fix: return field-level validation errors on POST /habits

Previously all validation failures in CreateHabitHandler returned a
generic {"error":"invalid input"}, making it impossible to tell
whether type, frequency, specific_days or specific_dates was the
problem. Errors are now wrapped with field + i18n key and the HTTP
layer replies via respondValidationErrorI18n, matching the pattern
already used by auth endpoints.

README.md

@@ -20,7 +20,7 @@ REST API for habit tracking built with Go. Self-hosted alternative for developer
 
 - Multiple habit types: Boolean, Counter, Value
 - Flexible scheduling: Daily, Weekly, Monthly
-- Statistics: Streaks, completion rates, progress tracking
+- Statistics: Streaks and completions tracking
 - JWT authentication, rate limiting, optional email verification
 - Registration modes: Open or closed
 - SQLite database (single file)
@@ -139,7 +139,9 @@ API runs on `http://localhost:8080`
 
 ## API Documentation
 
-Access the interactive Swagger UI at `http://localhost:8080/api/v1/docs`
+**Live:** [apocapoc.app/api/v1/docs](https://apocapoc.app/api/v1/docs)
+
+**Local:** `http://localhost:8080/api/v1/docs`
 
 Includes endpoint reference, schemas, authentication examples, and live testing.
 

cmd/api/main.go

@@ -14,6 +14,7 @@ import (
 
 	"apocapoc-api/internal/application/commands"
 	"apocapoc-api/internal/application/queries"
+	"apocapoc-api/internal/domain/services"
 	"apocapoc-api/internal/i18n"
 	"apocapoc-api/internal/infrastructure/auth"
 	"apocapoc-api/internal/infrastructure/backup"
@@ -94,7 +95,7 @@ func main() {
 	jwtService := auth.NewJWTService(cfg.JWTSecret, jwtExpiryHours)
 	passwordHasher := crypto.NewBcryptHasher()
 
-	var emailService *email.SMTPService
+	var emailService services.EmailService = &services.NoOpEmailService{}
 	if cfg.SMTPHost != "" {
 		smtpPort, err := strconv.Atoi(cfg.SMTPPort)
 		if err != nil {

docs/docs.go

@@ -1172,7 +1172,7 @@ const docTemplate = `{
                         "BearerAuth": []
                     }
                 ],
-                "description": "Get statistics for a specific habit including streaks and completion rates",
+                "description": "Get statistics for a specific habit including streaks and completions",
                 "produces": [
                     "application/json"
                 ],
@@ -1800,6 +1800,9 @@ const docTemplate = `{
                 "description": {
                     "type": "string"
                 },
+                "frequency": {
+                    "$ref": "#/definitions/value_objects.Frequency"
+                },
                 "name": {
                     "type": "string"
                 },

docs/swagger.json

@@ -1164,7 +1164,7 @@
                         "BearerAuth": []
                     }
                 ],
-                "description": "Get statistics for a specific habit including streaks and completion rates",
+                "description": "Get statistics for a specific habit including streaks and completions",
                 "produces": [
                     "application/json"
                 ],
@@ -1792,6 +1792,9 @@
                 "description": {
                     "type": "string"
                 },
+                "frequency": {
+                    "$ref": "#/definitions/value_objects.Frequency"
+                },
                 "name": {
                     "type": "string"
                 },

docs/swagger.yaml

@@ -268,6 +268,8 @@ definitions:
         type: boolean
       description:
         type: string
+      frequency:
+        $ref: '#/definitions/value_objects.Frequency'
       name:
         type: string
       specific_dates:
@@ -1189,8 +1191,7 @@ paths:
       - system
   /stats/habits/{id}:
     get:
-      description: Get statistics for a specific habit including streaks and completion
+      description: Get statistics for a specific habit including streaks and completions
-        rates
       parameters:
       - description: Habit ID
         in: path

internal/application/commands/create_habit.go

@@ -2,6 +2,7 @@ package commands
 
 import (
 	"context"
+	"fmt"
 
 	"apocapoc-api/internal/domain/entities"
 	"apocapoc-api/internal/domain/repositories"
@@ -32,19 +33,19 @@ func NewCreateHabitHandler(habitRepo repositories.HabitRepository) *CreateHabitH
 
 func (h *CreateHabitHandler) Handle(ctx context.Context, cmd CreateHabitCommand) (string, error) {
 	if !cmd.Type.IsValid() {
-		return "", errors.ErrInvalidInput
+		return "", fmt.Errorf("%w: type: type_invalid", errors.ErrInvalidInput)
 	}
 
 	if !cmd.Frequency.IsValid() {
-		return "", errors.ErrInvalidInput
+		return "", fmt.Errorf("%w: frequency: frequency_invalid", errors.ErrInvalidInput)
 	}
 
 	if cmd.Frequency == value_objects.FrequencyWeekly && len(cmd.SpecificDays) == 0 {
-		return "", errors.ErrInvalidInput
+		return "", fmt.Errorf("%w: specific_days: specific_days_required", errors.ErrInvalidInput)
 	}
 
 	if cmd.Frequency == value_objects.FrequencyMonthly && len(cmd.SpecificDates) == 0 {
-		return "", errors.ErrInvalidInput
+		return "", fmt.Errorf("%w: specific_dates: specific_dates_required", errors.ErrInvalidInput)
 	}
 
 	habit := entities.NewHabit(cmd.UserID, cmd.Name, cmd.Type, cmd.Frequency, cmd.CarryOver, cmd.IsNegative)

internal/application/commands/create_habit_test.go

@@ -4,6 +4,8 @@ import (
 	"apocapoc-api/internal/domain/repositories"
 	"apocapoc-api/internal/shared/pagination"
 	"context"
+	stderrors "errors"
+	"strings"
 	"testing"
 	"time"
 
@@ -110,8 +112,31 @@ func TestCreateHabitHandler_InvalidType(t *testing.T) {
 
 	_, err := handler.Handle(context.Background(), cmd)
 
-	if err != errors.ErrInvalidInput {
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+		t.Fatalf("Expected ErrInvalidInput wrapper, got %v", err)
+	}
+	if !strings.Contains(err.Error(), "type: type_invalid") {
+		t.Errorf("Expected 'type: type_invalid' in error, got %q", err.Error())
+	}
+}
+
+func TestCreateHabitHandler_EmptyType(t *testing.T) {
+	mock := &mockHabitRepo{}
+	handler := NewCreateHabitHandler(mock)
+
+	cmd := CreateHabitCommand{
+		UserID:    "user-123",
+		Name:      "Exercise",
+		Frequency: "DAILY",
+	}
+
+	_, err := handler.Handle(context.Background(), cmd)
+
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
+		t.Fatalf("Expected ErrInvalidInput wrapper, got %v", err)
+	}
+	if !strings.Contains(err.Error(), "type: type_invalid") {
+		t.Errorf("Expected 'type: type_invalid' in error, got %q", err.Error())
 	}
 }
 
@@ -128,8 +153,11 @@ func TestCreateHabitHandler_InvalidFrequency(t *testing.T) {
 
 	_, err := handler.Handle(context.Background(), cmd)
 
-	if err != errors.ErrInvalidInput {
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+		t.Fatalf("Expected ErrInvalidInput wrapper, got %v", err)
+	}
+	if !strings.Contains(err.Error(), "frequency: frequency_invalid") {
+		t.Errorf("Expected 'frequency: frequency_invalid' in error, got %q", err.Error())
 	}
 }
 
@@ -147,8 +175,11 @@ func TestCreateHabitHandler_WeeklyWithoutSpecificDays(t *testing.T) {
 
 	_, err := handler.Handle(context.Background(), cmd)
 
-	if err != errors.ErrInvalidInput {
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+		t.Fatalf("Expected ErrInvalidInput wrapper, got %v", err)
+	}
+	if !strings.Contains(err.Error(), "specific_days: specific_days_required") {
+		t.Errorf("Expected 'specific_days: specific_days_required' in error, got %q", err.Error())
 	}
 }
 
@@ -166,8 +197,11 @@ func TestCreateHabitHandler_MonthlyWithoutSpecificDates(t *testing.T) {
 
 	_, err := handler.Handle(context.Background(), cmd)
 
-	if err != errors.ErrInvalidInput {
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+		t.Fatalf("Expected ErrInvalidInput wrapper, got %v", err)
+	}
+	if !strings.Contains(err.Error(), "specific_dates: specific_dates_required") {
+		t.Errorf("Expected 'specific_dates: specific_dates_required' in error, got %q", err.Error())
 	}
 }
 

internal/application/commands/register_user.go

@@ -73,7 +73,7 @@ func (h *RegisterUserHandler) Handle(ctx context.Context, cmd RegisterUserComman
 	user := entities.NewUser(cmd.Email, hashedPassword)
 
 	emailVerificationRequired := false
-	if h.emailService != nil {
+	if h.emailService.IsEnabled() {
 		token, err := h.generateVerificationToken()
 		if err != nil {
 			return nil, fmt.Errorf("failed to generate verification token: %w", err)

internal/application/commands/register_user_test.go

@@ -2,6 +2,7 @@ package commands
 
 import (
 	"apocapoc-api/internal/domain/repositories"
+	"apocapoc-api/internal/domain/services"
 	"apocapoc-api/internal/shared/pagination"
 	"context"
 	"errors"
@@ -71,7 +72,7 @@ func TestRegisterUserHandler_Success(t *testing.T) {
 		},
 	}
 	hasher := &mockPasswordHasher{}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "open", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "open", false)
 
 	cmd := RegisterUserCommand{
 		Email:    "test@example.com",
@@ -88,7 +89,7 @@ func TestRegisterUserHandler_Success(t *testing.T) {
 	}
 
 	if result.EmailVerificationRequired {
-		t.Error("expected email verification to not be required when emailService is nil")
+		t.Error("expected email verification to not be required when email is disabled")
 	}
 
 	if createdUser == nil {
@@ -103,7 +104,7 @@ func TestRegisterUserHandler_Success(t *testing.T) {
 func TestRegisterUserHandler_InvalidEmail(t *testing.T) {
 	repo := &mockUserRepo{}
 	hasher := &mockPasswordHasher{}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "open", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "open", false)
 
 	tests := []struct {
 		name  string
@@ -135,7 +136,7 @@ func TestRegisterUserHandler_InvalidEmail(t *testing.T) {
 func TestRegisterUserHandler_InvalidPassword(t *testing.T) {
 	repo := &mockUserRepo{}
 	hasher := &mockPasswordHasher{}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "open", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "open", false)
 
 	tests := []struct {
 		name     string
@@ -174,7 +175,7 @@ func TestRegisterUserHandler_EmailAlreadyExists(t *testing.T) {
 		},
 	}
 	hasher := &mockPasswordHasher{}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "open", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "open", false)
 
 	cmd := RegisterUserCommand{
 		Email:    "test@example.com",
@@ -195,7 +196,7 @@ func TestRegisterUserHandler_PasswordHashingError(t *testing.T) {
 			return "", expectedErr
 		},
 	}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "open", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "open", false)
 
 	cmd := RegisterUserCommand{
 		Email:    "test@example.com",
@@ -216,7 +217,7 @@ func TestRegisterUserHandler_RepositoryError(t *testing.T) {
 		},
 	}
 	hasher := &mockPasswordHasher{}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "open", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "open", false)
 
 	cmd := RegisterUserCommand{
 		Email:    "test@example.com",
@@ -232,7 +233,7 @@ func TestRegisterUserHandler_RepositoryError(t *testing.T) {
 func TestRegisterUserHandler_EdgeCases(t *testing.T) {
 	repo := &mockUserRepo{}
 	hasher := &mockPasswordHasher{}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "open", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "open", false)
 
 	tests := []struct {
 		name    string
@@ -285,7 +286,7 @@ func TestRegisterUserHandler_EdgeCases(t *testing.T) {
 func TestRegisterUserHandler_ClosedRegistration(t *testing.T) {
 	repo := &mockUserRepo{}
 	hasher := &mockPasswordHasher{}
-	handler := NewRegisterUserHandler(repo, hasher, nil, "", "closed", false)
+	handler := NewRegisterUserHandler(repo, hasher, &services.NoOpEmailService{}, "", "closed", false)
 
 	cmd := RegisterUserCommand{
 		Email:    "test@example.com",

internal/application/commands/request_password_reset_test.go

@@ -89,6 +89,10 @@ func (m *mockRequestResetEmailService) HealthCheck() error {
 	return nil
 }
 
+func (m *mockRequestResetEmailService) IsEnabled() bool {
+	return true
+}
+
 func TestRequestPasswordResetHandler_Success(t *testing.T) {
 	user := entities.NewUser("test@example.com", "hash")
 	user.ID = "user-123"

internal/application/commands/update_habit.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"apocapoc-api/internal/domain/repositories"
+	"apocapoc-api/internal/domain/value_objects"
 	"apocapoc-api/internal/shared/errors"
 )
 
@@ -13,10 +14,11 @@ type UpdateHabitCommand struct {
 	UserID        string
 	Name          string
 	Description   string
-	CarryOver     bool
+	Frequency     value_objects.Frequency
-	TargetValue   *float64
 	SpecificDays  []int
 	SpecificDates []int
+	CarryOver     bool
+	TargetValue   *float64
 }
 
 type UpdateHabitHandler struct {
@@ -34,6 +36,18 @@ func (h *UpdateHabitHandler) Handle(ctx context.Context, cmd UpdateHabitCommand)
 		return errors.ErrInvalidInput
 	}
 
+	if !cmd.Frequency.IsValid() {
+		return errors.ErrInvalidInput
+	}
+
+	if cmd.Frequency == value_objects.FrequencyWeekly && len(cmd.SpecificDays) == 0 {
+		return errors.ErrInvalidInput
+	}
+
+	if cmd.Frequency == value_objects.FrequencyMonthly && len(cmd.SpecificDates) == 0 {
+		return errors.ErrInvalidInput
+	}
+
 	habit, err := h.habitRepo.FindByID(ctx, cmd.HabitID)
 	if err != nil {
 		return err
@@ -49,10 +63,11 @@ func (h *UpdateHabitHandler) Handle(ctx context.Context, cmd UpdateHabitCommand)
 
 	habit.Name = cmd.Name
 	habit.Description = cmd.Description
-	habit.CarryOver = cmd.CarryOver
+	habit.Frequency = cmd.Frequency
-	habit.TargetValue = cmd.TargetValue
 	habit.SpecificDays = cmd.SpecificDays
 	habit.SpecificDates = cmd.SpecificDates
+	habit.CarryOver = cmd.CarryOver
+	habit.TargetValue = cmd.TargetValue
 
 	return h.habitRepo.Update(ctx, habit)
 }

internal/application/commands/update_habit_test.go

@@ -48,9 +48,10 @@ func TestUpdateHabitHandler_UpdatesSuccessfully(t *testing.T) {
 		UserID:       "user-123",
 		Name:         "Morning Exercise",
 		Description:  "Updated description",
+		Frequency:    value_objects.FrequencyWeekly,
+		SpecificDays: []int{1, 3, 5},
 		CarryOver:    true,
 		TargetValue:  &newTargetValue,
-		SpecificDays: []int{1, 3, 5},
 	}
 
 	err := handler.Handle(context.Background(), cmd)
@@ -67,6 +68,14 @@ func TestUpdateHabitHandler_UpdatesSuccessfully(t *testing.T) {
 		t.Errorf("Expected description to be updated, got %s", habitRepo.updatedHabit.Description)
 	}
 
+	if habitRepo.updatedHabit.Frequency != value_objects.FrequencyWeekly {
+		t.Errorf("Expected frequency WEEKLY, got %s", habitRepo.updatedHabit.Frequency)
+	}
+
+	if len(habitRepo.updatedHabit.SpecificDays) != 3 {
+		t.Errorf("Expected 3 specific days, got %d", len(habitRepo.updatedHabit.SpecificDays))
+	}
+
 	if !habitRepo.updatedHabit.CarryOver {
 		t.Error("Expected CarryOver to be true")
 	}
@@ -74,10 +83,6 @@ func TestUpdateHabitHandler_UpdatesSuccessfully(t *testing.T) {
 	if habitRepo.updatedHabit.TargetValue == nil || *habitRepo.updatedHabit.TargetValue != 5.0 {
 		t.Errorf("Expected target value 5.0, got %v", habitRepo.updatedHabit.TargetValue)
 	}
-
-	if len(habitRepo.updatedHabit.SpecificDays) != 3 {
-		t.Errorf("Expected 3 specific days, got %d", len(habitRepo.updatedHabit.SpecificDays))
-	}
 }
 
 func TestUpdateHabitHandler_ReturnsErrorWhenHabitNotFound(t *testing.T) {
@@ -91,6 +96,7 @@ func TestUpdateHabitHandler_ReturnsErrorWhenHabitNotFound(t *testing.T) {
 		HabitID:   "non-existent",
 		UserID:    "user-123",
 		Name:      "Exercise",
+		Frequency: value_objects.FrequencyDaily,
 	}
 
 	err := handler.Handle(context.Background(), cmd)
@@ -114,6 +120,7 @@ func TestUpdateHabitHandler_ReturnsErrorWhenUserDoesNotOwnHabit(t *testing.T) {
 		HabitID:   "habit-1",
 		UserID:    "user-456", // Different user
 		Name:      "Exercise",
+		Frequency: value_objects.FrequencyDaily,
 	}
 
 	err := handler.Handle(context.Background(), cmd)
@@ -138,6 +145,7 @@ func TestUpdateHabitHandler_CannotUpdateArchivedHabit(t *testing.T) {
 		HabitID:   "habit-1",
 		UserID:    "user-123",
 		Name:      "Updated Exercise",
+		Frequency: value_objects.FrequencyDaily,
 	}
 
 	err := handler.Handle(context.Background(), cmd)
@@ -161,6 +169,7 @@ func TestUpdateHabitHandler_ValidatesInput(t *testing.T) {
 		HabitID:   "habit-1",
 		UserID:    "user-123",
 		Name:      "", // Empty name
+		Frequency: value_objects.FrequencyDaily,
 	}
 
 	err := handler.Handle(context.Background(), cmd)
@@ -169,3 +178,57 @@ func TestUpdateHabitHandler_ValidatesInput(t *testing.T) {
 		t.Errorf("Expected ErrInvalidInput for empty name, got %v", err)
 	}
 }
+
+func TestUpdateHabitHandler_InvalidFrequency(t *testing.T) {
+	habitRepo := &mockHabitRepoForUpdate{}
+	handler := NewUpdateHabitHandler(habitRepo)
+
+	cmd := UpdateHabitCommand{
+		HabitID:   "habit-1",
+		UserID:    "user-123",
+		Name:      "Exercise",
+		Frequency: "INVALID",
+	}
+
+	err := handler.Handle(context.Background(), cmd)
+
+	if err != errors.ErrInvalidInput {
+		t.Errorf("Expected ErrInvalidInput for invalid frequency, got %v", err)
+	}
+}
+
+func TestUpdateHabitHandler_WeeklyRequiresSpecificDays(t *testing.T) {
+	habitRepo := &mockHabitRepoForUpdate{}
+	handler := NewUpdateHabitHandler(habitRepo)
+
+	cmd := UpdateHabitCommand{
+		HabitID:   "habit-1",
+		UserID:    "user-123",
+		Name:      "Exercise",
+		Frequency: value_objects.FrequencyWeekly,
+	}
+
+	err := handler.Handle(context.Background(), cmd)
+
+	if err != errors.ErrInvalidInput {
+		t.Errorf("Expected ErrInvalidInput for weekly without specific days, got %v", err)
+	}
+}
+
+func TestUpdateHabitHandler_MonthlyRequiresSpecificDates(t *testing.T) {
+	habitRepo := &mockHabitRepoForUpdate{}
+	handler := NewUpdateHabitHandler(habitRepo)
+
+	cmd := UpdateHabitCommand{
+		HabitID:   "habit-1",
+		UserID:    "user-123",
+		Name:      "Exercise",
+		Frequency: value_objects.FrequencyMonthly,
+	}
+
+	err := handler.Handle(context.Background(), cmd)
+
+	if err != errors.ErrInvalidInput {
+		t.Errorf("Expected ErrInvalidInput for monthly without specific dates, got %v", err)
+	}
+}

internal/application/commands/verify_email_test.go

@@ -69,6 +69,10 @@ func (m *mockEmailService) HealthCheck() error {
 	return nil
 }
 
+func (m *mockEmailService) IsEnabled() bool {
+	return true
+}
+
 func TestVerifyEmailHandler_Success(t *testing.T) {
 	token := "valid-token"
 	expiry := time.Now().Add(24 * time.Hour)

internal/domain/services/email_service.go

@@ -10,4 +10,11 @@ type EmailMessage struct {
 type EmailService interface {
 	Send(message EmailMessage) error
 	HealthCheck() error
+	IsEnabled() bool
 }
+
+type NoOpEmailService struct{}
+
+func (n *NoOpEmailService) Send(_ EmailMessage) error { return nil }
+func (n *NoOpEmailService) HealthCheck() error        { return nil }
+func (n *NoOpEmailService) IsEnabled() bool           { return false }

internal/domain/services/streak.go

@@ -49,7 +49,8 @@ func buildEntryMap(entries []*entities.HabitEntry) map[string]*entities.HabitEnt
 }
 
 func allScheduledDates(habit *entities.Habit, now time.Time) []time.Time {
-	start := time.Date(habit.CreatedAt.Year(), habit.CreatedAt.Month(), habit.CreatedAt.Day(), 0, 0, 0, 0, time.UTC)
+	createdUTC := habit.CreatedAt.UTC()
+	start := time.Date(createdUTC.Year(), createdUTC.Month(), createdUTC.Day(), 0, 0, 0, 0, time.UTC)
 	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC)
 	freq := string(habit.Frequency)
 

internal/infrastructure/email/smtp_service.go

@@ -107,6 +107,10 @@ func (s *SMTPService) GetConfig() SMTPConfig {
 	return s.config
 }
 
+func (s *SMTPService) IsEnabled() bool {
+	return true
+}
+
 func (s *SMTPService) HealthCheck() error {
 	dialer := mail.NewDialer(s.config.Host, s.config.Port, s.config.Username, s.config.Password)
 	dialer.TLSConfig = &tls.Config{

internal/infrastructure/http/dto.go

@@ -22,6 +22,7 @@ type CreateHabitRequest struct {
 type UpdateHabitRequest struct {
 	Name          string                  `json:"name"`
 	Description   string                  `json:"description"`
+	Frequency     value_objects.Frequency `json:"frequency"`
 	SpecificDays  []int                   `json:"specific_days,omitempty"`
 	SpecificDates []int                   `json:"specific_dates,omitempty"`
 	CarryOver     bool                    `json:"carry_over"`

internal/infrastructure/http/habit_handlers.go

@@ -2,6 +2,7 @@ package http
 
 import (
 	"encoding/json"
+	stderrors "errors"
 	"net/http"
 	"strconv"
 	"strings"
@@ -97,8 +98,8 @@ func (h *HabitHandlers) CreateHabit(w http.ResponseWriter, r *http.Request) {
 
 	habitID, err := h.createHandler.Handle(r.Context(), cmd)
 	if err != nil {
-		if err == errors.ErrInvalidInput {
+		if stderrors.Is(err, errors.ErrInvalidInput) {
-			respondError(w, http.StatusBadRequest, err.Error())
+			respondValidationErrorI18n(w, r, h.translator, err)
 			return
 		}
 		respondErrorI18n(w, r, h.translator, http.StatusInternalServerError, "failed_create_habit")
@@ -313,10 +314,11 @@ func (h *HabitHandlers) UpdateHabit(w http.ResponseWriter, r *http.Request) {
 		UserID:        userID,
 		Name:          req.Name,
 		Description:   req.Description,
-		CarryOver:     req.CarryOver,
+		Frequency:     req.Frequency,
-		TargetValue:   req.TargetValue,
 		SpecificDays:  req.SpecificDays,
 		SpecificDates: req.SpecificDates,
+		CarryOver:     req.CarryOver,
+		TargetValue:   req.TargetValue,
 	}
 
 	if err := h.updateHandler.Handle(r.Context(), cmd); err != nil {

internal/infrastructure/http/habit_integration_test.go

@@ -89,6 +89,7 @@ func TestHabitCRUDFlow(t *testing.T) {
 		reqBody := UpdateHabitRequest{
 			Name:        "Morning Exercise",
 			Description: "Updated description",
+			Frequency:   "DAILY",
 		}
 
 		rr := makeRequest(t, *ts.Router, "PUT", "/api/v1/habits/"+habitID, reqBody, token)
@@ -122,6 +123,47 @@ func TestHabitCRUDFlow(t *testing.T) {
 		}
 	})
 
+	t.Run("Create habit with missing type returns field-level error", func(t *testing.T) {
+		token := registerAndLogin(t, *ts.Router, "validationuser@example.com", "Password123!")
+
+		reqBody := map[string]any{"name": "No Type"}
+		rr := makeRequest(t, *ts.Router, "POST", "/api/v1/habits", reqBody, token)
+
+		if rr.Code != http.StatusBadRequest {
+			t.Fatalf("Expected 400, got %d. Body: %s", rr.Code, rr.Body.String())
+		}
+
+		var resp ValidationErrorResponse
+		decodeResponse(t, rr, &resp)
+		if resp.Field != "type" {
+			t.Errorf("Expected field 'type', got %q. Body: %s", resp.Field, rr.Body.String())
+		}
+		if resp.Error == "" {
+			t.Errorf("Expected non-empty translated error message. Body: %s", rr.Body.String())
+		}
+	})
+
+	t.Run("Create weekly habit without specific_days returns field-level error", func(t *testing.T) {
+		token := registerAndLogin(t, *ts.Router, "weeklyuser@example.com", "Password123!")
+
+		reqBody := CreateHabitRequest{
+			Name:      "Cut nails",
+			Type:      "BOOLEAN",
+			Frequency: "WEEKLY",
+		}
+		rr := makeRequest(t, *ts.Router, "POST", "/api/v1/habits", reqBody, token)
+
+		if rr.Code != http.StatusBadRequest {
+			t.Fatalf("Expected 400, got %d. Body: %s", rr.Code, rr.Body.String())
+		}
+
+		var resp ValidationErrorResponse
+		decodeResponse(t, rr, &resp)
+		if resp.Field != "specific_days" {
+			t.Errorf("Expected field 'specific_days', got %q. Body: %s", resp.Field, rr.Body.String())
+		}
+	})
+
 	t.Run("Access other user's habit", func(t *testing.T) {
 		otherToken := registerAndLogin(t, *ts.Router, "otheruser@example.com", "Password123!")
 

internal/infrastructure/http/integration_test.go

@@ -11,6 +11,7 @@ import (
 
 	"apocapoc-api/internal/application/commands"
 	"apocapoc-api/internal/application/queries"
+	"apocapoc-api/internal/domain/services"
 	"apocapoc-api/internal/i18n"
 	"apocapoc-api/internal/infrastructure/auth"
 	"apocapoc-api/internal/infrastructure/crypto"
@@ -43,14 +44,15 @@ func setupTestServer(t *testing.T) *TestServer {
 	refreshTokenRepo := sqlite.NewRefreshTokenRepository(db)
 	passwordResetTokenRepo := sqlite.NewPasswordResetTokenRepository(db)
 
-	registerHandler := commands.NewRegisterUserHandler(userRepo, passwordHasher, nil, "", "open", false)
+	noOpEmail := &services.NoOpEmailService{}
+	registerHandler := commands.NewRegisterUserHandler(userRepo, passwordHasher, noOpEmail, "", "open", false)
 	loginHandler := queries.NewLoginUserHandler(userRepo, passwordHasher)
 	refreshTokenHandler := queries.NewRefreshTokenHandler(refreshTokenRepo, userRepo)
 	revokeTokenHandler := commands.NewRevokeTokenHandler(refreshTokenRepo)
 	revokeAllTokensHandler := commands.NewRevokeAllTokensHandler(refreshTokenRepo)
-	verifyEmailHandler := commands.NewVerifyEmailHandler(userRepo, nil, false)
+	verifyEmailHandler := commands.NewVerifyEmailHandler(userRepo, noOpEmail, false)
-	resendVerificationEmailHandler := commands.NewResendVerificationEmailHandler(userRepo, nil, "")
+	resendVerificationEmailHandler := commands.NewResendVerificationEmailHandler(userRepo, noOpEmail, "")
-	requestPasswordResetHandler := commands.NewRequestPasswordResetHandler(userRepo, passwordResetTokenRepo, nil, "")
+	requestPasswordResetHandler := commands.NewRequestPasswordResetHandler(userRepo, passwordResetTokenRepo, noOpEmail, "")
 	resetPasswordHandler := commands.NewResetPasswordHandler(userRepo, passwordResetTokenRepo, passwordHasher)
 	createHandler := commands.NewCreateHabitHandler(habitRepo)
 	getTodaysHandler := queries.NewGetTodaysHabitsHandler(habitRepo, entryRepo)

internal/infrastructure/http/stats_handlers.go

@@ -27,7 +27,7 @@ func NewStatsHandlers(
 
 // GetHabitStats godoc
 // @Summary Get habit statistics
-// @Description Get statistics for a specific habit including streaks and completion rates
+// @Description Get statistics for a specific habit including streaks and completions
 // @Tags stats
 // @Produce json
 // @Security BearerAuth

internal/infrastructure/http/stats_integration_test.go

@@ -121,6 +121,7 @@ func TestHabitUpdateAffectsStats(t *testing.T) {
 	t.Run("Stats remain after updating habit name", func(t *testing.T) {
 		updateReq := UpdateHabitRequest{
 			Name:      "Morning Running",
+			Frequency: "DAILY",
 		}
 		rr := makeRequest(t, *ts.Router, "PUT", "/api/v1/habits/"+habitID, updateReq, token)
 		if rr.Code != http.StatusOK {