refactor: introduce internal/domain/ layer, rename model.go → entity.go

Move all business-logic packages from internal/ root into internal/domain/:
  auth, cuisine, diary, dish, home, ingredient, language, menu, product,
  recipe, recognition, recommendation, savedrecipe, tag, units, user

Rename model.go → entity.go in packages that hold domain entities:
  diary, dish, home, ingredient, menu, product, recipe, savedrecipe, user

Update all import paths accordingly (adapters, infra/server, cmd/server,
tests). No logic changes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/cmd/server/providers.go

@@ -4,26 +4,26 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/food-ai/backend/internal/auth"
+	"github.com/food-ai/backend/internal/domain/auth"
 	"github.com/food-ai/backend/internal/infra/config"
-	"github.com/food-ai/backend/internal/diary"
-	"github.com/food-ai/backend/internal/dish"
+	"github.com/food-ai/backend/internal/domain/diary"
+	"github.com/food-ai/backend/internal/domain/dish"
 	"github.com/food-ai/backend/internal/adapters/openai"
-	"github.com/food-ai/backend/internal/home"
-	"github.com/food-ai/backend/internal/ingredient"
-	"github.com/food-ai/backend/internal/menu"
+	"github.com/food-ai/backend/internal/domain/home"
+	"github.com/food-ai/backend/internal/domain/ingredient"
+	"github.com/food-ai/backend/internal/domain/menu"
 	"github.com/food-ai/backend/internal/infra/middleware"
 	"github.com/food-ai/backend/internal/adapters/pexels"
-	"github.com/food-ai/backend/internal/product"
-	"github.com/food-ai/backend/internal/recipe"
-	"github.com/food-ai/backend/internal/recognition"
-	"github.com/food-ai/backend/internal/recommendation"
-	"github.com/food-ai/backend/internal/savedrecipe"
-	"github.com/food-ai/backend/internal/cuisine"
+	"github.com/food-ai/backend/internal/domain/product"
+	"github.com/food-ai/backend/internal/domain/recipe"
+	"github.com/food-ai/backend/internal/domain/recognition"
+	"github.com/food-ai/backend/internal/domain/recommendation"
+	"github.com/food-ai/backend/internal/domain/savedrecipe"
+	"github.com/food-ai/backend/internal/domain/cuisine"
 	"github.com/food-ai/backend/internal/infra/server"
-	"github.com/food-ai/backend/internal/tag"
-	"github.com/food-ai/backend/internal/units"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/tag"
+	"github.com/food-ai/backend/internal/domain/units"
+	"github.com/food-ai/backend/internal/domain/user"
 	"github.com/jackc/pgx/v5/pgxpool"
 )
 

backend/cmd/server/wire.go

@@ -5,23 +5,23 @@ package main
 import (
 	"net/http"
 
-	"github.com/food-ai/backend/internal/auth"
+	"github.com/food-ai/backend/internal/domain/auth"
 	"github.com/food-ai/backend/internal/adapters/firebase"
 	"github.com/food-ai/backend/internal/infra/config"
-	"github.com/food-ai/backend/internal/diary"
-	"github.com/food-ai/backend/internal/dish"
-	"github.com/food-ai/backend/internal/home"
-	"github.com/food-ai/backend/internal/ingredient"
-	"github.com/food-ai/backend/internal/menu"
+	"github.com/food-ai/backend/internal/domain/diary"
+	"github.com/food-ai/backend/internal/domain/dish"
+	"github.com/food-ai/backend/internal/domain/home"
+	"github.com/food-ai/backend/internal/domain/ingredient"
+	"github.com/food-ai/backend/internal/domain/menu"
 	"github.com/food-ai/backend/internal/infra/middleware"
 	"github.com/food-ai/backend/internal/adapters/openai"
 	"github.com/food-ai/backend/internal/adapters/pexels"
-	"github.com/food-ai/backend/internal/product"
-	"github.com/food-ai/backend/internal/recipe"
-	"github.com/food-ai/backend/internal/recognition"
-	"github.com/food-ai/backend/internal/recommendation"
-	"github.com/food-ai/backend/internal/savedrecipe"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/product"
+	"github.com/food-ai/backend/internal/domain/recipe"
+	"github.com/food-ai/backend/internal/domain/recognition"
+	"github.com/food-ai/backend/internal/domain/recommendation"
+	"github.com/food-ai/backend/internal/domain/savedrecipe"
+	"github.com/food-ai/backend/internal/domain/user"
 	"github.com/google/wire"
 	"github.com/jackc/pgx/v5/pgxpool"
 )

backend/cmd/server/wire_gen.go

@@ -7,20 +7,20 @@
 package main
 
 import (
-	"github.com/food-ai/backend/internal/auth"
+	"github.com/food-ai/backend/internal/domain/auth"
 	"github.com/food-ai/backend/internal/adapters/firebase"
 	"github.com/food-ai/backend/internal/infra/config"
-	"github.com/food-ai/backend/internal/diary"
-	"github.com/food-ai/backend/internal/dish"
-	"github.com/food-ai/backend/internal/home"
-	"github.com/food-ai/backend/internal/ingredient"
-	"github.com/food-ai/backend/internal/menu"
-	"github.com/food-ai/backend/internal/product"
-	"github.com/food-ai/backend/internal/recipe"
-	"github.com/food-ai/backend/internal/recognition"
-	"github.com/food-ai/backend/internal/recommendation"
-	"github.com/food-ai/backend/internal/savedrecipe"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/diary"
+	"github.com/food-ai/backend/internal/domain/dish"
+	"github.com/food-ai/backend/internal/domain/home"
+	"github.com/food-ai/backend/internal/domain/ingredient"
+	"github.com/food-ai/backend/internal/domain/menu"
+	"github.com/food-ai/backend/internal/domain/product"
+	"github.com/food-ai/backend/internal/domain/recipe"
+	"github.com/food-ai/backend/internal/domain/recognition"
+	"github.com/food-ai/backend/internal/domain/recommendation"
+	"github.com/food-ai/backend/internal/domain/savedrecipe"
+	"github.com/food-ai/backend/internal/domain/user"
 	"github.com/jackc/pgx/v5/pgxpool"
 	"net/http"
 )

backend/internal/adapters/firebase/auth.go

@@ -11,7 +11,7 @@ import (
 	firebaseAuth "firebase.google.com/go/v4/auth"
 	"google.golang.org/api/option"
 
-	"github.com/food-ai/backend/internal/auth"
+	"github.com/food-ai/backend/internal/domain/auth"
 )
 
 // Auth is the Firebase-backed implementation of auth.TokenVerifier.

backend/internal/domain/auth/service.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"fmt"
 
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 )
 
 type Service struct {

backend/internal/domain/menu/handler.go

@@ -11,10 +11,10 @@ import (
 	"time"
 
 	"github.com/food-ai/backend/internal/adapters/ai"
-	"github.com/food-ai/backend/internal/dish"
+	"github.com/food-ai/backend/internal/domain/dish"
 	"github.com/food-ai/backend/internal/infra/locale"
 	"github.com/food-ai/backend/internal/infra/middleware"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 	"github.com/go-chi/chi/v5"
 )
 

backend/internal/domain/recognition/handler.go

@@ -10,7 +10,7 @@ import (
 
 	"github.com/food-ai/backend/internal/adapters/ai"
 	"github.com/food-ai/backend/internal/infra/middleware"
-	"github.com/food-ai/backend/internal/ingredient"
+	"github.com/food-ai/backend/internal/domain/ingredient"
 )
 
 // IngredientRepository is the subset of ingredient.Repository used by this handler.

backend/internal/domain/recommendation/handler.go

@@ -11,7 +11,7 @@ import (
 	"github.com/food-ai/backend/internal/adapters/ai"
 	"github.com/food-ai/backend/internal/infra/locale"
 	"github.com/food-ai/backend/internal/infra/middleware"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 )
 
 // PhotoSearcher can search for a photo by text query.

backend/internal/domain/savedrecipe/repository.go

@@ -6,7 +6,7 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/food-ai/backend/internal/dish"
+	"github.com/food-ai/backend/internal/domain/dish"
 	"github.com/food-ai/backend/internal/infra/locale"
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"

backend/internal/domain/user/mocks/repository.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"time"
 
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 )
 
 type MockUserRepository struct {

backend/internal/infra/server/server.go

@@ -4,20 +4,20 @@ import (
 	"encoding/json"
 	"net/http"
 
-	"github.com/food-ai/backend/internal/auth"
-	"github.com/food-ai/backend/internal/diary"
-	"github.com/food-ai/backend/internal/dish"
-	"github.com/food-ai/backend/internal/home"
-	"github.com/food-ai/backend/internal/ingredient"
-	"github.com/food-ai/backend/internal/language"
-	"github.com/food-ai/backend/internal/menu"
+	"github.com/food-ai/backend/internal/domain/auth"
+	"github.com/food-ai/backend/internal/domain/diary"
+	"github.com/food-ai/backend/internal/domain/dish"
+	"github.com/food-ai/backend/internal/domain/home"
+	"github.com/food-ai/backend/internal/domain/ingredient"
+	"github.com/food-ai/backend/internal/domain/language"
+	"github.com/food-ai/backend/internal/domain/menu"
 	"github.com/food-ai/backend/internal/infra/middleware"
-	"github.com/food-ai/backend/internal/recipe"
-	"github.com/food-ai/backend/internal/product"
-	"github.com/food-ai/backend/internal/recognition"
-	"github.com/food-ai/backend/internal/recommendation"
-	"github.com/food-ai/backend/internal/savedrecipe"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/recipe"
+	"github.com/food-ai/backend/internal/domain/product"
+	"github.com/food-ai/backend/internal/domain/recognition"
+	"github.com/food-ai/backend/internal/domain/recommendation"
+	"github.com/food-ai/backend/internal/domain/savedrecipe"
+	"github.com/food-ai/backend/internal/domain/user"
 	"github.com/go-chi/chi/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 )

backend/tests/auth/handler_integration_test.go

@@ -11,11 +11,11 @@ import (
 	"testing"
 	"time"
 
-	"github.com/food-ai/backend/internal/auth"
-	"github.com/food-ai/backend/internal/auth/mocks"
+	"github.com/food-ai/backend/internal/domain/auth"
+	"github.com/food-ai/backend/internal/domain/auth/mocks"
 	"github.com/food-ai/backend/internal/infra/middleware"
 	"github.com/food-ai/backend/internal/testutil"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 	"github.com/go-chi/chi/v5"
 )
 

backend/tests/auth/jwt_test.go

@@ -4,7 +4,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/food-ai/backend/internal/auth"
+	"github.com/food-ai/backend/internal/domain/auth"
 )
 
 func TestGenerateAccessToken(t *testing.T) {

backend/tests/auth/service_test.go

@@ -6,10 +6,10 @@ import (
 	"testing"
 	"time"
 
-	"github.com/food-ai/backend/internal/auth"
-	"github.com/food-ai/backend/internal/auth/mocks"
-	"github.com/food-ai/backend/internal/user"
-	umocks "github.com/food-ai/backend/internal/user/mocks"
+	"github.com/food-ai/backend/internal/domain/auth"
+	"github.com/food-ai/backend/internal/domain/auth/mocks"
+	"github.com/food-ai/backend/internal/domain/user"
+	umocks "github.com/food-ai/backend/internal/domain/user/mocks"
 )
 
 func newTestService(verifier *mocks.MockTokenVerifier, repo *umocks.MockUserRepository) *auth.Service {

backend/tests/ingredient/repository_integration_test.go

@@ -6,7 +6,7 @@ import (
 	"context"
 	"testing"
 
-	"github.com/food-ai/backend/internal/ingredient"
+	"github.com/food-ai/backend/internal/domain/ingredient"
 	"github.com/food-ai/backend/internal/infra/locale"
 	"github.com/food-ai/backend/internal/testutil"
 )

backend/tests/recipe/repository_integration_test.go

@@ -6,7 +6,7 @@ import (
 	"context"
 	"testing"
 
-	"github.com/food-ai/backend/internal/recipe"
+	"github.com/food-ai/backend/internal/domain/recipe"
 	"github.com/food-ai/backend/internal/testutil"
 )
 

backend/tests/user/calories_test.go

@@ -4,7 +4,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 )
 
 func ptr[T any](v T) *T { return &v }

backend/tests/user/repository_integration_test.go

@@ -9,7 +9,7 @@ import (
 	"time"
 
 	"github.com/food-ai/backend/internal/testutil"
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 )
 
 func TestRepository_UpsertByFirebaseUID_Insert(t *testing.T) {

backend/tests/user/service_test.go

@@ -7,7 +7,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/food-ai/backend/internal/user"
+	"github.com/food-ai/backend/internal/domain/user"
 )
 
 func ptrStr(s string) *string     { return &s }