Integrate email notifications into signup and login (#38)

backend/notifications/README.md

@@ -40,7 +40,8 @@ Multiple service workers can safely compete for jobs through atomic claims.
 
 ## Templates and parameters
 
-See `templates.example.json`. Parameters use Go template map syntax such as
+See `templates.example.json`, including the `auth.activation` and `auth.login`
+English/Russian templates used by [product authentication](../../docs/auth-notifications.md). Parameters use Go template map syntax such as
 `{{.first_name}}`. Each revision declares the exact allowed parameter names and
 locale-specific content. Missing/extra parameters, unknown revisions/locales and
 invalid content are rejected before acceptance. Empty locale uses the default.

backend/notifications/templates.example.json

@@ -3,7 +3,11 @@
     "id": "exchange.completed",
     "version": "1",
     "default_locale": "en",
-    "parameters": ["first_name", "amount", "currency"],
+    "parameters": [
+      "first_name",
+      "amount",
+      "currency"
+    ],
     "locales": {
       "en": {
         "subject": "Your exchange is complete",
@@ -11,5 +15,45 @@
         "text": "Hi {{.first_name}}, your exchange of {{.amount}} {{.currency}} is complete."
       }
     }
+  },
+  {
+    "id": "auth.activation",
+    "version": "1",
+    "default_locale": "en",
+    "parameters": [
+      "url"
+    ],
+    "locales": {
+      "en": {
+        "subject": "Verify your SXCHNGE email",
+        "text": "Confirm your email: {{.url}}\nThis link expires in 24 hours. If you did not sign up, ignore this email.",
+        "html": "<p>Confirm your email to finish signing up.</p><p><a href=\"{{.url}}\">Verify email</a></p><p>This link expires in 24 hours. If you did not sign up, ignore this email.</p>"
+      },
+      "ru": {
+        "subject": "Подтвердите почту SXCHNGE",
+        "text": "Подтвердите почту: {{.url}}\nСсылка действует 24 часа. Если вы не регистрировались, проигнорируйте письмо.",
+        "html": "<p><a href=\"{{.url}}\">Подтвердить почту</a></p><p>Ссылка действует 24 часа. Если вы не регистрировались, проигнорируйте письмо.</p>"
+      }
+    }
+  },
+  {
+    "id": "auth.login",
+    "version": "1",
+    "default_locale": "en",
+    "parameters": [
+      "code"
+    ],
+    "locales": {
+      "en": {
+        "subject": "Your SXCHNGE login code",
+        "text": "Your login code is {{.code}}. It expires in 10 minutes. Never share this code.",
+        "html": "<p>Your login code is <strong>{{.code}}</strong>.</p><p>It expires in 10 minutes. Never share this code.</p>"
+      },
+      "ru": {
+        "subject": "Код входа SXCHNGE",
+        "text": "Ваш код входа: {{.code}}. Он действует 10 минут. Никому не сообщайте код.",
+        "html": "<p>Ваш код входа: <strong>{{.code}}</strong>.</p><p>Он действует 10 минут. Никому не сообщайте код.</p>"
+      }
+    }
   }
 ]

backend/product/README.md

@@ -24,8 +24,11 @@ organization, role, policy or seed; the runtime creates its indexes.
 The runtime mounts health, login, API login, refresh, rotation and logout routes.
 Customer/application-client records must exist for login. The customer service
 supports atomic account/activation creation and deletion with session revocation.
-Signup/profile HTTP wiring and verification delivery/completion remain follow-up
-work. The frontend still uses dummy services.
+Signup and email verification delivery/completion are available when
+`api.notifications` is configured. Flutter selects the backend using
+`SXCHNGE_API_URL` and `SXCHNGE_CLIENT_ID`. See
+[auth notification setup and contracts](../../docs/auth-notifications.md).
+Profile HTTP wiring remains follow-up work.
 
 Sendico integration is not wired. Its organization context belongs only to the
 future public HTTP adapter. There is no unused public API snapshot in this module;

backend/product/app/api/config.go

@@ -2,13 +2,15 @@ package api
 
 import (
 	mwa "git.sendico.io/tech/sxchnge/product/auth/config"
+	"git.sendico.io/tech/sxchnge/product/notifications"
 	verificationconfig "git.sendico.io/tech/sxchnge/product/verification/config"
 )
 
 type Config struct {
-	Mw           *mwa.Config                `yaml:"middleware"`
-	AuthStorage  *mwa.AuthStorageConfig     `yaml:"auth_storage"`
-	Verification *verificationconfig.Config `yaml:"verification"`
+	Notifications *notifications.Config      `yaml:"notifications"`
+	Mw            *mwa.Config                `yaml:"middleware"`
+	AuthStorage   *mwa.AuthStorageConfig     `yaml:"auth_storage"`
+	Verification  *verificationconfig.Config `yaml:"verification"`
 }
 
 func (c *Config) SharedConfig() *Config {

backend/product/app/http/middleware.go

@@ -7,9 +7,12 @@ import (
 
 	mr "git.sendico.io/tech/sxchnge/product/app/metrics"
 	"git.sendico.io/tech/sxchnge/product/auth/config"
+	"git.sendico.io/tech/sxchnge/product/auth/flow"
 	httprouter "git.sendico.io/tech/sxchnge/product/auth/http"
 	"git.sendico.io/tech/sxchnge/product/auth/response"
 	authstorage "git.sendico.io/tech/sxchnge/product/auth/storage"
+	accountservice "git.sendico.io/tech/sxchnge/product/customers"
+	"git.sendico.io/tech/sxchnge/product/notifications"
 	"git.sendico.io/tech/sxchnge/product/sessions/browser"
 	"git.sendico.io/tech/sxchnge/shared/database"
 	"git.sendico.io/tech/sxchnge/shared/errors"
@@ -26,11 +29,12 @@ import (
 )
 
 type Middleware struct {
-	logger       mlogger.Logger
-	router       *chi.Mux
-	apiEndpoint  string
-	metrics      mr.Metrics
-	epdispatcher *httprouter.Dispatcher
+	notifications *notifications.Client
+	logger        mlogger.Logger
+	router        *chi.Mux
+	apiEndpoint   string
+	metrics       mr.Metrics
+	epdispatcher  *httprouter.Dispatcher
 }
 
 func (mw *Middleware) Handler(service mservice.Type, endpoint string, method api.HTTPMethod, handler sresponse.HandlerFunc) {
@@ -47,6 +51,9 @@ func (mw *Middleware) PendingAccountHandler(service mservice.Type, endpoint stri
 
 func (mw *Middleware) Finish() {
 	mw.metrics.Finish()
+	if mw.notifications != nil {
+		_ = mw.notifications.Close()
+	}
 }
 
 func (mw *Middleware) installMiddleware(config *middleware.Config, debug bool) {
@@ -107,6 +114,7 @@ func CreateMiddleware(
 	config *middleware.Config,
 	authStorage *middleware.AuthStorageConfig,
 	debug bool,
+	notificationConfig ...*notifications.Config,
 ) (*Middleware, error) {
 	if config == nil {
 		return nil, merrors.InvalidArgument("middleware configuration is required", "middleware")
@@ -139,6 +147,23 @@ func CreateMiddleware(
 		return nil, err
 	}
 
+	var authFlow *flow.Service
+	if len(notificationConfig) > 0 && notificationConfig[0] != nil {
+		c := notificationConfig[0]
+		customers, err := accountservice.NewAccountService(p.logger, db, &config.Password, authStorage)
+		if err != nil {
+			return nil, err
+		}
+		authFlow = &flow.Service{Accounts: stores.Accounts, Customers: customers, Tokens: stores.Verification, Transactions: db.TransactionFactory(), Attempts: stores.LoginAttempts, Secret: middleware.SignatureConf(config).PrivateKey, ActivationURL: c.ActivationURL}
+		if err = authFlow.Validate(); err != nil {
+			return nil, err
+		}
+		p.notifications, err = notifications.Open(*c)
+		if err != nil {
+			return nil, err
+		}
+		authFlow.Sender = p.notifications
+	}
 	p.epdispatcher = httprouter.NewDispatcher(
 		p.logger,
 		p.router,
@@ -148,6 +173,7 @@ func CreateMiddleware(
 		stores.LoginAttempts,
 		config,
 		loginRateLimits,
+		authFlow,
 	)
 	return p, nil
 }

backend/product/app/runtime/bootstrap.go

@@ -83,6 +83,7 @@ func (a *APIImp) installRuntimeBasics(
 		a.config.Mw,
 		a.config.AuthStorage,
 		debug,
+		a.config.Notifications,
 	); err != nil {
 		a.logger.Error("Failed to create middleware", zap.Error(err))
 		return err

backend/product/app/runtime/bootstrap_test.go

@@ -2,7 +2,6 @@ package runtime_test
 
 import (
 	"context"
-	sharedmodel "git.sendico.io/tech/sxchnge/shared/model"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -14,6 +13,7 @@ import (
 	"git.sendico.io/tech/sxchnge/product/app/profile"
 	sharedruntime "git.sendico.io/tech/sxchnge/product/app/runtime"
 	"git.sendico.io/tech/sxchnge/shared/database"
+	sharedmodel "git.sendico.io/tech/sxchnge/shared/model"
 	"github.com/go-chi/chi/v5"
 	"github.com/stretchr/testify/require"
 	"github.com/testcontainers/testcontainers-go/modules/mongodb"
@@ -48,6 +48,8 @@ func TestProfileStartsOnEmptyDatabase(t *testing.T) {
 	t.Setenv("SXCHNGE_API_PROTOCOL", "http")
 	t.Setenv("SXCHNGE_API_ENDPOINT", "/api/v1")
 	t.Setenv("SXCHNGE_JWT_SECRET", "test-only-signing-key-at-least-32-bytes")
+	t.Setenv("SXCHNGE_NOTIFICATIONS_TOKEN", "test-notification-token-at-least-32-bytes")
+	example.API.Notifications.CAFile = "" // This startup test makes no notification RPCs.
 	root, routes := chi.NewRouter(), chi.NewRouter()
 	runtime, err := sharedruntime.CreateAPI(ctx, zap.NewNop(), &example.API, &example.API, factory, root, routes, false, profile.Runtime())
 	require.NoError(t, err)

backend/product/auth/flow/service.go

@@ -0,0 +1,215 @@
+// Package flow owns signup and email challenge workflows.
+package flow
+
+import (
+	"context"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"net/mail"
+	"net/url"
+	"strings"
+	"time"
+
+	accountservice "git.sendico.io/tech/sxchnge/product/customers"
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	account "git.sendico.io/tech/sxchnge/product/customers/store"
+	"git.sendico.io/tech/sxchnge/product/notifications"
+	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
+	verification "git.sendico.io/tech/sxchnge/product/verification/store"
+	"git.sendico.io/tech/sxchnge/shared/database/repository"
+	"git.sendico.io/tech/sxchnge/shared/database/transaction"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	ratelimits "git.sendico.io/tech/sxchnge/shared/ratelimit/store"
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+const Cooldown = time.Minute
+const LoginTTL = 10 * time.Minute
+
+type Service struct {
+	Accounts      account.DB
+	Customers     accountservice.AccountService
+	Tokens        verification.DB
+	Transactions  transaction.Factory
+	Attempts      ratelimits.Store
+	Sender        notifications.Sender
+	Secret        []byte
+	ActivationURL string
+}
+
+func (s *Service) Validate() error {
+	u, err := url.Parse(s.ActivationURL)
+	if err != nil || u.Host == "" || (u.Scheme != "https" && !(u.Scheme == "http" && (u.Hostname() == "localhost" || u.Hostname() == "127.0.0.1"))) || u.User != nil || u.Fragment != "" {
+		return merrors.InvalidArgument("activation URL must be an absolute HTTPS URL (HTTP allowed on localhost)")
+	}
+	if len(s.Secret) < 32 {
+		return merrors.InvalidArgument("authentication signing secret must be at least 32 bytes")
+	}
+	return nil
+}
+func NormalizeEmail(email string) (string, error) {
+	email = strings.ToLower(strings.TrimSpace(email))
+	a, err := mail.ParseAddress(email)
+	if err != nil || a.Address != email || len(email) > 254 {
+		return "", merrors.InvalidArgument("valid email required")
+	}
+	return email, nil
+}
+func (s *Service) key(parts ...string) string {
+	h := hmac.New(sha256.New, s.Secret)
+	for _, p := range parts {
+		h.Write([]byte(p))
+		h.Write([]byte{0})
+	}
+	return hex.EncodeToString(h.Sum(nil))
+}
+func (s *Service) Limit(ctx context.Context, ip, email string) error {
+	now := time.Now().UTC()
+	start := now.Truncate(time.Hour)
+	for _, scope := range []struct {
+		kind, value string
+		limit       int
+	}{{"auth_email", email, 10}, {"auth_ip", ip, 30}} {
+		count, err := s.Attempts.Increment(ctx, scope.kind, ratelimits.HashScope(scope.kind, scope.value), start, start.Add(time.Hour))
+		if err != nil {
+			return merrors.ServiceUnavailableWrap(err, "authentication rate limit unavailable")
+		}
+		if count > scope.limit {
+			return verification.ErrorIssuanceRateLimited(scope.kind, start.Add(time.Hour).Sub(now))
+		}
+	}
+	return nil
+}
+func (s *Service) Signup(ctx context.Context, a *customer.Account, ip, key string) (*customer.Account, error) {
+	email, err := NormalizeEmail(a.Login)
+	if err != nil {
+		return nil, err
+	}
+	a.Login = email
+	a.Name = strings.TrimSpace(a.Name)
+	if len(a.Name) > 200 || len(a.Password) > 72 {
+		return nil, merrors.InvalidArgument("name or password too long")
+	}
+	if err = s.Limit(ctx, ip, email); err != nil {
+		return nil, err
+	}
+	raw, err := s.Customers.CreateAccount(ctx, a)
+	if errors.Is(err, merrors.ErrDataConflict) {
+		existing, lookup := s.Accounts.GetByEmail(ctx, email)
+		if lookup != nil {
+			return nil, lookup
+		}
+		// A retry after a queue failure may resume only with the original password.
+		if existing.Status != customer.AccountPendingVerification || !existing.MatchPassword(a.Password) {
+			return nil, merrors.DataConflict("email already registered")
+		}
+		a = existing
+	} else if err != nil {
+		return nil, err
+	}
+	if raw != "" {
+		u, _ := url.Parse(s.ActivationURL)
+		q := u.Query()
+		q.Set("token", raw)
+		u.RawQuery = q.Encode()
+		locale := "en"
+		if strings.HasPrefix(a.Locale, "ru") {
+			locale = "ru"
+		}
+		err = s.Sender.Send(ctx, notifications.Message{Key: s.key("signup", raw), UserID: a.ID.Hex(), Email: a.Login, Locale: locale, Template: "auth.activation", Parameters: map[string]string{"url": u.String()}, ExpiresAt: time.Now().UTC().Add(23 * time.Hour)})
+	} else {
+		_, err = s.Issue(ctx, a, verificationmodel.PurposeAccountActivation, "", key)
+	}
+	return a, err
+}
+func (s *Service) ResendActivation(ctx context.Context, email, ip, key string) error {
+	email, err := NormalizeEmail(email)
+	if err != nil {
+		return err
+	}
+	if err = s.Limit(ctx, ip, email); err != nil {
+		return err
+	}
+	a, err := s.Accounts.GetByEmail(ctx, email)
+	if errors.Is(err, merrors.ErrNoData) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	if a.Status != customer.AccountPendingVerification || a.IsArchived() {
+		return nil
+	}
+	_, err = s.Issue(ctx, a, verificationmodel.PurposeAccountActivation, "", key)
+	return err
+}
+func (s *Service) Issue(ctx context.Context, a *customer.Account, purpose verificationmodel.VerificationPurpose, scope, key string, deadlines ...time.Time) (time.Time, error) {
+	if strings.TrimSpace(key) == "" || len(key) > 128 {
+		return time.Time{}, merrors.InvalidArgument("idempotency key required (maximum 128 characters)")
+	}
+	secretKey := s.key(a.ID.Hex(), string(purpose), scope, key)
+	req := verification.NewOTPRequest(a.ID, purpose, "").WithTTL(LoginTTL).WithMaxRetries(5)
+	if purpose == verificationmodel.PurposeAccountActivation {
+		req = verification.NewLinkRequest(a.ID, purpose, "").WithTTL(24 * time.Hour)
+	}
+	if len(deadlines) > 0 {
+		remaining := time.Until(deadlines[0])
+		if remaining <= 0 {
+			return time.Time{}, verification.ErorrTokenExpired()
+		}
+		if remaining < req.Ttl {
+			req.WithTTL(remaining)
+		}
+	}
+	req.WithContextRef(scope).WithIdempotencyKey(secretKey).WithCooldown(Cooldown)
+	now := time.Now().UTC()
+	// Destination limits span every challenge/context, including password retries.
+	req.WithIssuanceLimits(verification.NewIssuanceLimit("auth_delivery", a.Login, 5, time.Hour, now))
+	result, err := s.Tokens.CreateWithResult(ctx, req)
+	if err != nil {
+		return time.Time{}, err
+	}
+	if !result.ExpiresAt.After(now) {
+		return time.Time{}, verification.ErorrTokenExpired()
+	}
+	locale := "en"
+	if strings.HasPrefix(strings.ToLower(a.Locale), "ru") {
+		locale = "ru"
+	}
+	message := notifications.Message{Key: secretKey, UserID: a.ID.Hex(), Email: a.Login, Locale: locale, Template: "auth.login", ExpiresAt: result.ExpiresAt, Parameters: map[string]string{"code": result.VerificationToken}}
+	if purpose == verificationmodel.PurposeAccountActivation {
+		u, _ := url.Parse(s.ActivationURL)
+		q := u.Query()
+		q.Set("token", result.VerificationToken)
+		u.RawQuery = q.Encode()
+		message.Template = "auth.activation"
+		message.Parameters = map[string]string{"url": u.String()}
+	}
+	// Replay recovers ambiguous RPC failures using the same rendered payload and expiry.
+	if err = s.Sender.Send(ctx, message); err != nil {
+		return time.Time{}, err
+	}
+	return result.ExpiresAt, nil
+}
+func (s *Service) Activate(ctx context.Context, raw string) error {
+	if len(raw) != 43 {
+		return verification.ErorrTokenNotFound()
+	}
+	_, err := s.Transactions.CreateTransaction().Execute(ctx, func(tx context.Context) (any, error) {
+		token, err := s.Tokens.Consume(tx, bson.NilObjectID, verificationmodel.PurposeAccountActivation, "", raw)
+		if err != nil {
+			return nil, err
+		}
+		a := &customer.Account{}
+		if err = s.Accounts.Get(tx, token.AccountRef, a); err != nil {
+			return nil, err
+		}
+		if a.Status != customer.AccountPendingVerification || a.IsArchived() {
+			return nil, merrors.Unauthorized("account cannot be activated")
+		}
+		return nil, s.Accounts.Patch(tx, a.ID, repository.Patch().Set(repository.Field("status"), customer.AccountActive))
+	})
+	return err
+}

backend/product/auth/flow/service_test.go

@@ -0,0 +1,74 @@
+package flow
+
+import (
+	"context"
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	"git.sendico.io/tech/sxchnge/product/notifications"
+	model "git.sendico.io/tech/sxchnge/product/verification/model"
+	verification "git.sendico.io/tech/sxchnge/product/verification/store"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"github.com/stretchr/testify/require"
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"strings"
+	"testing"
+	"time"
+)
+
+type tokenStub struct {
+	verification.DB
+	request *verification.Request
+	result  verification.CreateResult
+	err     error
+}
+
+func (s *tokenStub) CreateWithResult(_ context.Context, r *verification.Request) (verification.CreateResult, error) {
+	s.request = r
+	return s.result, s.err
+}
+
+type senderStub struct {
+	messages []notifications.Message
+	err      error
+}
+
+func (s *senderStub) Send(_ context.Context, m notifications.Message) error {
+	s.messages = append(s.messages, m)
+	return s.err
+}
+func TestIssueRetriesSamePayloadAndBindsServerSecret(t *testing.T) {
+	expiry := time.Now().UTC().Add(time.Minute)
+	tokens := &tokenStub{result: verification.CreateResult{VerificationToken: "123456", ExpiresAt: expiry}}
+	sender := &senderStub{err: merrors.ServiceUnavailable("queue")}
+	service := &Service{Tokens: tokens, Sender: sender, Secret: []byte(strings.Repeat("s", 32))}
+	a := &customer.Account{}
+	a.ID = bson.NewObjectID()
+	a.Login = "user@example.com"
+	a.Locale = "ru-RU"
+	_, err := service.Issue(context.Background(), a, model.PurposeLogin, "pending-scope", "client-key", expiry)
+	require.Error(t, err)
+	key := *tokens.request.IdempotencyKey
+	require.NotEqual(t, "client-key", key)
+	require.Equal(t, "pending-scope", tokens.request.ContextRef)
+	require.LessOrEqual(t, tokens.request.Ttl, time.Minute)
+	sender.err = nil
+	_, err = service.Issue(context.Background(), a, model.PurposeLogin, "pending-scope", "client-key", expiry)
+	require.NoError(t, err)
+	require.Equal(t, sender.messages[0], sender.messages[1])
+	require.Equal(t, "ru", sender.messages[0].Locale)
+	service.Secret = []byte(strings.Repeat("b", 32))
+	require.NotEqual(t, key, service.key(a.ID.Hex(), string(model.PurposeLogin), "pending-scope", "client-key"))
+	tokens.result.ExpiresAt = time.Now().Add(-time.Minute)
+	_, err = service.Issue(context.Background(), a, model.PurposeLogin, "pending-scope", "expired")
+	require.ErrorIs(t, err, verification.ErrTokenExpired)
+	require.Len(t, sender.messages, 2)
+}
+func TestValidateActivationDestination(t *testing.T) {
+	for _, destination := range []string{"https://app.example/verify-email", "http://localhost:5126/verify-email"} {
+		s := &Service{Secret: []byte(strings.Repeat("s", 32)), ActivationURL: destination}
+		require.NoError(t, s.Validate())
+	}
+	for _, destination := range []string{"http://app.example/verify-email", "//app.example", "https://user:pass@app.example/verify-email", "https://app.example/#/verify"} {
+		s := &Service{Secret: []byte(strings.Repeat("s", 32)), ActivationURL: destination}
+		require.Error(t, s.Validate())
+	}
+}

backend/product/auth/http/dispatcher.go

@@ -3,9 +3,8 @@ package router
 import (
 	"os"
 
-	"github.com/go-chi/chi/v5"
-
 	"git.sendico.io/tech/sxchnge/product/auth/config"
+	"git.sendico.io/tech/sxchnge/product/auth/flow"
 	rauthorized "git.sendico.io/tech/sxchnge/product/auth/http/authorized"
 	rpublic "git.sendico.io/tech/sxchnge/product/auth/http/public"
 	"git.sendico.io/tech/sxchnge/product/auth/response"
@@ -16,6 +15,7 @@ import (
 	"git.sendico.io/tech/sxchnge/shared/logging"
 	"git.sendico.io/tech/sxchnge/shared/ratelimit/store"
 	"git.sendico.io/tech/sxchnge/shared/service"
+	"github.com/go-chi/chi/v5"
 )
 
 type Dispatcher struct {
@@ -45,6 +45,7 @@ func NewDispatcher(
 	attempts ratelimits.Store,
 	config *middleware.Config,
 	loginRateLimits middleware.LoginRateLimits,
+	flows ...*flow.Service,
 ) *Dispatcher {
 	d := &Dispatcher{
 		logger: logger.Named("api_dispatcher"),
@@ -54,7 +55,7 @@ func NewDispatcher(
 	endpoint := os.Getenv(config.EndPointEnv)
 	signature := middleware.SignatureConf(config)
 	router.Group(func(r chi.Router) {
-		d.public = rpublic.NewRouter(d.logger, endpoint, db, vdb, rtdb, attempts, r, &config.Token, &signature, loginRateLimits)
+		d.public = rpublic.NewRouter(d.logger, endpoint, db, vdb, rtdb, attempts, r, &config.Token, &signature, loginRateLimits, flows...)
 	})
 	router.Group(func(r chi.Router) {
 		d.protected = rauthorized.NewRouter(d.logger, endpoint, r, db, rtdb, &config.Token, &signature)

backend/product/auth/http/public/login.go

@@ -5,8 +5,6 @@ import (
 	"crypto/subtle"
 	"encoding/json"
 	"errors"
-	customermodel "git.sendico.io/tech/sxchnge/product/customers/model"
-	sessionmodel "git.sendico.io/tech/sxchnge/product/sessions/model"
 	"net/http"
 	"strings"
 
@@ -14,6 +12,8 @@ import (
 	"git.sendico.io/tech/sxchnge/product/auth/ipguard"
 	"git.sendico.io/tech/sxchnge/product/auth/request"
 	"git.sendico.io/tech/sxchnge/product/auth/response"
+	customermodel "git.sendico.io/tech/sxchnge/product/customers/model"
+	sessionmodel "git.sendico.io/tech/sxchnge/product/sessions/model"
 	"git.sendico.io/tech/sxchnge/shared/errors"
 	"git.sendico.io/tech/sxchnge/shared/http/response"
 	"git.sendico.io/tech/sxchnge/shared/logging"
@@ -195,7 +195,7 @@ func decodeLogin(r *http.Request, logger mlogger.Logger) (*srequest.Login, http.
 		return nil, response.BadPayload(logger, mservice.Accounts, err)
 	}
 	req.Login = strings.TrimSpace(req.Login)
-	req.Password = strings.TrimSpace(req.Password)
+	// Preserve passwords exactly as entered.
 	req.ClientID = strings.TrimSpace(req.ClientID)
 	req.DeviceID = strings.TrimSpace(req.DeviceID)
 	req.ClientSecret = strings.TrimSpace(req.ClientSecret)
@@ -225,6 +225,9 @@ func (a *PublicRouter) login(r *http.Request) http.HandlerFunc {
 	if h = a.validateClientAccountBinding(client, account); h != nil {
 		return h
 	}
+	if a.flow != nil {
+		return a.beginLogin(r, account, req.SessionIdentifier, randomKey())
+	}
 	return a.respondPendingLogin(account)
 }
 

backend/product/auth/http/public/metrics.go

@@ -0,0 +1,35 @@
+package public
+
+import (
+	"net/http"
+	"time"
+
+	sresponse "git.sendico.io/tech/sxchnge/product/auth/response"
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var flowRequests = promauto.NewCounterVec(prometheus.CounterOpts{Name: "sxchnge_auth_flow_requests_total", Help: "Authentication flow outcomes; success means this HTTP step completed, not email delivery."}, []string{"operation", "outcome"})
+var flowDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{Name: "sxchnge_auth_flow_duration_seconds", Help: "Authentication HTTP step latency."}, []string{"operation"})
+
+func measured(operation string, handler sresponse.HandlerFunc) sresponse.HandlerFunc {
+	return func(r *http.Request) http.HandlerFunc {
+		start := time.Now()
+		response := handler(r)
+		return func(w http.ResponseWriter, r *http.Request) {
+			wrapped := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+			response(wrapped, r)
+			outcome := "accepted"
+			if wrapped.Status() >= 500 {
+				outcome = "unavailable"
+			} else if wrapped.Status() == 429 {
+				outcome = "limited"
+			} else if wrapped.Status() >= 400 {
+				outcome = "rejected"
+			}
+			flowRequests.WithLabelValues(operation, outcome).Inc()
+			flowDuration.WithLabelValues(operation).Observe(time.Since(start).Seconds())
+		}
+	}
+}

backend/product/auth/http/public/router.go

@@ -4,6 +4,7 @@ import (
 	"time"
 
 	"git.sendico.io/tech/sxchnge/product/auth/config"
+	"git.sendico.io/tech/sxchnge/product/auth/flow"
 	re "git.sendico.io/tech/sxchnge/product/auth/http/endpoint"
 	"git.sendico.io/tech/sxchnge/product/auth/response"
 	"git.sendico.io/tech/sxchnge/product/customers/store"
@@ -17,6 +18,7 @@ import (
 )
 
 type PublicRouter struct {
+	flow      *flow.Service
 	logger    mlogger.Logger
 	db        account.DB
 	imp       *re.HttpEndpointRouter
@@ -44,6 +46,7 @@ func NewRouter(
 	config *middleware.TokenConfig,
 	signature *middleware.Signature,
 	limits middleware.LoginRateLimits,
+	flows ...*flow.Service,
 ) *PublicRouter {
 	l := logger.Named("public")
 	hr := PublicRouter{
@@ -59,7 +62,15 @@ func NewRouter(
 		now:       time.Now,
 	}
 
-	hr.InstallHandler(hr.service, "/login", api.Post, hr.login)
+	if len(flows) > 0 && flows[0] != nil {
+		hr.flow = flows[0]
+		hr.InstallHandler(hr.service, "/signup", api.Post, measured("signup", hr.signup))
+		hr.InstallHandler(hr.service, "/verification/send", api.Post, measured("activation_send", hr.resendActivation))
+		hr.InstallHandler(hr.service, "/verification/confirm", api.Post, measured("activation", hr.activate))
+		hr.InstallHandler(hr.service, "/login/resend", api.Post, measured("login_send", hr.resendLogin))
+		hr.InstallHandler(hr.service, "/login/verify", api.Post, measured("login_verify", hr.verifyLogin))
+	}
+	hr.InstallHandler(hr.service, "/login", api.Post, measured("login", hr.login))
 	hr.InstallHandler(hr.service, "/login/api", api.Post, hr.apiLogin)
 	hr.InstallHandler(hr.service, "/rotate", api.Post, hr.rotateRefreshToken)
 	hr.InstallHandler(hr.service, "/refresh", api.Post, hr.refreshAccessToken)

backend/product/auth/http/public/verification.go

@@ -0,0 +1,240 @@
+package public
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"git.sendico.io/tech/sxchnge/product/auth/flow"
+	"git.sendico.io/tech/sxchnge/product/auth/ipguard"
+	authmodel "git.sendico.io/tech/sxchnge/product/auth/model"
+	sresponse "git.sendico.io/tech/sxchnge/product/auth/response"
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	session "git.sendico.io/tech/sxchnge/product/sessions/model"
+	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
+	verification "git.sendico.io/tech/sxchnge/product/verification/store"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"git.sendico.io/tech/sxchnge/shared/http/response"
+	"git.sendico.io/tech/sxchnge/shared/logging/mask"
+	"github.com/go-chi/jwtauth/v5"
+	"go.uber.org/zap"
+)
+
+type signupRequest struct {
+	Name     string `json:"name"`
+	Email    string `json:"email"`
+	Password string `json:"password"`
+	Locale   string `json:"locale"`
+	Key      string `json:"idempotencyKey"`
+}
+type challengeRequest struct {
+	PendingToken string                    `json:"pendingToken"`
+	Code         string                    `json:"code"`
+	Key          string                    `json:"idempotencyKey"`
+	Session      session.SessionIdentifier `json:"sessionIdentifier"`
+}
+type challengeResponse struct {
+	UserID       string              `json:"userId"`
+	PendingToken sresponse.TokenData `json:"pendingToken"`
+	Target       string              `json:"target"`
+	ExpiresAt    time.Time           `json:"expiresAt"`
+	ResendAt     time.Time           `json:"resendAt"`
+}
+
+func decodeFlow(r *http.Request, dst any) error {
+	d := json.NewDecoder(io.LimitReader(r.Body, 8193))
+	d.DisallowUnknownFields()
+	if err := d.Decode(dst); err != nil {
+		return merrors.InvalidArgument("invalid request")
+	}
+	var extra any
+	if err := d.Decode(&extra); err != io.EOF {
+		return merrors.InvalidArgument("invalid request")
+	}
+	return nil
+}
+func requestIP(r *http.Request) string {
+	if ip := ipguard.ClientIP(r); ip != nil {
+		return ip.String()
+	}
+	return "unresolved"
+}
+func (pr *PublicRouter) flowError(err error) http.HandlerFunc {
+	if details, ok := verification.Throttle(err); ok {
+		return pr.loginRateLimited(details.RetryAfter)
+	}
+	switch {
+	case errors.Is(err, verification.ErrTokenExpired):
+		return response.BadRequest(pr.logger, pr.service, "expired", "Verification expired; request a new email")
+	case errors.Is(err, verification.ErrTokenAttemptsExceeded):
+		return response.BadRequest(pr.logger, pr.service, "locked", "Too many attempts; request a new code")
+	case errors.Is(err, verification.ErrTokenNotFound), errors.Is(err, verification.ErrTokenAlreadyUsed):
+		return response.BadRequest(pr.logger, pr.service, "invalid", "Verification is invalid or already used")
+	case errors.Is(err, merrors.ErrDataConflict):
+		return response.BadRequest(pr.logger, pr.service, "email_in_use", "Email is already registered")
+	case errors.Is(err, merrors.ErrInvalidArg):
+		return response.BadRequest(pr.logger, pr.service, "invalid_request", "Check the request fields")
+	case errors.Is(err, merrors.ErrUnauthorized):
+		return response.Unauthorized(pr.logger, pr.service, "credentials required")
+	default:
+		// Do not include downstream errors: they may contain transport/request details.
+		pr.logger.Warn("Authentication flow dependency failed")
+		return func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Cache-Control", "no-store")
+			w.WriteHeader(http.StatusServiceUnavailable)
+			_, _ = w.Write([]byte(`{"data":{"code":"unavailable","details":"Unable to complete verification. Please retry."}}`))
+		}
+	}
+}
+func (pr *PublicRouter) signup(r *http.Request) http.HandlerFunc {
+	var req signupRequest
+	if err := decodeFlow(r, &req); err != nil {
+		return pr.flowError(err)
+	}
+	if req.Key == "" || len(req.Key) > 128 {
+		return pr.flowError(merrors.InvalidArgument("idempotency key required"))
+	}
+	a := &customer.Account{Password: req.Password}
+	a.Name = req.Name
+	a.Login = req.Email
+	a.Locale = req.Locale
+	a, err := pr.flow.Signup(r.Context(), a, requestIP(r), req.Key)
+	if err != nil {
+		return pr.flowError(err)
+	}
+	pr.logger.Info("Signup verification queued", zap.String("account_ref", a.ID.Hex()))
+	return response.Accepted(pr.logger, map[string]string{"userId": a.ID.Hex()})
+}
+func (pr *PublicRouter) resendActivation(r *http.Request) http.HandlerFunc {
+	var req struct {
+		Email string `json:"email"`
+		Key   string `json:"idempotencyKey"`
+	}
+	if err := decodeFlow(r, &req); err != nil {
+		return pr.flowError(err)
+	}
+	if req.Key == "" || len(req.Key) > 128 {
+		return pr.flowError(merrors.InvalidArgument("idempotency key required"))
+	}
+	if err := pr.flow.ResendActivation(r.Context(), req.Email, requestIP(r), req.Key); err != nil {
+		return pr.flowError(err)
+	}
+	return response.Accepted(pr.logger, map[string]bool{"accepted": true})
+}
+func (pr *PublicRouter) activate(r *http.Request) http.HandlerFunc {
+	var req struct {
+		Token string `json:"token"`
+	}
+	if err := decodeFlow(r, &req); err != nil {
+		return pr.flowError(err)
+	}
+	if err := pr.flow.Activate(r.Context(), req.Token); err != nil {
+		return pr.flowError(err)
+	}
+	pr.logger.Info("Account activation completed")
+	return response.Accepted(pr.logger, map[string]bool{"verified": true})
+}
+func challengeScope(raw string) string {
+	h := sha256.Sum256([]byte(raw))
+	return hex.EncodeToString(h[:])
+}
+func (pr *PublicRouter) beginLogin(r *http.Request, a *customer.Account, sessionID session.SessionIdentifier, key string) http.HandlerFunc {
+	if sessionID.ClientID == "" || sessionID.DeviceID == "" || len(sessionID.DeviceID) > 128 {
+		return pr.flowError(merrors.InvalidArgument("session identifier required"))
+	}
+	claims := authmodel.PendingAccount2Claims(a, pendingLoginTTLMinutes)
+	claims["clientId"] = sessionID.ClientID
+	claims["deviceId"] = sessionID.DeviceID
+	// Independent challenges, even when password requests arrive within one second.
+	claims["nonce"] = randomKey()
+	ja := jwtauth.New(pr.signature.Algorithm, pr.signature.PrivateKey, pr.signature.PublicKey)
+	_, raw, err := ja.Encode(claims)
+	if err != nil {
+		return pr.flowError(err)
+	}
+	token := sresponse.TokenData{Token: raw, Expiration: time.Unix(claims["exp"].(int64), 0)}
+	return pr.queueLogin(r, a, token, key)
+}
+func randomKey() string { return rand.Text() }
+func (pr *PublicRouter) queueLogin(r *http.Request, a *customer.Account, token sresponse.TokenData, key string) http.HandlerFunc {
+	expires, err := pr.flow.Issue(r.Context(), a, verificationmodel.PurposeLogin, challengeScope(token.Token), key, token.Expiration)
+	if err != nil {
+		return pr.flowError(err)
+	}
+	if token.Expiration.Before(expires) {
+		expires = token.Expiration
+	}
+	pr.logger.Info("Login verification queued", zap.String("account_ref", a.ID.Hex()))
+	return response.Accepted(pr.logger, challengeResponse{UserID: a.ID.Hex(), PendingToken: token, Target: mask.Email(a.Login), ExpiresAt: expires, ResendAt: time.Now().Add(flow.Cooldown)})
+}
+func (pr *PublicRouter) pending(ctx context.Context, raw string) (*customer.Account, *authmodel.AccountToken, error) {
+	if len(raw) > 8192 {
+		return nil, nil, merrors.Unauthorized("invalid pending token")
+	}
+	ja := jwtauth.New(pr.signature.Algorithm, pr.signature.PrivateKey, pr.signature.PublicKey)
+	t, err := jwtauth.VerifyToken(ja, raw)
+	if err != nil {
+		return nil, nil, merrors.Unauthorized("invalid pending token")
+	}
+	_, claims, err := jwtauth.FromContext(jwtauth.NewContext(ctx, t, nil))
+	if err != nil {
+		return nil, nil, err
+	}
+	token, err := authmodel.Claims2Token(claims)
+	if err != nil || !token.Pending || token.ClientID == "" || token.DeviceID == "" {
+		return nil, nil, merrors.Unauthorized("pending login required")
+	}
+	a := &customer.Account{}
+	if err = pr.db.Get(ctx, token.AccountRef, a); err != nil {
+		return nil, nil, err
+	}
+	if !a.IsActive() || a.IsArchived() {
+		return nil, nil, merrors.Unauthorized("inactive account")
+	}
+	return a, token, nil
+}
+func (pr *PublicRouter) resendLogin(r *http.Request) http.HandlerFunc {
+	var req challengeRequest
+	if err := decodeFlow(r, &req); err != nil {
+		return pr.flowError(err)
+	}
+	a, t, err := pr.pending(r.Context(), req.PendingToken)
+	if err != nil {
+		return pr.flowError(err)
+	}
+	return pr.queueLogin(r, a, sresponse.TokenData{Token: req.PendingToken, Expiration: t.Expiration}, req.Key)
+}
+func (pr *PublicRouter) verifyLogin(r *http.Request) http.HandlerFunc {
+	var req challengeRequest
+	if err := decodeFlow(r, &req); err != nil {
+		return pr.flowError(err)
+	}
+	a, t, err := pr.pending(r.Context(), req.PendingToken)
+	if err != nil {
+		return pr.flowError(err)
+	}
+	client, h := pr.resolveLoginClient(r.Context(), r, t.ClientID)
+	if h != nil {
+		return h
+	}
+	if h = pr.validateClientAccountBinding(client, a); h != nil {
+		return h
+	}
+	code := strings.TrimSpace(req.Code)
+	if len(code) != 6 {
+		return pr.flowError(verification.ErorrTokenNotFound())
+	}
+	if _, err = pr.flow.Tokens.Consume(r.Context(), a.ID, verificationmodel.PurposeLogin, challengeScope(req.PendingToken), code); err != nil {
+		return pr.flowError(err)
+	}
+	pr.logger.Info("Login verification completed", zap.String("account_ref", a.ID.Hex()))
+	return pr.refreshAndRespondLogin(r.Context(), r, &t.SessionIdentifier, a)
+}

backend/product/auth/http/public/verification_integration_test.go

@@ -0,0 +1,129 @@
+package public
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+	"time"
+
+	middleware "git.sendico.io/tech/sxchnge/product/auth/config"
+	"git.sendico.io/tech/sxchnge/product/auth/flow"
+	authstorage "git.sendico.io/tech/sxchnge/product/auth/storage"
+	accountservice "git.sendico.io/tech/sxchnge/product/customers"
+	customer "git.sendico.io/tech/sxchnge/product/customers/model"
+	"git.sendico.io/tech/sxchnge/product/notifications"
+	session "git.sendico.io/tech/sxchnge/product/sessions/model"
+	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/go-chi/chi/v5"
+	"github.com/stretchr/testify/require"
+	"github.com/testcontainers/testcontainers-go/modules/mongodb"
+	"go.uber.org/zap"
+)
+
+type capturedMail struct {
+	messages []notifications.Message
+	fail     bool
+}
+
+func (m *capturedMail) Send(_ context.Context, r notifications.Message) error {
+	m.messages = append(m.messages, r)
+	if m.fail {
+		return merrors.ServiceUnavailable("test queue unavailable")
+	}
+	return nil
+}
+func TestSignupActivationAndLoginEmailFlow(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+	container, err := mongodb.Run(ctx, "mongo:8", 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": "auth_flow"}})
+	require.NoError(t, err)
+	t.Cleanup(factory.CloseConnection)
+	stores, err := authstorage.OpenStores(zap.NewNop(), factory, nil)
+	require.NoError(t, err)
+	customers, err := accountservice.NewAccountService(zap.NewNop(), factory, &middleware.PasswordConfig{Check: middleware.PasswordChecks{MinLength: 12}}, nil)
+	require.NoError(t, err)
+	mail := &capturedMail{}
+	service := &flow.Service{Accounts: stores.Accounts, Customers: customers, Tokens: stores.Verification, Transactions: factory.TransactionFactory(), Attempts: stores.LoginAttempts, Sender: mail, Secret: []byte(strings.Repeat("s", 32)), ActivationURL: "https://app.example/verify-email"}
+	require.NoError(t, service.Validate())
+	// Keep the real verification/customer stores and capture only session writes.
+	sessions := &testRefreshTokenDB{client: &session.Client{ClientID: "web"}}
+	routes := chi.NewRouter()
+	NewRouter(zap.NewNop(), "/api/v1", stores.Accounts, stores.Verification, sessions, nil, routes, &middleware.TokenConfig{Length: 32, Expiration: middleware.TokenExpiration{Account: 1, Refresh: 24}}, &middleware.Signature{Algorithm: "HS256", PrivateKey: service.Secret}, middleware.LoginRateLimits{}, service)
+	post := func(path string, body any) *httptest.ResponseRecorder {
+		raw, err := json.Marshal(body)
+		require.NoError(t, err)
+		r := httptest.NewRequest(http.MethodPost, "/api/v1/accounts/"+path, strings.NewReader(string(raw)))
+		r.RemoteAddr = "192.0.2.1:1234"
+		w := httptest.NewRecorder()
+		routes.ServeHTTP(w, r)
+		return w
+	}
+	signup := map[string]any{"name": "Customer", "email": "USER@example.com", "password": " correct password ", "locale": "ru", "idempotencyKey": "signup-one"}
+	w := post("signup", signup)
+	require.Equal(t, 202, w.Code, w.Body.String())
+	require.Len(t, mail.messages, 1)
+	require.Equal(t, "auth.activation", mail.messages[0].Template)
+	require.Equal(t, "user@example.com", mail.messages[0].Email)
+	require.Equal(t, "ru", mail.messages[0].Locale)
+	activationURL, err := url.Parse(mail.messages[0].Parameters["url"])
+	require.NoError(t, err)
+	activation := activationURL.Query().Get("token")
+	require.NotEmpty(t, activation)
+	a, err := stores.Accounts.GetByEmail(ctx, "user@example.com")
+	require.NoError(t, err)
+	require.False(t, a.IsActive())
+	login := map[string]any{"login": map[string]string{"login": "user@example.com", "password": " correct password "}, "clientId": "web", "deviceId": "browser"}
+	require.Equal(t, 403, post("login", login).Code)
+	require.Equal(t, 400, post("verification/confirm", map[string]string{"token": "invalid"}).Code)
+	w = post("verification/confirm", map[string]string{"token": activation})
+	require.Equal(t, 202, w.Code, w.Body.String())
+	require.Equal(t, 400, post("verification/confirm", map[string]string{"token": activation}).Code)
+	a, err = stores.Accounts.GetByEmail(ctx, a.Login)
+	require.NoError(t, err)
+	require.Equal(t, customer.AccountActive, a.Status)
+	w = post("login", login)
+	require.Equal(t, 202, w.Code, w.Body.String())
+	require.Len(t, mail.messages, 2)
+	require.Empty(t, sessions.tokens)
+	var pending struct {
+		Data challengeResponse `json:"data"`
+	}
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &pending))
+	require.NotEmpty(t, pending.Data.PendingToken.Token)
+	require.NotContains(t, w.Body.String(), mail.messages[1].Parameters["code"])
+	code := mail.messages[1].Parameters["code"]
+	require.Len(t, code, 6)
+	wrong := "000000"
+	if code == wrong {
+		wrong = "111111"
+	}
+	require.Equal(t, 400, post("login/verify", map[string]string{"pendingToken": pending.Data.PendingToken.Token, "code": wrong}).Code)
+	require.Empty(t, sessions.tokens)
+	require.Equal(t, 429, post("login/resend", map[string]string{"pendingToken": pending.Data.PendingToken.Token, "idempotencyKey": "resend-too-soon"}).Code)
+	w = post("login/verify", map[string]string{"pendingToken": pending.Data.PendingToken.Token, "code": code})
+	require.Equal(t, 200, w.Code, w.Body.String())
+	require.Len(t, sessions.tokens, 1)
+	require.Equal(t, "browser", sessions.tokens[0].DeviceID)
+	require.Equal(t, 400, post("login/verify", map[string]string{"pendingToken": pending.Data.PendingToken.Token, "code": code}).Code)
+	require.Len(t, sessions.tokens, 1)
+	// A queue outage cannot report a successful login challenge or create a session.
+	mail.fail = true
+	require.Equal(t, 503, post("login", login).Code)
+	require.Len(t, sessions.tokens, 1)
+}

backend/product/config.example.yml

@@ -31,3 +31,9 @@ api:
       token_length: 32
       check:
         min_length: 12
+  notifications:
+    address: localhost:8443
+    token_env: SXCHNGE_NOTIFICATIONS_TOKEN
+    ca_file: ../notifications/tls/ca.pem
+    server_name: localhost
+    activation_url: http://localhost:5126/verify-email

backend/product/go.mod

@@ -69,13 +69,17 @@ require (
 	go.opentelemetry.io/otel/trace v1.44.0 // indirect
 	go.uber.org/multierr v1.10.0 // indirect
 	go.yaml.in/yaml/v3 v3.0.5 // indirect
+	golang.org/x/net v0.58.0 // indirect
 	golang.org/x/sync v0.22.0 // indirect
 	golang.org/x/sys v0.47.0 // indirect
 	golang.org/x/text v0.41.0 // indirect
-	google.golang.org/protobuf v1.36.11 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260526163538-3dc84a4a5aaa // indirect
 )
 
+replace git.sendico.io/tech/sxchnge/shared => ../shared
+
 require (
+	git.sendico.io/tech/sxchnge/notifications/interface v0.0.0
 	git.sendico.io/tech/sxchnge/shared v0.0.0
 	github.com/go-chi/chi/v5 v5.3.2
 	github.com/go-chi/cors v1.2.2
@@ -89,8 +93,10 @@ require (
 	go.mongodb.org/mongo-driver/v2 v2.9.0
 	go.uber.org/zap v1.28.0
 	golang.org/x/crypto v0.56.0
+	google.golang.org/grpc v1.83.2
+	google.golang.org/protobuf v1.36.12
 	gopkg.in/yaml.v3 v3.0.1
 	moul.io/chizap v1.0.3
 )
 
-replace git.sendico.io/tech/sxchnge/shared => ../shared
+replace git.sendico.io/tech/sxchnge/notifications/interface => ../notifications/interface

backend/product/go.sum

@@ -63,6 +63,8 @@ github.com/go-viper/mapstructure/v2 v2.5.0 h1:vM5IJoUAy3d7zRSVtIwQgBj7BiWtMPfmPE
 github.com/go-viper/mapstructure/v2 v2.5.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/goccy/go-json v0.10.3 h1:KZ5WoDbxAIgm2HNbYckL0se1fHD6rz5j4ywS6ebzDqA=
 github.com/goccy/go-json v0.10.3/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
+github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
+github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
@@ -226,6 +228,8 @@ golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwY
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/net v0.58.0 h1:ynWG7rqYi4ccpTEuPZ2QGWHktVEM9DMCj9yzDE0Q7To=
+golang.org/x/net v0.58.0/go.mod h1:YwCddHnFlT7eLQqVprV19OnhLGtc5xOKgE0RyqgfWAU=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -267,8 +271,14 @@ golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
-google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+gonum.org/v1/gonum v0.17.0 h1:VbpOemQlsSMrYmn7T2OUvQ4dqxQXU+ouZFQsZOx50z4=
+gonum.org/v1/gonum v0.17.0/go.mod h1:El3tOrEuMpv2UdMrbNlKEh9vd86bmQ6vqIcDwxEOc1E=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20260526163538-3dc84a4a5aaa h1:mZHHdPZl0dbGHCflZgAq/Q468DWVFcU2whhB2KAo8fk=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20260526163538-3dc84a4a5aaa/go.mod h1:4Hqkh8ycfw05ld/3BWL7rJOSfebL2Q+DVDeRgYgxUU8=
+google.golang.org/grpc v1.83.2 h1:EManeRomTObA0BU7I8vXgg/78uE5MJ9M8B39EX2WscU=
+google.golang.org/grpc v1.83.2/go.mod h1:YPI1hK3kDked6iHvgX3tR0y+nX/qpMFKhPgFsokw1S8=
+google.golang.org/protobuf v1.36.12 h1:pJOKDDOyeXErUroCihFAd5LQuwXBSpVnKGrj5o/fwxc=
+google.golang.org/protobuf v1.36.12/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=

backend/product/notifications/client.go

@@ -0,0 +1,88 @@
+// Package notifications adapts the internal notification wire contract to product models.
+package notifications
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"os"
+	"time"
+
+	pb "git.sendico.io/tech/sxchnge/notifications/interface/notifications/v1"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+type Config struct {
+	Address       string `yaml:"address"`
+	TokenEnv      string `yaml:"token_env"`
+	CAFile        string `yaml:"ca_file"`
+	ServerName    string `yaml:"server_name"`
+	ActivationURL string `yaml:"activation_url"`
+}
+type Message struct {
+	Key, UserID, Email, Locale, Template string
+	Parameters                           map[string]string
+	ExpiresAt                            time.Time
+}
+type Sender interface {
+	Send(context.Context, Message) error
+}
+type Client struct {
+	conn  *grpc.ClientConn
+	rpc   pb.NotificationsServiceClient
+	token string
+}
+
+func Open(c Config) (*Client, error) {
+	token := os.Getenv(c.TokenEnv)
+	if c.Address == "" || len(token) < 32 {
+		return nil, merrors.InvalidArgument("notification address and caller token of at least 32 bytes are required")
+	}
+	tlsConfig := &tls.Config{MinVersion: tls.VersionTLS12, ServerName: c.ServerName}
+	if c.CAFile != "" {
+		pem, err := os.ReadFile(c.CAFile)
+		if err != nil {
+			return nil, merrors.InternalWrap(err, "read notification CA")
+		}
+		pool, err := x509.SystemCertPool()
+		if err != nil {
+			pool = x509.NewCertPool()
+		}
+		if !pool.AppendCertsFromPEM(pem) {
+			return nil, merrors.InvalidArgument("invalid notification CA")
+		}
+		tlsConfig.RootCAs = pool
+	}
+	conn, err := grpc.NewClient(c.Address, grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)))
+	if err != nil {
+		return nil, merrors.InternalWrap(err, "create notification client")
+	}
+	return &Client{conn: conn, rpc: pb.NewNotificationsServiceClient(conn), token: token}, nil
+}
+func (c *Client) Close() error { return c.conn.Close() }
+func (c *Client) Send(ctx context.Context, m Message) error {
+	ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+	ctx = metadata.AppendToOutgoingContext(ctx, "authorization", "Bearer "+c.token)
+	res, err := c.rpc.Send(ctx, request(m))
+	if err != nil {
+		return merrors.ServiceUnavailableWrap(err, "notification queue unavailable")
+	}
+	if res.GetNotification().GetId() == "" || len(res.GetNotification().GetDeliveries()) != 1 {
+		return merrors.ServiceUnavailable("notification queue returned no receipt")
+	}
+	for _, d := range res.Notification.Deliveries {
+		switch d.State {
+		case pb.DeliveryState_DELIVERY_STATE_FAILED, pb.DeliveryState_DELIVERY_STATE_EXPIRED, pb.DeliveryState_DELIVERY_STATE_UNKNOWN:
+			return merrors.ServiceUnavailable("notification could not be delivered")
+		}
+	}
+	return nil
+}
+func request(m Message) *pb.SendRequest {
+	return &pb.SendRequest{IdempotencyKey: m.Key, UserId: m.UserID, TemplateId: m.Template, TemplateVersion: "1", Locale: m.Locale, Parameters: m.Parameters, ExpiresAt: timestamppb.New(m.ExpiresAt), Targets: []*pb.Target{{Destination: &pb.Target_Email{Email: &pb.EmailTarget{Address: m.Email}}}}}
+}

backend/product/notifications/client_test.go

@@ -0,0 +1,90 @@
+package notifications
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/pem"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	pb "git.sendico.io/tech/sxchnge/notifications/interface/notifications/v1"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/metadata"
+)
+
+type rpcStub struct {
+	pb.NotificationsServiceClient
+	request *pb.SendRequest
+	auth    string
+	result  *pb.SendResponse
+	err     error
+}
+
+func (s *rpcStub) Send(ctx context.Context, r *pb.SendRequest, _ ...grpc.CallOption) (*pb.SendResponse, error) {
+	s.request = r
+	md, _ := metadata.FromOutgoingContext(ctx)
+	s.auth = md.Get("authorization")[0]
+	return s.result, s.err
+}
+func TestSendMapsOwnedContractAndRejectsFailedReceipt(t *testing.T) {
+	rpc := &rpcStub{result: &pb.SendResponse{Notification: &pb.Notification{Id: "job", Deliveries: []*pb.Delivery{{State: pb.DeliveryState_DELIVERY_STATE_QUEUED}}}}}
+	client := &Client{rpc: rpc, token: "service-secret"}
+	expiry := time.Now().Add(time.Minute)
+	m := Message{Key: "key", UserID: "customer", Email: "user@example.com", Locale: "ru", Template: "auth.login", Parameters: map[string]string{"code": "123456"}, ExpiresAt: expiry}
+	require.NoError(t, client.Send(context.Background(), m))
+	require.Equal(t, "Bearer service-secret", rpc.auth)
+	require.Equal(t, m.Email, rpc.request.Targets[0].GetEmail().Address)
+	require.Equal(t, "1", rpc.request.TemplateVersion)
+	require.Equal(t, m.Parameters, rpc.request.Parameters)
+	require.WithinDuration(t, expiry, rpc.request.ExpiresAt.AsTime(), time.Nanosecond)
+	rpc.result.Notification.Deliveries[0].State = pb.DeliveryState_DELIVERY_STATE_UNKNOWN
+	require.ErrorIs(t, client.Send(context.Background(), m), merrors.ErrServiceUnavailable)
+	rpc.result = nil
+	require.ErrorIs(t, client.Send(context.Background(), m), merrors.ErrServiceUnavailable)
+}
+func TestOpenRequiresCredentialsAndValidCA(t *testing.T) {
+	_, err := Open(Config{Address: "localhost:8443", TokenEnv: "ABSENT_NOTIFICATION_TEST_TOKEN"})
+	require.ErrorIs(t, err, merrors.ErrInvalidArg)
+	t.Setenv("TEST_NOTIFICATION_TOKEN", "test-token-that-is-at-least-32-bytes")
+	_, err = Open(Config{Address: "localhost:8443", TokenEnv: "TEST_NOTIFICATION_TOKEN", CAFile: "missing.pem"})
+	require.Error(t, err)
+}
+
+type tlsRPC struct {
+	pb.UnimplementedNotificationsServiceServer
+	auth chan string
+}
+
+func (s *tlsRPC) Send(ctx context.Context, _ *pb.SendRequest) (*pb.SendResponse, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	s.auth <- md.Get("authorization")[0]
+	return &pb.SendResponse{Notification: &pb.Notification{Id: "tls-job", Deliveries: []*pb.Delivery{{State: pb.DeliveryState_DELIVERY_STATE_QUEUED}}}}, nil
+}
+func TestOpenUsesVerifiedTLSAndCallerAuthentication(t *testing.T) {
+	fixture := httptest.NewTLSServer(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))
+	cert := fixture.TLS.Certificates[0]
+	fixture.Close()
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	server := grpc.NewServer(grpc.Creds(credentials.NewTLS(&tls.Config{Certificates: []tls.Certificate{cert}, MinVersion: tls.VersionTLS12})))
+	rpc := &tlsRPC{auth: make(chan string, 1)}
+	pb.RegisterNotificationsServiceServer(server, rpc)
+	go func() { _ = server.Serve(listener) }()
+	t.Cleanup(server.Stop)
+	ca := filepath.Join(t.TempDir(), "ca.pem")
+	require.NoError(t, os.WriteFile(ca, pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: cert.Certificate[0]}), 0600))
+	t.Setenv("TEST_TLS_CALLER_TOKEN", "test-service-token-with-at-least-32-bytes")
+	client, err := Open(Config{Address: listener.Addr().String(), TokenEnv: "TEST_TLS_CALLER_TOKEN", CAFile: ca})
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = client.Close() })
+	require.NoError(t, client.Send(context.Background(), Message{ExpiresAt: time.Now().Add(time.Minute)}))
+	require.Equal(t, "Bearer test-service-token-with-at-least-32-bytes", <-rpc.auth)
+}

backend/product/verification/store/consume_logging.go

@@ -1,24 +1,13 @@
 package verification
 
 import (
+	"strings"
+
 	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"git.sendico.io/tech/sxchnge/shared/logging/fields"
 	"go.uber.org/zap"
-	"strings"
 )
 
-const hashPreviewChars = 12
-
-func hashPreview(value string) string {
-	if value == "" {
-		return ""
-	}
-	if len(value) <= hashPreviewChars {
-		return value
-	}
-	return value[:hashPreviewChars] + "..."
-}
-
 func tokenIsDigitsOnly(value string) bool {
 	if value == "" {
 		return false
@@ -38,7 +27,6 @@ func tokenStateFields(token *verificationmodel.VerificationToken) []zap.Field {
 		zap.String("token_purpose", string(token.Purpose)),
 		zap.Bool("token_has_target", strings.TrimSpace(token.Target) != ""),
 		zap.Bool("token_has_idempotency_key", token.IdempotencyKey != nil),
-		zap.String("token_verify_hash_prefix", hashPreview(token.VerifyTokenHash)),
 		zap.Bool("token_has_salt", token.Salt != nil),
 		zap.Bool("token_used", token.UsedAt != nil),
 		zap.Time("token_expires_at", token.ExpiresAt),
@@ -46,18 +34,12 @@ func tokenStateFields(token *verificationmodel.VerificationToken) []zap.Field {
 		zap.Bool("token_has_max_retries", token.MaxRetries != nil),
 	}
 
-	if token.Salt != nil {
-		fields = append(fields, zap.String("token_salt_prefix", hashPreview(*token.Salt)))
-	}
 	if token.UsedAt != nil {
 		fields = append(fields, zap.Time("token_used_at", *token.UsedAt))
 	}
 	if token.MaxRetries != nil {
 		fields = append(fields, zap.Int("token_max_retries", *token.MaxRetries))
 	}
-	if token.IdempotencyKey != nil {
-		fields = append(fields, zap.String("token_idempotency_key_prefix", hashPreview(*token.IdempotencyKey)))
-	}
 	if strings.TrimSpace(token.ContextRef) != "" {
 		fields = append(fields, zap.String("token_context_ref", token.ContextRef))
 	}

backend/product/verification/store/consume_lookup.go

@@ -3,8 +3,8 @@ package verification
 import (
 	"context"
 	"errors"
-	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 
+	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	mutil "git.sendico.io/tech/sxchnge/shared/database/query"
 	"git.sendico.io/tech/sxchnge/shared/database/repository"
 	"git.sendico.io/tech/sxchnge/shared/database/repository/builder"
@@ -132,8 +132,6 @@ func (db *verificationDB) lookupConsumeOTPToken(
 			zap.Time("candidate_expires_at", token.ExpiresAt),
 			zap.Int("candidate_attempts", token.Attempts),
 			zap.Bool("candidate_has_max_retries", token.MaxRetries != nil),
-			zap.String("candidate_stored_hash_prefix", hashPreview(token.VerifyTokenHash)),
-			zap.String("candidate_computed_hash_prefix", hashPreview(hash)),
 			zap.Bool("candidate_match", match),
 		)
 		if match {

backend/product/verification/store/consume_scope.go

@@ -1,10 +1,10 @@
 package verification
 
 import (
-	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"strings"
 	"time"
 
+	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"git.sendico.io/tech/sxchnge/shared/database/repository"
 	"git.sendico.io/tech/sxchnge/shared/database/repository/builder"
 	"go.mongodb.org/mongo-driver/v2/bson"
@@ -72,7 +72,6 @@ func (scope consumeScope) startFields() []zap.Field {
 		zap.Int("raw_token_trimmed_len", len(scope.trimmedRawToken)),
 		zap.Bool("raw_token_digits_only", tokenIsDigitsOnly(scope.rawToken)),
 		zap.Bool("raw_token_has_edge_whitespace", scope.rawToken != scope.trimmedRawToken),
-		zap.String("raw_token_hash_prefix", hashPreview(tokenHash(scope.rawToken))),
 	)
 }
 

backend/product/verification/store/create.go

@@ -3,9 +3,9 @@ package verification
 import (
 	"context"
 	"errors"
-	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"time"
 
+	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"git.sendico.io/tech/sxchnge/shared/database/repository"
 	"git.sendico.io/tech/sxchnge/shared/database/repository/builder"
 	"git.sendico.io/tech/sxchnge/shared/errors"
@@ -21,7 +21,7 @@ func activeContextFilter(request *Request, now time.Time) builder.Query {
 	filters := []builder.Query{
 		repository.Filter("accountRef", request.AccountRef),
 		repository.Filter("purpose", request.Purpose),
-		repository.Filter("target", request.Target),
+		targetFilter(request.Target),
 		repository.Filter("usedAt", nil),
 		repository.Query().Comparison(repository.Field("expiresAt"), builder.Gt, now),
 	}
@@ -33,7 +33,7 @@ func cooldownActiveContextFilter(request *Request, now, cutoff time.Time) builde
 	filters := []builder.Query{
 		repository.Filter("accountRef", request.AccountRef),
 		repository.Filter("purpose", request.Purpose),
-		repository.Filter("target", request.Target),
+		targetFilter(request.Target),
 		repository.Filter("usedAt", nil),
 		repository.Query().Comparison(repository.Field("expiresAt"), builder.Gt, now),
 		repository.Query().Comparison(repository.Field("createdAt"), builder.Gt, cutoff),
@@ -140,7 +140,10 @@ func (db *verificationDB) CreateWithResult(
 		// Always store an idempotency key. Client keys enable replay; generated
 		// keys avoid null-key collisions on older Mongo indexes and keep
 		// transaction retries deterministic.
-		idempotencyKey = syntheticIdempotencyKey()
+		idempotencyKey, err = syntheticIdempotencyKey()
+		if err != nil {
+			return CreateResult{}, err
+		}
 		hasIdempotency = true
 	}
 
@@ -246,3 +249,12 @@ func (db *verificationDB) CreateWithResult(
 	createResult.VerificationToken = raw
 	return createResult, nil
 }
+
+// Older records omit an empty target; Mongo does not equate a missing field
+// with the empty string. Match both forms for cooldown, invalidation and replay.
+func targetFilter(target string) builder.Query {
+	if target != "" {
+		return repository.Filter("target", target)
+	}
+	return repository.Query().Or(repository.Filter("target", ""), repository.Filter("target", nil))
+}

backend/product/verification/store/idempotency.go

@@ -2,15 +2,16 @@ package verification
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/base64"
 	"errors"
-	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"strings"
 
+	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	mutil "git.sendico.io/tech/sxchnge/shared/database/query"
 	"git.sendico.io/tech/sxchnge/shared/database/repository"
 	"git.sendico.io/tech/sxchnge/shared/database/repository/builder"
 	"git.sendico.io/tech/sxchnge/shared/errors"
-	"go.mongodb.org/mongo-driver/v2/bson"
 )
 
 func normalizedIdempotencyKey(value *string) (string, bool) {
@@ -24,8 +25,12 @@ func normalizedIdempotencyKey(value *string) (string, bool) {
 	return key, true
 }
 
-func syntheticIdempotencyKey() string {
-	return "auto:" + bson.NewObjectID().Hex()
+func syntheticIdempotencyKey() (string, error) {
+	b := make([]byte, 32)
+	if _, err := rand.Read(b); err != nil {
+		return "", merrors.InternalWrap(err, "generate verification key")
+	}
+	return "auto:" + base64.RawURLEncoding.EncodeToString(b), nil
 }
 
 func idempotencyContextFilter(
@@ -35,7 +40,7 @@ func idempotencyContextFilter(
 	return repository.Query().And(
 		repository.Filter("accountRef", request.AccountRef),
 		repository.Filter("purpose", request.Purpose),
-		repository.Filter("target", request.Target),
+		targetFilter(request.Target),
 		repository.Filter("idempotencyKey", idempotencyKey),
 	)
 }
@@ -75,6 +80,12 @@ func (db *verificationDB) lookupIdempotencyReplay(ctx context.Context, request *
 		if existingContextRef != request.ContextRef {
 			return nil, false, ErrorIdempotencyConflict()
 		}
+		if tokens[i].UsedAt != nil {
+			return nil, false, ErorrTokenAlreadyUsed()
+		}
+		if tokens[i].MaxRetries != nil && tokens[i].Attempts >= *tokens[i].MaxRetries {
+			return nil, false, ErrorTokenAttemptsExceeded()
+		}
 		if replayed == nil {
 			token := tokens[i]
 			replayed = &token

backend/product/verification/store/token_query_matcher_test.go

@@ -1,9 +1,9 @@
 package verification
 
 import (
-	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"time"
 
+	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"git.sendico.io/tech/sxchnge/shared/database/repository/builder"
 	"go.mongodb.org/mongo-driver/v2/bson"
 )
@@ -62,6 +62,18 @@ func matchBsonD(filter bson.D, tok *verificationmodel.VerificationToken) bool {
 
 func matchElem(elem bson.E, tok *verificationmodel.VerificationToken) bool {
 	switch elem.Key {
+	case "$or":
+		arr, ok := elem.Value.(bson.A)
+		if !ok {
+			return false
+		}
+		for _, sub := range arr {
+			d, ok := sub.(bson.D)
+			if ok && matchBsonD(d, tok) {
+				return true
+			}
+		}
+		return false
 	case "$and":
 		arr, ok := elem.Value.(bson.A)
 		if !ok {

backend/product/verification/store/verification_idempotency_test.go

@@ -3,12 +3,13 @@ package verification
 import (
 	"context"
 	"errors"
+	"testing"
+	"time"
+
 	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.mongodb.org/mongo-driver/v2/bson"
-	"testing"
-	"time"
 )
 
 func TestCreate_CooldownBlocksCreation(t *testing.T) {
@@ -174,3 +175,16 @@ func TestCreate_IdempotencySurvivesCallbackRetry(t *testing.T) {
 	}
 	repo.mu.Unlock()
 }
+
+func TestCreateWithResultReplayCannotRedeliverConsumedCode(t *testing.T) {
+	db := newTestVerificationDB(t)
+	ctx := context.Background()
+	id := bson.NewObjectID()
+	r := NewOTPRequest(id, verificationmodel.PurposeLogin, "").WithIdempotencyKey("private-server-key").WithContextRef("login")
+	first, err := db.Create(ctx, r)
+	require.NoError(t, err)
+	_, err = db.Consume(ctx, id, verificationmodel.PurposeLogin, "login", first)
+	require.NoError(t, err)
+	_, err = db.CreateWithResult(ctx, r)
+	require.ErrorIs(t, err, ErrTokenAlreadyUsed)
+}