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

@@ -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

@@ -95,7 +95,7 @@ func main() {
 	jwtService := auth.NewJWTService(cfg.JWTSecret, jwtExpiryHours)
 	passwordHasher := crypto.NewBcryptHasher()
 
-	var emailService services.EmailService
+	var emailService services.EmailService = &services.NoOpEmailService{}
 	if cfg.SMTPHost != "" {
 		smtpPort, err := strconv.Atoi(cfg.SMTPPort)
 		if err != nil {

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 {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+	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())
+	}
+}
+
+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 {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
+		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 {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
+		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 {
-		t.Errorf("Expected ErrInvalidInput, got %v", err)
+	if !stderrors.Is(err, errors.ErrInvalidInput) {
+		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/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/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 {
-			respondError(w, http.StatusBadRequest, err.Error())
+		if stderrors.Is(err, errors.ErrInvalidInput) {
+			respondValidationErrorI18n(w, r, h.translator, err)
 			return
 		}
 		respondErrorI18n(w, r, h.translator, http.StatusInternalServerError, "failed_create_habit")

internal/infrastructure/http/habit_integration_test.go

@@ -123,6 +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)
-	resendVerificationEmailHandler := commands.NewResendVerificationEmailHandler(userRepo, nil, "")
-	requestPasswordResetHandler := commands.NewRequestPasswordResetHandler(userRepo, passwordResetTokenRepo, nil, "")
+	verifyEmailHandler := commands.NewVerifyEmailHandler(userRepo, noOpEmail, false)
+	resendVerificationEmailHandler := commands.NewResendVerificationEmailHandler(userRepo, noOpEmail, "")
+	requestPasswordResetHandler := commands.NewRequestPasswordResetHandler(userRepo, passwordResetTokenRepo, noOpEmail, "")
 	resetPasswordHandler := commands.NewResetPasswordHandler(userRepo, passwordResetTokenRepo, passwordHasher)
 	createHandler := commands.NewCreateHabitHandler(habitRepo)
 	getTodaysHandler := queries.NewGetTodaysHabitsHandler(habitRepo, entryRepo)