feat: dynamic units table with localized names via GET /units

- Add units + unit_translations tables with FK constraints on products and ingredient_mappings
- Normalize products.unit from Russian strings (г, кг) to English codes (g, kg)
- Load units at startup (in-memory registry) and serve via GET /units (language-aware)
- Replace hardcoded _units lists and _mapUnit() functions in Flutter with unitsProvider FutureProvider
- Re-fetches automatically when language changes

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

backend/cmd/server/main.go

@@ -20,6 +20,7 @@ import (
 	"github.com/food-ai/backend/internal/locale"
 	"github.com/food-ai/backend/internal/menu"
 	"github.com/food-ai/backend/internal/middleware"
+	"github.com/food-ai/backend/internal/units"
 	"github.com/food-ai/backend/internal/pexels"
 	"github.com/food-ai/backend/internal/product"
 	"github.com/food-ai/backend/internal/recognition"
@@ -78,6 +79,11 @@ func run() error {
 	}
 	slog.Info("languages loaded", "count", len(locale.Languages))
 
+	if err := units.LoadFromDB(ctx, pool); err != nil {
+		return fmt.Errorf("load units: %w", err)
+	}
+	slog.Info("units loaded", "count", len(units.Records))
+
 	// Firebase auth
 	firebaseAuth, err := auth.NewFirebaseAuthOrNoop(cfg.FirebaseCredentialsFile)
 	if err != nil {

backend/internal/server/server.go

@@ -11,6 +11,7 @@ import (
 	"github.com/food-ai/backend/internal/language"
 	"github.com/food-ai/backend/internal/menu"
 	"github.com/food-ai/backend/internal/middleware"
+	"github.com/food-ai/backend/internal/units"
 	"github.com/food-ai/backend/internal/product"
 	"github.com/food-ai/backend/internal/recognition"
 	"github.com/food-ai/backend/internal/recommendation"
@@ -47,6 +48,7 @@ func NewRouter(
 	// Public
 	r.Get("/health", healthCheck(pool))
 	r.Get("/languages", language.List)
+	r.Get("/units", units.List)
 	r.Route("/auth", func(r chi.Router) {
 		r.Post("/login", authHandler.Login)
 		r.Post("/refresh", authHandler.Refresh)

backend/internal/units/handler.go

@@ -0,0 +1,28 @@
+package units
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/food-ai/backend/internal/locale"
+)
+
+type unitItem struct {
+	Code string `json:"code"`
+	Name string `json:"name"`
+}
+
+// List handles GET /units — returns units with names in the requested language.
+func List(w http.ResponseWriter, r *http.Request) {
+	lang := locale.FromContext(r.Context())
+	items := make([]unitItem, 0, len(Records))
+	for _, u := range Records {
+		name, ok := u.Translations[lang]
+		if !ok {
+			name = u.Code // fallback to English code
+		}
+		items = append(items, unitItem{Code: u.Code, Name: name})
+	}
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]any{"units": items})
+}

backend/internal/units/registry.go

@@ -0,0 +1,73 @@
+package units
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// Record is a unit loaded from DB with all its translations.
+type Record struct {
+	Code         string
+	SortOrder    int
+	Translations map[string]string // lang → localized name
+}
+
+// Records is the ordered list of active units, populated by LoadFromDB at startup.
+var Records []Record
+
+// LoadFromDB queries units + unit_translations and populates Records.
+func LoadFromDB(ctx context.Context, pool *pgxpool.Pool) error {
+	rows, err := pool.Query(ctx, `
+		SELECT u.code, u.sort_order, ut.lang, ut.name
+		FROM units u
+		LEFT JOIN unit_translations ut ON ut.unit_code = u.code
+		ORDER BY u.sort_order, ut.lang`)
+	if err != nil {
+		return fmt.Errorf("load units from db: %w", err)
+	}
+	defer rows.Close()
+
+	byCode := map[string]*Record{}
+	var order []string
+	for rows.Next() {
+		var code string
+		var sortOrder int
+		var lang, name *string
+		if err := rows.Scan(&code, &sortOrder, &lang, &name); err != nil {
+			return err
+		}
+		if _, ok := byCode[code]; !ok {
+			byCode[code] = &Record{Code: code, SortOrder: sortOrder, Translations: map[string]string{}}
+			order = append(order, code)
+		}
+		if lang != nil && name != nil {
+			byCode[code].Translations[*lang] = *name
+		}
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+
+	result := make([]Record, 0, len(order))
+	for _, code := range order {
+		result = append(result, *byCode[code])
+	}
+	Records = result
+	return nil
+}
+
+// NameFor returns the localized name for a unit code.
+// Falls back to the code itself when no translation exists.
+func NameFor(code, lang string) string {
+	for _, u := range Records {
+		if u.Code == code {
+			if name, ok := u.Translations[lang]; ok {
+				return name
+			}
+			return u.Code
+		}
+	}
+	return code
+}

backend/migrations/014_create_units.sql

@@ -0,0 +1,58 @@
+-- +goose Up
+
+CREATE TABLE units (
+    code       VARCHAR(20) PRIMARY KEY,
+    sort_order SMALLINT    NOT NULL DEFAULT 0
+);
+INSERT INTO units (code, sort_order) VALUES
+    ('g',    1),
+    ('kg',   2),
+    ('ml',   3),
+    ('l',    4),
+    ('pcs',  5),
+    ('pack', 6);
+
+CREATE TABLE unit_translations (
+    unit_code  VARCHAR(20) NOT NULL REFERENCES units(code) ON DELETE CASCADE,
+    lang       VARCHAR(10) NOT NULL,
+    name       TEXT        NOT NULL,
+    PRIMARY KEY (unit_code, lang)
+);
+INSERT INTO unit_translations (unit_code, lang, name) VALUES
+    ('g',    'ru', 'г'),
+    ('kg',   'ru', 'кг'),
+    ('ml',   'ru', 'мл'),
+    ('l',    'ru', 'л'),
+    ('pcs',  'ru', 'шт'),
+    ('pack', 'ru', 'уп');
+
+-- Normalize products.unit from Russian display strings to English codes
+UPDATE products SET unit = 'g'    WHERE unit = 'г';
+UPDATE products SET unit = 'kg'   WHERE unit = 'кг';
+UPDATE products SET unit = 'ml'   WHERE unit = 'мл';
+UPDATE products SET unit = 'l'    WHERE unit = 'л';
+UPDATE products SET unit = 'pcs'  WHERE unit = 'шт';
+UPDATE products SET unit = 'pack' WHERE unit = 'уп';
+-- Normalize any remaining unknown values
+UPDATE products SET unit = 'pcs' WHERE unit NOT IN (SELECT code FROM units);
+
+-- Nullify unknown default_unit values in ingredient_mappings before adding FK
+UPDATE ingredient_mappings
+    SET default_unit = NULL
+    WHERE default_unit IS NOT NULL
+      AND default_unit NOT IN (SELECT code FROM units);
+
+-- Foreign key constraints
+ALTER TABLE products
+    ADD CONSTRAINT fk_product_unit
+    FOREIGN KEY (unit) REFERENCES units(code);
+
+ALTER TABLE ingredient_mappings
+    ADD CONSTRAINT fk_default_unit
+    FOREIGN KEY (default_unit) REFERENCES units(code);
+
+-- +goose Down
+ALTER TABLE ingredient_mappings DROP CONSTRAINT IF EXISTS fk_default_unit;
+ALTER TABLE products             DROP CONSTRAINT IF EXISTS fk_product_unit;
+DROP TABLE IF EXISTS unit_translations;
+DROP TABLE IF EXISTS units;

client/lib/core/api/language_repository.dart

@@ -8,8 +8,8 @@ class LanguageRepository {
   LanguageRepository(this._api);
 
   Future<Map<String, String>> fetchLanguages() async {
-    final response = await _api.dio.get('/languages');
+    final data = await _api.get('/languages');
-    final List<dynamic> items = response.data['languages'] as List;
+    final List<dynamic> items = data['languages'] as List;
     return {
       for (final item in items)
         item['code'] as String: item['native_name'] as String,

client/lib/core/api/unit_repository.dart

@@ -0,0 +1,22 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../auth/auth_provider.dart';
+import 'api_client.dart';
+
+class UnitRepository {
+  final ApiClient _api;
+  UnitRepository(this._api);
+
+  Future<Map<String, String>> fetchUnits() async {
+    final data = await _api.get('/units');
+    final List<dynamic> items = data['units'] as List;
+    return {
+      for (final item in items)
+        item['code'] as String: item['name'] as String,
+    };
+  }
+}
+
+final unitRepositoryProvider = Provider<UnitRepository>(
+  (ref) => UnitRepository(ref.watch(apiClientProvider)),
+);

client/lib/core/locale/unit_provider.dart

@@ -0,0 +1,12 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../api/unit_repository.dart';
+import 'language_provider.dart';
+
+/// Fetches and caches units with localized names.
+/// Returns map of code → localized name (e.g. {'g': 'г', 'kg': 'кг'}).
+/// Re-fetches automatically when languageProvider changes.
+final unitsProvider = FutureProvider<Map<String, String>>((ref) {
+  ref.watch(languageProvider); // invalidate when language changes
+  return ref.read(unitRepositoryProvider).fetchUnits();
+});

client/lib/features/menu/shopping_list_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../core/locale/unit_provider.dart';
 import '../../shared/models/shopping_item.dart';
 import 'menu_provider.dart';
 
@@ -191,14 +192,14 @@ class _ShoppingTile extends ConsumerWidget {
       ),
       subtitle: item.inStock > 0
           ? Text(
-              '${item.inStock.toStringAsFixed(0)} ${item.unit} есть дома',
+              '${item.inStock.toStringAsFixed(0)} ${ref.watch(unitsProvider).valueOrNull?[item.unit] ?? item.unit} есть дома',
               style: theme.textTheme.bodySmall?.copyWith(
                 color: Colors.green,
               ),
             )
           : null,
       trailing: Text(
-        '$amountStr ${item.unit}',
+        '$amountStr ${ref.watch(unitsProvider).valueOrNull?[item.unit] ?? item.unit}',
         style: theme.textTheme.bodyMedium?.copyWith(
           fontWeight: FontWeight.w600,
         ),

client/lib/features/products/add_product_screen.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../core/locale/unit_provider.dart';
 import '../../shared/models/ingredient_mapping.dart';
 import 'product_provider.dart';
 
@@ -18,7 +19,7 @@ class _AddProductScreenState extends ConsumerState<AddProductScreen> {
   final _qtyController = TextEditingController(text: '1');
   final _daysController = TextEditingController(text: '7');
 
-  String _unit = 'шт';
+  String _unit = 'pcs';
   String? _category;
   String? _mappingId;
   bool _saving = false;
@@ -28,8 +29,6 @@ class _AddProductScreenState extends ConsumerState<AddProductScreen> {
   bool _searching = false;
   Timer? _debounce;
 
-  static const _units = ['г', 'кг', 'мл', 'л', 'шт'];
-
   @override
   void dispose() {
     _nameController.dispose();
@@ -69,8 +68,7 @@ class _AddProductScreenState extends ConsumerState<AddProductScreen> {
       _mappingId = mapping.id;
       _category = mapping.category;
       if (mapping.defaultUnit != null) {
-        // Map backend unit codes to display units
+        _unit = mapping.defaultUnit!;
-        _unit = _mapUnit(mapping.defaultUnit!);
       }
       if (mapping.storageDays != null) {
         _daysController.text = mapping.storageDays.toString();
@@ -79,21 +77,6 @@ class _AddProductScreenState extends ConsumerState<AddProductScreen> {
     });
   }
 
-  String _mapUnit(String backendUnit) {
-    switch (backendUnit.toLowerCase()) {
-      case 'g':
-        return 'г';
-      case 'kg':
-        return 'кг';
-      case 'ml':
-        return 'мл';
-      case 'l':
-        return 'л';
-      default:
-        return 'шт';
-    }
-  }
-
   Future<void> _submit() async {
     final name = _nameController.text.trim();
     if (name.isEmpty) {
@@ -170,7 +153,8 @@ class _AddProductScreenState extends ConsumerState<AddProductScreen> {
                                 ? Text(_categoryLabel(m.category!))
                                 : null,
                             trailing: m.defaultUnit != null
-                                ? Text(m.defaultUnit!,
+                                ? Text(
+                                    ref.watch(unitsProvider).valueOrNull?[m.defaultUnit!] ?? m.defaultUnit!,
                                     style:
                                         Theme.of(context).textTheme.bodySmall)
                                 : null,
@@ -197,15 +181,18 @@ class _AddProductScreenState extends ConsumerState<AddProductScreen> {
                   ),
                 ),
                 const SizedBox(width: 12),
-                DropdownButtonHideUnderline(
+                ref.watch(unitsProvider).when(
-                  child: DropdownButton<String>(
+                  data: (units) => DropdownButtonHideUnderline(
-                    value: _units.contains(_unit) ? _unit : _units.last,
+                    child: DropdownButton<String>(
-                    items: _units
+                      value: units.containsKey(_unit) ? _unit : units.keys.first,
-                        .map((u) =>
+                      items: units.entries
-                            DropdownMenuItem(value: u, child: Text(u)))
+                          .map((e) => DropdownMenuItem(value: e.key, child: Text(e.value)))
-                        .toList(),
+                          .toList(),
-                    onChanged: (v) => setState(() => _unit = v!),
+                      onChanged: (v) => setState(() => _unit = v!),
+                    ),
                   ),
+                  loading: () => const SizedBox(width: 60, child: LinearProgressIndicator()),
+                  error: (_, __) => const Text('?'),
                 ),
               ],
             ),

client/lib/features/products/products_screen.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
+import '../../core/locale/unit_provider.dart';
 import '../../shared/models/product.dart';
 import 'product_provider.dart';
 
@@ -205,7 +206,7 @@ class _ProductTile extends ConsumerWidget {
         ),
         title: Text(product.name),
         subtitle: Text(
-          '${_formatQty(product.quantity)} ${product.unit}',
+          '${_formatQty(product.quantity)} ${ref.watch(unitsProvider).valueOrNull?[product.unit] ?? product.unit}',
           style: theme.textTheme.bodySmall,
         ),
         trailing: Column(
@@ -303,8 +304,6 @@ class _EditProductSheetState extends ConsumerState<_EditProductSheet> {
       TextEditingController(text: widget.product.storageDays.toString());
   bool _saving = false;
 
-  static const _units = ['г', 'кг', 'мл', 'л', 'шт'];
-
   @override
   void dispose() {
     _qtyController.dispose();
@@ -340,12 +339,16 @@ class _EditProductSheetState extends ConsumerState<_EditProductSheet> {
                 ),
               ),
               const SizedBox(width: 12),
-              DropdownButton<String>(
+              ref.watch(unitsProvider).when(
-                value: _units.contains(_unit) ? _unit : _units.first,
+                data: (units) => DropdownButton<String>(
-                items: _units
+                  value: units.containsKey(_unit) ? _unit : units.keys.first,
-                    .map((u) => DropdownMenuItem(value: u, child: Text(u)))
+                  items: units.entries
-                    .toList(),
+                      .map((e) => DropdownMenuItem(value: e.key, child: Text(e.value)))
-                onChanged: (v) => setState(() => _unit = v!),
+                      .toList(),
+                  onChanged: (v) => setState(() => _unit = v!),
+                ),
+                loading: () => const SizedBox(width: 60, child: LinearProgressIndicator()),
+                error: (_, __) => const Text('?'),
               ),
             ],
           ),

client/lib/features/recipes/recipe_detail_screen.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../core/locale/unit_provider.dart';
 import '../../core/theme/app_colors.dart';
 import '../../shared/models/recipe.dart';
 import '../../shared/models/saved_recipe.dart';
@@ -370,13 +371,13 @@ class _TagsRow extends StatelessWidget {
   }
 }
 
-class _IngredientsSection extends StatelessWidget {
+class _IngredientsSection extends ConsumerWidget {
   final List<RecipeIngredient> ingredients;
 
   const _IngredientsSection({required this.ingredients});
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
     if (ingredients.isEmpty) return const SizedBox.shrink();
 
     return Padding(
@@ -401,7 +402,7 @@ class _IngredientsSection extends StatelessWidget {
                   const SizedBox(width: 10),
                   Expanded(child: Text(ing.name)),
                   Text(
-                    '${_formatAmount(ing.amount)} ${ing.unit}',
+                    '${_formatAmount(ing.amount)} ${ref.watch(unitsProvider).valueOrNull?[ing.unit] ?? ing.unit}',
                     style: const TextStyle(
                         color: AppColors.textSecondary, fontSize: 13),
                   ),

client/lib/features/scan/recognition_confirm_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../core/locale/unit_provider.dart';
 import '../products/product_provider.dart';
 import 'recognition_service.dart';
 
@@ -21,8 +22,6 @@ class _RecognitionConfirmScreenState
   late final List<_EditableItem> _items;
   bool _saving = false;
 
-  static const _units = ['г', 'кг', 'мл', 'л', 'шт', 'уп'];
-
   @override
   void initState() {
     super.initState();
@@ -30,7 +29,7 @@ class _RecognitionConfirmScreenState
         .map((item) => _EditableItem(
               name: item.name,
               quantity: item.quantity,
-              unit: _mapUnit(item.unit),
+              unit: item.unit,
               category: item.category,
               mappingId: item.mappingId,
               storageDays: item.storageDays,
@@ -39,27 +38,6 @@ class _RecognitionConfirmScreenState
         .toList();
   }
 
-  String _mapUnit(String unit) {
-    // Backend may return 'pcs', 'g', 'kg', etc. — normalise to display units.
-    switch (unit.toLowerCase()) {
-      case 'g':
-        return 'г';
-      case 'kg':
-        return 'кг';
-      case 'ml':
-        return 'мл';
-      case 'l':
-        return 'л';
-      case 'pcs':
-      case 'шт':
-        return 'шт';
-      case 'уп':
-        return 'уп';
-      default:
-        return unit;
-    }
-  }
-
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -80,7 +58,7 @@ class _RecognitionConfirmScreenState
               itemCount: _items.length,
               itemBuilder: (_, i) => _ItemTile(
                 item: _items[i],
-                units: _units,
+                units: ref.watch(unitsProvider).valueOrNull ?? {},
                 onDelete: () => setState(() => _items.removeAt(i)),
                 onChanged: () => setState(() {}),
               ),
@@ -173,7 +151,7 @@ class _ItemTile extends StatefulWidget {
   });
 
   final _EditableItem item;
-  final List<String> units;
+  final Map<String, String> units;
   final VoidCallback onDelete;
   final VoidCallback onChanged;
 
@@ -268,21 +246,23 @@ class _ItemTileState extends State<_ItemTile> {
               ),
             ),
             const SizedBox(width: 8),
-            DropdownButton<String>(
+            widget.units.isEmpty
-              value: widget.units.contains(widget.item.unit)
+                ? const SizedBox(width: 48)
-                  ? widget.item.unit
+                : DropdownButton<String>(
-                  : widget.units.last,
+                    value: widget.units.containsKey(widget.item.unit)
-              underline: const SizedBox(),
+                        ? widget.item.unit
-              items: widget.units
+                        : widget.units.keys.first,
-                  .map((u) => DropdownMenuItem(value: u, child: Text(u)))
+                    underline: const SizedBox(),
-                  .toList(),
+                    items: widget.units.entries
-              onChanged: (v) {
+                        .map((e) => DropdownMenuItem(value: e.key, child: Text(e.value)))
-                if (v != null) {
+                        .toList(),
-                  setState(() => widget.item.unit = v);
+                    onChanged: (v) {
-                  widget.onChanged();
+                      if (v != null) {
-                }
+                        setState(() => widget.item.unit = v);
-              },
+                        widget.onChanged();
-            ),
+                      }
+                    },
+                  ),
             IconButton(
               icon: const Icon(Icons.close),
               onPressed: widget.onDelete,