
+		dto.Status = "pending"
+	}
+	if dto.Status != "unverified" && !validRef(dto.SubmissionRef) {
+		return identity.Verification{}, merrors.ServiceUnavailable("invalid identity receipt")
+	}
+	profile := identity.Profile{FullName: dto.Profile.FullName, DateOfBirth: dto.Profile.DateOfBirth, ResidenceCountry: dto.Profile.ResidenceCountry}
+	if dto.Status != "unverified" {
+		if err := profile.Validate(); err != nil {
+			return identity.Verification{}, merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "invalid identity profile response")
+		}
+	}
+	return identity.Verification{Status: dto.Status, UpgradePending: dto.UpgradePending, Reason: dto.Reason, SubmissionID: dto.SubmissionRef, Profile: profile}, nil
+}
+func (c *Client) Verification(ctx context.Context, subject string) (identity.Verification, error) {
+	var dto verificationDTO
+	if err := c.identityRequest(ctx, subject, "", http.MethodGet, "", nil, &dto); err != nil {
+		return identity.Verification{}, err
+	}
+	return mapVerification(dto, subject)
+}
+func (c *Client) SubmitVerification(ctx context.Context, subject, key string, p identity.Profile, f identity.Facts, document, selfie []byte) (identity.Verification, error) {
+	var body bytes.Buffer
+	writer := multipart.NewWriter(&body)
+	profile, err := json.Marshal(profileDTO{FullName: p.FullName, DateOfBirth: p.DateOfBirth, ResidenceCountry: p.ResidenceCountry, Email: f.Email, CustomerRef: f.CustomerRef})
+	if err != nil {
+		return identity.Verification{}, merrors.OpaqueWrap(merrors.ErrInternal, err, "encode identity profile")
+	}
+	if err = writer.WriteField("profile", string(profile)); err != nil {
+		return identity.Verification{}, err
+	}
+	if err = writer.WriteField("source_submission_ref", key); err != nil {
+		return identity.Verification{}, err
+	}
+	for i, data := range [][]byte{document, selfie} {
+		name := "document"
+		if i == 1 {
+			name = "selfie"
+		}
+		part, writeErr := writer.CreateFormFile(name, name)
+		if writeErr != nil {
+			return identity.Verification{}, writeErr
+		}
+		if _, writeErr = part.Write(data); writeErr != nil {
+			return identity.Verification{}, writeErr
+		}
+	}
+	if err = writer.Close(); err != nil {
+		return identity.Verification{}, err
+	}
+	var dto verificationDTO
+	if err = c.identityRequest(ctx, subject, "", http.MethodPost, writer.FormDataContentType(), body.Bytes(), &dto); err != nil {
+		return identity.Verification{}, err
+	}
+	return mapVerification(dto, subject)
+}
+func (c *Client) Limits(ctx context.Context, subject string) (identity.Limits, error) {
+	var dto policyDTO
+	if err := c.identityRequest(ctx, subject, "/limits", http.MethodGet, "", nil, &dto); err != nil {
+		return identity.Limits{}, err
+	}
+	if (dto.Tier != "basic" && dto.Tier != "verified") || dto.ProfileRef == "" || dto.Entries == nil {
+		return identity.Limits{}, merrors.ServiceUnavailable("invalid limits response")
+	}
+	entries := make([]identity.Limit, 0, len(dto.Entries))
+	for _, v := range dto.Entries {
+		entries = append(entries, identity.Limit{Operation: v.Operation, Period: v.Period, Currency: v.Currency, Cap: v.Cap, Remaining: v.Remaining, Used: v.Used, Reserved: v.Reserved})
+	}
+	return identity.Limits{Tier: dto.Tier, ProfileRef: dto.ProfileRef, Entries: entries}, nil
+}

backend/product/providers/sendico/verification_test.go

@@ -0,0 +1,79 @@
+package sendico
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"git.sendico.io/tech/sxchnge/product/identity"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"github.com/stretchr/testify/require"
+)
+
+func TestProofWireContractAndLimitsProjection(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Contains(t, r.Header.Get("Authorization"), "Bearer ")
+		expected := "/api/v1/identity_facts/" + org + "/proofs/" + subject
+		if r.URL.Path == expected+"/limits" {
+			require.Equal(t, http.MethodGet, r.Method)
+			_, _ = io.WriteString(w, `{"status":"success","data":{"tier":"verified","profile_ref":"profile_personal_verified","entries":[{"operation":"Transfer","period":"day","currency":"BTC","cap":"0.12345678","remaining":"0.10000001","used":"0.02","reserved":"0.00345677"}]}}`)
+			return
+		}
+		require.Equal(t, expected, r.URL.Path)
+		if r.Method == http.MethodPost {
+			reader, err := r.MultipartReader()
+			require.NoError(t, err)
+			fields := map[string]string{}
+			for {
+				part, err := reader.NextPart()
+				if err == io.EOF {
+					break
+				}
+				require.NoError(t, err)
+				data, err := io.ReadAll(part)
+				require.NoError(t, err)
+				fields[part.FormName()] = string(data)
+			}
+			require.Equal(t, "document bytes", fields["document"])
+			require.Equal(t, "selfie bytes", fields["selfie"])
+			require.Equal(t, "stable-source", fields["source_submission_ref"])
+			var profile map[string]string
+			require.NoError(t, json.Unmarshal([]byte(fields["profile"]), &profile))
+			require.Equal(t, "Legal Name", profile["full_name"])
+			require.Equal(t, "local-customer", profile["external_customer_ref"])
+			require.Equal(t, "verified@example.test", profile["email"])
+		}
+		_, _ = io.WriteString(w, `{"status":"success","data":{"subject_ref":"`+subject+`","submission_ref":"`+submission+`","status":"approved","upgrade_pending":true,"profile":{"full_name":"Legal Name","date_of_birth":"1990-04-23","residence_country":"PL"}}}`)
+	}))
+	defer server.Close()
+	client, err := Open(config(t, server.URL))
+	require.NoError(t, err)
+	result, err := client.SubmitVerification(t.Context(), subject, "stable-source", identity.Profile{FullName: "Legal Name", DateOfBirth: "1990-04-23", ResidenceCountry: "PL"}, identity.Facts{Email: "verified@example.test", CustomerRef: "local-customer"}, []byte("document bytes"), []byte("selfie bytes"))
+	require.NoError(t, err)
+	require.Equal(t, "pending", result.Status)
+	require.True(t, result.UpgradePending)
+	policy, err := client.Limits(t.Context(), subject)
+	require.NoError(t, err)
+	require.Equal(t, "0.12345678", policy.Entries[0].Cap)
+	require.Equal(t, "verified", policy.Tier)
+	require.Equal(t, 4*time.Second, client.http.Timeout)
+}
+func TestProofRateLimitPreservesTypedRecoveryWithoutUpstreamBody(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Retry-After", "120")
+		w.WriteHeader(429)
+		_, _ = io.WriteString(w, "private identity assertions")
+	}))
+	defer server.Close()
+	client, err := Open(config(t, server.URL))
+	require.NoError(t, err)
+	_, err = client.Verification(t.Context(), subject)
+	require.Error(t, err)
+	require.NotContains(t, err.Error(), "private identity assertions")
+	throttle, ok := merrors.ThrottleDetailsFrom(err)
+	require.True(t, ok)
+	require.Equal(t, 120*time.Second, throttle.RetryAfter)
+}

backend/product/twofactor/service.go

@@ -87,7 +87,7 @@ func validScope(scope model.Scope) bool {
 		return false
 	}
 	switch scope.Purpose {
-	case vmodel.PurposeLogin, vmodel.PurposePayout, vmodel.PurposeFactorPreference:
+	case vmodel.PurposeLogin, vmodel.PurposePayment, vmodel.PurposePayout, vmodel.PurposeFactorPreference:
 		return true
 	}
 	return false

backend/product/verification/model/verificaton.go

@@ -21,6 +21,7 @@ const (
 	PurposeFactorPreference  VerificationPurpose = "factor_preference"
 	PurposeFactorProof       VerificationPurpose = "factor_proof"
 	PurposePayout            VerificationPurpose = "payout"
+	PurposePayment           VerificationPurpose = "payment"
 )
 
 func VPToString(code VerificationPurpose) string {
@@ -45,6 +46,8 @@ func VPFromString(s string) (VerificationPurpose, error) {
 		return PurposeFactorPreference, nil
 	case string(PurposeFactorProof):
 		return PurposeFactorProof, nil
+	case string(PurposePayment):
+		return PurposePayment, nil
 	case string(PurposePayout):
 		return PurposePayout, nil
 	default:

backend/shared/database/internal/repository/repository_filter.go

@@ -70,6 +70,9 @@ func (r *MongoRepository) PatchOneByFilter(ctx context.Context, query builder.Qu
 	if errors.Is(err, mongo.ErrNoDocuments) {
 		return false, nil
 	}
+	if mongo.IsDuplicateKeyError(err) {
+		return false, merrors.OpaqueWrap(merrors.ErrDataConflict, err, "duplicate_key")
+	}
 	if err != nil {
 		return false, err
 	}

docs/identity-verification.md

@@ -0,0 +1,124 @@
+# Customer identity verification
+
+Task [SXCHNGE #48](https://git.sendico.io/tech/sxchnge/issues/48), following
+[sign-up Facts intake](signup-facts.md). Platform implementation:
+[Sendico #2885](https://git.sendico.io/tech/sendico/issues/2885).
+
+## Customer flow
+
+Sign-up still creates a basic account and submits its initial name/email/customer
+reference as immutable facts. Email verification and login remain independent of
+identity proof collection. After the first authenticated login in an app session,
+an unverified customer is offered verification and can choose **Keep basic
+limits**. An unavailable optional identity dependency does not prevent login.
+**Accounts → Identity verification**, **Limits**, and the existing identity
+navigation let the customer return later.
+
+The customer supplies their full legal name, date of birth (YYYY-MM-DD), country
+of residence, an ID document photo and a selfie holding that same document. The
+backend supplies the authenticated customer's email and reference. The client
+cannot choose a platform subject, organization, source principal, review status
+or limits profile. JPEG/PNG photos must decode, be at least 600×600, at most
+40 megapixels and no larger than 10 MiB each. Sendico also enforces its existing
+configured evidence cap, MIME/extension rules and submission rate limits.
+
+Unsent fields and photos stay in memory, survive retryable errors and are cleared
+on successful submission, discard or page disposal. Previews leave Flutter's
+image cache on exit/replacement. Profile edits or photo replacements create a
+new request key; unchanged retries retain their key. Draft loss requires an
+explicit discard choice. No sensitive extras enter browser history or analytics.
+
+A successful submission means **pending staff review**. Corrections permit a new
+submission; rejection retains basic access and the existing support route. A
+recorded approval with an unfinished limits assignment is shown as **Limits
+upgrade pending**, rather than verified. Refresh fetches the real reviewed state
+and the authoritative limits. Production uses no simulated KYC review controls
+or illustrative limit amounts. Demo mode remains separately simulated.
+
+## Boundaries and contracts
+
+The authenticated local routes are `GET/POST /accounts/identity` and
+`GET /accounts/limits`, under the configured API mount. Multipart POST fields are
+`profile` (JSON), `document`, `selfie`, and `idempotencyKey`. A customer ID is
+always resolved from the full authenticated session. Pending-login tokens do not
+provide account access. Browser and native requests both carry the access token;
+browser refresh cookies remain an auth concern.
+
+The existing `signup_facts` binding resolves each local customer to one independent
+Sendico subject. A conditional unique `(namespace, subjectRef)` index prevents
+binding the same provider subject to two customers. Empty registration claims
+are excluded. Existing duplicates cause bootstrap to fail and require controlled
+reconciliation; the application never guesses a replacement subject. Credential
+rotation must retain the configured source account.
+
+The Sendico adapter exclusively uses public HTTP:
+
+- `GET/POST /identity_facts/{organization}/proofs/{subject}`;
+- `GET /identity_facts/{organization}/proofs/{subject}/limits`.
+
+Adapter DTOs and mappers remain separate from local models and local HTTP DTOs.
+There are no Sendico database, gRPC, bus or sibling-module imports in SXCHNGE.
+Provider organization/source settings remain in the adapter configuration.
+Uploads have a bounded 60-second upstream timeout and redirects are rejected.
+Upstream error bodies and photo bytes are never logged. Rate-limit responses
+retain typed recovery. Registration's existing non-idempotent reconciliation
+rules are unchanged.
+
+Visible policy entries retain exact decimal strings, currency, group labels and
+per-operation minimum/maximum, day and month slots. Usage is not invented for
+per-operation slots. The backend owns the effective policy and remaining
+capacity. The existing wallet remains a simulated service; this contribution
+connects identity and visible limits, not real money movement. Future money
+adapters must use the platform-owned customer account resource and authoritative
+Limits reservation path, not a browser-selected policy or displayed balance.
+
+## Review and rollout
+
+Staff work in the existing **Sendico backoffice → KYC → Identity proof review**.
+The platform stores private proofs, immutable profile assertions, review history
+and the reviewed limits assignment. See the platform's
+`docs/customer-identity-proofs.md` for authorization, retry and retention details.
+
+Deploy Sendico Product/provider, Backoffice, Limits and backoffice frontend
+changes together before enabling the new SXCHNGE frontend/backend adapters.
+Existing `api.sendico` settings are reused. The integration account needs
+organization read/update access. The platform's existing evidence/storage,
+cleanup, discovery and limits configuration must be provisioned. Its ACCOUNT
+default for SXCHNGE must be the existing unverified profile, and the existing
+verified profile and personal-account visible view must be active. No new runtime
+configuration parameters or live submissions are introduced by this work.
+
+Merge [SXCHNGE sign-up Facts PR #47](https://git.sendico.io/tech/sxchnge/pulls/47)
+before [this flow's PR #49](https://git.sendico.io/tech/sxchnge/pulls/49).
+For the combined existing backoffice, apply
+[Sendico identity-proofs PR #2886](https://git.sendico.io/tech/sendico/pulls/2886)
+before [Facts review PR #2887](https://git.sendico.io/tech/sendico/pulls/2887).
+They share one Limits assignment contract and retain both review destinations.
+Proof cases go to Identity proof review; generic Facts review cannot link them
+to a login account or assign limits through that path. Deploy the reconciled
+Sendico services and frontend before using this flow. Deployment is separate.
+
+## UX, measurement and validation
+
+Existing KYC journey events measure preparation, selection, accepted submission,
+status reads, retries, abandonment and latency. Profile contents, filenames,
+photo bytes and credentials are excluded. Submission success is an intake
+outcome, not proof of approval. Pending asynchronous staff review is not counted
+as customer abandonment. A resumed route starts a new client attempt; immutable
+submission IDs deduplicate backend business outcomes.
+
+Authoritative completion is the staff decision plus the Limits assignment
+receipt for that submission. Backend IDs correlate these records without becoming
+metric labels. Existing identity request counters/histograms distinguish accepted,
+invalid, denied, conflict, rate-limited and unavailable operations and include
+actual authorization/I/O duration. Client analytics still defaults to the
+existing in-memory sink; retained cross-device analytics depends on deployment.
+
+Review covers optional onboarding, later account navigation, editable profile,
+readable ID/selfie guidance, disabled actions, error/session recovery, input
+preservation, correction/rejection/pending/approval, exact monetary presentation,
+EN/RU at narrow widths and large text, keyboard access and private-image cache
+eviction. Tests use synthetic data, local HTTP servers and disposable MongoDB.
+No live ID documents, live email, production review or deployment were exercised.
+Full validation commands and final PR links are recorded in `implementation.md`
+and the task.

docs/implementation.md

@@ -883,3 +883,88 @@ parallelism resolved that infrastructure contention. The next full run exposed
 the new locale fixture disposal error noted above; the corrected final run
 passed, including EN/RU support states and verification recovery. No checks were
 weakened or unrelated work changed.
+
+## Customer identity verification — task #48
+
+[Implementation and rollout](identity-verification.md) adds optional verification
+on authenticated onboarding and later from the account: legal profile, ID photo
+and selfie holding the same ID. Real adapters replace demo KYC/limits in backend
+mode. Sendico's existing backoffice owns decisions and the reviewed Limits profile;
+SXCHNGE has no local tenancy, roles or policy engine. Provider-subject uniqueness,
+private bounded uploads, stable retries, exact decimal policy projections and
+explicit upgrade-pending feedback are included. The unrelated notifications
+runtime configuration is excluded.
+
+Delivered in [PR #49](https://git.sendico.io/tech/sxchnge/pulls/49), branch
+`identity-verification-48`, implementation commit `1354551`. It is stacked on
+[sign-up Facts PR #47](https://git.sendico.io/tech/sxchnge/pulls/47), which must
+merge first, and requires
+[Sendico PR #2886](https://git.sendico.io/tech/sendico/pulls/2886) to be deployed
+before enabling the new flow. Tracking tasks:
+[SXCHNGE #48](https://git.sendico.io/tech/sxchnge/issues/48) and
+[Sendico #2885](https://git.sendico.io/tech/sendico/issues/2885).
+
+Completion review covered the full backend and frontend contribution, including
+subject ownership, private uploads, idempotent retries, session changes, exact
+limits, DTO/mapper/service/model/provider boundaries, and the UX/measurement
+checklists. Review fixes included duplicate-binding error classification,
+upgrade-pending feedback, bounded response timeouts and stale-session protection.
+
+Final validation passed: `GOFLAGS=-p=1 make test` (all backend race tests and all
+frontend suites; 79 app tests), `make lint-backend`, changed-Dart formatting,
+and `flutter analyze` in the app and shared KYC package. Focused KYC adapter and
+onboarding tests passed (20 tests), as did focused Go identity/provider/HTTP
+checks. An initial parallel run hit the existing Testcontainers reaper deadline;
+serial Go package execution resolved local Docker contention without weakening
+checks. No optional security scan, live customer proof, email, production
+approval, deployment or merge was performed. Generated outputs remain ignored.
+
+Reconciliation follow-up: the shared Limits assignment implementation and its
+persisted-state validation are owned by Sendico PR #2886. The subsequent
+[Sendico Facts review PR #2887](https://git.sendico.io/tech/sendico/pulls/2887)
+retains both Product providers, Backoffice services and KYC destinations, and
+routes proof cases to Identity proof review while blocking generic login linking
+and assignment. Apply #2886 before #2887 and deploy the combined Sendico result
+before this SXCHNGE flow. The public proof/limits contract is unchanged; this
+SXCHNGE follow-up changes documentation only and requires consistency/diff checks.
+
+## Sendico quotations and payment execution — task #50
+
+[Task #50](https://git.sendico.io/tech/sxchnge/issues/50), branch `payments-50`,
+connects backend wallet mode through the authenticated customer BFF to Sendico's
+public account, quotation, by-quote execution and payment-status APIs. It is
+stacked on `identity-verification-48` / PR #49; merge #47 → #49 first.
+
+The separate public-provider prerequisite is
+[Sendico PR #2897](https://git.sendico.io/tech/sendico/pulls/2897), task #2896.
+It validates independent customer context and selects the reviewed ACCOUNT limits
+resource rather than the integration login or an unassigned CUSTOMER policy.
+Deploy its Product Edge and Quotation/Orchestrator consumers together before
+SXCHNGE. The BFF requires an exact customer-context acknowledgement from quotes.
+
+The contribution adds durable customer/namespace/subject-bound quotation ownership,
+transactional payment-factor authorization, unique quote/execution keys, stable
+provider replay, payment-reference reconciliation and authoritative status polling.
+Live UI uses provisioned destinations, accurate quote expiry, explicit missing
+method/loading/error/pending states and long labels at narrow widths. It clears
+account state on customer changes. DTO/mapper/service/model/provider boundaries,
+shared database wrappers, existing credentials and explicit demo mode are retained.
+
+Validation passed: `make test`, `make lint-backend`, `make test-frontend` after the
+final UI review, changed-Dart format verification, and app/wallet `flutter analyze`.
+The final frontend run passed 21 wallet and 81 app tests, plus the unchanged shared
+package suites. Tests include synthetic public HTTP, Mongo transaction rollback,
+unique-key/customer isolation, lost-response reconciliation, factor retry and
+session replacement. Sendico's full backend test/lint targets also passed.
+
+[Payment contracts, provisioning, UX measurement and limitations](payments.md)
+document rollout. Dedicated customer ledger/method bindings and platform access
+must be provisioned through existing operator APIs; this work does not run live
+payments or deploy either repository. Generic ambiguous rejections remain pending
+for operational reconciliation. Cross-session analytics retention, additional
+funding/recipient onboarding, backend locale saving and external history ingestion
+remain separate capabilities. Unrelated notifications runtime changes are excluded.
+
+Delivered in [PR #51](https://git.sendico.io/tech/sxchnge/pulls/51), targeting
+`identity-verification-48`. Merge order is #47 → #49 → #51; deploy Sendico #2897
+before SXCHNGE #51. Both implementation branches are pushed and remain unmerged.

docs/payments.md

@@ -0,0 +1,168 @@
+# Customer quotations and payment execution
+
+Task [SXCHNGE #50](https://git.sendico.io/tech/sxchnge/issues/50), branch
+`payments-50`, based on `identity-verification-48` / PR #49. Provider prerequisite:
+[Sendico #2896](https://git.sendico.io/tech/sendico/issues/2896).
+
+## Boundary and behavior
+
+The authenticated app uses `BackendWalletService` whenever backend authentication
+is configured. Explicit service injection remains available for tests; demo mode
+continues to use the isolated in-memory wallet. Missing provider configuration
+returns an unavailable wallet, never demonstration balances or fake settlements.
+
+The path is Flutter DTO → mapper → service → domain model → provider → UI, then
+SXCHNGE's authenticated customer BFF → Sendico public HTTP. The existing confirmed
+identity binding resolves each signed-in customer to an independent subject.
+Neither a browser-selected organization nor an integration-login-owned balance
+is used as that customer's financial resource.
+
+Consumed public endpoints, below the existing configured API prefix:
+
+- `GET /payments/fx/currencies/{organization}` for accounting scales;
+- `GET /ledger_accounts/{organization}` and
+  `GET /ledger_accounts/{organization}/{ledger}/balance`;
+- `POST /payments/quote/{organization}` with `external_subject_ref`;
+- `POST /payments/by-quote/{organization}`;
+- `GET /payments/by-ref/{payment}` for authoritative status.
+
+The adapter requires the exact `externalSubjectRef` acknowledgement on the quote
+response. An old deployment that ignores the new request field cannot silently
+produce an acceptable integration-principal quote. Public provider DTOs and
+mappers stay inside the adapter. No Sendico modules, databases, gRPC clients or
+message bus are imported by SXCHNGE.
+
+Amounts are parsed and formatted as exact decimal strings at the provider
+boundary and represented as integer minor units locally. Unknown scales, values
+beyond the browser's exact integer range, excess fractional precision, unknown
+payment states, unexecutable quotes and mismatched payment/quote references fail
+closed. Source principal, total debit and net destination credit come from the
+quote; rates account for different currency precisions. Only same-currency saved
+payout/funding methods are currently represented by the wallet review model.
+Exchange connects two dedicated currency ledgers belonging to the same customer.
+
+## Provisioning and rollout
+
+Merge/deploy the identity prerequisites first: SXCHNGE #47 → #49 and the Sendico
+identity-proof/limits-assignment work documented in `identity-verification.md`.
+Deploy the Sendico #2896 Product Edge and the Quotation/Orchestrator builds that
+consume the changed shared payment-storage Limits adapter together. Then deploy
+SXCHNGE #50. The Edge acknowledgement is a compatibility guard; it does not replace
+coordinated deployment of the platform's financial services.
+
+Reuse `api.sendico` and its existing Vault-rendered token file. Do not put provider
+credentials or organization/source settings in Flutter. Provision the integration
+account's organization membership, payment-create/read, ledger-account/balance
+read and the permissions needed to resolve its stored payment methods. Verify
+those permissions in the intended environment before enabling real operations.
+
+Through Sendico's existing operator APIs, provision one dedicated unowned
+organization ledger per customer currency, with active `asset` / `operating`
+semantics, no negative balance and metadata:
+
+| Ledger metadata | Meaning |
+| --- | --- |
+| `sxchnge_subject_ref` | Confirmed independent subject reference from sign-up |
+| `sxchnge_payout_method_ref` | Optional prevalidated same-currency saved payout method |
+| `sxchnge_payout_label` | Safe customer-visible destination label, e.g. bank plus masked suffix |
+| `sxchnge_funding_method_ref` | Optional same-currency saved funding source supported by the platform route |
+
+These are financial-resource bindings maintained by trusted provisioning, not
+client choices or new runtime configuration. Do not tag a pooled/integration-login
+ledger as a customer ledger. Do not place full bank/card details or secret values
+in labels or metadata. The BFF checks subject, organization, account type, role,
+status and owner on each account projection/quotation. It accepts only the bound
+saved payout method and replaces its opaque reference with the safe label in the
+reviewed quote. No arbitrary recipient identifier or free-text bank input can
+be executed from the live UI. Missing bindings have an explanatory disabled
+review action. Funding uses a quote for the provisioned stored source; it does
+not mint money or treat demo top-ups as real deposits. Additional destinations,
+recipient onboarding and other funding instructions remain separate features.
+
+An empty set of provisioned ledgers is an empty wallet. Existing organization
+payments and pooled balances are never imported into customer history. This
+integration exposes the durable operations initiated through this BFF, with live
+provider reconciliation; independent inbound deposits/history ingestion and
+pagination are not added by this contribution. Ledger balances are posted ledger
+projections; execution-time solvency and holds remain the platform's authority.
+
+## Authorization, idempotency and recovery
+
+Local routes are under `/accounts/wallet`: snapshot GET, `/profile` GET,
+`/quote`, `/challenge`, `/resend`, `/verify`, `/submit` and `/submission` POST.
+All use the existing full authenticated-account wrapper, access token and browser
+CSRF guard. Pending-login credentials cannot access them. Local quote references
+are random BFF IDs; provider quote/payment references are not accepted as user
+ownership evidence.
+
+`payment_quotes` stores customer, adapter namespace, confirmed subject, immutable
+quote, upstream quote reference, authorized execution key and eventual payment
+reference. A unique partial index enforces customer/namespace/key uniqueness.
+The existing second-factor service uses the dedicated `payment` purpose and
+exact local quote context. Successful code verification consumes its one-use
+proof in the same local Mongo transaction that records execution authorization.
+No external I/O runs in that transaction and raw factor proofs never leave the
+server. Verification response retries retain their key and recover committed
+intent. Resend uses a separate stable-per-retry issuance key.
+
+Submit/reconciliation replays `sxchnge:payment:<local-quote-id>` at Sendico.
+A quote cannot be authorized under a second execution key. A network failure or
+lost provider response remains uncertain; it never permits execution with a new
+provider key. Once the provider payment reference is attached, refresh uses GET.
+Authorization is durable: reopening the wallet reconciles authorized intents even
+if the original client never received verification/submission success. Unknown
+outcomes remain pending and do not hide unrelated balances. `needs_attention`
+also stays pending; only `settled`/`failed` become terminal UI outcomes.
+
+Generic upstream errors cannot prove that no payment exists. An unresolved
+pre-execution rejection (including an expired quote after durable authorization)
+therefore requires operational reconciliation rather than automatic release or a
+new payment. Inspect the local quote/provider reference and platform audit trail;
+never delete/rekey a record to bypass uncertainty. The UI's live copy does not
+promise a debit, refund or completion from mere acceptance. Only local drafts,
+not durable authorized intents, count as abandoned when a user leaves.
+
+The adapter rejects changed-session HTTP responses, and the app clears wallet
+snapshots/journeys when the authenticated customer changes. Account-language
+reads use the authenticated customer. Backend language saving is deliberately
+unsupported and reports failure; the previous demo setting is not presented as
+persisted backend state.
+
+## UX, observation and validation
+
+The existing typed transfer journey recorder measures draft → quotation →
+second-factor challenge/verification → submission → authoritative settlement.
+Attempts/retries share their client journey; accepted operations finish once
+when the wallet observes a terminal platform status. An uncertain result is not
+success. Leaving an unresolved asynchronous operation is not draft abandonment.
+Use the existing per-attempt timestamps for durations and a 30-minute inactivity
+window for unfinished local drafts; server-authorized pending operations remain
+outside that abandonment denominator. Compare draft-to-quote and quote-to-submit
+drop-off, intent-to-terminal completion/failure and time to terminal outcome.
+The existing recorder provides in-memory client evidence only: deployment of a
+retained analytics sink and backend event delivery is needed for cross-session
+conversion/settlement measurement. No amounts, recipients, bank labels, codes or
+credentials enter analytics. Structured server logs use quote/payment references
+and bounded states; operational reconciliation uses the durable database record.
+
+Tests cover public wire requests, exact money, source/destination isolation,
+blocked/unknown states, factor errors and retry keys, changed-session responses,
+durable authorization rollback/uniqueness, lost-response reconciliation and
+customer/provider-namespace isolation. Widget checks exercise saved destinations
+and the missing-destination state at 320px with 1.6× text, alongside the existing
+EN/RU workspace flows. Default Flutter keyboard/focus semantics are retained;
+full browser/screen-reader acceptance and live funded settlement are deployment
+checks, not claimed by synthetic tests. No live payments or deployment are run.
+
+Validation passed after review: `make test` (backend race tests and all frontend
+suites), `make lint-backend`, a subsequent `make test-frontend` after the final
+long-label UI adjustment, changed-Dart format verification, and `flutter analyze`
+in `frontend/app` and `frontend/packages/sxchnge_wallet`. The final frontend run
+passed 21 wallet, 20 KYC, 7 analytics, 40 auth, 3 theme, 3 theme-example and 81 app
+tests. The provider prerequisite passed Sendico's full backend test/lint targets.
+
+Delivery: [SXCHNGE PR #51](https://git.sendico.io/tech/sxchnge/pulls/51), stacked
+on PR #49. Merge #47 → #49 → #51. The separate
+[Sendico provider PR #2897](https://git.sendico.io/tech/sendico/pulls/2897) must be
+deployed before enabling this consumer. Both implementation branches are pushed;
+merge, deployment and real financial-resource provisioning remain separate.

docs/signup-facts.md

@@ -175,3 +175,8 @@ The EN/RU error state is exercised at a 390px viewport with 1.5x text scaling;
 existing keyboard regression tests and a code review of the live-region semantics
 cover the unchanged controls. No manual browser or screen-reader walkthrough
 against a live Sendico deployment was performed.
+
+The initial sign-up assertion remains a separate immutable submission. Optional
+profile/ID/selfie collection, later account uploads and reviewed limits are now
+covered by [Customer identity verification](identity-verification.md), task #48.
+Proofs are not required to activate or log into a basic account.

docs/ux/kyc.md

@@ -2,6 +2,11 @@
 
 Task [#20](https://git.sendico.io/tech/sxchnge/issues/20). Plan recorded before implementation.
 
+> This original demo plan is retained as design history. Production identity
+> uploads, staff review and authoritative limits are implemented by task #48;
+> see [Customer identity verification](../identity-verification.md). Demo behavior
+> below applies only when the backend adapters are not selected.
+
 ## User outcome and scope
 
 Understand current access, decide whether higher limits are useful, and submit two

frontend/app/README.md

@@ -15,7 +15,15 @@ flutter run -d chrome
 
 A responsive login/sign-up preview with a themed brand panel, email and password validation, password visibility controls, keyboard submission, and inline feedback. Sign-up additionally asks for a name and matching password confirmation. The 12-character sign-up minimum is a UI preview policy and must be aligned with the backend when authentication is integrated.
 
-No authentication endpoint is configured. Submission validates locally and calls the shared dummy authentication services; it never creates an account, starts a session, sends credentials, or persists them. Passwords are cleared when switching modes. Password managers/autofill integration is deferred until real authentication exists. LoginProvider and SignupProvider own loading/results/errors; SxchngeApp accepts injected loginService and signupService implementations. Dummy completion is explicitly labeled and does not establish a real session.
+Without backend configuration the app uses dummy services. The existing
+`SXCHNGE_API_URL` and `SXCHNGE_CLIENT_ID` select authenticated backend auth,
+identity, limits and wallet adapters. Wallet operations use Sendico through the
+BFF after the provider prerequisites and dedicated customer resource bindings
+are provisioned; they do not use demo balances in backend mode. LoginProvider,
+SignupProvider and shared wallet providers own loading/results/errors.
+SxchngeApp retains explicit service injection for tests and previews. See
+[quotation/payment integration](../../docs/payments.md) for setup, supported
+funding/destinations, authorization, reconciliation and rollout.
 
 The interface uses `ColorScheme` and `TextTheme` roles from `sxchnge_theme`; the desktop brand panel installs the package's dark theme locally. Entrance animation respects reduced-motion preferences. The public website remains separate in `website/`.
 

frontend/app/lib/auth/form.dart

@@ -8,6 +8,8 @@ import 'package:sxchnge_analytics/sxchnge_analytics.dart';
 
 import 'package:sxchnge_auth/sxchnge_auth.dart';
 
+import 'package:sxchnge_kyc/sxchnge_kyc.dart';
+
 import '../routing/routes.dart';
 import '../security/challenge.dart';
 import 'feedback.dart';
@@ -127,7 +129,16 @@ class _AuthFormState extends State<AuthForm> {
         }
         await login.complete(challenge, grant);
         if (mounted && login.state.status == AuthStatus.success) {
-          context.go('/accounts');
+          final accepted = login.state.result!;
+          final offer = await context.read<IdentityOnboardingProvider>().offer(
+            accepted.userId,
+          );
+          if (mounted &&
+              !_signUp &&
+              identical(login.state.result, accepted) &&
+              login.state.status == AuthStatus.success) {
+            context.go(offer ? '/identity?onboarding=1' : '/accounts');
+          }
         }
       }
     }
@@ -299,7 +310,9 @@ class _AuthFormState extends State<AuthForm> {
               const SizedBox(height: 28),
               FilledButton(
                 key: const ValueKey('submit'),
-                onPressed: state.isLoading ? null : _submit,
+                onPressed: state.isLoading || state.status == AuthStatus.success
+                    ? null
+                    : _submit,
                 child: Padding(
                   padding: const EdgeInsets.symmetric(vertical: 4),
                   child: Row(

frontend/app/lib/kyc/copy.dart

@@ -22,16 +22,17 @@ String reasonText(AppLocalizations l, ReviewReason r) => switch (r) {
   ReviewReason.passportExpired => l.kycExpiredReason,
   ReviewReason.unableToVerify => l.kycDeniedReason,
 };
-String errorText(AppLocalizations l, KycError e) => switch (e) {
+String errorText(AppLocalizations l, KycError e, {bool photo = false}) =>
-  KycError.unavailable => l.kycErrorUnavailable,
+    switch (e) {
-  KycError.internal => l.kycErrorInternal,
+      KycError.unavailable => l.kycErrorUnavailable,
-  KycError.permission => l.kycErrorPermission,
+      KycError.internal => l.kycErrorInternal,
-  KycError.format => l.kycErrorFormat,
+      KycError.permission => photo ? l.kycErrorPermission : l.kycErrorAccess,
-  KycError.tooLarge => l.kycErrorLarge,
+      KycError.format => l.kycErrorFormat,
-  KycError.unreadable => l.kycErrorUnreadable,
+      KycError.tooLarge => l.kycErrorLarge,
-  KycError.tooSmall => l.kycErrorSmall,
+      KycError.unreadable => l.kycErrorUnreadable,
-  KycError.incomplete => l.kycErrorIncomplete,
+      KycError.tooSmall => l.kycErrorSmall,
-  KycError.sessionExpired => l.kycErrorSession,
+      KycError.incomplete => l.kycErrorIncomplete,
-  KycError.rateLimited => l.kycErrorRate,
+      KycError.sessionExpired => l.kycErrorSession,
-  KycError.conflict => l.kycErrorConflict,
+      KycError.rateLimited => l.kycErrorRate,
-};
+      KycError.conflict => l.kycErrorConflict,
+    };

frontend/app/lib/kyc/form.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:sxchnge_kyc/sxchnge_kyc.dart';
 
 import 'photo.dart';
+import 'profile.dart';
 
 import '../generated/i18n/app_localizations.dart';
 
@@ -26,6 +27,10 @@ class IdentityForm extends StatelessWidget {
           ),
         ),
         const SizedBox(height: 16),
+        if (p.step == 0) ...[
+          ProfileForm(provider: p),
+          const SizedBox(height: 24),
+        ],
         LinearProgressIndicator(
           value: (p.step + 1) / 3,
           semanticsLabel: titles[p.step],
@@ -47,6 +52,10 @@ class IdentityForm extends StatelessWidget {
                   ),
           ),
         if (p.step == 2) ...[
+          Text(
+            '${p.profile.fullName}\n${p.profile.dateOfBirth} · ${p.profile.residenceCountry}',
+          ),
+          const SizedBox(height: 16),
           Text(l.kycReviewHelp),
           const SizedBox(height: 16),
           PhotoPanel(kind: PhotoKind.passport, photo: p.passport, review: true),
@@ -68,7 +77,10 @@ class IdentityForm extends StatelessWidget {
             ),
           FilledButton(
             key: const ValueKey('kyc-next'),
-            onPressed: p.busy || (p.step == 0 ? p.passport : p.selfie) == null
+            onPressed:
+                p.busy ||
+                    (p.step == 0 && !p.profile.isComplete) ||
+                    (p.step == 0 ? p.passport : p.selfie) == null
                 ? null
                 : p.next,
             child: Text(l.kycNext),

frontend/app/lib/kyc/limits.dart

@@ -7,6 +7,7 @@ import 'package:provider/provider.dart';
 import 'package:sxchnge_kyc/sxchnge_kyc.dart';
 
 import '../generated/i18n/app_localizations.dart';
+import 'policy.dart';
 
 class LimitsPanel extends StatelessWidget {
   const LimitsPanel({super.key});
@@ -48,7 +49,9 @@ class LimitsPanel extends StatelessWidget {
                 style: t.textTheme.titleLarge,
               ),
               const SizedBox(height: 12),
-              if (data.rows.isEmpty) Text(l.kycLimitsEmpty),
+              if (data.rows.isEmpty && data.entries.isEmpty)
+                Text(l.kycLimitsEmpty),
+              for (final row in data.entries) PolicyRow(row: row),
               for (final row in data.rows) ...[
                 const Divider(height: 32),
                 Text(

frontend/app/lib/kyc/page.dart

@@ -16,7 +16,8 @@ import 'status.dart';
 import '../generated/i18n/app_localizations.dart';
 
 class IdentityPage extends StatefulWidget {
-  const IdentityPage({super.key});
+  const IdentityPage({super.key, this.onboarding = false});
+  final bool onboarding;
   @override
   State<IdentityPage> createState() => IdentityPageState();
 }
@@ -98,6 +99,10 @@ class IdentityPageState extends State<IdentityPage> {
     if (!await allowExit() || !mounted) return;
     _identity.exit();
     if (account) {
+      if (widget.onboarding) {
+        context.go('/accounts');
+        return;
+      }
       if (context.canPop()) {
         context.pop();
       } else {
@@ -166,7 +171,11 @@ class IdentityPageState extends State<IdentityPage> {
                             key: _feedbackKey,
                             liveRegion: true,
                             child: Text(
-                              errorText(l, p.error!),
+                              errorText(
+                                l,
+                                p.error!,
+                                photo: p.photoError != null,
+                              ),
                               key: const ValueKey('kyc-error'),
                               style: TextStyle(color: t.colorScheme.error),
                             ),
@@ -178,6 +187,16 @@ class IdentityPageState extends State<IdentityPage> {
                             l.kycStatusStale,
                             style: TextStyle(color: t.colorScheme.error),
                           ),
+                        if (p.error == KycError.sessionExpired)
+                          TextButton(
+                            onPressed: () async {
+                              if (await allowExit() && mounted) {
+                                _identity.exit();
+                                if (context.mounted) context.go('/');
+                              }
+                            },
+                            child: Text(l.login),
+                          ),
                         Focus(
                           includeSemantics: false,
                           key: _contentKey,
@@ -198,7 +217,7 @@ class IdentityPageState extends State<IdentityPage> {
                           const LimitsPanel(),
                         ],
                         const SizedBox(height: 16),
-                        if (p.editing)
+                        if (p.editing && !widget.onboarding)
                           TextButton(
                             onPressed: p.busy ? null : _leave,
                             child: Text(l.kycSkip),
@@ -207,7 +226,15 @@ class IdentityPageState extends State<IdentityPage> {
                           onPressed: p.busy
                               ? null
                               : () => _leave(account: true),
-                          child: Text(l.wLimits),
+                          child: Text(
+                            widget.onboarding
+                                ? (p.record?.status ==
+                                              IdentityStatus.unverified ||
+                                          p.editing
+                                      ? l.kycSkip
+                                      : l.kycContinue)
+                                : l.wLimits,
+                          ),
                         ),
                       ],
                     ),

frontend/app/lib/kyc/policy.dart

@@ -0,0 +1,55 @@
+import 'package:flutter/material.dart';
+
+import 'package:sxchnge_kyc/sxchnge_kyc.dart';
+
+import '../generated/i18n/app_localizations.dart';
+
+/// Display exact provider decimals; never infer currency scale or active caps.
+class PolicyRow extends StatelessWidget {
+  const PolicyRow({super.key, required this.row});
+  final PolicyLimit row;
+  @override
+  Widget build(BuildContext context) {
+    final l = AppLocalizations.of(context)!;
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        const Divider(height: 32),
+        Text(
+          '${row.operation} · ${switch (row.period) {
+            'day' => l.kycDay,
+            'month' => l.kycMonth,
+            'operationMin' => l.kycOperationMinimum,
+            'operationMax' => l.kycOperationMaximum,
+            _ => row.period,
+          }}',
+          style: Theme.of(context).textTheme.titleMedium,
+        ),
+        const SizedBox(height: 12),
+        Wrap(
+          spacing: 28,
+          runSpacing: 16,
+          children: [
+            _amount(context, l.kycCurrent, row.cap),
+            if (row.remaining.isNotEmpty)
+              _amount(context, l.kycRemaining, row.remaining),
+            if (row.used.isNotEmpty) _amount(context, l.wUsage, row.used),
+            if (row.reserved.isNotEmpty)
+              _amount(context, l.kycReserved, row.reserved),
+          ],
+        ),
+      ],
+    );
+  }
+
+  Widget _amount(BuildContext context, String label, String amount) => Column(
+    crossAxisAlignment: CrossAxisAlignment.start,
+    children: [
+      Text(label),
+      Text(
+        '$amount ${row.currency}',
+        style: Theme.of(context).textTheme.titleLarge,
+      ),
+    ],
+  );
+}

frontend/app/lib/kyc/profile.dart

@@ -0,0 +1,67 @@
+import 'package:flutter/material.dart';
+
+import 'package:sxchnge_kyc/sxchnge_kyc.dart';
+
+import '../generated/i18n/app_localizations.dart';
+
+class ProfileForm extends StatelessWidget {
+  const ProfileForm({super.key, required this.provider});
+  final IdentityProvider provider;
+
+  @override
+  Widget build(BuildContext context) {
+    final p = provider;
+    final l = AppLocalizations.of(context)!;
+    void update({String? name, String? birth, String? country}) =>
+        p.updateProfile(
+          IdentityProfile(
+            fullName: name ?? p.profile.fullName,
+            dateOfBirth: birth ?? p.profile.dateOfBirth,
+            residenceCountry: country ?? p.profile.residenceCountry,
+          ),
+        );
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.stretch,
+      children: [
+        Text(l.kycProfileHelp),
+        const SizedBox(height: 16),
+        TextFormField(
+          key: const ValueKey('kyc-name'),
+          initialValue: p.profile.fullName,
+          enabled: !p.busy,
+          maxLength: 200,
+          autofillHints: const [AutofillHints.name],
+          decoration: InputDecoration(labelText: l.kycFullName),
+          onChanged: (value) => update(name: value),
+        ),
+        const SizedBox(height: 16),
+        TextFormField(
+          key: const ValueKey('kyc-birth'),
+          initialValue: p.profile.dateOfBirth,
+          enabled: !p.busy,
+          keyboardType: TextInputType.datetime,
+          autofillHints: const [AutofillHints.birthday],
+          decoration: InputDecoration(
+            labelText: l.kycBirth,
+            helperText: l.kycBirthHelp,
+          ),
+          onChanged: (value) => update(birth: value.trim()),
+        ),
+        const SizedBox(height: 16),
+        TextFormField(
+          key: const ValueKey('kyc-country'),
+          initialValue: p.profile.residenceCountry,
+          enabled: !p.busy,
+          maxLength: 2,
+          textCapitalization: TextCapitalization.characters,
+          decoration: InputDecoration(
+            labelText: l.kycCountry,
+            helperText: l.kycCountryHelp,
+          ),
+          onChanged: (value) => update(country: value.trim().toUpperCase()),
+        ),
+        if (!p.profile.isComplete) Text(l.kycProfileRequired),
+      ],
+    );
+  }
+}

frontend/app/lib/kyc/status.dart

@@ -44,7 +44,9 @@ class StatusPanel extends StatelessWidget {
                 header: true,
                 liveRegion: true,
                 child: Text(
-                  statusTitle(l, status),
+                  record.upgradePending
+                      ? l.kycUpgradePendingTitle
+                      : statusTitle(l, status),
                   key: ValueKey('kyc-${status.name}'),
                   style: t.textTheme.headlineMedium?.copyWith(
                     color: t.colorScheme.onPrimaryContainer,
@@ -53,7 +55,9 @@ class StatusPanel extends StatelessWidget {
               ),
               const SizedBox(height: 12),
               Text(
-                statusBody(l, status),
+                record.upgradePending
+                    ? l.kycUpgradePendingBody
+                    : statusBody(l, status),
                 style: TextStyle(color: t.colorScheme.onPrimaryContainer),
               ),
               if (record.reason != null) ...[

frontend/app/lib/l10n/en.arb

@@ -73,19 +73,19 @@
   "kycUnverified": "Not verified",
   "kycPending": "In review",
   "kycApproved": "Identity verified",
-  "kycChanges": "New photos needed",
+  "kycChanges": "Changes requested",
   "kycDenied": "Verification declined",
-  "kycUnverifiedBody": "You can keep using your account with basic limits. Submit a passport photo and a selfie holding it to request an upgrade.",
+  "kycUnverifiedBody": "You can keep using your account with basic limits. Submit an ID document photo and a selfie holding it to request an upgrade.",
   "kycPendingBody": "Your submission is awaiting a human review. Basic limits remain active until approval. You do not need to submit again.",
   "kycApprovedBody": "Your review is complete. Check your current limits below.",
-  "kycChangesBody": "Your account remains available with basic limits. Replace the photos and submit a new review request.",
+  "kycChangesBody": "Basic limits remain available. Check your details, replace the photos and submit a new review request.",
   "kycDeniedBody": "Basic limits remain available. If you believe this decision is incorrect, contact support for a review.",
-  "kycPassportReason": "The passport details could not be read. Retake the photo in good light, with every edge visible.",
+  "kycPassportReason": "The ID document details could not be read. Retake the photo in good light, with every edge visible.",
-  "kycSelfieReason": "Your face or passport was not clear in the selfie. Keep both visible and in focus.",
+  "kycSelfieReason": "Your face or ID document was not clear in the selfie. Keep both visible and in focus.",
-  "kycExpiredReason": "The passport has expired. Use a valid passport and take both photos again.",
+  "kycExpiredReason": "The ID document has expired. Use a valid ID document and take both photos again.",
   "kycDeniedReason": "We could not verify your identity from this submission.",
   "kycStart": "Verify identity",
-  "kycResubmit": "Replace photos",
+  "kycResubmit": "Update details and photos",
   "kycRefresh": "Refresh status & limits",
   "kycSupport": "Contact support",
   "kycSupportBody": "Support is currently unavailable. Please try again later.",
@@ -100,11 +100,11 @@
   "kycLimitsError": "Limits could not be refreshed. Any values below are out of date. Retry to see your current access.",
   "kycLimitsEmpty": "No limits were returned. Refresh or check with support before making a transaction.",
   "kycLoading": "Loading your status…",
-  "kycPassport": "Passport photo",
+  "kycPassport": "ID document photo",
-  "kycSelfie": "Selfie with passport",
+  "kycSelfie": "Selfie with ID document",
-  "kycReview": "Review your photos",
+  "kycReview": "Review details and photos",
-  "kycPassportHelp": "Open your valid passport to the photo page. Show all four edges and keep text sharp. Avoid glare, blur and covered details.",
+  "kycPassportHelp": "Photograph the photo page or front of your valid ID document. Show all four edges and keep every detail readable. Avoid glare, blur and covered details.",
-  "kycSelfieHelp": "Hold the open passport beside your face. Show your whole face and the photo page in the same image. Keep both sharp and uncovered.",
+  "kycSelfieHelp": "Hold the same ID document beside your face. Show your whole face and the document details in the same image, sharp and uncovered.",
   "kycFileRules": "JPEG or PNG · up to 10 MB · at least 600 × 600 pixels. Take a photo with your camera, then choose it here.",
   "kycChoose": "Choose photo",
   "kycReplace": "Choose a different photo",
@@ -113,12 +113,12 @@
   "kycBack": "Back",
   "kycSkip": "Keep basic limits",
   "kycClose": "Back to account",
-  "kycReviewHelp": "Check that both photos are readable and show the same passport. A staff member will review them; submission does not immediately raise your limits.",
+  "kycReviewHelp": "Check your details and make sure both photos are readable and show the same ID document. When you submit, they are stored privately for staff review. Submission does not immediately raise your limits.",
-  "kycConfirm": "These photos show me and my own valid passport.",
+  "kycConfirm": "These photos show me and my own valid ID document.",
   "kycSubmit": "Submit for review",
   "kycWorking": "Processing… Please keep this page open.",
-  "kycDiscardTitle": "Discard these photos?",
+  "kycDiscardTitle": "Discard this verification draft?",
-  "kycDiscardBody": "Your draft is only in memory. Leaving will remove the selected photos; you can start again later.",
+  "kycDiscardBody": "Leaving removes unsent profile changes and selected photos from this session. You can start again later.",
   "kycStay": "Keep editing",
   "kycDiscard": "Discard & leave",
   "kycErrorUnavailable": "The service is unavailable. Your selected photos are still here. Try again.",
@@ -264,5 +264,30 @@
   },
   "factorEmailMethod": "Email code",
   "factorAppMethod": "Authenticator app",
-  "factorAppExpired": "This verification has expired. Return and start again."
+  "factorAppExpired": "This verification has expired. Return and start again.",
+  "kycProfileHelp": "Enter your details exactly as shown on your identity document.",
+  "kycFullName": "Full legal name",
+  "kycBirth": "Date of birth",
+  "kycBirthHelp": "YYYY-MM-DD, for example 1990-04-23",
+  "kycCountry": "Country of residence",
+  "kycCountryHelp": "Two-letter country code, for example PL or DE",
+  "kycProfileRequired": "Enter your full name, a valid date of birth and a two-letter country code to continue.",
+  "kycContinue": "Continue to my account",
+  "kycOperationMinimum": "Per operation minimum",
+  "kycOperationMaximum": "Per operation maximum",
+  "kycErrorAccess": "Verification is unavailable for this account. Contact support if this continues.",
+  "kycUpgradePendingTitle": "Limits upgrade pending",
+  "kycUpgradePendingBody": "Your identity review is approved. We are waiting for confirmation of the limits upgrade. You do not need to submit your photos again.",
+  "wNoPayoutMethod": "No payout destination is set up for this account. Contact support to add one.",
+  "wNoFundingMethod": "No funding method is set up for this account. Contact support for funding instructions.",
+  "wLivePending": "Your payment is awaiting a final outcome. Refresh to see its latest status and balance.",
+  "wLiveFailed": "Your payment did not complete. Refresh your accounts to see the current available balance.",
+  "wLiveQuoteNotice": "Quote expires in {seconds} seconds.",
+  "@wLiveQuoteNotice": {
+    "placeholders": {
+      "seconds": {
+        "type": "int"
+      }
+    }
+  }
 }

frontend/app/lib/l10n/ru.arb

@@ -73,19 +73,19 @@
   "kycUnverified": "Личность не подтверждена",
   "kycPending": "На проверке",
   "kycApproved": "Личность подтверждена",
-  "kycChanges": "Нужны новые фото",
+  "kycChanges": "Нужны исправления",
   "kycDenied": "Верификация отклонена",
-  "kycUnverifiedBody": "Вы можете пользоваться аккаунтом с базовыми лимитами. Для повышения отправьте фото паспорта и селфи с ним.",
+  "kycUnverifiedBody": "Вы можете пользоваться аккаунтом с базовыми лимитами. Для повышения отправьте фото документа и селфи с ним.",
   "kycPendingBody": "Заявка ожидает проверки сотрудником. До одобрения действуют базовые лимиты. Повторная отправка не нужна.",
   "kycApprovedBody": "Проверка завершена. Актуальные лимиты указаны ниже.",
-  "kycChangesBody": "Аккаунт доступен с базовыми лимитами. Замените фото и отправьте новую заявку.",
+  "kycChangesBody": "Базовые лимиты доступны. Проверьте данные, замените фото и отправьте новый запрос на проверку.",
   "kycDeniedBody": "Базовые лимиты остаются доступными. Если вы не согласны с решением, обратитесь в поддержку для пересмотра.",
-  "kycPassportReason": "Данные паспорта не удалось прочитать. Переснимите при хорошем освещении, чтобы все края были видны.",
+  "kycPassportReason": "Данные документа не удалось прочитать. Переснимите при хорошем освещении, чтобы все края были видны.",
-  "kycSelfieReason": "На селфи плохо видно лицо или паспорт. Оба должны быть в кадре и в фокусе.",
+  "kycSelfieReason": "На селфи плохо видно лицо или документ. Оба должны быть в кадре и в фокусе.",
-  "kycExpiredReason": "Срок действия паспорта истёк. Используйте действующий паспорт и сделайте оба фото заново.",
+  "kycExpiredReason": "Срок действия документа истёк. Используйте действующий документ и сделайте оба фото заново.",
   "kycDeniedReason": "По этой заявке не удалось подтвердить вашу личность.",
   "kycStart": "Подтвердить личность",
-  "kycResubmit": "Заменить фото",
+  "kycResubmit": "Исправить данные и фото",
   "kycRefresh": "Обновить статус и лимиты",
   "kycSupport": "Обратиться в поддержку",
   "kycSupportBody": "Поддержка сейчас недоступна. Попробуйте позже.",
@@ -100,11 +100,11 @@
   "kycLimitsError": "Не удалось обновить лимиты. Значения ниже могут быть устаревшими. Повторите запрос.",
   "kycLimitsEmpty": "Сервис не вернул лимиты. Обновите данные или уточните их в поддержке перед операцией.",
   "kycLoading": "Загружаем ваш статус…",
-  "kycPassport": "Фото паспорта",
+  "kycPassport": "Фото документа",
-  "kycSelfie": "Селфи с паспортом",
+  "kycSelfie": "Селфи с документом",
-  "kycReview": "Проверьте фото",
+  "kycReview": "Проверьте данные и фото",
-  "kycPassportHelp": "Откройте действующий паспорт на странице с фото. Все четыре края и текст должны быть чётко видны. Избегайте бликов и размытия, не закрывайте данные.",
+  "kycPassportHelp": "Снимите страницу с фото или лицевую сторону действующего документа. Все четыре края и данные должны быть чётко видны. Избегайте бликов и размытия.",
-  "kycSelfieHelp": "Держите открытый паспорт рядом с лицом. Лицо целиком и страница с фото должны быть в одном кадре, чёткими и ничем не закрытыми.",
+  "kycSelfieHelp": "Держите тот же документ рядом с лицом. Лицо целиком и данные документа должны быть в одном кадре, чёткими и ничем не закрытыми.",
   "kycFileRules": "JPEG или PNG · до 10 МБ · не менее 600 × 600 пикселей. Сделайте фото камерой, затем выберите его здесь.",
   "kycChoose": "Выбрать фото",
   "kycReplace": "Выбрать другое фото",
@@ -113,12 +113,12 @@
   "kycBack": "Назад",
   "kycSkip": "Оставить базовые лимиты",
   "kycClose": "К аккаунту",
-  "kycReviewHelp": "Убедитесь, что оба фото читаемы и на них один паспорт. Их проверит сотрудник. Отправка не повышает лимиты сразу.",
+  "kycReviewHelp": "Проверьте данные: оба фото должны быть читаемы и показывать один документ. После отправки они хранятся конфиденциально для проверки сотрудником. Отправка не повышает лимиты сразу.",
-  "kycConfirm": "На фото я и мой действующий паспорт.",
+  "kycConfirm": "На фото я и мой действующий документ.",
   "kycSubmit": "Отправить на проверку",
   "kycWorking": "Обработка… Не закрывайте страницу.",
-  "kycDiscardTitle": "Удалить выбранные фото?",
+  "kycDiscardTitle": "Удалить черновик проверки?",
-  "kycDiscardBody": "Черновик хранится только в памяти. При выходе выбранные фото будут удалены. Позже можно начать заново.",
+  "kycDiscardBody": "Несохранённые данные и выбранные фото будут удалены из этой сессии. Вы сможете начать заново позже.",
   "kycStay": "Продолжить",
   "kycDiscard": "Удалить и выйти",
   "kycErrorUnavailable": "Сервис недоступен. Выбранные фото сохранены в памяти. Повторите попытку.",
@@ -128,7 +128,7 @@
   "kycErrorLarge": "Изображение слишком большое. Выберите файл до 10 МБ и 40 мегапикселей.",
   "kycErrorUnreadable": "Изображение повреждено или не читается. Выберите другое фото.",
   "kycErrorSmall": "Фото слишком маленькое. Ширина и высота должны быть не менее 600 пикселей.",
-  "kycErrorIncomplete": "Выберите оба фото и подтвердите, что на них вы и ваш паспорт.",
+  "kycErrorIncomplete": "Выберите оба фото и подтвердите, что на них вы и ваш документ.",
   "kycErrorSession": "Сессия истекла. Войдите снова и проверьте статус верификации.",
   "kycErrorRate": "Слишком много запросов. Немного подождите и повторите попытку.",
   "kycErrorConflict": "Статус проверки изменился. Обновите его, прежде чем продолжить.",
@@ -264,5 +264,30 @@
   },
   "factorEmailMethod": "Код из письма",
   "factorAppMethod": "Приложение-аутентификатор",
-  "factorAppExpired": "Срок проверки истёк. Вернитесь и начните снова."
+  "factorAppExpired": "Срок проверки истёк. Вернитесь и начните снова.",
+  "kycProfileHelp": "Укажите данные точно как в документе, удостоверяющем личность.",
+  "kycFullName": "Полное имя по документу",
+  "kycBirth": "Дата рождения",
+  "kycBirthHelp": "ГГГГ-ММ-ДД, например 1990-04-23",
+  "kycCountry": "Страна проживания",
+  "kycCountryHelp": "Код страны из двух букв, например PL или DE",
+  "kycProfileRequired": "Укажите полное имя, корректную дату рождения и код страны из двух букв.",
+  "kycContinue": "Перейти в личный кабинет",
+  "kycOperationMinimum": "Минимум на операцию",
+  "kycOperationMaximum": "Максимум на операцию",
+  "kycErrorAccess": "Проверка недоступна для этого аккаунта. Если это повторяется, обратитесь в поддержку.",
+  "kycUpgradePendingTitle": "Ожидается повышение лимитов",
+  "kycUpgradePendingBody": "Проверка личности одобрена. Ожидается подтверждение повышения лимитов. Отправлять фото повторно не нужно.",
+  "wNoPayoutMethod": "Для этого счёта не настроен способ вывода. Обратитесь в поддержку.",
+  "wNoFundingMethod": "Для этого счёта не настроен способ пополнения. Обратитесь в поддержку за инструкциями.",
+  "wLivePending": "Ожидается окончательный результат платежа. Обновите страницу, чтобы проверить статус и баланс.",
+  "wLiveFailed": "Платёж не завершён. Обновите счета, чтобы проверить доступный баланс.",
+  "wLiveQuoteNotice": "Предложение истекает через {seconds} сек.",
+  "@wLiveQuoteNotice": {
+    "placeholders": {
+      "seconds": {
+        "type": "int"
+      }
+    }
+  }
 }

frontend/app/lib/main.dart

@@ -63,17 +63,32 @@ class _SxchngeAppState extends State<SxchngeApp> {
   late final _locale = widget.localeProvider ?? LocaleProvider();
 
   late final _analytics = widget.analyticsService ?? DummyAnalyticsService();
-  late final _factors =
+  late final _authFactors =
       widget.backend ?? widget.twoFactorService ?? DummyTwoFactorService();
+  late final _factors = _walletService is BackendWalletService
+      ? WalletFactorService(_walletService, _authFactors)
+      : _authFactors;
   late final _security = SecurityProvider(_factors, _analytics);
-  late final _identity = widget.identityService ?? DummyIdentityService();
+  late final _identity =
+      widget.identityService ??
+      (widget.backend == null
+          ? DummyIdentityService()
+          : BackendIdentityService(
+              baseUri: widget.backend!.baseUri,
+              accessToken: () => widget.backend!.session?.accessToken,
+            ));
   late final _walletService =
       widget.walletService ??
-      DummyWalletService(
+      (widget.backend != null
-        _identity,
+          ? BackendWalletService(
-        initialLocale: _locale.locale.languageCode,
+              baseUri: widget.backend!.baseUri,
-        factors: _factors,
+              accessToken: () => widget.backend!.session?.accessToken,
-      );
+            )
+          : DummyWalletService(
+              _identity,
+              initialLocale: _locale.locale.languageCode,
+              factors: _authFactors,
+            ));
   late final _wallet = WalletProvider(
     _walletService,
     _analytics,
@@ -81,7 +96,9 @@ class _SxchngeAppState extends State<SxchngeApp> {
   );
   late final _limits =
       widget.limitsService ??
-      (_walletService is DummyWalletService
+      (_identity is BackendIdentityService
+          ? BackendLimitsService(_identity)
+          : _walletService is DummyWalletService
           ? WalletLimitsService(_walletService)
           : DummyLimitsService(_identity));
   late final _journeys = JourneyRecorder(_analytics);
@@ -100,14 +117,21 @@ class _SxchngeAppState extends State<SxchngeApp> {
         : () => widget.backend!.session != null,
   )..routeInformationProvider.addListener(_routeChanged);
   String _previousPath = '/';
+  String? _walletCustomer;
 
   @override
   void initState() {
     super.initState();
     _previousPath = _router.routeInformationProvider.value.uri.path;
+    _walletCustomer = widget.backend?.session?.userId;
   }
 
   void _routeChanged() {
+    final customer = widget.backend?.session?.userId;
+    if (customer != _walletCustomer) {
+      _walletCustomer = customer;
+      _wallet.reset();
+    }
     final path = _router.routeInformationProvider.value.uri.path;
     if (path == '/' && _previousPath != '/' && _previousPath != '/two-factor') {
       _journeys.abandon(JourneyExit.navigation);
@@ -121,7 +145,13 @@ class _SxchngeAppState extends State<SxchngeApp> {
     _router.dispose();
     _journeys.dispose();
     _wallet.dispose();
+    if (_walletService is BackendWalletService) {
+      _walletService.close();
+    }
     _security.dispose();
+    if (_identity is BackendIdentityService) {
+      _identity.close();
+    }
     _locale.dispose();
     widget.backend?.close();
     super.dispose();
@@ -136,6 +166,7 @@ class _SxchngeAppState extends State<SxchngeApp> {
       Provider<JourneyRecorder>.value(value: _journeys),
       Provider<AnalyticsService>.value(value: _analytics),
       Provider<IdentityService>.value(value: _identity),
+      Provider(create: (_) => IdentityOnboardingProvider(_identity)),
       Provider<LimitsService>.value(value: _limits),
       Provider<PhotoService>.value(value: widget.photoService),
       ChangeNotifierProvider.value(value: _locale),

frontend/app/lib/routing/router.dart

@@ -116,7 +116,10 @@ GoRouter createAppRouter({bool Function()? authenticated}) {
           GoRoute(
             path: '/identity',
             name: AppRoutes.identity,
-            builder: (context, state) => IdentityPage(key: identityKey),
+            builder: (context, state) => IdentityPage(
+              key: identityKey,
+              onboarding: state.uri.queryParameters['onboarding'] == '1',
+            ),
             onExit: (context, state) async =>
                 await identityKey.currentState?.allowExit() ?? true,
           ),

frontend/app/lib/workspace/accounts.dart

@@ -47,6 +47,22 @@ class AccountsPage extends StatelessWidget {
               ),
               const SizedBox(height: 12),
               Text(l.wSubheading, style: t.textTheme.bodyLarge),
+              const SizedBox(height: 16),
+              Card(
+                child: Padding(
+                  padding: const EdgeInsets.all(16),
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    children: [
+                      Text(l.kycIntro),
+                      TextButton(
+                        onPressed: () => context.push('/identity'),
+                        child: Text(l.wIdentity),
+                      ),
+                    ],
+                  ),
+                ),
+              ),
               const SizedBox(height: 28),
               if (p.loading) const LinearProgressIndicator(),
               if (p.failed)

frontend/app/lib/workspace/copy.dart

@@ -28,17 +28,25 @@ String statusText(AppLocalizations l, OperationStatus s) => switch (s) {
   OperationStatus.completed => l.wCompleted,
   OperationStatus.failed => l.wFailed,
 };
-String fundsText(AppLocalizations l, WalletOperation o) =>
+String fundsText(
-    switch ((o.status, o.quote.request.kind)) {
+  AppLocalizations l,
-      (OperationStatus.pending, TransferKind.topUp) => l.wPendingTopUp,
+  WalletOperation o, {
-      (OperationStatus.pending, TransferKind.exchange) => l.wPendingExchange,
+  bool simulated = true,
-      (OperationStatus.pending, TransferKind.payout) => l.wPendingPayout,
+}) => !simulated && o.status == OperationStatus.pending
-      (OperationStatus.completed, TransferKind.topUp) => l.wCompleteTopUp,
+    ? l.wLivePending
-      (OperationStatus.completed, TransferKind.exchange) => l.wCompleteExchange,
+    : !simulated && o.status == OperationStatus.failed
-      (OperationStatus.completed, TransferKind.payout) => l.wCompletePayout,
+    ? l.wLiveFailed
-      (OperationStatus.failed, TransferKind.topUp) => l.wFailedTopUp,
+    : switch ((o.status, o.quote.request.kind)) {
-      _ => l.wFailedOutgoing,
+        (OperationStatus.pending, TransferKind.topUp) => l.wPendingTopUp,
-    };
+        (OperationStatus.pending, TransferKind.exchange) => l.wPendingExchange,
+        (OperationStatus.pending, TransferKind.payout) => l.wPendingPayout,
+        (OperationStatus.completed, TransferKind.topUp) => l.wCompleteTopUp,
+        (OperationStatus.completed, TransferKind.exchange) =>
+          l.wCompleteExchange,
+        (OperationStatus.completed, TransferKind.payout) => l.wCompletePayout,
+        (OperationStatus.failed, TransferKind.topUp) => l.wFailedTopUp,
+        _ => l.wFailedOutgoing,
+      };
 String walletError(AppLocalizations l, WalletError e) => switch (e) {
   WalletError.invalidAmount => l.wInvalidAmount,
   WalletError.insufficientFunds => l.wInsufficient,

frontend/app/lib/workspace/operation.dart

@@ -97,7 +97,7 @@ class _OperationPageState extends State<OperationPage> {
                       ),
                       const SizedBox(height: 16),
                       Text(
-                        fundsText(l, o),
+                        fundsText(l, o, simulated: p.service.isSimulated),
                         style: TextStyle(
                           color: o.status == OperationStatus.failed
                               ? c.onErrorContainer

frontend/app/lib/workspace/transfer.dart

@@ -133,6 +133,15 @@ class TransferPageState extends State<TransferPage> {
       final t = Theme.of(context);
       final accounts = wallet.data?.accounts ?? [];
       final source = wallet.account(p.source);
+      final live = !wallet.service.isSimulated;
+      final expiresIn =
+          p.quote?.expiresAt.difference(DateTime.now()).inSeconds ?? 0;
+      final unavailableMethod =
+          live &&
+          ((widget.kind == TransferKind.payout &&
+                  (source?.payoutMethod.isEmpty ?? true)) ||
+              (widget.kind == TransferKind.topUp &&
+                  !(source?.canFund ?? false)));
       return SingleChildScrollView(
         padding: const EdgeInsets.all(24),
         child: Center(
@@ -207,7 +216,15 @@ class TransferPageState extends State<TransferPage> {
                       ] else if (p.quote != null) ...[
                         TransferSummary(quote: p.quote!),
                         const SizedBox(height: 16),
-                        Text(p.expired ? l.wExpired : l.wQuoteNotice),
+                        Text(
+                          p.expired
+                              ? l.wExpired
+                              : live
+                              ? l.wLiveQuoteNotice(
+                                  expiresIn < 0 ? 0 : expiresIn,
+                                )
+                              : l.wQuoteNotice,
+                        ),
                         const SizedBox(height: 20),
                         if (p.expired)
                           FilledButton(
@@ -299,21 +316,39 @@ class TransferPageState extends State<TransferPage> {
                           ),
                           if (widget.kind == TransferKind.payout) ...[
                             const SizedBox(height: 20),
-                            TextField(
+                            if (live && source?.payoutMethod.isNotEmpty == true)
-                              key: const ValueKey('transfer-recipient'),
+                              InputDecorator(
-                              controller: _recipient,
+                                decoration: InputDecoration(
-                              enabled: !p.busy,
+                                  labelText: l.wRecipient,
-                              decoration: InputDecoration(
+                                ),
-                                labelText: l.wRecipient,
+                                child: Text(source!.payoutLabel),
-                                hintText: l.wRecipientHint,
                               ),
-                              onChanged: (v) => p.change(recipient: v),
+                            if (!live)
+                              TextField(
+                                key: const ValueKey('transfer-recipient'),
+                                controller: _recipient,
+                                enabled: !p.busy,
+                                decoration: InputDecoration(
+                                  labelText: l.wRecipient,
+                                  hintText: l.wRecipientHint,
+                                ),
+                                onChanged: (v) => p.change(recipient: v),
+                              ),
+                          ],
+                          if (unavailableMethod) ...[
+                            const SizedBox(height: 12),
+                            Text(
+                              widget.kind == TransferKind.payout
+                                  ? l.wNoPayoutMethod
+                                  : l.wNoFundingMethod,
                             ),
                           ],
                           const SizedBox(height: 28),
                           FilledButton(
                             key: const ValueKey('transfer-review'),
-                            onPressed: p.busy ? null : p.review,
+                            onPressed: p.busy || unavailableMethod
+                                ? null
+                                : p.review,
                             child: Text(l.wReview),
                           ),
                           if (p.error == WalletError.limitExceeded)

frontend/app/test/kyc_test.dart

@@ -67,6 +67,10 @@ void main() {
 
   Future<void> submit(WidgetTester t) async {
     await tap(t, find.byKey(const ValueKey('kyc-start')));
+    await t.enterText(find.byKey(const ValueKey('kyc-name')), 'Example Person');
+    await t.enterText(find.byKey(const ValueKey('kyc-birth')), '1990-04-23');
+    await t.enterText(find.byKey(const ValueKey('kyc-country')), 'PL');
+    await t.pumpAndSettle();
     await tap(t, find.byKey(const ValueKey('pick-passport')));
     await tap(t, find.byKey(const ValueKey('kyc-next')));
     await tap(t, find.byKey(const ValueKey('pick-selfie')));
@@ -100,6 +104,25 @@ void main() {
     await tap(t, find.text('Contact support'));
     expect(find.byType(AlertDialog), findsOneWidget);
   });
+  testWidgets('optional onboarding can be skipped before collecting proofs', (
+    t,
+  ) async {
+    t.platformDispatcher.defaultRouteNameTestValue = '/identity?onboarding=1';
+    addTearDown(t.platformDispatcher.clearDefaultRouteNameTestValue);
+    await t.pumpWidget(
+      SxchngeApp(
+        identityService: DummyIdentityService(delay: Duration.zero),
+        photoService: Photos(bytes),
+      ),
+    );
+    await t.pumpAndSettle();
+    final router = GoRouter.of(
+      t.element(find.byKey(const ValueKey('kyc-start'))),
+    );
+    await tap(t, find.text('Keep basic limits'));
+    expect(router.routeInformationProvider.value.uri.path, '/accounts');
+    expect(find.byType(AlertDialog), findsNothing);
+  });
   testWidgets('correctable rejection can be resubmitted', (t) async {
     await open(t);
     await submit(t);

frontend/app/test/payout_backend_test.dart

@@ -0,0 +1,101 @@
+import 'package:flutter/material.dart';
+
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:sxchnge_kyc/sxchnge_kyc.dart';
+
+import 'package:sxchnge_wallet/sxchnge_wallet.dart';
+
+import 'package:sxchnge_app/main.dart';
+
+const destinationLabel =
+    'Saved bank ending 1234 — Personal current account for daily transfers and reimbursements';
+
+class LiveWallet extends DummyWalletService {
+  LiveWallet({this.hasMethod = true})
+    : super(DummyIdentityService(delay: Duration.zero), delay: Duration.zero);
+  final bool hasMethod;
+  String? received;
+  @override
+  bool get isSimulated => false;
+  @override
+  Future<WalletSnapshot> fetch() async => WalletSnapshot(
+    accounts: [
+      CurrencyAccount(
+        id: 'real-account',
+        currency: 'EUR',
+        precision: 2,
+        available: 7500,
+        payoutMethod: hasMethod ? 'method-ref' : '',
+        payoutLabel: hasMethod ? destinationLabel : '',
+        canFund: false,
+      ),
+    ],
+    operations: [],
+  );
+  @override
+  Future<Quote> quote(TransferRequest request) async {
+    received = request.recipient;
+    return Quote(
+      id: 'quote',
+      request: TransferRequest(
+        kind: request.kind,
+        source: request.source,
+        amount: request.amount,
+        recipient: destinationLabel,
+      ),
+      fee: 100,
+      debit: request.amount + 100,
+      credit: request.amount,
+      expiresAt: DateTime.now().add(const Duration(minutes: 5)),
+      rateNumerator: 1,
+      rateDenominator: 1,
+    );
+  }
+}
+
+void main() {
+  for (final hasMethod in [true, false]) {
+    testWidgets(
+      'backend payout ${hasMethod ? 'reviews saved destination' : 'explains missing destination'} at narrow width',
+      (t) async {
+        t.view.physicalSize = const Size(320, 1100);
+        t.view.devicePixelRatio = 1;
+        t.platformDispatcher.textScaleFactorTestValue = 1.6;
+        t.platformDispatcher.defaultRouteNameTestValue = '/payout';
+        addTearDown(t.view.resetPhysicalSize);
+        addTearDown(t.view.resetDevicePixelRatio);
+        addTearDown(t.platformDispatcher.clearTextScaleFactorTestValue);
+        addTearDown(t.platformDispatcher.clearDefaultRouteNameTestValue);
+        final wallet = LiveWallet(hasMethod: hasMethod);
+        await t.pumpWidget(SxchngeApp(walletService: wallet));
+        await t.pumpAndSettle();
+        expect(find.byKey(const ValueKey('transfer-recipient')), findsNothing);
+        await t.enterText(find.byKey(const ValueKey('transfer-amount')), '20');
+        final review = find.byKey(const ValueKey('transfer-review'));
+        await t.ensureVisible(review);
+        if (hasMethod) {
+          expect(find.text(destinationLabel), findsOneWidget);
+          await t.tap(review);
+          await t.pumpAndSettle();
+          expect(wallet.received, 'method-ref');
+          expect(find.text(destinationLabel), findsOneWidget);
+          expect(
+            find.byKey(const ValueKey('transfer-confirm')),
+            findsOneWidget,
+          );
+        } else {
+          expect(t.widget<FilledButton>(review).onPressed, isNull);
+          expect(
+            find.text(
+              'No payout destination is set up for this account. Contact support to add one.',
+            ),
+            findsOneWidget,
+          );
+        }
+        expect(t.takeException(), isNull);
+        await t.pumpWidget(const SizedBox.shrink());
+      },
+    );
+  }
+}

frontend/packages/sxchnge_kyc/lib/src/mappers/backend.dart

@@ -0,0 +1,51 @@
+import '../models/identity.dart';
+import '../models/limits.dart';
+import '../transport/backend.dart';
+
+abstract final class VerificationMapper {
+  static Limits limits(PolicyDTO dto) => Limits(
+    tier: AccountTier.values.byName(dto.tier),
+    rows: const [],
+    simulated: false,
+    profileRef: dto.profileRef,
+    entries: dto.entries
+        .map(
+          (v) => PolicyLimit(
+            operation: v.operation,
+            period: v.period,
+            currency: v.currency,
+            cap: v.cap,
+            remaining: v.remaining,
+            used: v.used,
+            reserved: v.reserved,
+          ),
+        )
+        .toList(),
+  );
+  static Identity fromDTO(VerificationDTO dto) => Identity(
+    upgradePending: dto.upgradePending,
+    status: IdentityStatus.values.byName(dto.status),
+    reason: dto.reason == null || dto.reason!.isEmpty
+        ? null
+        : ReviewReason.values.byName(dto.reason!),
+    submissionId: dto.id,
+    profile: IdentityProfile(
+      fullName: dto.profile.fullName,
+      dateOfBirth: dto.profile.dateOfBirth,
+      residenceCountry: dto.profile.residenceCountry,
+    ),
+  );
+  static ProfileDTO profile(IdentityProfile value) => ProfileDTO(
+    value.fullName.trim(),
+    value.dateOfBirth,
+    value.residenceCountry,
+  );
+  static KycException failure(int status) => KycException(switch (status) {
+    400 || 413 || 415 || 422 => KycError.format,
+    401 => KycError.sessionExpired,
+    403 => KycError.permission,
+    409 => KycError.conflict,
+    429 => KycError.rateLimited,
+    _ => KycError.unavailable,
+  });
+}

frontend/packages/sxchnge_kyc/lib/src/models/identity.dart

@@ -36,16 +36,40 @@ class Identity {
     this.reason,
     this.submissionId,
     this.simulated = false,
+    this.profile = const IdentityProfile(),
+    this.upgradePending = false,
   });
   final IdentityStatus status;
   final ReviewReason? reason;
   final String? submissionId;
   final bool simulated;
+  final IdentityProfile profile;
+  final bool upgradePending;
   bool get canSubmit =>
       status == IdentityStatus.unverified ||
       status == IdentityStatus.changesRequested;
 }
 
+/// Customer assertions awaiting human review, distinct from a verified identity.
+class IdentityProfile {
+  const IdentityProfile({
+    this.fullName = '',
+    this.dateOfBirth = '',
+    this.residenceCountry = '',
+  });
+  final String fullName, dateOfBirth, residenceCountry;
+  bool get isComplete {
+    final date = DateTime.tryParse(dateOfBirth);
+    return fullName.trim().isNotEmpty &&
+        fullName.length <= 200 &&
+        RegExp(r'^\d{4}-\d{2}-\d{2}$').hasMatch(dateOfBirth) &&
+        date != null &&
+        date.toIso8601String().startsWith(dateOfBirth) &&
+        date.isBefore(DateTime.now()) &&
+        RegExp(r'^[A-Z]{2}$').hasMatch(residenceCountry);
+  }
+}
+
 /// Ephemeral image data only. Never serialize this model into storage or telemetry.
 class Photo {
   Photo(Uint8List bytes)

frontend/packages/sxchnge_kyc/lib/src/models/limits.dart

@@ -33,8 +33,28 @@ class Limits {
     required this.tier,
     required List<VisibleLimit> rows,
     required this.simulated,
-  }) : rows = List.unmodifiable(rows);
+    this.profileRef,
+    List<PolicyLimit> entries = const [],
+  }) : rows = List.unmodifiable(rows),
+       entries = List.unmodifiable(entries);
   final AccountTier tier;
   final List<VisibleLimit> rows;
   final bool simulated;
+  final String? profileRef;
+  final List<PolicyLimit> entries;
+}
+
+/// Authoritative policy amounts in major units. Keep decimal strings intact,
+/// including currencies whose precision differs from fiat's common two digits.
+class PolicyLimit {
+  const PolicyLimit({
+    required this.operation,
+    required this.period,
+    required this.currency,
+    required this.cap,
+    required this.remaining,
+    required this.used,
+    required this.reserved,
+  });
+  final String operation, period, currency, cap, remaining, used, reserved;
 }

frontend/packages/sxchnge_kyc/lib/src/providers/identity.dart

@@ -22,6 +22,7 @@ class IdentityProvider extends ChangeNotifier {
   Identity? record;
   Photo? passport;
   Photo? selfie;
+  IdentityProfile profile = const IdentityProfile();
   KycError? error;
   PhotoKind? photoError;
   bool busy = false;
@@ -31,11 +32,13 @@ class IdentityProvider extends ChangeNotifier {
   int step = 0;
   bool _disposed = false;
   String? _key;
-  bool get hasDraft => passport != null || selfie != null;
+  bool _profileTouched = false;
+  bool get hasDraft => passport != null || selfie != null || _profileTouched;
   bool get canSubmit =>
       !busy &&
       !stale &&
       confirmed &&
+      profile.isComplete &&
       passport != null &&
       selfie != null &&
       (record?.canSubmit ?? false);
@@ -57,6 +60,7 @@ class IdentityProvider extends ChangeNotifier {
       final result = await service.fetch();
       if (_disposed) return;
       record = result;
+      if (!editing) profile = result.profile;
       stale = false;
       await onStatusChanged?.call();
       if (_disposed) return;
@@ -144,6 +148,7 @@ class IdentityProvider extends ChangeNotifier {
 
   void next() {
     if (busy ||
+        (step == 0 && !profile.isComplete) ||
         (step == 0 && passport == null) ||
         (step == 1 && selfie == null))
       return;
@@ -152,6 +157,15 @@ class IdentityProvider extends ChangeNotifier {
     _notify();
   }
 
+  void updateProfile(IdentityProfile value) {
+    if (busy || !editing) return;
+    profile = value;
+    _profileTouched = true;
+    confirmed = false;
+    _key = null;
+    _notify();
+  }
+
   void confirm(bool value) {
     if (!busy) {
       confirmed = value;
@@ -172,6 +186,7 @@ class IdentityProvider extends ChangeNotifier {
     final op = _begin(JourneyStep.kycSubmission);
     try {
       final result = await service.submit(
+        profile: profile,
         passport: passport!,
         selfie: selfie!,
         idempotencyKey: _key!,
@@ -217,6 +232,8 @@ class IdentityProvider extends ChangeNotifier {
   }
 
   void _clear() {
+    _profileTouched = false;
+    profile = const IdentityProfile();
     passport = null;
     selfie = null;
     confirmed = false;

frontend/packages/sxchnge_kyc/lib/src/providers/onboarding.dart

@@ -0,0 +1,23 @@
+import '../models/identity.dart';
+import '../services/contracts.dart';
+
+/// Offers optional verification once per customer in this app session. Identity
+/// dependency failures must never prevent an already authenticated basic login.
+class IdentityOnboardingProvider {
+  IdentityOnboardingProvider(this.service);
+  final IdentityService service;
+  final _offered = <String>{};
+  Future<bool> offer(String customer) async {
+    if (customer.isEmpty || service.isSimulated || !_offered.add(customer))
+      return false;
+    try {
+      final identity = await service.fetch().timeout(
+        const Duration(seconds: 3),
+      );
+      return identity.status == IdentityStatus.unverified ||
+          identity.status == IdentityStatus.changesRequested;
+    } catch (_) {
+      return false;
+    }
+  }
+}

frontend/packages/sxchnge_kyc/lib/src/services/backend.dart

@@ -0,0 +1,130 @@
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+
+import 'package:http/http.dart' as http;
+
+import '../mappers/backend.dart';
+import '../models/identity.dart';
+import '../models/limits.dart';
+import '../transport/backend.dart';
+import 'contracts.dart';
+import 'http/client.dart';
+
+/// Credentials are read for each operation, so a replaced session cannot leave
+/// documents attached to a previously authenticated customer.
+class BackendIdentityService implements IdentityService {
+  BackendIdentityService({
+    required this.baseUri,
+    required this.accessToken,
+    http.Client? client,
+  }) : _client = client ?? createClient() {
+    if (!baseUri.hasAuthority ||
+        baseUri.hasQuery ||
+        baseUri.hasFragment ||
+        baseUri.userInfo.isNotEmpty ||
+        (baseUri.scheme != 'https' &&
+            !(baseUri.scheme == 'http' &&
+                ['localhost', '127.0.0.1'].contains(baseUri.host))))
+      throw ArgumentError('Valid identity API URL required');
+  }
+  final Uri baseUri;
+  final String? Function() accessToken;
+  final http.Client _client;
+  @override
+  bool get isSimulated => false;
+  Uri get _uri => baseUri.replace(
+    path: '${baseUri.path.replaceFirst(RegExp(r"/$"), "")}/accounts/identity',
+  );
+
+  Future<String> _send(http.BaseRequest request) async {
+    final token = accessToken();
+    if (token == null) throw const KycException(KycError.sessionExpired);
+    request.followRedirects = false;
+    request.headers.addAll({
+      'Authorization': 'Bearer $token',
+      if (kIsWeb) 'X-CSRF-Protection': '1',
+    });
+    try {
+      final response = await _client
+          .send(request)
+          .then(http.Response.fromStream)
+          .timeout(const Duration(seconds: 60));
+      if (token != accessToken())
+        throw const KycException(KycError.sessionExpired);
+      if (response.statusCode < 200 || response.statusCode >= 300)
+        throw VerificationMapper.failure(response.statusCode);
+      return response.body;
+    } on KycException {
+      rethrow;
+    } catch (_) {
+      throw const KycException(KycError.unavailable);
+    }
+  }
+
+  Future<T> _mapped<T>(Future<String> response, T Function(String) map) async {
+    try {
+      return map(await response);
+    } on KycException {
+      rethrow;
+    } catch (_) {
+      throw const KycException(KycError.unavailable);
+    }
+  }
+
+  @override
+  Future<Identity> fetch() => _mapped(
+    _send(http.Request('GET', _uri)),
+    (body) => VerificationMapper.fromDTO(VerificationDTO.decode(body)),
+  );
+  Future<Limits> fetchLimits() => _mapped(
+    _send(
+      http.Request(
+        'GET',
+        _uri.replace(
+          path: _uri.path.replaceFirst(RegExp(r'/identity$'), '/limits'),
+        ),
+      ),
+    ),
+    (body) => VerificationMapper.limits(PolicyDTO.decode(body)),
+  );
+  @override
+  Future<Identity> submit({
+    required IdentityProfile profile,
+    required Photo passport,
+    required Photo selfie,
+    required String idempotencyKey,
+  }) async {
+    if (!profile.isComplete) throw const KycException(KycError.incomplete);
+    final request = http.MultipartRequest('POST', _uri)
+      ..fields.addAll({
+        'profile': jsonEncode(VerificationMapper.profile(profile).toJson()),
+        'idempotencyKey': idempotencyKey,
+      })
+      ..files.addAll([
+        http.MultipartFile.fromBytes(
+          'document',
+          passport.bytes,
+          filename: 'document',
+        ),
+        http.MultipartFile.fromBytes(
+          'selfie',
+          selfie.bytes,
+          filename: 'selfie',
+        ),
+      ]);
+    return _mapped(
+      _send(request),
+      (body) => VerificationMapper.fromDTO(VerificationDTO.decode(body)),
+    );
+  }
+
+  void close() => _client.close();
+}
+
+class BackendLimitsService implements LimitsService {
+  const BackendLimitsService(this.identity);
+  final BackendIdentityService identity;
+  @override
+  Future<Limits> fetch() => identity.fetchLimits();
+}

frontend/packages/sxchnge_kyc/lib/src/services/contracts.dart

@@ -8,6 +8,7 @@ abstract interface class IdentityService {
   /// Backend adapters must scope the key to the authenticated account and reject
   /// stale/duplicate review transitions. Retrying the same key is idempotent.
   Future<Identity> submit({
+    required IdentityProfile profile,
     required Photo passport,
     required Photo selfie,
     required String idempotencyKey,

frontend/packages/sxchnge_kyc/lib/src/services/dummy.dart

@@ -27,6 +27,7 @@ class DummyIdentityService implements IdentityService {
 
   @override
   Future<Identity> submit({
+    required IdentityProfile profile,
     required Photo passport,
     required Photo selfie,
     required String idempotencyKey,
@@ -35,7 +36,7 @@ class DummyIdentityService implements IdentityService {
     if (_lastKey == idempotencyKey) return IdentityMapper.fromDTO(_record);
     if (!IdentityMapper.fromDTO(_record).canSubmit)
       throw const KycException(KycError.conflict);
-    if (passport.bytes.isEmpty || selfie.bytes.isEmpty)
+    if (!profile.isComplete || passport.bytes.isEmpty || selfie.bytes.isEmpty)
       throw const KycException(KycError.incomplete);
     _lastKey = idempotencyKey;
     _record = IdentityDTO('pending', id: idempotencyKey);

frontend/packages/sxchnge_kyc/lib/src/services/http/browser.dart

@@ -0,0 +1,4 @@
+import 'package:http/browser_client.dart';
+import 'package:http/http.dart' as http;
+
+http.Client createClient() => BrowserClient()..withCredentials = true;

frontend/packages/sxchnge_kyc/lib/src/services/http/client.dart

@@ -0,0 +1 @@
+export 'native.dart' if (dart.library.js_interop) 'browser.dart';

frontend/packages/sxchnge_kyc/lib/src/services/http/native.dart

@@ -0,0 +1,3 @@
+import 'package:http/http.dart' as http;
+
+http.Client createClient() => http.Client();

frontend/packages/sxchnge_kyc/lib/src/transport/backend.dart

@@ -0,0 +1,74 @@
+import 'dart:convert';
+
+class ProfileDTO {
+  const ProfileDTO(this.fullName, this.dateOfBirth, this.residenceCountry);
+  factory ProfileDTO.fromJson(Map<String, dynamic> data) => ProfileDTO(
+    data['fullName'] as String? ?? '',
+    data['dateOfBirth'] as String? ?? '',
+    data['residenceCountry'] as String? ?? '',
+  );
+  final String fullName, dateOfBirth, residenceCountry;
+  Map<String, String> toJson() => {
+    'fullName': fullName,
+    'dateOfBirth': dateOfBirth,
+    'residenceCountry': residenceCountry,
+  };
+}
+
+class VerificationDTO {
+  const VerificationDTO(
+    this.status,
+    this.reason,
+    this.id,
+    this.profile, {
+    this.upgradePending = false,
+  });
+  factory VerificationDTO.decode(String body) {
+    final envelope = jsonDecode(body) as Map<String, dynamic>;
+    if (envelope['status'] != 'success')
+      throw const FormatException('Unaccepted verification');
+    final data = envelope['data'] as Map<String, dynamic>;
+    return VerificationDTO(
+      data['status'] as String,
+      data['reason'] as String?,
+      data['submissionId'] as String?,
+      ProfileDTO.fromJson(data['profile'] as Map<String, dynamic>),
+      upgradePending: data['upgradePending'] as bool? ?? false,
+    );
+  }
+  final String status;
+  final String? reason, id;
+  final ProfileDTO profile;
+  final bool upgradePending;
+}
+
+class PolicyDTO {
+  const PolicyDTO(this.tier, this.profileRef, this.entries);
+  factory PolicyDTO.decode(String body) {
+    final envelope = jsonDecode(body) as Map<String, dynamic>;
+    if (envelope['status'] != 'success')
+      throw const FormatException('Unaccepted limits');
+    final data = envelope['data'] as Map<String, dynamic>;
+    return PolicyDTO(
+      data['tier'] as String,
+      data['profileRef'] as String,
+      (data['entries'] as List)
+          .map((v) => LimitDTO.fromJson(v as Map<String, dynamic>))
+          .toList(),
+    );
+  }
+  final String tier, profileRef;
+  final List<LimitDTO> entries;
+}
+
+class LimitDTO {
+  LimitDTO.fromJson(Map<String, dynamic> d)
+    : operation = d['operation'] as String,
+      period = d['period'] as String,
+      currency = d['currency'] as String,
+      cap = d['cap'] as String,
+      remaining = d['remaining'] as String,
+      used = d['used'] as String,
+      reserved = d['reserved'] as String;
+  final String operation, period, currency, cap, remaining, used, reserved;
+}

frontend/packages/sxchnge_kyc/lib/src/transport/contracts.dart

@@ -1,7 +1,7 @@
 import '../models/identity.dart';
 import '../models/limits.dart';
 
-// Transport contracts for the stub. Replace with generated backend DTOs later.
+// Transport fixtures for simulated services. Production owns its backend DTOs.
 class IdentityDTO {
   const IdentityDTO(this.status, {this.reason, this.id, this.simulated = true});
   final String status;

frontend/packages/sxchnge_kyc/lib/sxchnge_kyc.dart

@@ -1,7 +1,9 @@
 export 'src/models/identity.dart';
 export 'src/models/limits.dart';
 export 'src/providers/identity.dart';
+export 'src/providers/onboarding.dart';
 export 'src/providers/limits.dart';
 export 'src/services/contracts.dart';
+export 'src/services/backend.dart';
 export 'src/services/dummy.dart';
 export 'src/services/photos.dart';

frontend/packages/sxchnge_kyc/pubspec.yaml

@@ -6,6 +6,7 @@ environment:
   sdk: '>=3.13.0 <4.0.0'
   flutter: '>=3.47.0'
 dependencies:
+  http: ^1.6.0
   flutter:
     sdk: flutter
   image: ^4.9.0

frontend/packages/sxchnge_kyc/test/backend_test.dart

@@ -0,0 +1,161 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+
+import 'package:sxchnge_kyc/sxchnge_kyc.dart';
+
+String response({String status = 'pending'}) => jsonEncode({
+  'status': 'success',
+  'data': {
+    'status': status,
+    'submissionId': 'submission',
+    'profile': {
+      'fullName': 'Legal Name',
+      'dateOfBirth': '1990-04-23',
+      'residenceCountry': 'PL',
+    },
+  },
+});
+void main() {
+  test('an approved review with an unfinished upgrade stays pending and cannot resubmit', () async {
+    final payload = jsonDecode(response()) as Map<String, dynamic>;
+    (payload['data'] as Map<String, dynamic>)['upgradePending'] = true;
+    final service = BackendIdentityService(
+      baseUri: Uri.parse('https://api.example.test'),
+      accessToken: () => 'token',
+      client: MockClient((_) async => http.Response(jsonEncode(payload), 200)),
+    );
+    addTearDown(service.close);
+    final result = await service.fetch();
+    expect(result.status, IdentityStatus.pending);
+    expect(result.upgradePending, true);
+    expect(result.canSubmit, false);
+  });
+  test(
+    'uploads profile plus both files, credentials scoped to current session',
+    () async {
+      final service = BackendIdentityService(
+        baseUri: Uri.parse('https://api.example.test/api/v1'),
+        accessToken: () => 'session-token',
+        client: MockClient((request) async {
+          expect(request.url.path, '/api/v1/accounts/identity');
+          expect(request.headers['Authorization'], 'Bearer session-token');
+          expect(request.followRedirects, false);
+          expect(
+            request.headers['content-type'],
+            contains('multipart/form-data'),
+          );
+          expect(request.body, contains('name="document"'));
+          expect(request.body, contains('name="selfie"'));
+          expect(request.body, contains('"fullName":"Legal Name"'));
+          expect(request.body, contains('stable-key'));
+          expect(request.body, isNot(contains('customer_ref')));
+          return http.Response(response(), 200);
+        }),
+      );
+      addTearDown(service.close);
+      final result = await service.submit(
+        profile: const IdentityProfile(
+          fullName: 'Legal Name',
+          dateOfBirth: '1990-04-23',
+          residenceCountry: 'PL',
+        ),
+        passport: Photo(Uint8List.fromList([1])),
+        selfie: Photo(Uint8List.fromList([2])),
+        idempotencyKey: 'stable-key',
+      );
+      expect(result.status, IdentityStatus.pending);
+      expect(result.simulated, false);
+    },
+  );
+  test('session switch rejects a late response', () async {
+    var token = 'first';
+    final pending = Completer<http.Response>();
+    final service = BackendIdentityService(
+      baseUri: Uri.parse('https://api.example.test'),
+      accessToken: () => token,
+      client: MockClient((_) => pending.future),
+    );
+    addTearDown(service.close);
+    final result = service.fetch();
+    token = 'second';
+    pending.complete(http.Response(response(), 200));
+    await expectLater(
+      result,
+      throwsA(
+        isA<KycException>().having(
+          (e) => e.code,
+          'code',
+          KycError.sessionExpired,
+        ),
+      ),
+    );
+  });
+  test(
+    'production limits preserve exact decimals and never use demo rows',
+    () async {
+      final service = BackendIdentityService(
+        baseUri: Uri.parse('https://api.example.test'),
+        accessToken: () => 'token',
+        client: MockClient((request) async {
+          expect(request.url.path, '/accounts/limits');
+          return http.Response(
+            jsonEncode({
+              'status': 'success',
+              'data': {
+                'tier': 'verified',
+                'profileRef': 'verified-policy',
+                'entries': [
+                  {
+                    'operation': 'Transfer',
+                    'period': 'day',
+                    'currency': 'BTC',
+                    'cap': '0.12345678',
+                    'remaining': '0.10000001',
+                    'used': '0.02',
+                    'reserved': '0.00345677',
+                  },
+                ],
+              },
+            }),
+            200,
+          );
+        }),
+      );
+      addTearDown(service.close);
+      final result = await BackendLimitsService(service).fetch();
+      expect(result.rows, isEmpty);
+      expect(result.simulated, false);
+      expect(result.entries.single.cap, '0.12345678');
+      expect(result.tier, AccountTier.verified);
+    },
+  );
+  test(
+    'unavailable, conflict and expired sessions retain typed recovery',
+    () async {
+      for (final pair in [
+        (503, KycError.unavailable),
+        (409, KycError.conflict),
+        (401, KycError.sessionExpired),
+      ]) {
+        final service = BackendIdentityService(
+          baseUri: Uri.parse('https://api.example.test'),
+          accessToken: () => 'token',
+          client: MockClient(
+            (_) async => http.Response('private upstream details', pair.$1),
+          ),
+        );
+        addTearDown(service.close);
+        await expectLater(
+          service.fetch(),
+          throwsA(isA<KycException>().having((e) => e.code, 'code', pair.$2)),
+        );
+      }
+    },
+  );
+}

frontend/packages/sxchnge_kyc/test/kyc_test.dart

@@ -37,6 +37,13 @@ class BrokenAnalytics implements AnalyticsService {
 Future<void> draft(IdentityProvider p) async {
   await p.refresh();
   p.start();
+  p.updateProfile(
+    const IdentityProfile(
+      fullName: "Example Person",
+      dateOfBirth: "1990-04-23",
+      residenceCountry: "PL",
+    ),
+  );
   await p.pick(PhotoKind.passport);
   p.next();
   await p.pick(PhotoKind.selfie);
@@ -170,6 +177,11 @@ void main() {
       1,
     );
     final replay = await service.submit(
+      profile: const IdentityProfile(
+        fullName: "Example Person",
+        dateOfBirth: "1990-04-23",
+        residenceCountry: "PL",
+      ),
       passport: photos.result!,
       selfie: photos.result!,
       idempotencyKey: p.record!.submissionId!,

frontend/packages/sxchnge_kyc/test/onboarding_test.dart

@@ -0,0 +1,41 @@
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:sxchnge_kyc/sxchnge_kyc.dart';
+
+class RealIdentity extends DummyIdentityService {
+  IdentityStatus status = IdentityStatus.unverified;
+  bool unavailable = false;
+  @override
+  bool get isSimulated => false;
+  @override
+  Future<Identity> fetch() async {
+    if (unavailable) throw const KycException(KycError.unavailable);
+    return Identity(status: status);
+  }
+}
+
+void main() {
+  test('offers optional verification once to a basic customer and allows later corrections', () async {
+    final service = RealIdentity(),
+        provider = IdentityOnboardingProvider(RealIdentity());
+    expect(await provider.offer('customer'), true);
+    expect(await provider.offer('customer'), false);
+    final subject = IdentityOnboardingProvider(service);
+    service.status = IdentityStatus.pending;
+    expect(await subject.offer('pending'), false);
+    service.status = IdentityStatus.approved;
+    expect(await subject.offer('approved'), false);
+    service.status = IdentityStatus.changesRequested;
+    expect(await subject.offer('correction'), true);
+  });
+  test(
+    'a failed optional identity dependency never blocks basic login',
+    () async {
+      final service = RealIdentity()..unavailable = true;
+      expect(
+        await IdentityOnboardingProvider(service).offer('customer'),
+        false,
+      );
+    },
+  );
+}

frontend/packages/sxchnge_wallet/README.md

@@ -32,8 +32,9 @@ wallet state changes. The adapter reuses the KYC package's limit DTO and mapper.
 
 ## Integration boundary
 
-Replace `WalletService` and `LimitsService` together with authenticated backend
+Backend mode now uses `BackendWalletService` and `WalletFactorService` with the
-adapters. The backend must provide authorization, authoritative quotes/balances,
+authenticated BFF; `BackendLimitsService` supplies the reviewed platform projection.
+See [payment provisioning and rollout](../../../docs/payments.md). The backend must provide authorization, authoritative quotes/balances,
 atomic limits enforcement, durable idempotency and operation reconciliation.
 Add supported payment methods and validated recipients from that contract, rather
 than interpreting the demo input as production bank validation. Replace profile

frontend/packages/sxchnge_wallet/lib/src/mappers/backend.dart

@@ -0,0 +1,52 @@
+import 'package:sxchnge_auth/sxchnge_auth.dart';
+
+import '../models/wallet.dart';
+import '../transport/backend.dart';
+import '../transport/wallet.dart';
+
+abstract final class BackendMapper {
+  static Map<String, Object?> request(TransferRequest r) => {
+    'kind': r.kind.name,
+    'source': r.source,
+    'destination': r.destination ?? '',
+    'amount': r.amount,
+    'recipient': r.recipient,
+  };
+  static WalletSnapshot snapshot(BackendDTO d) => WalletSnapshot(
+    accounts: d.accounts.map(WalletMapper.account).toList(),
+    operations: d.operations.map(WalletMapper.operation).toList(),
+  );
+  static Quote quote(BackendDTO d) => WalletMapper.quote(d.quoteValue);
+  static WalletOperation? operation(BackendDTO d) => d.operationValue == null
+      ? null
+      : WalletMapper.operation(d.operationValue!);
+  static AccountProfile profile(BackendDTO d) =>
+      WalletMapper.profile(ProfileDTO(d.locale));
+  static FactorChallenge challenge(
+    BackendDTO d,
+    FactorPurpose purpose,
+    String operation,
+  ) {
+    final c = d.challenge;
+    return FactorChallenge(
+      id: c.id,
+      purpose: purpose,
+      operation: operation,
+      target: c.target,
+      expiresAt: c.expires,
+      resendAt: c.resend,
+    );
+  }
+
+  static WalletError failure(BackendDTO d) =>
+      WalletError.values.where((v) => v.name == d.error).firstOrNull ??
+      WalletError.unavailable;
+  static FactorError factorFailure(BackendDTO d) => switch (d.error) {
+    'factorInvalid' => FactorError.invalid,
+    'factorExpired' || 'expiredQuote' => FactorError.expired,
+    'factorLocked' => FactorError.locked,
+    'factorCooldown' => FactorError.cooldown,
+    'factorRequired' => FactorError.required,
+    _ => FactorError.unavailable,
+  };
+}

frontend/packages/sxchnge_wallet/lib/src/models/wallet.dart

@@ -25,9 +25,14 @@ class CurrencyAccount {
     required this.currency,
     required this.precision,
     required this.available,
+    this.payoutMethod = '',
+    this.payoutLabel = '',
+    this.canFund = true,
   });
   final String id, currency;
   final int precision, available;
+  final String payoutMethod, payoutLabel;
+  final bool canFund;
 
   /// Locale-aware decimal input, integer money. Grouping/exponents are rejected.
   int? parse(String input) {

frontend/packages/sxchnge_wallet/lib/src/providers/transfer.dart

@@ -19,6 +19,8 @@ class TransferProvider extends ChangeNotifier {
             .firstOrNull
             ?.id ??
         'usd';
+    wallet.addListener(_walletChanged);
+    _syncAccounts();
     final op = recorder.begin(
       journey,
       JourneyStep.transferDraft,
@@ -26,6 +28,30 @@ class TransferProvider extends ChangeNotifier {
     );
     recorder.finish(op, simulated: wallet.service.isSimulated);
   }
+  void _syncAccounts() {
+    final accounts = wallet.data?.accounts;
+    if (accounts == null ||
+        accounts.isEmpty ||
+        busy ||
+        uncertain ||
+        quote != null)
+      return;
+    if (!accounts.any((a) => a.id == source)) source = accounts.first.id;
+    if (!accounts.any((a) => a.id == destination) || destination == source) {
+      destination = accounts.where((a) => a.id != source).firstOrNull?.id;
+    }
+    if (!wallet.service.isSimulated && kind == TransferKind.payout) {
+      recipient = wallet.account(source)?.payoutMethod ?? '';
+    }
+  }
+
+  void _walletChanged() {
+    if (_disposed) return;
+    final previous = source;
+    _syncAccounts();
+    if (source != previous) notifyListeners();
+  }
+
   final WalletProvider wallet;
   final TransferKind kind;
   final JourneyRecorder recorder;
@@ -45,7 +71,8 @@ class TransferProvider extends ChangeNotifier {
     TransferKind.exchange => JourneyKind.exchange,
     TransferKind.payout => JourneyKind.payout,
   };
-  bool get hasDraft => amount.isNotEmpty || recipient.isNotEmpty;
+  bool get hasDraft =>
+      amount.isNotEmpty || (wallet.service.isSimulated && recipient.isNotEmpty);
   bool get expired =>
       quote != null && !DateTime.now().isBefore(quote!.expiresAt);
   void change({
@@ -59,6 +86,7 @@ class TransferProvider extends ChangeNotifier {
     this.destination = destination ?? this.destination;
     this.amount = amount ?? this.amount;
     this.recipient = recipient ?? this.recipient;
+    if (source != null) _syncAccounts();
     quote = null;
     noSubmission = false;
     error = null;
@@ -171,6 +199,7 @@ class TransferProvider extends ChangeNotifier {
     error = null;
     factorError = null;
     notifyListeners();
+    _key ??= approval?.token;
     _key ??= List.generate(
       16,
       (_) => Random.secure().nextInt(256).toRadixString(16).padLeft(2, '0'),
@@ -266,6 +295,7 @@ class TransferProvider extends ChangeNotifier {
   @override
   void dispose() {
     _disposed = true;
+    wallet.removeListener(_walletChanged);
     recipient = '';
     if (!_handedOff) recorder.dispose();
     super.dispose();

frontend/packages/sxchnge_wallet/lib/src/providers/wallet.dart

@@ -140,6 +140,21 @@ class WalletProvider extends ChangeNotifier {
     return !saveFailed;
   }
 
+  /// Drop account-scoped state when the authenticated customer changes.
+  void reset() {
+    _revision++;
+    _poll?.cancel();
+    for (final pair in _settlements.values) {
+      pair.$1.dispose(abandonActive: false);
+    }
+    _settlements.clear();
+    data = null;
+    preferredLocale = null;
+    loading = failed = profileLoading = profileFailed = saving = saveFailed =
+        false;
+    notifyListeners();
+  }
+
   @override
   void dispose() {
     _disposed = true;

frontend/packages/sxchnge_wallet/lib/src/services/backend.dart

@@ -0,0 +1,130 @@
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+
+import 'package:http/http.dart' as http;
+
+import 'package:sxchnge_auth/sxchnge_auth.dart';
+
+import '../mappers/backend.dart';
+import '../models/wallet.dart';
+import '../transport/backend.dart';
+import 'contracts.dart';
+import 'http/client.dart';
+
+class BackendWalletService implements WalletService {
+  BackendWalletService({
+    required this.baseUri,
+    required this.accessToken,
+    http.Client? client,
+  }) : _client = client ?? createClient() {
+    if (!baseUri.hasAuthority ||
+        baseUri.hasQuery ||
+        baseUri.hasFragment ||
+        baseUri.userInfo.isNotEmpty ||
+        (baseUri.scheme != 'https' &&
+            !(baseUri.scheme == 'http' &&
+                ['localhost', '127.0.0.1'].contains(baseUri.host))))
+      throw ArgumentError('Valid wallet API URL required');
+  }
+  final Uri baseUri;
+  final String? Function() accessToken;
+  final http.Client _client;
+  @override
+  bool get isSimulated => false;
+  Future<BackendDTO> send(
+    String path, {
+    Map<String, Object?>? body,
+    bool factor = false,
+  }) async {
+    final token = accessToken();
+    if (token == null) throw const WalletException(WalletError.unavailable);
+    final uri = baseUri.replace(
+      path:
+          '${baseUri.path.replaceFirst(RegExp(r"/$"), "")}/accounts/wallet$path',
+    );
+    final request = http.Request(body == null ? 'GET' : 'POST', uri)
+      ..followRedirects = false;
+    request.headers.addAll({
+      'Authorization': 'Bearer $token',
+      'Content-Type': 'application/json',
+      if (kIsWeb) 'X-CSRF-Protection': '1',
+    });
+    if (body != null) request.body = jsonEncode(body);
+    try {
+      final response = await _client
+          .send(request)
+          .then(http.Response.fromStream)
+          .timeout(const Duration(seconds: 40));
+      if (token != accessToken())
+        throw const WalletException(WalletError.unavailable);
+      final dto = BackendDTO.decode(response.body);
+      if (response.statusCode < 200 ||
+          response.statusCode >= 300 ||
+          !dto.accepted) {
+        if (factor || dto.error.startsWith('factor'))
+          throw FactorException(BackendMapper.factorFailure(dto));
+        throw WalletException(BackendMapper.failure(dto));
+      }
+      return dto;
+    } on FactorException {
+      rethrow;
+    } on WalletException {
+      rethrow;
+    } catch (_) {
+      throw const WalletException(WalletError.unavailable);
+    }
+  }
+
+  Future<T> _mapped<T>(
+    Future<BackendDTO> dto,
+    T Function(BackendDTO) map,
+  ) async {
+    try {
+      return map(await dto);
+    } on FactorException {
+      rethrow;
+    } on WalletException {
+      rethrow;
+    } catch (_) {
+      throw const WalletException(WalletError.unavailable);
+    }
+  }
+
+  @override
+  Future<WalletSnapshot> fetch() => _mapped(send(''), BackendMapper.snapshot);
+  @override
+  Future<Quote> quote(TransferRequest request) => _mapped(
+    send('/quote', body: BackendMapper.request(request)),
+    BackendMapper.quote,
+  );
+  @override
+  Future<WalletOperation> submit(
+    String quoteId,
+    String idempotencyKey, {
+    String? approval,
+  }) async {
+    final value = await _mapped(
+      send(
+        '/submit',
+        body: {'quoteId': quoteId, 'idempotencyKey': idempotencyKey},
+      ),
+      BackendMapper.operation,
+    );
+    if (value == null) throw const WalletException(WalletError.uncertain);
+    return value;
+  }
+
+  @override
+  Future<WalletOperation?> findSubmission(String idempotencyKey) => _mapped(
+    send('/submission', body: {'idempotencyKey': idempotencyKey}),
+    BackendMapper.operation,
+  );
+  @override
+  Future<AccountProfile> profile() =>
+      _mapped(send('/profile'), BackendMapper.profile);
+  @override
+  Future<AccountProfile> saveLocale(String locale) async =>
+      throw const WalletException(WalletError.unsupported);
+  void close() => _client.close();
+}

frontend/packages/sxchnge_wallet/lib/src/services/factors.dart

@@ -0,0 +1,149 @@
+import 'dart:math';
+
+import 'package:sxchnge_auth/sxchnge_auth.dart';
+
+import '../mappers/backend.dart';
+import '../transport/backend.dart';
+import 'backend.dart';
+
+/// Composes authentication factors with quote-bound payment authorization.
+/// Money codes authorize a durable BFF intent; raw verification proofs remain
+/// server-side and cannot be reused as login grants.
+class WalletFactorService implements TwoFactorService {
+  WalletFactorService(this.wallet, this.auth);
+  final BackendWalletService wallet;
+  final TwoFactorService auth;
+  final _challenges = <String, FactorChallenge>{};
+  final _keys = <String, String>{};
+  final _resends = <String, String>{};
+  String _key() => List.generate(
+    24,
+    (_) => Random.secure().nextInt(256).toRadixString(16).padLeft(2, '0'),
+  ).join();
+  String? _token;
+  @override
+  bool get isSimulated => false;
+  void _session({bool required = true}) {
+    final token = wallet.accessToken();
+    if (token != _token) {
+      _challenges.clear();
+      _keys.clear();
+      _resends.clear();
+      _token = token;
+    }
+    if (required && token == null)
+      throw const FactorException(FactorError.unavailable);
+  }
+
+  Future<T> _mapped<T>(
+    Future<BackendDTO> dto,
+    T Function(BackendDTO) map,
+  ) async {
+    final token = wallet.accessToken();
+    try {
+      final value = await dto;
+      if (token != wallet.accessToken())
+        throw const FactorException(FactorError.unavailable);
+      return map(value);
+    } on FactorException {
+      rethrow;
+    } catch (_) {
+      throw const FactorException(FactorError.unavailable);
+    }
+  }
+
+  @override
+  Future<FactorChallenge?> begin(
+    FactorPurpose purpose,
+    String operation,
+  ) async {
+    if (![
+      FactorPurpose.topUp,
+      FactorPurpose.exchange,
+      FactorPurpose.payout,
+    ].contains(purpose))
+      return auth.begin(purpose, operation);
+    _session();
+    final c = await _mapped(
+      wallet.send('/challenge', body: {'quoteId': operation}, factor: true),
+      (d) => BackendMapper.challenge(d, purpose, operation),
+    );
+    _session();
+    _challenges[c.id] = c;
+    _keys.putIfAbsent(
+      operation,
+      () => List.generate(
+        24,
+        (_) => Random.secure().nextInt(256).toRadixString(16).padLeft(2, '0'),
+      ).join(),
+    );
+    return c;
+  }
+
+  @override
+  Future<FactorChallenge> resend(String challengeId) async {
+    _session(required: false);
+    final c = _challenges[challengeId];
+    if (c == null) return auth.resend(challengeId);
+    final result = await _mapped(
+      wallet.send(
+        '/resend',
+        body: {
+          'quoteId': c.operation,
+          'challengeId': c.id,
+          'idempotencyKey': _resends.putIfAbsent(c.id, _key),
+        },
+        factor: true,
+      ),
+      (d) => BackendMapper.challenge(d, c.purpose, c.operation),
+    );
+    _session();
+    _resends.remove(c.id);
+    _challenges[result.id] = result;
+    return result;
+  }
+
+  @override
+  Future<FactorGrant> verify(String challengeId, String code) async {
+    _session(required: false);
+    final c = _challenges[challengeId];
+    if (c == null) return auth.verify(challengeId, code);
+    final key = _keys[c.operation]!;
+    return _mapped(
+      wallet.send(
+        '/verify',
+        body: {
+          'quoteId': c.operation,
+          'challengeId': c.id,
+          'code': code,
+          'idempotencyKey': key,
+        },
+        factor: true,
+      ),
+      (d) {
+        if (d.key != key) throw const FactorException(FactorError.unavailable);
+        return FactorGrant(key);
+      },
+    );
+  }
+
+  @override
+  Future<FactorSettings> fetch() => auth.fetch();
+  @override
+  Future<FactorSettings> setEnabled(bool enabled, String grant) =>
+      auth.setEnabled(enabled, grant);
+  @override
+  Future<void> authorize(
+    FactorPurpose purpose,
+    String operation,
+    String? grant,
+  ) async {
+    if ([
+      FactorPurpose.topUp,
+      FactorPurpose.exchange,
+      FactorPurpose.payout,
+    ].contains(purpose))
+      throw const FactorException(FactorError.required);
+    await auth.authorize(purpose, operation, grant);
+  }
+}

frontend/packages/sxchnge_wallet/lib/src/services/http/browser.dart

@@ -0,0 +1,4 @@
+import 'package:http/browser_client.dart';
+import 'package:http/http.dart' as http;
+
+http.Client createClient() => BrowserClient()..withCredentials = true;

frontend/packages/sxchnge_wallet/lib/src/services/http/client.dart

@@ -0,0 +1 @@
+export 'native.dart' if (dart.library.js_interop) 'browser.dart';

frontend/packages/sxchnge_wallet/lib/src/services/http/native.dart

@@ -0,0 +1,3 @@
+import 'package:http/http.dart' as http;
+
+http.Client createClient() => http.Client();

frontend/packages/sxchnge_wallet/lib/src/transport/backend.dart

@@ -0,0 +1,78 @@
+import 'dart:convert';
+
+import 'wallet.dart';
+
+/// Local BFF transport only; provider and widgets never parse response maps.
+class BackendDTO {
+  BackendDTO.decode(String body) {
+    final envelope = jsonDecode(body) as Map<String, dynamic>;
+    accepted = envelope['status'] == 'success';
+    data = envelope['data'];
+  }
+  late final bool accepted;
+  late final dynamic data;
+  String get error =>
+      (data as Map<String, dynamic>?)?['error'] as String? ?? 'unavailable';
+  String get locale => (data as Map<String, dynamic>)['locale'] as String;
+  String get key => (data as Map<String, dynamic>)['idempotencyKey'] as String;
+  List<AccountDTO> get accounts =>
+      ((data as Map<String, dynamic>)['accounts'] as List).map((v) {
+        final d = v as Map<String, dynamic>;
+        return AccountDTO(
+          d['id'] as String,
+          d['currency'] as String,
+          d['precision'] as int,
+          d['available'] as int,
+          payoutMethod: d['payoutMethod'] as String,
+          payoutLabel: d['payoutLabel'] as String,
+          canFund: d['canFund'] as bool,
+        );
+      }).toList();
+  List<OperationDTO> get operations =>
+      ((data as Map<String, dynamic>)['operations'] as List)
+          .map((v) => operation(v as Map<String, dynamic>))
+          .toList();
+  QuoteDTO get quoteValue => quote(data as Map<String, dynamic>);
+  OperationDTO? get operationValue =>
+      data == null ? null : operation(data as Map<String, dynamic>);
+  static QuoteDTO quote(Map<String, dynamic> d) {
+    final r = d['request'] as Map<String, dynamic>;
+    return QuoteDTO(
+      d['id'] as String,
+      RequestDTO(
+        r['kind'] as String,
+        r['source'] as String,
+        (r['destination'] as String?)?.isEmpty == true
+            ? null
+            : r['destination'] as String?,
+        r['amount'] as int,
+        r['recipient'] as String? ?? '',
+      ),
+      d['fee'] as int,
+      d['debit'] as int,
+      d['credit'] as int,
+      DateTime.parse(d['expiresAt'] as String),
+      d['rateNumerator'] as int,
+      d['rateDenominator'] as int,
+    );
+  }
+
+  static OperationDTO operation(Map<String, dynamic> d) => OperationDTO(
+    d['id'] as String,
+    quote(d['quote'] as Map<String, dynamic>),
+    DateTime.parse(d['createdAt'] as String),
+    DateTime.parse(d['createdAt'] as String),
+    status: d['status'] as String,
+  );
+  ChallengeDTO get challenge => ChallengeDTO(data as Map<String, dynamic>);
+}
+
+class ChallengeDTO {
+  ChallengeDTO(Map<String, dynamic> d)
+    : id = d['challengeId'] as String,
+      target = d['target'] as String,
+      expires = DateTime.parse(d['expiresAt'] as String),
+      resend = DateTime.parse(d['resendAt'] as String);
+  final String id, target;
+  final DateTime expires, resend;
+}

frontend/packages/sxchnge_wallet/lib/src/transport/wallet.dart

@@ -1,7 +1,17 @@
 import '../models/wallet.dart';
 
 class AccountDTO {
-  AccountDTO(this.id, this.currency, this.precision, this.available);
+  AccountDTO(
+    this.id,
+    this.currency,
+    this.precision,
+    this.available, {
+    this.payoutMethod = '',
+    this.payoutLabel = '',
+    this.canFund = true,
+  });
+  final String payoutMethod, payoutLabel;
+  final bool canFund;
   final String id, currency;
   final int precision;
   int available;
@@ -64,6 +74,9 @@ abstract final class WalletMapper {
     currency: d.currency,
     precision: d.precision,
     available: d.available,
+    payoutMethod: d.payoutMethod,
+    payoutLabel: d.payoutLabel,
+    canFund: d.canFund,
   );
   static RequestDTO request(TransferRequest r) =>
       RequestDTO(r.kind.name, r.source, r.destination, r.amount, r.recipient);

frontend/packages/sxchnge_wallet/lib/sxchnge_wallet.dart

@@ -4,3 +4,5 @@ export 'src/providers/transfer.dart';
 export 'src/services/contracts.dart';
 export 'src/services/dummy.dart';
 export 'src/providers/limits.dart';
+export 'src/services/backend.dart';
+export 'src/services/factors.dart';

frontend/packages/sxchnge_wallet/pubspec.yaml

@@ -6,6 +6,7 @@ environment:
   sdk: '>=3.13.0 <4.0.0'
   flutter: '>=3.47.0'
 dependencies:
+  http: ^1.6.0
   flutter:
     sdk: flutter
   sxchnge_auth:

frontend/packages/sxchnge_wallet/test/backend_test.dart

@@ -0,0 +1,245 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+
+import 'package:sxchnge_analytics/sxchnge_analytics.dart';
+
+import 'package:sxchnge_auth/sxchnge_auth.dart';
+
+import 'package:sxchnge_wallet/sxchnge_wallet.dart';
+
+Map<String, Object?> quoteData() => {
+  'id': 'local-quote',
+  'request': {
+    'kind': 'payout',
+    'source': 'ledger',
+    'destination': '',
+    'recipient': 'Saved bank ending 1234',
+    'amount': 2001,
+  },
+  'fee': 100,
+  'debit': 2101,
+  'credit': 2001,
+  'expiresAt': DateTime.now()
+      .add(const Duration(minutes: 5))
+      .toUtc()
+      .toIso8601String(),
+  'rateNumerator': 1,
+  'rateDenominator': 1,
+};
+Map<String, Object?> operationData(String status) => {
+  'id': 'local-quote',
+  'quote': quoteData(),
+  'status': status,
+  'createdAt': DateTime.now().toUtc().toIso8601String(),
+};
+http.Response success(Object? data) =>
+    http.Response(jsonEncode({'status': 'success', 'data': data}), 200);
+void main() {
+  test('backend wallet maps accounts, authoritative quote, execution and reconciliation', () async {
+    final requests = <http.Request>[];
+    final service = BackendWalletService(
+      baseUri: Uri.parse('https://bff.example/api/v1'),
+      accessToken: () => 'session',
+      client: MockClient((r) async {
+        requests.add(r);
+        expect(r.headers['Authorization'], 'Bearer session');
+        expect(r.followRedirects, false);
+        switch (r.url.path) {
+          case '/api/v1/accounts/wallet':
+            return success({
+              'accounts': [
+                {
+                  'id': 'ledger',
+                  'currency': 'EUR',
+                  'precision': 2,
+                  'available': 7500,
+                  'payoutMethod': 'method',
+                  'payoutLabel': 'Saved bank ending 1234',
+                  'canFund': false,
+                },
+              ],
+              'operations': <Object>[],
+            });
+          case '/api/v1/accounts/wallet/quote':
+            expect(jsonDecode(r.body), {
+              'kind': 'payout',
+              'source': 'ledger',
+              'destination': '',
+              'amount': 2001,
+              'recipient': 'method',
+            });
+            return success(quoteData());
+          case '/api/v1/accounts/wallet/submit':
+            expect(jsonDecode(r.body), {
+              'quoteId': 'local-quote',
+              'idempotencyKey': 'authorized-key',
+            });
+            return success(operationData('pending'));
+          case '/api/v1/accounts/wallet/submission':
+            return success(operationData('completed'));
+          default:
+            return success({'locale': 'ru'});
+        }
+      }),
+    );
+    addTearDown(service.close);
+    expect(service.isSimulated, false);
+    final data = await service.fetch();
+    expect(data.accounts.single.available, 7500);
+    expect(data.accounts.single.payoutLabel, 'Saved bank ending 1234');
+    final q = await service.quote(
+      const TransferRequest(
+        kind: TransferKind.payout,
+        source: 'ledger',
+        recipient: 'method',
+        amount: 2001,
+      ),
+    );
+    expect(q.debit, 2101);
+    expect(q.request.recipient, 'Saved bank ending 1234');
+    expect(
+      (await service.submit(q.id, 'authorized-key')).status,
+      OperationStatus.pending,
+    );
+    expect(
+      (await service.findSubmission('authorized-key'))!.status,
+      OperationStatus.completed,
+    );
+    expect((await service.profile()).locale, 'ru');
+    expect(requests.length, 5);
+  });
+  test('session replacement rejects late responses and never returns stale balances', () async {
+    String? token = 'one';
+    final response = Completer<http.Response>();
+    final service = BackendWalletService(
+      baseUri: Uri.parse('https://bff.example'),
+      accessToken: () => token,
+      client: MockClient((_) => response.future),
+    );
+    addTearDown(service.close);
+    final result = service.fetch();
+    token = 'two';
+    response.complete(success({'accounts': [], 'operations': []}));
+    await expectLater(result, throwsA(isA<WalletException>()));
+    token = null;
+    await expectLater(service.fetch(), throwsA(isA<WalletException>()));
+  });
+  test(
+    'malformed or unsuccessful responses cannot report payment success',
+    () async {
+      for (final response in [
+        http.Response('broken', 200),
+        http.Response('{"status":"error","data":{"error":"uncertain"}}', 503),
+        success(null),
+      ]) {
+        final service = BackendWalletService(
+          baseUri: Uri.parse('https://bff.example'),
+          accessToken: () => 'session',
+          client: MockClient((_) async => response),
+        );
+        await expectLater(
+          service.submit('quote', 'key'),
+          throwsA(isA<WalletException>()),
+        );
+        service.close();
+      }
+    },
+  );
+  test(
+    'payment factor keeps authorization and resend keys stable across retry',
+    () async {
+      final bodies = <Map<String, dynamic>>[];
+      var fail = true;
+      final wallet = BackendWalletService(
+        baseUri: Uri.parse('https://bff.example'),
+        accessToken: () => 'session',
+        client: MockClient((r) async {
+          final body = jsonDecode(r.body) as Map<String, dynamic>;
+          bodies.add(body);
+          if (r.url.path.endsWith('/verify')) {
+            if (fail) {
+              fail = false;
+              return http.Response(
+                '{"status":"error","data":{"error":"factorInvalid"}}',
+                400,
+              );
+            }
+            return success({'idempotencyKey': body['idempotencyKey']});
+          }
+          return success({
+            'challengeId': 'challenge',
+            'target': 'a***@example.com',
+            'expiresAt': DateTime.now()
+                .add(const Duration(minutes: 1))
+                .toUtc()
+                .toIso8601String(),
+            'resendAt': DateTime.now().toUtc().toIso8601String(),
+          });
+        }),
+      );
+      addTearDown(wallet.close);
+      final factor = WalletFactorService(wallet, DummyTwoFactorService());
+      final challenge = (await factor.begin(FactorPurpose.payout, 'quote'))!;
+      await expectLater(
+        factor.verify(challenge.id, 'bad'),
+        throwsA(
+          isA<FactorException>().having(
+            (e) => e.code,
+            'code',
+            FactorError.invalid,
+          ),
+        ),
+      );
+      final grant = await factor.verify(challenge.id, '123456');
+      expect(grant.token, bodies[1]['idempotencyKey']);
+      expect(bodies[1]['idempotencyKey'], bodies[2]['idempotencyKey']);
+      await factor.resend(challenge.id);
+      expect(bodies.last['idempotencyKey'], isNotEmpty);
+    },
+  );
+  test('provider waits for real account IDs and submits with the authorized intent key', () async {
+    final service = BackendWalletService(
+      baseUri: Uri.parse('https://bff.example'),
+      accessToken: () => 'session',
+      client: MockClient((r) async {
+        if (r.url.path.endsWith('/quote')) return success(quoteData());
+        if (r.url.path.endsWith('/submit')) {
+          expect(jsonDecode(r.body)['idempotencyKey'], 'approved-intent-key');
+          return success(operationData('completed'));
+        }
+        return success({
+          'accounts': [
+            {
+              'id': 'ledger',
+              'currency': 'EUR',
+              'precision': 2,
+              'available': 7500,
+              'payoutMethod': 'method',
+              'payoutLabel': 'Saved bank ending 1234',
+              'canFund': false,
+            },
+          ],
+          'operations': <Object>[],
+        });
+      }),
+    );
+    addTearDown(service.close);
+    final wallet = WalletProvider(service, DummyAnalyticsService());
+    addTearDown(wallet.dispose);
+    final draft = TransferProvider(wallet, TransferKind.payout);
+    addTearDown(draft.dispose);
+    await wallet.refresh();
+    expect(draft.source, 'ledger');
+    expect(draft.recipient, 'method');
+    expect(draft.hasDraft, false);
+    draft.change(amount: '20.01');
+    await draft.review();
+    await draft.submit(approval: const FactorGrant('approved-intent-key'));
+    expect(draft.result, isNotNull);
+  });
+}